CA1080198A - Pyrolyzed beads of a resinous polymer - Google Patents
Pyrolyzed beads of a resinous polymerInfo
- Publication number
- CA1080198A CA1080198A CA245,934A CA245934A CA1080198A CA 1080198 A CA1080198 A CA 1080198A CA 245934 A CA245934 A CA 245934A CA 1080198 A CA1080198 A CA 1080198A
- Authority
- CA
- Canada
- Prior art keywords
- particles
- carbon
- ang
- macroporous
- synthetic polymer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
- C08F8/50—Partial depolymerisation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2810/00—Chemical modification of a polymer
- C08F2810/20—Chemical modification of a polymer leading to a crosslinking, either explicitly or inherently
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S521/00—Synthetic resins or natural rubbers -- part of the class 520 series
- Y10S521/918—Physical aftertreatment of a cellular product
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S521/00—Synthetic resins or natural rubbers -- part of the class 520 series
- Y10S521/921—Preparing a nonpolyurethane cellular particle from a nonparticulate material
Abstract
ABSTRACT OF THE DISCLOSURE
The invention provides partially pyrolyzed particles of a macroporous synthetic polymer having properties suitable for use in adsorption, molecular screening and/or catalysis and a resistance to crushing and particle sloughage greater than that of known spherical adsorbent particles or that of granular activated carbon, comprising the product of controlled thermal degradation of a macroporous synthetic polymer containing a carbon-fixing moiety and derived from one or more ethylenically unsaturated monomers, or from monomers which may be condensed to yield macroporous polymers, or mixtures thereof, which partically pyrolyzed particles have: (a) at least 85% by weight of carbon, (b) multimodal pore distribution with macropores ranging in size from about 50 .ANG. to about 100,000 .ANG.
in average critical dimension and with macropores ranging in size from about 4 .ANG. to about 50 .ANG. in average critical dimension, and (c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1. A process for producing the aforesaid partically pyrolyzed particles is also described.
This process comprises thermally degrading at a temperature between about 300°C and about 900°C, preferably between about 400°C and 800°C, and in an inert gaseous atmosphere optionally containing an activating gas, a macroporous synthetic polymer containing a carbon-fixing moiety and derived from one or more ethylenically unsaturated monomers or monomers which may be condensed to yield macroporous polymers, or mixtures thereof, for a time sufficient to drive off sufficient volatile components of the synthetic polymer to yield particles having the characteristics described above; and thereafter cooling said particles under said inert atmosphere to a temp-erature below that which would cause oxidation in air. The pyrolyzed particles so produced are particularly useful as adsorbents in both gaseous and liquid media to remove impurities therefrom.
The invention provides partially pyrolyzed particles of a macroporous synthetic polymer having properties suitable for use in adsorption, molecular screening and/or catalysis and a resistance to crushing and particle sloughage greater than that of known spherical adsorbent particles or that of granular activated carbon, comprising the product of controlled thermal degradation of a macroporous synthetic polymer containing a carbon-fixing moiety and derived from one or more ethylenically unsaturated monomers, or from monomers which may be condensed to yield macroporous polymers, or mixtures thereof, which partically pyrolyzed particles have: (a) at least 85% by weight of carbon, (b) multimodal pore distribution with macropores ranging in size from about 50 .ANG. to about 100,000 .ANG.
in average critical dimension and with macropores ranging in size from about 4 .ANG. to about 50 .ANG. in average critical dimension, and (c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1. A process for producing the aforesaid partically pyrolyzed particles is also described.
This process comprises thermally degrading at a temperature between about 300°C and about 900°C, preferably between about 400°C and 800°C, and in an inert gaseous atmosphere optionally containing an activating gas, a macroporous synthetic polymer containing a carbon-fixing moiety and derived from one or more ethylenically unsaturated monomers or monomers which may be condensed to yield macroporous polymers, or mixtures thereof, for a time sufficient to drive off sufficient volatile components of the synthetic polymer to yield particles having the characteristics described above; and thereafter cooling said particles under said inert atmosphere to a temp-erature below that which would cause oxidation in air. The pyrolyzed particles so produced are particularly useful as adsorbents in both gaseous and liquid media to remove impurities therefrom.
Description
108019~
Disclosure This invention concerns partially pyrolyzed particles of resinous polymers, methods of their pyrolysis, applications for removing impurities such as sulfur compounds, monomers, and other industrial contaminants or pollytants from gases and purifying pollutant-containing liquid streams ;
such as phenolics from waste streams and barbiturates from blood. Particularly the invention concerns partially pyrolyzed macroreticular materials as adsorbents for vinyl chloride removal, blood purification, phenolic recovery and, when metals are incorporated, particularly as catalytic agents for industri-al and laboratory processes.
The most commonly used adsorbent today is activated carbon. The production of activated carbon for industrial purposes employs a wide variety of carbonaceous starting materials such as anthracite and bituminous coal, coke, carbonized shells, peat, etc. Suitability of such materials depends on a low ash content and availability in a uniform and unchanging quality.
Methods of activation can be considered in two categories. The first category includes "chemical activation" processes, in which the carbonaceous materials or sometimes the chars are impregnated with one or more activating agents such as zinc chloride, alkali carbonates, sulphates, bisulphates, sulfuric or phosphoric acid and then pyrolyzed (carbonized). The action of these materials a ~080198 .
appears to be one of dehydration with high yields of carbon unaccompanied by tarry materials. The second category includes ,' processes known as "heat treatment" in which chars are heated to temperatures between 350 and 1,000C in the presence of CO2, N2' 2~ HCl, C12, H2O and other gases. A portion of the char is burned as the surface area and "activityl' of the carbon increases. Via careful control of activation parameters, manu-facturers are today able to produce high surface area products (800-2,000 M2/g) in a wide range of uniform particle sizes.
Production of activated carbon by the above processes gives materials with the highest available carbon capacities for a wide variety of adsorbates in both the liquid ~;
and gas phases. However, these materials possess the following disadvantages:
a) difficult and expensive thermal regeneration b) high regeneration losses of 10%/cycle c) friability of active carbon particles d) lack of control of starting materials Adsorbents produced according to the invention via pyrolysis of synthetic organic polymers are preferably spheres which possess a great deal of structural integrity. They do not easily break apart or slough dust particles as is the case for active carbon. Because of this lack of friability, the re-generative losses are frequently lower than is common for active carbon.
Pyrolysis of synthetic organic polymers further allows a much greater degree of control of the starting ' ~08~198 materials and hence of the final product than is possible with naturally occurring raw materials used for production of activated carbons.
Incorporation of desirable elements and functional groups to enhance adsorbency for specific adsorbates is easily achieved. Control of the average pore size and pore size distribution is much more easily achieved with well defined synthetic starting materials. This increased control allows the production of adsorbents designed for specific adsorbates with adsorbent capacities far greater than is possible with activated carbons.
The present invention provides partially pyrolyzed particles, preferably in the form of beads or spheres, produced by the controlled decomposition of a synthetic `~polymer of specific initial porosity. In a preferred embodi-ment, the pyrolyzed particles are derived from the thermal decomposition of macroreticular ion exchange resins contain-ing a macroporous structure.
According to one aspect of this invention, there- ~ !
fo,re, there are provided partially pyrolysed particles of a macroporous synthetic polymer having properties suitable for use in adsorption, molecular screening and/or catalysis and a resistance to crushing and particle sloughage greater than that of known spherical adsorbent particles or that of granular activated carbon, comprising the product of controlled thermal degradation of a macroporous synthetic polymer containing a carbon-fixing moiety and derived from one or more ethylenical-ly unsaturated monomers, or from monomers which may be condensed to yield macroporous polymers, or mixtures thereof, which partially pyrolyzed particles have: (a) at least 85~ by weight of carbon, (b) multimodal pore distribution with ~ _ 5 _ o o macropores ranging in size from about 50 A to about 100,000 A
in average critical dimension and with m~cropores ranging in O O
size from about 4 A to about 50 A in average critical dimension, and (c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1.
According to another aspect, the present invention provides a process for producing partially pyrolyzed particles of a macroporous synthetic polymer having properties suitable for used in adsorption, molecular separations, and/or catalysis and a resistance to crushing and particle sloughage greater than that of known spherical adsorbent particles or that of granular activated carbon, which comprises thermally degrading at a temperature between about 300C and about 900C and in an inert gaseous atmosphere optionally containing an activating gas, a macroporous synthetic polymer containing a carbon-fixing moiety ~nd derived from one or more ethylenically unsaturated monomers or from monomers which may be condensed to yield macroporous polymers, or mixtures thereof, for a time sufficient to drive off sufficient volatile components of the synthetic polymer to yield particles having: (a) at least 85% by weight of carbon, (b) multimodal pore distribu-tion with macropores ranging in size from about 50 A to about 100,000 A in average critical dimension and with m~cropores ranging in size from about 4 A to about 50 A in average critical dimension, and (c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1; and thereafter cooling said particles under said inert atmosphere to a temperature below that which would cause oxidation in air.
In general pyrolysis comprises subjecting the starting polymer to controlled temperatures for controlled periods of -5a-~r-~
time under certain ambient conditions. The primary purpose of pyrolysis is thermal degradation while efficiently removing the volatile products produced.
The maximum temperatures may range from about 300C to up to about 900C, depending on the polymer to be treated and the desired composition of the final --5b-108~98 pyrolyzed particles. Higher temperatures, e~g., about 700C
and higher, result in extensive degradation of the polymer with the formation of molecular sieve sized pores in the product.
Most desirably, thermal decomposition (alternatively denoted "pyrolysis" or "heat treatment") is conducted in an inert atmosphere comprised of, for example, argon, neon, helium, nitrogen, or the like, using beads of macroreticular synthetic polymer substituted with a carbon-fixing moiety which permits the polymer to char without fusing in order to retain the macro-reticular structure and give a high yield of carbon. Among the suitable carbon-fixing moieties are sulfonate, carboxyl, amine, halogen, oxygen, sulfonate salts, carboxylate salts and quaternary amine salts. These groups are introduced into the starting polymex by well-known conventional techniques, such as those reactions used to functionalize polymers for production of ion exchange resins. Carbon-fixing moieties may also be pro-duced by imbibing a reactive precursor thereof into the pores of macroreticular polymer which thereupon, or during heating, chemically binds carbon-fixing moieties onto the polymer.
Examples of these latter reactive precursors include sul-furic acid, oxidizing agents, nitric acid, Lewis acids, acrylic acid, and the like.
Suitable temperatures for practicing the process of this invention are generally within the range of 300C to about 900C, although higher temperatures may be suitable depending upon the polymer to be treated and the desired composition of the final pyrolyzed product. At temperatures above about 700C
the starting polymer degrades extensively with the ~-formatlon of molecular sieve sized pores in the product~
i.e., about 4 - 6 A average critical dimension, yielding a pre~erred class o~ adsorbents according to this invention. At lower temperatures, the thermally-formed pores usually range from about 6 A to as high as 50 A in average critical size. A preferred range of pyrolysis temperatures is between about 400C and ~00C.
As will be explained more fully hereinafter, temperature control is essential to yield a partially pyrolyzed material having the composition, surface area, pore structures and other physical characteristics of the desired product. The duration of thermal treatment is relatively unimportant, provlding a minimum exposure time to the elevated temperature is allowed.
By controlling the conditions of thermal decomposition, in particular the temperature, the elemental composition, and most importantly the carbon to hydrogen atom ratio (C/H), of the flnal product particles ls flxed at the deslred composition.
Controlled heat treatment ylelds particles intermediate in C/H ratio composition between activated carbon and the known polymeric adsorbents.
The ~ollowing table illustrates the effect of maxlmum pyrolysls temperature on the C/H ratlo of the final product, utilizing macroreticular functionallzed polymers as the starting materials.
:
- `` 1080198 Table Starting Material Maximum Pyrolysis C/H Ratio Composition Temperature of Product (1) Styrene/Divinylbenzene copolymer adsorbent (control)
Disclosure This invention concerns partially pyrolyzed particles of resinous polymers, methods of their pyrolysis, applications for removing impurities such as sulfur compounds, monomers, and other industrial contaminants or pollytants from gases and purifying pollutant-containing liquid streams ;
such as phenolics from waste streams and barbiturates from blood. Particularly the invention concerns partially pyrolyzed macroreticular materials as adsorbents for vinyl chloride removal, blood purification, phenolic recovery and, when metals are incorporated, particularly as catalytic agents for industri-al and laboratory processes.
The most commonly used adsorbent today is activated carbon. The production of activated carbon for industrial purposes employs a wide variety of carbonaceous starting materials such as anthracite and bituminous coal, coke, carbonized shells, peat, etc. Suitability of such materials depends on a low ash content and availability in a uniform and unchanging quality.
Methods of activation can be considered in two categories. The first category includes "chemical activation" processes, in which the carbonaceous materials or sometimes the chars are impregnated with one or more activating agents such as zinc chloride, alkali carbonates, sulphates, bisulphates, sulfuric or phosphoric acid and then pyrolyzed (carbonized). The action of these materials a ~080198 .
appears to be one of dehydration with high yields of carbon unaccompanied by tarry materials. The second category includes ,' processes known as "heat treatment" in which chars are heated to temperatures between 350 and 1,000C in the presence of CO2, N2' 2~ HCl, C12, H2O and other gases. A portion of the char is burned as the surface area and "activityl' of the carbon increases. Via careful control of activation parameters, manu-facturers are today able to produce high surface area products (800-2,000 M2/g) in a wide range of uniform particle sizes.
Production of activated carbon by the above processes gives materials with the highest available carbon capacities for a wide variety of adsorbates in both the liquid ~;
and gas phases. However, these materials possess the following disadvantages:
a) difficult and expensive thermal regeneration b) high regeneration losses of 10%/cycle c) friability of active carbon particles d) lack of control of starting materials Adsorbents produced according to the invention via pyrolysis of synthetic organic polymers are preferably spheres which possess a great deal of structural integrity. They do not easily break apart or slough dust particles as is the case for active carbon. Because of this lack of friability, the re-generative losses are frequently lower than is common for active carbon.
Pyrolysis of synthetic organic polymers further allows a much greater degree of control of the starting ' ~08~198 materials and hence of the final product than is possible with naturally occurring raw materials used for production of activated carbons.
Incorporation of desirable elements and functional groups to enhance adsorbency for specific adsorbates is easily achieved. Control of the average pore size and pore size distribution is much more easily achieved with well defined synthetic starting materials. This increased control allows the production of adsorbents designed for specific adsorbates with adsorbent capacities far greater than is possible with activated carbons.
The present invention provides partially pyrolyzed particles, preferably in the form of beads or spheres, produced by the controlled decomposition of a synthetic `~polymer of specific initial porosity. In a preferred embodi-ment, the pyrolyzed particles are derived from the thermal decomposition of macroreticular ion exchange resins contain-ing a macroporous structure.
According to one aspect of this invention, there- ~ !
fo,re, there are provided partially pyrolysed particles of a macroporous synthetic polymer having properties suitable for use in adsorption, molecular screening and/or catalysis and a resistance to crushing and particle sloughage greater than that of known spherical adsorbent particles or that of granular activated carbon, comprising the product of controlled thermal degradation of a macroporous synthetic polymer containing a carbon-fixing moiety and derived from one or more ethylenical-ly unsaturated monomers, or from monomers which may be condensed to yield macroporous polymers, or mixtures thereof, which partially pyrolyzed particles have: (a) at least 85~ by weight of carbon, (b) multimodal pore distribution with ~ _ 5 _ o o macropores ranging in size from about 50 A to about 100,000 A
in average critical dimension and with m~cropores ranging in O O
size from about 4 A to about 50 A in average critical dimension, and (c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1.
According to another aspect, the present invention provides a process for producing partially pyrolyzed particles of a macroporous synthetic polymer having properties suitable for used in adsorption, molecular separations, and/or catalysis and a resistance to crushing and particle sloughage greater than that of known spherical adsorbent particles or that of granular activated carbon, which comprises thermally degrading at a temperature between about 300C and about 900C and in an inert gaseous atmosphere optionally containing an activating gas, a macroporous synthetic polymer containing a carbon-fixing moiety ~nd derived from one or more ethylenically unsaturated monomers or from monomers which may be condensed to yield macroporous polymers, or mixtures thereof, for a time sufficient to drive off sufficient volatile components of the synthetic polymer to yield particles having: (a) at least 85% by weight of carbon, (b) multimodal pore distribu-tion with macropores ranging in size from about 50 A to about 100,000 A in average critical dimension and with m~cropores ranging in size from about 4 A to about 50 A in average critical dimension, and (c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1; and thereafter cooling said particles under said inert atmosphere to a temperature below that which would cause oxidation in air.
In general pyrolysis comprises subjecting the starting polymer to controlled temperatures for controlled periods of -5a-~r-~
time under certain ambient conditions. The primary purpose of pyrolysis is thermal degradation while efficiently removing the volatile products produced.
The maximum temperatures may range from about 300C to up to about 900C, depending on the polymer to be treated and the desired composition of the final --5b-108~98 pyrolyzed particles. Higher temperatures, e~g., about 700C
and higher, result in extensive degradation of the polymer with the formation of molecular sieve sized pores in the product.
Most desirably, thermal decomposition (alternatively denoted "pyrolysis" or "heat treatment") is conducted in an inert atmosphere comprised of, for example, argon, neon, helium, nitrogen, or the like, using beads of macroreticular synthetic polymer substituted with a carbon-fixing moiety which permits the polymer to char without fusing in order to retain the macro-reticular structure and give a high yield of carbon. Among the suitable carbon-fixing moieties are sulfonate, carboxyl, amine, halogen, oxygen, sulfonate salts, carboxylate salts and quaternary amine salts. These groups are introduced into the starting polymex by well-known conventional techniques, such as those reactions used to functionalize polymers for production of ion exchange resins. Carbon-fixing moieties may also be pro-duced by imbibing a reactive precursor thereof into the pores of macroreticular polymer which thereupon, or during heating, chemically binds carbon-fixing moieties onto the polymer.
Examples of these latter reactive precursors include sul-furic acid, oxidizing agents, nitric acid, Lewis acids, acrylic acid, and the like.
Suitable temperatures for practicing the process of this invention are generally within the range of 300C to about 900C, although higher temperatures may be suitable depending upon the polymer to be treated and the desired composition of the final pyrolyzed product. At temperatures above about 700C
the starting polymer degrades extensively with the ~-formatlon of molecular sieve sized pores in the product~
i.e., about 4 - 6 A average critical dimension, yielding a pre~erred class o~ adsorbents according to this invention. At lower temperatures, the thermally-formed pores usually range from about 6 A to as high as 50 A in average critical size. A preferred range of pyrolysis temperatures is between about 400C and ~00C.
As will be explained more fully hereinafter, temperature control is essential to yield a partially pyrolyzed material having the composition, surface area, pore structures and other physical characteristics of the desired product. The duration of thermal treatment is relatively unimportant, provlding a minimum exposure time to the elevated temperature is allowed.
By controlling the conditions of thermal decomposition, in particular the temperature, the elemental composition, and most importantly the carbon to hydrogen atom ratio (C/H), of the flnal product particles ls flxed at the deslred composition.
Controlled heat treatment ylelds particles intermediate in C/H ratio composition between activated carbon and the known polymeric adsorbents.
The ~ollowing table illustrates the effect of maxlmum pyrolysls temperature on the C/H ratlo of the final product, utilizing macroreticular functionallzed polymers as the starting materials.
:
- `` 1080198 Table Starting Material Maximum Pyrolysis C/H Ratio Composition Temperature of Product (1) Styrene/Divinylbenzene copolymer adsorbent (control)
(2) Styrene/divinylbenzene ion exchange resin with sulfonic acid ~~~tionality (H~form) 400C 1.~6
(3) Same as (2) 500C 2.20
(4) Same as (2) ~OODC 2.85
(5) Same as (2) 800C 9.00
(6) Activated carbon (negligible hydrogen) ;.
A wlde range of pyrolyzed resins may be produced by varying the porosity and/or chemical compos-ltion of the starting polymer and also by varying the conditions o~ thermal decomposition. In general, the pyrolyzed resins of the invention have a carbon to hydrogen ratio of 1.5 : 1 to 20 : 1, preferably 2.0 : 1 to 10 : 1, whereas activated carbon normally has a C/H ratio much higher, at least greater than ~0 : 1 (Carbon and Graphite Handbook, Charles L. Mantell, Interscience Publishers, N. Y. 1968, p. 198). The product particle~ contain at least ~5% by weight of carbon with the remainder being principally hydrogen, alkali metals, alkallne earth metals, nitrogen, oxygen, sulfur, chlorine, etc., derived from the polymer ~ or the functional group (carbon-fixing moiety) contained thereon and hydrogen~ oxygen, sulfur, nitrogen, alkali ` 1080198 metals, transition metals, alkaline earth metals and other elements introduced into the polymer pores as components of a filler (may serve as a catalyst and/or carbon-fixing moiety or have some other functional purpose).
The pore structure of the final product must `
contain at least two distinct sets of pores of differing average size, i.e., multimodal pore distribution.
The larger pores originate from the macroporous resinous starting material which preferably contain macropores ranging from between about 50 to about 100,000 Angstroms in average critical dimenxion. The smaller pores, as mentioned previously, generally range in size from ; about 4 to about 50 ~, depending largely upon the 15~ maximum temperature during pyrolysls. Such multimodal pore dlstribution is considered a novel and essential characteristic of the composition of the invention.
'rhe pyr-olyzed polymers of the invention have relatively large surface area resulting from the macroporoslty of the starting material and the smaller pores developed during pyrolysis. In general the overall surface area as measured by N2 adsorption ~ ran~es between about 50 and 1500 M2/gram- Of this, -: the macropores will normally contribute about 6 to about 700 M2/gram, preferably 6 - 200 M2/g, as calculated by mercury lntruslon techniques, with the remainder contributed by the thermal treatment. Pore-~ree polymers, such as "gel" type resins which have been subJected to thermal treatment in the prior art (see, e.g., _g_ 10801~
East German Patent No. 27,022, February 12, 1964 and No.
63,768, September 20, 1968) do not contribute the large pores essential to the adsorbents of the invention nor do they perform with the efficiency of the pyrolyzed polymers described herein. The following table illustrates the effect of macro-porosity on product composition:
Table II
Adsorbents from sulfonated styrene/divinyl-benzene copolymers* with varying macroporosity Before Pyrolysis After Surface Sample Polymer % Aver.porearea Surface No. type DVB size A (M2/g) area 1 non-porous 8 0 0 32 2 Macroporous 20 300 45 338 3 " 50 approx.100 130 267 4 " 80 50 570 570 " 6 r_20,000 6 360 ; * All copolymers were sulfonated to at least 90%
of theoretical maximum and heated in inert atmosphere to 800C.
It may be noted from the data of Table II that the final surface area is not always directly related to the porosity of the starting material. The starting surface areas of the macroporous polymers span a factor of nearly 100 while the heat treated resins only differ by a factor of about 2. The non-porous "gel" resin has a surface area well below the range of the starting materials of the invention and yielded a product wlth surface area substantlally below the heat treated macroporous resin.
The duratlon of pyrolysis depends upon the time needed to remove the volatlles from the particular polymer and the heat transfer characteristics of ~he method selected. In general, the pyrolysls ls very rapid when the heat transfer is rapid, e.g., in an oven where a shallow bed of material ls pyrolyzed, or ln a fluidized bed. To prevent burning of the pyrolyzed polymer, normally the temperature of the polymer i8 reduced to not more than 400C, preferably not more than 300C, be~ore the pyrolyzed material 18 exposed to alr.
''','J The most desirable method of operation involves rapid heating to the maximum temperature, holding the temperature at the maximum for a short period Or tlme (in the order of 0 - 20 minutes) and thereafter qulckly reducing the temperature to room temperature before exposing the sample. Products according to the invention have been produced by thls preferred method by heating ~20 to 800C and coollng in a period of 20 - 30 minutes.
Longer holdlng periods at the elevated temperatures are also satisfactory, slnce no additional decomposition appears to occur unless the temperature is increased.
Activatlng gases such as C02, NH3, 2~ H20 or combinatlons thereo~ in small amounts ~end to react with the polymer during pyrolysis and thereby increase the surface area o~ the final material. Such gases are option~l and ~ay be used to obtain special ch~racteristics o~ the adsorbents.
~080~98 The ~tartlng polymers which may be used to produce the pyrolyzed resins of the invention include macroretlcular homopolymers or copolymers of one or more monoethylenlcally or polyethylenically unsaturated monomers or monomers whlch may be reacted by condensatlon to yield macroretlcular polymers and copolymers. The macroreticular reslns used as precursors in the formation of macroreticular heat treated polymer~ are not claimed as new composition~ of matter in them~elves. Any of the known materials of this type with an approprlate carbon-fixing moiety i~ sultable. The pre~erred monomers are those aliphatic and aromatlc materials which are ethylenically unsaturated.
Examples of suitable monoethylenically un~at-urated monomers that may be used in making the granular macroretlcular resin include: esters o~ acrylic and methacrylic acid such as methyl, ethyl, 2-chloro ethyl, propyl, isobutyl, isopropyl, butyl, tert-butyl, sec-butyl, ethylhexyl, amyl, hexyl, octyl, decyl, dodecyl, cyclohexyl, isobornyl, benzyl, phenyl, alkylphenyl, ethoxymethyl, ethoxyethyl, ethoxypropyl, propoxymethyl, propoxyethyl, propoxypropyl, ethoxyphenyl, ethoxybenzyl, ethoxycyclo-hexul, hydroxyethyl, hydroxypropyl, ethylene, propylene, isobutylene, diisobutylene, styrene, ethylvinylbenzene, vinyltoluene, vinylbenæylchloride, vinyl chloride, vlnyl acetate, vinylidene chloride, dlcyclopentadlene, acrylonitrile, methacrylonitrlle, acrylamide, methacryl-amide, diacetone acrylamide, functional monomers such as ~08019~
., , vinylbenzene, sulfonic acid, vinyl esters, including -~
vinyl acetate, vinyl propionate, vinyl butyrate, vinyl laurate, vinyl ketones includ~ng vinyl methyl ketone, vlnyl ethyl ketone, vinyl isopropyl ketone, vlnyl n-butyl ketone, vinyl hexyl ketone, vinyl octyl ketone, methyl isopropenyl ketone, vinyl aldehydes including acrolein, methacrolein, crotonaldehyde, vinyl ether~ including vinyl methyl ether, vinyl ethyl ether, :~
vinyl propyl ether, vlnyl isobutyl ether, vinylidene compounds including vinylidene chloride bromide, or bromochloride, also the corresponding neutral or ~. .
hal~-acld hal~-esters or ~ree dlaclds of the unsaturated : dicarboxylic aclds lncluding itaconic, citraconic, aconltlc, fumarlc, and maleic acids, substituted :l15 acrylamides, such as N-monoalkyl, -N,N-dialkyl-, and . N-dialkylaminoalkylacrylamides or methacrylarnides where the alkyl groups may have ~rom one to eighteen carbon atoms, such as methyl, ethyl, isopropyl, butyl, hexyl, cyclohexyl, octyl, dodecyl, hexadecyl and octadecyl aminoalkyl esters of acrylic or methacrylic acid, such as ~-dimethylaminoethyl, ~-diethylaminoethyl or 6-dimethylaminohexyl acrylates and methacrylates, alkylthioethyl methacrylates and acrylates such as ethylthioethyl methacrylate, vinylpyridine~, such as 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinyl-pyridine, and so on.
108~198 In the case of copolymers containing ethylthioethyl ' methacrylate, the products can be oxidized to, if desired, the corresponding sulfoxide or sulfone. ~:
Polyethylenically unsaturated monomers which ordinarily act as though they have only one such unsaturated group, such as isoprene, butadiene, and chloroprene, may be used as part of the monoethylenically unsaturated category.
Examples of polyethylenically unsaturated compounds include: divinylbenzene, divinylpyridine, divinylnaphthalenes, diallyl phthalate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropanetrimethacrylate, divinylsul-fone, polyvinyl or polyallyl ethers of glycol, of glycerol, of pentaerythritol, of diethyleneglycol, of monothio or dithio-derivatives of glycols, and of resorcinol, divinylketone, divinylsulfide, allyl acrylate, diallyl maleate, diallyl fumarate, diallyl succinate, diallyl carbonate, diallyl malonate, diallyl oxalate, diallyl adipate, diallyl sebacate, divinyl sebacate, diallyl tartrate, diallyl silicate, triallyl tricarballylate, triallyl aconitate, triallyl citrate, triallyl phosphate, N,N'-methylenediacrylamide, N,N'-methylenedimethacrylamide, N,N'-ethylenediacrylamide, trivinylbenzene, trivinylnaphthalenes, and polyvinylanthracenes.
" 1080~9~3 A preferred class of monomers of this type are aromatic ethylenically unsaturated molecules such as styrene, ~ vinyl pyridine, vinyl naphthalene, vinyl toluene, phenyl L, acrylate, vinyl xylenes, ethylvinylbenzene.
Examples of preferred polyethylenically unsatu-rated compounds include divinyl pyridine, divinyl naphthalene, ~- divinylbenzene, trivinylbenzene, alkyldivinylbenzenes having from 1 to 4 alkyl groups of 1 to 2 carbon atoms substituted in the benzene nucleus, and alkyltrivinylbenzenes having 1 to 3 alkyl groups of 1 to 2 carbon atoms substituted in the benzene nucleus. Besides the homopolymers and copolymers of ~ these poly(vinyl) benzene monomers, one or more of them may L,`~ be copolymerized with up to 98% (by weight of the total monomer mixture) of (1) monoethylenically unsaturated monomers, or (2) polyethylenically unsaturated monomers other than the poly-(vinyl)benzenes just defined, or (3) a mixture of (1) and (2).
Examples of the alkyl-substituted di- and tri-vinyl-benzenes are the various vinyltoluenes, divinylethylbenzene, 1,4-divinyl - 2,3,5,6 - tetramethylbenzene, 1,3,5 - trivinyl - 2,4,6 - trimethylbenzene, 1,4-divinyl, 2,3,6 - triethylbenzene, 1,2,4 - trivinyl - 3,5 - diethylbenzene, 1,3,5-trivinyl-2-methylbenzene.
Most preferred are copolymers of styrene, divinyl-benzene and ethylvinylbenzene.
Examples of suitable condensation monomers include:
(a) aliphatic dibasic acids such as maleic acid, fumaric acid, itaconic acid, l,l-cyclobutanedicarboxylic acid, etc.; (b) ~08~9~3 ;
aliphatic diamines such as piperazine, 2-methylpiperazine, cis, cis-bis (4-aminocyclohexyl) methane, metaxylylenediamine, etc.; (c) glycols such as diethylene glycol, triethylene glycol, -1,2-butanediol, neopentyl glycol etc.; (d) bischloroformates such as cis and trans - 1,4-cyclohexyl bischloroformate, 2,2,2,4-tetramethyl-1,3-cyclobutyl bischloroformate and bis-chloroformates of other glycols mentioned above, etc.;
(e) hydroxy acids such as salicyclic acid, m- and _-hydroxy-benzoic acid and lactones, derived therefrom such as the propiolactones, valerolactones, caprolactones, etc.; (f) diisocyanates such as cis and trans - cyclopropane -1, 2-di-isocyanate, cis and trans-cyclobutane-1-2-diisocyanate etc.;
(g) aromatic diacids and their derivatives (the esters, anhydrides and acid chlorides) such as phthalic acid, phthalic anhydride, terephthalic acid, isophthalic acid, dimethylphthalate, etc.; (h) aromatic diamines such as benzidine, 4,4'-methylene-diamine, bis (4-aminophenyl) ether, etc.; (i) bisphenols such as bisphenol A, bisphenol C, bisphenol F, phenolphthalein, resorcinol, etc.; (j) bisphenol bis(chloroformates) such as bisphenol A bis(chloroformate), 4,4'-dihydroxybenzophenone bis(chloroformate) etc.; (k) carbonyl and thiocarbonyl compounds such as formaldehyde, acetaldehyde, thioacetone, acetone, etc.;
(1) phenol and derivatives such as phenol, alkylphenols, etc.;
(m) polyfunctional cross-linking agents such as tri or poly basic acids such as trimellitic acid, tri or polyols such as glycerol, tri or polyamines such as diethylenetriamine; and other condensation monomers and mixtures of the foregoing.
i~80~98 Ion exchange resins produced from aromatic : and/or aliphatic monomers provide a preferred class o~
starting polymers for production of porous adsorbents.
The ion exchange re~in may also contain a functional group selected from cation, anion, strong base, weak base, sulfonic acid, carboxylic acid, oxygen containing, halogen and mixtures of the same. Further, such ion exchange resins may optionally contain an oxidizing agent, a reactive substance, sulfuric acid, nitric acid, acrylic acid, or the like at least partially filling the macropores of the polymer before heat treatment.
The synthetic polymer may be impregnated with a filler such as carbon black, charcoal, bonechar, sawdust or other carbonaceous material prior to pyrolysls. SUCh fillers provide an economical source of carbon which may be added in amounts up to about 90~ by weight of the polymer.
The starting polymers, when ion exchange resins, may optionally contain a variety of metals in their atomically dispersed form at the ionic sites.
These metals may include iron, copper, silver, nickel, manganese, palladium, cobalt, titanium, zirconium, sodium, potassium, calcium, zinc, cadmium, ruthenium, uranlum and rare earths 3uch a~ lanthanum. By utilizing the lon exchange me¢hanism lt 18 po~sible for the ~killed technlclan to aontrol the amount of metal that 1~ ~o be lnoorporated as well as the dlstrlhutlon.
Although the lncorporation of metals onto the -lr-`: :
108~1g8 resins is primarily to aid their ability to serve as catalytic agents, useful adsorbents may also contain metal.
Synthetic polymers, ion exchange resins whether in the acid, base or metal salt form are commercially available.
According to the invention there is also provided an adsorption process for separating components from a gaseous or liquid medium which comprises contacting the medium with particles ; of a pyrolyzed synthetic polymer.
For example it has been discovered that a styrene-divinylbenzene based strongly acidic exchange resin pyro-lyzed from any of the forms of Hydrogen, Iron (III), Copper (II), Silver(I) or Calcium(II) can decrease the concentration of vinylchloride in air, preferably dry air, from an initial con-centration of 2 ppm - 300,000 ppm to a level of less than 1 ppm at flow rates of 1 bedvolume/hour to 600 bedvolume/min., preferably 10 - 200 bedvolume/minute.
Compared to activated carbon the adsorbents of the invention show advantages such as a lower heat of adsorption, less polymerization of adsorbed monomers on the surface, less regenerant required due to diffusion kinetics, less loss of capacity upon multicycling and lower leakage before breakthrough.
Similar performances have been noticed when other impurities such as SO2 and H2S are removed. The adsorbents of the inven-tion are particularly useful in the air pollution abatement field to remove components such as sulfur containing molecules, halogenated hydrocarbons, organic acids, aldehydes, alcohols, ketones, alkanes, amines, ammonia, acrylonitrile, ~ 108~198 aromatics, oil vapors, halogens, solvents, monomers, organic decomposition products, hydrogen cyanide, carbon monoxide and mercury vapors.
Specific chlorinated hydrocarbons include: :
1,2,3,4,10 10-Hexachloro-1,4,4a,5,8,8a-hexahydro-1,4 endo-exo-5, 8-dimethanonaphthalene 2-Chloro-4-ethylamino-6-isopropylamino-s-triazine Polychlorobicyclopentadiene isomers Isomers of benzenehexachloride 60~ Octochloro-4,7-methanotetrahydroindane 1,1-Dichloro-2,2-bis-(_-ethylphenyl)ethane 1,1,1-Trichloro-2,2-bis (_-chlorophenyl)ethane Dichlorodiphenyl dichloroethylene 1,1-bis(_-Chlorophenyl)-2,2,2-trichloroethanol 2,2-Dichlorovinyl dimethyl phosphate 1,2,3,4,10, 10-Hexachloro-6, 7-epoxy-1,4,4a,5,6,-
A wlde range of pyrolyzed resins may be produced by varying the porosity and/or chemical compos-ltion of the starting polymer and also by varying the conditions o~ thermal decomposition. In general, the pyrolyzed resins of the invention have a carbon to hydrogen ratio of 1.5 : 1 to 20 : 1, preferably 2.0 : 1 to 10 : 1, whereas activated carbon normally has a C/H ratio much higher, at least greater than ~0 : 1 (Carbon and Graphite Handbook, Charles L. Mantell, Interscience Publishers, N. Y. 1968, p. 198). The product particle~ contain at least ~5% by weight of carbon with the remainder being principally hydrogen, alkali metals, alkallne earth metals, nitrogen, oxygen, sulfur, chlorine, etc., derived from the polymer ~ or the functional group (carbon-fixing moiety) contained thereon and hydrogen~ oxygen, sulfur, nitrogen, alkali ` 1080198 metals, transition metals, alkaline earth metals and other elements introduced into the polymer pores as components of a filler (may serve as a catalyst and/or carbon-fixing moiety or have some other functional purpose).
The pore structure of the final product must `
contain at least two distinct sets of pores of differing average size, i.e., multimodal pore distribution.
The larger pores originate from the macroporous resinous starting material which preferably contain macropores ranging from between about 50 to about 100,000 Angstroms in average critical dimenxion. The smaller pores, as mentioned previously, generally range in size from ; about 4 to about 50 ~, depending largely upon the 15~ maximum temperature during pyrolysls. Such multimodal pore dlstribution is considered a novel and essential characteristic of the composition of the invention.
'rhe pyr-olyzed polymers of the invention have relatively large surface area resulting from the macroporoslty of the starting material and the smaller pores developed during pyrolysis. In general the overall surface area as measured by N2 adsorption ~ ran~es between about 50 and 1500 M2/gram- Of this, -: the macropores will normally contribute about 6 to about 700 M2/gram, preferably 6 - 200 M2/g, as calculated by mercury lntruslon techniques, with the remainder contributed by the thermal treatment. Pore-~ree polymers, such as "gel" type resins which have been subJected to thermal treatment in the prior art (see, e.g., _g_ 10801~
East German Patent No. 27,022, February 12, 1964 and No.
63,768, September 20, 1968) do not contribute the large pores essential to the adsorbents of the invention nor do they perform with the efficiency of the pyrolyzed polymers described herein. The following table illustrates the effect of macro-porosity on product composition:
Table II
Adsorbents from sulfonated styrene/divinyl-benzene copolymers* with varying macroporosity Before Pyrolysis After Surface Sample Polymer % Aver.porearea Surface No. type DVB size A (M2/g) area 1 non-porous 8 0 0 32 2 Macroporous 20 300 45 338 3 " 50 approx.100 130 267 4 " 80 50 570 570 " 6 r_20,000 6 360 ; * All copolymers were sulfonated to at least 90%
of theoretical maximum and heated in inert atmosphere to 800C.
It may be noted from the data of Table II that the final surface area is not always directly related to the porosity of the starting material. The starting surface areas of the macroporous polymers span a factor of nearly 100 while the heat treated resins only differ by a factor of about 2. The non-porous "gel" resin has a surface area well below the range of the starting materials of the invention and yielded a product wlth surface area substantlally below the heat treated macroporous resin.
The duratlon of pyrolysis depends upon the time needed to remove the volatlles from the particular polymer and the heat transfer characteristics of ~he method selected. In general, the pyrolysls ls very rapid when the heat transfer is rapid, e.g., in an oven where a shallow bed of material ls pyrolyzed, or ln a fluidized bed. To prevent burning of the pyrolyzed polymer, normally the temperature of the polymer i8 reduced to not more than 400C, preferably not more than 300C, be~ore the pyrolyzed material 18 exposed to alr.
''','J The most desirable method of operation involves rapid heating to the maximum temperature, holding the temperature at the maximum for a short period Or tlme (in the order of 0 - 20 minutes) and thereafter qulckly reducing the temperature to room temperature before exposing the sample. Products according to the invention have been produced by thls preferred method by heating ~20 to 800C and coollng in a period of 20 - 30 minutes.
Longer holdlng periods at the elevated temperatures are also satisfactory, slnce no additional decomposition appears to occur unless the temperature is increased.
Activatlng gases such as C02, NH3, 2~ H20 or combinatlons thereo~ in small amounts ~end to react with the polymer during pyrolysis and thereby increase the surface area o~ the final material. Such gases are option~l and ~ay be used to obtain special ch~racteristics o~ the adsorbents.
~080~98 The ~tartlng polymers which may be used to produce the pyrolyzed resins of the invention include macroretlcular homopolymers or copolymers of one or more monoethylenlcally or polyethylenically unsaturated monomers or monomers whlch may be reacted by condensatlon to yield macroretlcular polymers and copolymers. The macroreticular reslns used as precursors in the formation of macroreticular heat treated polymer~ are not claimed as new composition~ of matter in them~elves. Any of the known materials of this type with an approprlate carbon-fixing moiety i~ sultable. The pre~erred monomers are those aliphatic and aromatlc materials which are ethylenically unsaturated.
Examples of suitable monoethylenically un~at-urated monomers that may be used in making the granular macroretlcular resin include: esters o~ acrylic and methacrylic acid such as methyl, ethyl, 2-chloro ethyl, propyl, isobutyl, isopropyl, butyl, tert-butyl, sec-butyl, ethylhexyl, amyl, hexyl, octyl, decyl, dodecyl, cyclohexyl, isobornyl, benzyl, phenyl, alkylphenyl, ethoxymethyl, ethoxyethyl, ethoxypropyl, propoxymethyl, propoxyethyl, propoxypropyl, ethoxyphenyl, ethoxybenzyl, ethoxycyclo-hexul, hydroxyethyl, hydroxypropyl, ethylene, propylene, isobutylene, diisobutylene, styrene, ethylvinylbenzene, vinyltoluene, vinylbenæylchloride, vinyl chloride, vlnyl acetate, vinylidene chloride, dlcyclopentadlene, acrylonitrile, methacrylonitrlle, acrylamide, methacryl-amide, diacetone acrylamide, functional monomers such as ~08019~
., , vinylbenzene, sulfonic acid, vinyl esters, including -~
vinyl acetate, vinyl propionate, vinyl butyrate, vinyl laurate, vinyl ketones includ~ng vinyl methyl ketone, vlnyl ethyl ketone, vinyl isopropyl ketone, vlnyl n-butyl ketone, vinyl hexyl ketone, vinyl octyl ketone, methyl isopropenyl ketone, vinyl aldehydes including acrolein, methacrolein, crotonaldehyde, vinyl ether~ including vinyl methyl ether, vinyl ethyl ether, :~
vinyl propyl ether, vlnyl isobutyl ether, vinylidene compounds including vinylidene chloride bromide, or bromochloride, also the corresponding neutral or ~. .
hal~-acld hal~-esters or ~ree dlaclds of the unsaturated : dicarboxylic aclds lncluding itaconic, citraconic, aconltlc, fumarlc, and maleic acids, substituted :l15 acrylamides, such as N-monoalkyl, -N,N-dialkyl-, and . N-dialkylaminoalkylacrylamides or methacrylarnides where the alkyl groups may have ~rom one to eighteen carbon atoms, such as methyl, ethyl, isopropyl, butyl, hexyl, cyclohexyl, octyl, dodecyl, hexadecyl and octadecyl aminoalkyl esters of acrylic or methacrylic acid, such as ~-dimethylaminoethyl, ~-diethylaminoethyl or 6-dimethylaminohexyl acrylates and methacrylates, alkylthioethyl methacrylates and acrylates such as ethylthioethyl methacrylate, vinylpyridine~, such as 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinyl-pyridine, and so on.
108~198 In the case of copolymers containing ethylthioethyl ' methacrylate, the products can be oxidized to, if desired, the corresponding sulfoxide or sulfone. ~:
Polyethylenically unsaturated monomers which ordinarily act as though they have only one such unsaturated group, such as isoprene, butadiene, and chloroprene, may be used as part of the monoethylenically unsaturated category.
Examples of polyethylenically unsaturated compounds include: divinylbenzene, divinylpyridine, divinylnaphthalenes, diallyl phthalate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropanetrimethacrylate, divinylsul-fone, polyvinyl or polyallyl ethers of glycol, of glycerol, of pentaerythritol, of diethyleneglycol, of monothio or dithio-derivatives of glycols, and of resorcinol, divinylketone, divinylsulfide, allyl acrylate, diallyl maleate, diallyl fumarate, diallyl succinate, diallyl carbonate, diallyl malonate, diallyl oxalate, diallyl adipate, diallyl sebacate, divinyl sebacate, diallyl tartrate, diallyl silicate, triallyl tricarballylate, triallyl aconitate, triallyl citrate, triallyl phosphate, N,N'-methylenediacrylamide, N,N'-methylenedimethacrylamide, N,N'-ethylenediacrylamide, trivinylbenzene, trivinylnaphthalenes, and polyvinylanthracenes.
" 1080~9~3 A preferred class of monomers of this type are aromatic ethylenically unsaturated molecules such as styrene, ~ vinyl pyridine, vinyl naphthalene, vinyl toluene, phenyl L, acrylate, vinyl xylenes, ethylvinylbenzene.
Examples of preferred polyethylenically unsatu-rated compounds include divinyl pyridine, divinyl naphthalene, ~- divinylbenzene, trivinylbenzene, alkyldivinylbenzenes having from 1 to 4 alkyl groups of 1 to 2 carbon atoms substituted in the benzene nucleus, and alkyltrivinylbenzenes having 1 to 3 alkyl groups of 1 to 2 carbon atoms substituted in the benzene nucleus. Besides the homopolymers and copolymers of ~ these poly(vinyl) benzene monomers, one or more of them may L,`~ be copolymerized with up to 98% (by weight of the total monomer mixture) of (1) monoethylenically unsaturated monomers, or (2) polyethylenically unsaturated monomers other than the poly-(vinyl)benzenes just defined, or (3) a mixture of (1) and (2).
Examples of the alkyl-substituted di- and tri-vinyl-benzenes are the various vinyltoluenes, divinylethylbenzene, 1,4-divinyl - 2,3,5,6 - tetramethylbenzene, 1,3,5 - trivinyl - 2,4,6 - trimethylbenzene, 1,4-divinyl, 2,3,6 - triethylbenzene, 1,2,4 - trivinyl - 3,5 - diethylbenzene, 1,3,5-trivinyl-2-methylbenzene.
Most preferred are copolymers of styrene, divinyl-benzene and ethylvinylbenzene.
Examples of suitable condensation monomers include:
(a) aliphatic dibasic acids such as maleic acid, fumaric acid, itaconic acid, l,l-cyclobutanedicarboxylic acid, etc.; (b) ~08~9~3 ;
aliphatic diamines such as piperazine, 2-methylpiperazine, cis, cis-bis (4-aminocyclohexyl) methane, metaxylylenediamine, etc.; (c) glycols such as diethylene glycol, triethylene glycol, -1,2-butanediol, neopentyl glycol etc.; (d) bischloroformates such as cis and trans - 1,4-cyclohexyl bischloroformate, 2,2,2,4-tetramethyl-1,3-cyclobutyl bischloroformate and bis-chloroformates of other glycols mentioned above, etc.;
(e) hydroxy acids such as salicyclic acid, m- and _-hydroxy-benzoic acid and lactones, derived therefrom such as the propiolactones, valerolactones, caprolactones, etc.; (f) diisocyanates such as cis and trans - cyclopropane -1, 2-di-isocyanate, cis and trans-cyclobutane-1-2-diisocyanate etc.;
(g) aromatic diacids and their derivatives (the esters, anhydrides and acid chlorides) such as phthalic acid, phthalic anhydride, terephthalic acid, isophthalic acid, dimethylphthalate, etc.; (h) aromatic diamines such as benzidine, 4,4'-methylene-diamine, bis (4-aminophenyl) ether, etc.; (i) bisphenols such as bisphenol A, bisphenol C, bisphenol F, phenolphthalein, resorcinol, etc.; (j) bisphenol bis(chloroformates) such as bisphenol A bis(chloroformate), 4,4'-dihydroxybenzophenone bis(chloroformate) etc.; (k) carbonyl and thiocarbonyl compounds such as formaldehyde, acetaldehyde, thioacetone, acetone, etc.;
(1) phenol and derivatives such as phenol, alkylphenols, etc.;
(m) polyfunctional cross-linking agents such as tri or poly basic acids such as trimellitic acid, tri or polyols such as glycerol, tri or polyamines such as diethylenetriamine; and other condensation monomers and mixtures of the foregoing.
i~80~98 Ion exchange resins produced from aromatic : and/or aliphatic monomers provide a preferred class o~
starting polymers for production of porous adsorbents.
The ion exchange re~in may also contain a functional group selected from cation, anion, strong base, weak base, sulfonic acid, carboxylic acid, oxygen containing, halogen and mixtures of the same. Further, such ion exchange resins may optionally contain an oxidizing agent, a reactive substance, sulfuric acid, nitric acid, acrylic acid, or the like at least partially filling the macropores of the polymer before heat treatment.
The synthetic polymer may be impregnated with a filler such as carbon black, charcoal, bonechar, sawdust or other carbonaceous material prior to pyrolysls. SUCh fillers provide an economical source of carbon which may be added in amounts up to about 90~ by weight of the polymer.
The starting polymers, when ion exchange resins, may optionally contain a variety of metals in their atomically dispersed form at the ionic sites.
These metals may include iron, copper, silver, nickel, manganese, palladium, cobalt, titanium, zirconium, sodium, potassium, calcium, zinc, cadmium, ruthenium, uranlum and rare earths 3uch a~ lanthanum. By utilizing the lon exchange me¢hanism lt 18 po~sible for the ~killed technlclan to aontrol the amount of metal that 1~ ~o be lnoorporated as well as the dlstrlhutlon.
Although the lncorporation of metals onto the -lr-`: :
108~1g8 resins is primarily to aid their ability to serve as catalytic agents, useful adsorbents may also contain metal.
Synthetic polymers, ion exchange resins whether in the acid, base or metal salt form are commercially available.
According to the invention there is also provided an adsorption process for separating components from a gaseous or liquid medium which comprises contacting the medium with particles ; of a pyrolyzed synthetic polymer.
For example it has been discovered that a styrene-divinylbenzene based strongly acidic exchange resin pyro-lyzed from any of the forms of Hydrogen, Iron (III), Copper (II), Silver(I) or Calcium(II) can decrease the concentration of vinylchloride in air, preferably dry air, from an initial con-centration of 2 ppm - 300,000 ppm to a level of less than 1 ppm at flow rates of 1 bedvolume/hour to 600 bedvolume/min., preferably 10 - 200 bedvolume/minute.
Compared to activated carbon the adsorbents of the invention show advantages such as a lower heat of adsorption, less polymerization of adsorbed monomers on the surface, less regenerant required due to diffusion kinetics, less loss of capacity upon multicycling and lower leakage before breakthrough.
Similar performances have been noticed when other impurities such as SO2 and H2S are removed. The adsorbents of the inven-tion are particularly useful in the air pollution abatement field to remove components such as sulfur containing molecules, halogenated hydrocarbons, organic acids, aldehydes, alcohols, ketones, alkanes, amines, ammonia, acrylonitrile, ~ 108~198 aromatics, oil vapors, halogens, solvents, monomers, organic decomposition products, hydrogen cyanide, carbon monoxide and mercury vapors.
Specific chlorinated hydrocarbons include: :
1,2,3,4,10 10-Hexachloro-1,4,4a,5,8,8a-hexahydro-1,4 endo-exo-5, 8-dimethanonaphthalene 2-Chloro-4-ethylamino-6-isopropylamino-s-triazine Polychlorobicyclopentadiene isomers Isomers of benzenehexachloride 60~ Octochloro-4,7-methanotetrahydroindane 1,1-Dichloro-2,2-bis-(_-ethylphenyl)ethane 1,1,1-Trichloro-2,2-bis (_-chlorophenyl)ethane Dichlorodiphenyl dichloroethylene 1,1-bis(_-Chlorophenyl)-2,2,2-trichloroethanol 2,2-Dichlorovinyl dimethyl phosphate 1,2,3,4,10, 10-Hexachloro-6, 7-epoxy-1,4,4a,5,6,-
7 dimethanonaphthalene 1,2,3,4,10, 10-Hexachloro-6, 7-epoxy-1,4,4a,5,6,7,-
8,8a-octahydro-1,4-endo-endo-5,8-dimethano-naphthalene 74% 1,4,5,6,7,8 8a-Heptachloro-32,4,7a-tetrahydro-4, 7-methanoindene 1,2,3,4,5,6-Hexachlorocyclohexane 2,2-bis(p-Methoxyphenyl)-l,l,l-trichloroethane Chlorinated camphene with 67-69~ chlorine 108i~98 Other components which may be adsorbed from liquids by the adsorbents of the invention include chlorinated phenols, nitro phenols, surface active agents such as detergents, emulsifiers, dispersants and wetting agents, hydrocarbons such as toluene and benzene, organic and inorganic dye wastes, color bodies from sugars, oils and fats, odoriferous esters and monomers.
The adsorbents when exhausted may be regenerated.
The particular regenerant most suitable will depend on the ~;
nature of the adsorbed species, but in general will include brine, solvents, hot water, acids and steam. The thermal regenerability of the adsorbents constitutes a distinct advantage.
Adsorbents Without Activiation Superior adsorbents are produced by this invention without the necessity of "activation" common to many carbonaceous adsorbents designated "active carbon".
Adsorbents with properties both superior to and different from all other adsorbents are produced directly in one step by heat treating polymers as described above. Activation with reactive gases is an optional process sometimes desirable for the modification of adsorbent properties but is not a necessary part of the invention. As shown in Tables III and IV below, the adsorption properties are markedly influenced by the maximum temperature to which the resin is exposed. As shown in Table III a temperature of 500C produces an adsorbent which is optimum for chloroform removal from water.
~080198 Resins heat treated to 800C are capable of selectively adsorbing molecules according to size ~-(see Table TV). The 800C example is even more effective in selecting for hexane over carbon tetrachloride than indicated in Table IV since nearly all of the CC14 is adsorbed on the surface of the macropores and not in the micropores.
The apparently superior selectivity of the commercial carbon molecular sieve (example 5~ is clearly due to much less surface area in the macropores. The resin heat treated to 500C
(No. 1 in Table IV) shows much less selectivity for the two different sized molecules, emphasizing the important influence that the maximum temperature during heat treatment has on adsorbent properties.
Table III
Equilibrium Aqueous Chloroform Capacities for Various Adsorbents All adsorbents in equilibrium with 2 ppm CHC13 in deionized water at room temperature.
Equilibrium Capa-No. Sample city 2 ppm 1 *S/DVB polymeric adsorbent 6.0 mg/g dry adsorbent 2 Pittsburgh Granular Activated Carbon 10~2 3 Sulfonated S/DVB resin pyrolyzed to 800C 21 4 Same as No. 3 but oxygen activated 28 Same as No. 3 pyrolyzed to 500C 45 *S/DVB = Copolymer of styrene and divinylbenzene Table IV
Molecular Screening Determination via Equilibrium ~apo'r Uptake' '' ' '''' Capacity (ul/g) No..... Sample CCl4 Hexane2 1 Sulfonated S/DVB
pyrolyzed to 500C 12.1 15.6 2 Same as No. 1 pyrolyzed to 800C 3.4 15.7 3 Pittsburgh Activated Carbon 41.0 40.9 4 Same as No. 2 oxygen etched 17.6 22.7 Carbon molecular sieve from Takeda Chemical Industries 0.50 12.1 Effective minimum size 6.lA
Effective minimum size 4.3A
The following examples serve to illustrate but not limit the invention.
Example 1.
A 40 g sample of "Amberlite 200" (Registered Trademark of Rohm and Haas Company for a styrene/DVB sul-fonic acid ion exchange resin) in the Na+ form (49.15% solids) was placed in a filter tube and washed with 200 cc of D. I. H2O. 20 g of FeC13 6H2O were dissolved in about 1 1 of D.I. H2O and passed through the resin sample in a columnar manner over a period of about four hours. Uniform and complete loading could be observed visually. The sample was then washed with 1 1 of D.I. H2O, aspirated for 5 minutes and air dried for 18 hours.
10 grams of this sample was then pyrolyzed together with several other samples in a furnace equipped for input of 7 1 of argon gas per minute. The sample was raised to a temperature of 706C over a period of 6 hrs.
with step increases of about 110C each hour. The sample `
108~198 was held at the maximum temperature of 1/2 hour. The power to the furnace was shut off and the furnace and contents were allowed to cool undisturbed to room temperature with the argon flow;ng continuously over the next 16 hours. ;~
The yield of solid material was 43~ after pyrolysis. The physical characteristics of this sample are listed in Table V along with the data for Samples B through G, and I through K which were prepared in the same manner.
Example 2 The technique of example I is modified in that 250 gm of "Amberlite 200" in hydrogen form (obtained by converting the sodium form with hydrochloric acid) is pyrolyzed by raising the temperature continuously over six hours to 760C. The sample is then allowed to cool over the next twelve hours after which it shows a surface area of 390 m2/g.
Process Examples Adsorption of Vinyl Chloride Then cubic centimeters of sample are placed in a 1.69 centimeter inner diameter stainless steel column.
The bed depth is then 5.05 centimeters. Through the use of a dilution device with a mixing chamber, a gas stream of 580 ppm vinyl chloride in air is generated and passed through the column at a volumetric flow rate of 800 ml/min.
The column flow rate is therefore 80 bed volumes/minute. All experiments are conducted at ambient temperature and a pressure of 16 psig. A flow of 10 ml/min is diverted from the effluent and fed into a flame ionization detector for continuous vinyl chloride analysis. Conventional Rohm 1~8~198 .,, Cl h a uI~ ~ ~ I~ ~ ", ~
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, u~ ~C m ~ H 1 .. -- 24 --~L080~98 and Haas adsorbents and a Calgon activated carbon are also tested. The results are shown below.
Table VI
Adsorption of Vi'ny;l Chloride on Sample K, H~ Form, Pyrolyzed Elapsed TimeLeakage Instantaneous (min) (ppm VCM) Leakage O O O
o o ::
0 0 :
100 o o 125 0 a 150 o o 166 l ~1 200 34 5.8 300 580 100 ' Table VII
Adsorption of Vinyl Chloride on Sample B, Fe(III) Form, Pyrolyzed and:Le:a:ch:ed with H2SO4,:B:ed Vo:lume ~ 20 cc :
Elapsed TimeLeakage Instantaneous %
(min) (ppm) Leakage O O O
100 o o 109 1 .2 125 284 ~49 :
.~
:108~1913 Table VIII
Adsorption of Vinyl ChIoride on Sample C, Cu(II) Form, Pvrolvz'ed' ''' - - ' Elapsed TimeLeakage Instantaneous (mln) (ppm VCM) Leakage 125 0 o 143 1 0.2 150 2 0.4 Adsorption of Vinyl Chloride on Sample A Fe(III) form Pyrolyzed Elapsed TimeLeakage Instantaneous (min) (ppm VCM) Leakage O O O
125 2.0 0.3 150 26 4.5 116 1 0.2 :
' 30 .
~080198 'Tabl'e X
Adsorption of Vinyl ChIoride on '`Pittsburgh PCB"* 12 x 30 Activated Carbon '' ' ' ''''' ' ''''' ' '''''' Elapsed Time Leakage Instantaneous %
(min) - (ppm) Leakage ' O O O
117 1 0.2 200 5~0 100 Further Process Examples The adsorption is performed with a bed of 9.5 cc of Resin J which is subjected to a vinyl chloride influent stream containing 350 ppm and having a flow rate of 160 bed volumes per minute. Regeneration is carried out using steam at 130 - 160C for 20 minutes, followed by drying with air for 10 minutes. The experiment is performed for 15 cycles to show the lack of capacity loss over several cycles. Results are shown in the following table.
Table XI
Cycle Time*Volume Capacity Weight Capacity 1 45 6.9 11.1 3 42 6.4 10.3 49 7 5 12.1 7 45 6.9 11.1 ;
The adsorbents when exhausted may be regenerated.
The particular regenerant most suitable will depend on the ~;
nature of the adsorbed species, but in general will include brine, solvents, hot water, acids and steam. The thermal regenerability of the adsorbents constitutes a distinct advantage.
Adsorbents Without Activiation Superior adsorbents are produced by this invention without the necessity of "activation" common to many carbonaceous adsorbents designated "active carbon".
Adsorbents with properties both superior to and different from all other adsorbents are produced directly in one step by heat treating polymers as described above. Activation with reactive gases is an optional process sometimes desirable for the modification of adsorbent properties but is not a necessary part of the invention. As shown in Tables III and IV below, the adsorption properties are markedly influenced by the maximum temperature to which the resin is exposed. As shown in Table III a temperature of 500C produces an adsorbent which is optimum for chloroform removal from water.
~080198 Resins heat treated to 800C are capable of selectively adsorbing molecules according to size ~-(see Table TV). The 800C example is even more effective in selecting for hexane over carbon tetrachloride than indicated in Table IV since nearly all of the CC14 is adsorbed on the surface of the macropores and not in the micropores.
The apparently superior selectivity of the commercial carbon molecular sieve (example 5~ is clearly due to much less surface area in the macropores. The resin heat treated to 500C
(No. 1 in Table IV) shows much less selectivity for the two different sized molecules, emphasizing the important influence that the maximum temperature during heat treatment has on adsorbent properties.
Table III
Equilibrium Aqueous Chloroform Capacities for Various Adsorbents All adsorbents in equilibrium with 2 ppm CHC13 in deionized water at room temperature.
Equilibrium Capa-No. Sample city 2 ppm 1 *S/DVB polymeric adsorbent 6.0 mg/g dry adsorbent 2 Pittsburgh Granular Activated Carbon 10~2 3 Sulfonated S/DVB resin pyrolyzed to 800C 21 4 Same as No. 3 but oxygen activated 28 Same as No. 3 pyrolyzed to 500C 45 *S/DVB = Copolymer of styrene and divinylbenzene Table IV
Molecular Screening Determination via Equilibrium ~apo'r Uptake' '' ' '''' Capacity (ul/g) No..... Sample CCl4 Hexane2 1 Sulfonated S/DVB
pyrolyzed to 500C 12.1 15.6 2 Same as No. 1 pyrolyzed to 800C 3.4 15.7 3 Pittsburgh Activated Carbon 41.0 40.9 4 Same as No. 2 oxygen etched 17.6 22.7 Carbon molecular sieve from Takeda Chemical Industries 0.50 12.1 Effective minimum size 6.lA
Effective minimum size 4.3A
The following examples serve to illustrate but not limit the invention.
Example 1.
A 40 g sample of "Amberlite 200" (Registered Trademark of Rohm and Haas Company for a styrene/DVB sul-fonic acid ion exchange resin) in the Na+ form (49.15% solids) was placed in a filter tube and washed with 200 cc of D. I. H2O. 20 g of FeC13 6H2O were dissolved in about 1 1 of D.I. H2O and passed through the resin sample in a columnar manner over a period of about four hours. Uniform and complete loading could be observed visually. The sample was then washed with 1 1 of D.I. H2O, aspirated for 5 minutes and air dried for 18 hours.
10 grams of this sample was then pyrolyzed together with several other samples in a furnace equipped for input of 7 1 of argon gas per minute. The sample was raised to a temperature of 706C over a period of 6 hrs.
with step increases of about 110C each hour. The sample `
108~198 was held at the maximum temperature of 1/2 hour. The power to the furnace was shut off and the furnace and contents were allowed to cool undisturbed to room temperature with the argon flow;ng continuously over the next 16 hours. ;~
The yield of solid material was 43~ after pyrolysis. The physical characteristics of this sample are listed in Table V along with the data for Samples B through G, and I through K which were prepared in the same manner.
Example 2 The technique of example I is modified in that 250 gm of "Amberlite 200" in hydrogen form (obtained by converting the sodium form with hydrochloric acid) is pyrolyzed by raising the temperature continuously over six hours to 760C. The sample is then allowed to cool over the next twelve hours after which it shows a surface area of 390 m2/g.
Process Examples Adsorption of Vinyl Chloride Then cubic centimeters of sample are placed in a 1.69 centimeter inner diameter stainless steel column.
The bed depth is then 5.05 centimeters. Through the use of a dilution device with a mixing chamber, a gas stream of 580 ppm vinyl chloride in air is generated and passed through the column at a volumetric flow rate of 800 ml/min.
The column flow rate is therefore 80 bed volumes/minute. All experiments are conducted at ambient temperature and a pressure of 16 psig. A flow of 10 ml/min is diverted from the effluent and fed into a flame ionization detector for continuous vinyl chloride analysis. Conventional Rohm 1~8~198 .,, Cl h a uI~ ~ ~ I~ ~ ", ~
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, u~ ~C m ~ H 1 .. -- 24 --~L080~98 and Haas adsorbents and a Calgon activated carbon are also tested. The results are shown below.
Table VI
Adsorption of Vi'ny;l Chloride on Sample K, H~ Form, Pyrolyzed Elapsed TimeLeakage Instantaneous (min) (ppm VCM) Leakage O O O
o o ::
0 0 :
100 o o 125 0 a 150 o o 166 l ~1 200 34 5.8 300 580 100 ' Table VII
Adsorption of Vinyl Chloride on Sample B, Fe(III) Form, Pyrolyzed and:Le:a:ch:ed with H2SO4,:B:ed Vo:lume ~ 20 cc :
Elapsed TimeLeakage Instantaneous %
(min) (ppm) Leakage O O O
100 o o 109 1 .2 125 284 ~49 :
.~
:108~1913 Table VIII
Adsorption of Vinyl ChIoride on Sample C, Cu(II) Form, Pvrolvz'ed' ''' - - ' Elapsed TimeLeakage Instantaneous (mln) (ppm VCM) Leakage 125 0 o 143 1 0.2 150 2 0.4 Adsorption of Vinyl Chloride on Sample A Fe(III) form Pyrolyzed Elapsed TimeLeakage Instantaneous (min) (ppm VCM) Leakage O O O
125 2.0 0.3 150 26 4.5 116 1 0.2 :
' 30 .
~080198 'Tabl'e X
Adsorption of Vinyl ChIoride on '`Pittsburgh PCB"* 12 x 30 Activated Carbon '' ' ' ''''' ' ''''' ' '''''' Elapsed Time Leakage Instantaneous %
(min) - (ppm) Leakage ' O O O
117 1 0.2 200 5~0 100 Further Process Examples The adsorption is performed with a bed of 9.5 cc of Resin J which is subjected to a vinyl chloride influent stream containing 350 ppm and having a flow rate of 160 bed volumes per minute. Regeneration is carried out using steam at 130 - 160C for 20 minutes, followed by drying with air for 10 minutes. The experiment is performed for 15 cycles to show the lack of capacity loss over several cycles. Results are shown in the following table.
Table XI
Cycle Time*Volume Capacity Weight Capacity 1 45 6.9 11.1 3 42 6.4 10.3 49 7 5 12.1 7 45 6.9 11.1 ;
9 45 6.9 11.1 11 37 5.6 9.0 13 40 6.1 9.8 6.9 11.1 ' * Elapsed time at 1 ppm leakage in minutes :;
The results of comparative experiments on other commercial resins and carbon are shown in the following table.
; Table XII
Adsorbent Volume Capacity Weight Capacity (mg/cc) (mg/gm) Sample D 14.4 13.5 Sample F 9.8 13.1 Sample G 2.9 3.2 "Pittsburgh BPL"* 12 x 30 Activated Carbon8.5 17.0 "Kureha"** Spherical Activa,ted Carbon13.9 26.7 Sample H~lll) 29.2 47.1 Sample H(l) 26.6 42.4 "Pittsburgh PCB" 12 x 30 Carbon (11) 7.6 16.8 "Pittsburgh lP~)B" 12 x 30 Carbon ( 11.4 25.3 (1) Run with a 460 ppm influent concentration at 160 BV/ min over a 10 cc sample (11) Run with a 350 ppm influent concentration at 160 BV/
min over a 10 cc sample (111) Run with a 1070 ppm influent concentration at 160 BV/
min over a 10 cc sample (lV) Run with a 860 ppm influent concentration at 160 BV/
min over a 10 cc sample It should be noted that sample H prepared by the procedure of Example II is a preferred embodiment.
Sample J when compared to PCB 12 x 30 carbon shows a smaller drop in capacity when the relative humidity is ~-increased as shown herein below.
Volume Capacity mg/cc R. Humidity PCB 12 x 30 Sample J
0 11.4 6.4 52 9.6 7.4 ` 60 4.1 4.8 - 100 -- 2.3 Influent concentration - 850 to 1100 ppm ' ~';
*Trademark **Trademark Phenol Ad~o~r ~i~n 20 cc of Sample I is subjected to an influent concentration of 500 ppm of phenol dissolved in D. I. water.
The flow rate is 4 BV~hr. The sample shows a leakage of less than 1 ppm at 38 bed volumes. The samplels capacity is calculated to be 1.56 lbs./cubic ft. or 25Ø mg~gm at a leakage of 3 ppm.
"Amberlite XAD-4"* a commercial adsorbent when used as a comparison shows a capacity of 0.9 lbs./cubic ft. or 14.4 mg/gm at a leakage of 6 ppm.
Sample I is regenerated with methanol at a rate of 2 BV/hr. and required 5 BV to be 71% regenerated.
Sample B is evaluated for adsorbent capacity for H2S and SO2. The results indicate that significant amounts of both pollutants are adsorbed. Similar measurements for an activated carbon indicate a negligible adsorption of SO2 at 100C.
Synthetic organic polymers other than ion exchange ;
resins have been evaluated for adsorbent capacity. A sample of polyacrylonitrile crosslinked with 15% divinyl benzene has been pyrolyzed under a variety of experimental conditions and evaluated for SO2 adsorbancy. The experimental conditions and results are presented in Table XIII. Once again, significant quantities of SO2 are adsorbed. Example N is of particular interest since an oxidation of the copolymer in air prior to pyrolysis significantly increases the adsorption capacity of the pyrolyzed product for SO2.
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1080~98 Crush Resistance Th,e physical integrity o~ beads o~ pyrolyzed poly-mers is greater than that of other spherical adsorbents and granular activated carbon as indicated in Table XIv~ Superior resistance to fragmentation is expected to result in a greatly extended useful life compared to granular carbon for which attrition losses can be large. Also the lack of sloughage of particulate matter by the pyrolyzed polymers allows their use in applications for which activated carbon is unacceptable such as blood treatment.
TABLE XIV
Crush S'trength Of Macroretricul'ar Pyrolyzed Polymers 'And Other Adsorbents Description No. Type Crush Strength (Kg) Sulfonated S/DVB ¦ 1 400C 2.3 heat treated ¦ 2 under inert at- ( 2 500C >3.1 mosphere to in- \ 2 dicated tempera- ¦ 3 600C >3.4 ture ' ~4 800C ~3~4 2 1000C 3.6 20 Spherical Acti- ~6 "Kureha" 0.93 vated Carbon ~7 Sample of un- 0.51 known Japanese origin used for blood treatment experiments.
' ' Granular Acti- 8 "Pittsburgh -~O.90 ~, vated Carbon BPL"4 lMass which must be placed on upper of two parallel plates to i fragment particle between plates-average of at least 10 trials.
2Lower limit because at least one particle was not broken at maximum setting of 3.6 Kg.
3No beads were broken at maximum setting.
4Since particles are irregularly shaped, experiment was halted when a corner was knocked off.
1080~98 i) Carbon Fixing Moieties A wide variety of moieties have been shown to cause carbon fixation during pyrolysis. A partial list of moieties and the effectiveness of each is given in Table XV.
The exact chemical nature of the moiety is unimportant since any group which serves to prevent volatilization of the carbon during pyrolysis is satisfactory for the process.
ii) Imbided Carbon-Fixing Agents Filling the pores of a macroreticular copolymer with a reactive substance prior to pyrolysis serves to pre-vent volatilization of the carbon in the copolymer. In the case of sulfuric acid the material has been shown to go through a sulfonation reaction during heating which produces a substance similar to the starting material of sample 1 in Table XV. The greater carbon yield obtained via imbibing rather than presulfonation is unexpected indicating the pro-cess may be superior to other techniques of carbon fixation.
iii) Impregnated Polymers Impregnation is exemplified in No. 4 of Table XVI
for which the pores of a carbon black containing S/DVB copoly-mer were filled with H2S04 and pyrolyzed. The carbon yièld is higher than the corresponding experiment (sample 1) per-formed without the presence of the carbon black.
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Example 3 The following experiment produced sample No. 1 in Table XVI.
A sample of 30~79 g of the macroreticular copoly- -mer (20% DVB~S) was placed in a 30mm O.D. quartz tube suitable for subsequent heat treatment. One end of the tube was blocked with quartz wool and the copolymer was piled on top of the quartz wool with the tube held vertically~ Isopro~
panol, D.I. water and 98% H2SO4 (1 ~each) were passed in se-quence through the resin over a 1.5 hr. period. Excess H2SO4 was drained during a 10 min. hold. Approximately 5.5 g of acid remained in the pores of the resin. The tube was placed horizontally in a tube furnace and N2 passed through the tube at 4,800 cc/min. During heatings white smoke and then a red-dish, pungent smelling oil were emitted from the sample. The final product was black, shiny, free flowing beads roughly the same size as the starting resin.
Example 4 The following experiment produced sample 2 of Table XVI.
A benzoic acid copolymer was prepared from a chloro-methylated resin (20% DVB/S) by nitric acid oxidation. A
charge of 20.21 g of the solvent swelled and vacuum dried resin was placed in a quartz tube plugged at one end with quartz wool.
The tube was held horizontally inside a "Glas-col"* heating mantle and heated gradually to 800C. over a period of 200 mins. ;
The sample was cooled to room temperature within about 120 min.
Nitrogen flowed through the tube during heating at a rate of 4800 cc/min. White smoke was emitted by the sample during heating. The final product consisted of shiny metallic black beads.
* Trademark
The results of comparative experiments on other commercial resins and carbon are shown in the following table.
; Table XII
Adsorbent Volume Capacity Weight Capacity (mg/cc) (mg/gm) Sample D 14.4 13.5 Sample F 9.8 13.1 Sample G 2.9 3.2 "Pittsburgh BPL"* 12 x 30 Activated Carbon8.5 17.0 "Kureha"** Spherical Activa,ted Carbon13.9 26.7 Sample H~lll) 29.2 47.1 Sample H(l) 26.6 42.4 "Pittsburgh PCB" 12 x 30 Carbon (11) 7.6 16.8 "Pittsburgh lP~)B" 12 x 30 Carbon ( 11.4 25.3 (1) Run with a 460 ppm influent concentration at 160 BV/ min over a 10 cc sample (11) Run with a 350 ppm influent concentration at 160 BV/
min over a 10 cc sample (111) Run with a 1070 ppm influent concentration at 160 BV/
min over a 10 cc sample (lV) Run with a 860 ppm influent concentration at 160 BV/
min over a 10 cc sample It should be noted that sample H prepared by the procedure of Example II is a preferred embodiment.
Sample J when compared to PCB 12 x 30 carbon shows a smaller drop in capacity when the relative humidity is ~-increased as shown herein below.
Volume Capacity mg/cc R. Humidity PCB 12 x 30 Sample J
0 11.4 6.4 52 9.6 7.4 ` 60 4.1 4.8 - 100 -- 2.3 Influent concentration - 850 to 1100 ppm ' ~';
*Trademark **Trademark Phenol Ad~o~r ~i~n 20 cc of Sample I is subjected to an influent concentration of 500 ppm of phenol dissolved in D. I. water.
The flow rate is 4 BV~hr. The sample shows a leakage of less than 1 ppm at 38 bed volumes. The samplels capacity is calculated to be 1.56 lbs./cubic ft. or 25Ø mg~gm at a leakage of 3 ppm.
"Amberlite XAD-4"* a commercial adsorbent when used as a comparison shows a capacity of 0.9 lbs./cubic ft. or 14.4 mg/gm at a leakage of 6 ppm.
Sample I is regenerated with methanol at a rate of 2 BV/hr. and required 5 BV to be 71% regenerated.
Sample B is evaluated for adsorbent capacity for H2S and SO2. The results indicate that significant amounts of both pollutants are adsorbed. Similar measurements for an activated carbon indicate a negligible adsorption of SO2 at 100C.
Synthetic organic polymers other than ion exchange ;
resins have been evaluated for adsorbent capacity. A sample of polyacrylonitrile crosslinked with 15% divinyl benzene has been pyrolyzed under a variety of experimental conditions and evaluated for SO2 adsorbancy. The experimental conditions and results are presented in Table XIII. Once again, significant quantities of SO2 are adsorbed. Example N is of particular interest since an oxidation of the copolymer in air prior to pyrolysis significantly increases the adsorption capacity of the pyrolyzed product for SO2.
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1080~98 Crush Resistance Th,e physical integrity o~ beads o~ pyrolyzed poly-mers is greater than that of other spherical adsorbents and granular activated carbon as indicated in Table XIv~ Superior resistance to fragmentation is expected to result in a greatly extended useful life compared to granular carbon for which attrition losses can be large. Also the lack of sloughage of particulate matter by the pyrolyzed polymers allows their use in applications for which activated carbon is unacceptable such as blood treatment.
TABLE XIV
Crush S'trength Of Macroretricul'ar Pyrolyzed Polymers 'And Other Adsorbents Description No. Type Crush Strength (Kg) Sulfonated S/DVB ¦ 1 400C 2.3 heat treated ¦ 2 under inert at- ( 2 500C >3.1 mosphere to in- \ 2 dicated tempera- ¦ 3 600C >3.4 ture ' ~4 800C ~3~4 2 1000C 3.6 20 Spherical Acti- ~6 "Kureha" 0.93 vated Carbon ~7 Sample of un- 0.51 known Japanese origin used for blood treatment experiments.
' ' Granular Acti- 8 "Pittsburgh -~O.90 ~, vated Carbon BPL"4 lMass which must be placed on upper of two parallel plates to i fragment particle between plates-average of at least 10 trials.
2Lower limit because at least one particle was not broken at maximum setting of 3.6 Kg.
3No beads were broken at maximum setting.
4Since particles are irregularly shaped, experiment was halted when a corner was knocked off.
1080~98 i) Carbon Fixing Moieties A wide variety of moieties have been shown to cause carbon fixation during pyrolysis. A partial list of moieties and the effectiveness of each is given in Table XV.
The exact chemical nature of the moiety is unimportant since any group which serves to prevent volatilization of the carbon during pyrolysis is satisfactory for the process.
ii) Imbided Carbon-Fixing Agents Filling the pores of a macroreticular copolymer with a reactive substance prior to pyrolysis serves to pre-vent volatilization of the carbon in the copolymer. In the case of sulfuric acid the material has been shown to go through a sulfonation reaction during heating which produces a substance similar to the starting material of sample 1 in Table XV. The greater carbon yield obtained via imbibing rather than presulfonation is unexpected indicating the pro-cess may be superior to other techniques of carbon fixation.
iii) Impregnated Polymers Impregnation is exemplified in No. 4 of Table XVI
for which the pores of a carbon black containing S/DVB copoly-mer were filled with H2S04 and pyrolyzed. The carbon yièld is higher than the corresponding experiment (sample 1) per-formed without the presence of the carbon black.
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Example 3 The following experiment produced sample No. 1 in Table XVI.
A sample of 30~79 g of the macroreticular copoly- -mer (20% DVB~S) was placed in a 30mm O.D. quartz tube suitable for subsequent heat treatment. One end of the tube was blocked with quartz wool and the copolymer was piled on top of the quartz wool with the tube held vertically~ Isopro~
panol, D.I. water and 98% H2SO4 (1 ~each) were passed in se-quence through the resin over a 1.5 hr. period. Excess H2SO4 was drained during a 10 min. hold. Approximately 5.5 g of acid remained in the pores of the resin. The tube was placed horizontally in a tube furnace and N2 passed through the tube at 4,800 cc/min. During heatings white smoke and then a red-dish, pungent smelling oil were emitted from the sample. The final product was black, shiny, free flowing beads roughly the same size as the starting resin.
Example 4 The following experiment produced sample 2 of Table XVI.
A benzoic acid copolymer was prepared from a chloro-methylated resin (20% DVB/S) by nitric acid oxidation. A
charge of 20.21 g of the solvent swelled and vacuum dried resin was placed in a quartz tube plugged at one end with quartz wool.
The tube was held horizontally inside a "Glas-col"* heating mantle and heated gradually to 800C. over a period of 200 mins. ;
The sample was cooled to room temperature within about 120 min.
Nitrogen flowed through the tube during heating at a rate of 4800 cc/min. White smoke was emitted by the sample during heating. The final product consisted of shiny metallic black beads.
* Trademark
Claims (9)
1. Partially pyrolyzed particles of a macroporous synthetic polymer having properties suitable for use in adsorption, molecular screening and/or catalysis and a resistance to crushing and particle sloughage greater than that of known spherical adsorbent particles or that of granular activated carbon, comprising the product of controlled thermal degradation of a macroporous synthetic polymer containing a carbon-fixing moiety and derived from one or more ethylenically unsaturated monomers, or from monomers which may be condensed to yield macroporous polymers, or mixtures thereof, which partially pyrolyzed particles have:
(a) at least 85% by weight of carbon, (b) multimodal pore distribution with macropores ranging in size from about 50 .ANG.
to about 100,000 .ANG. in average critical dimension and with micropores ranging in size from about 4 .ANG. to about 50 .ANG. in average critical dimension, and (c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1.
(a) at least 85% by weight of carbon, (b) multimodal pore distribution with macropores ranging in size from about 50 .ANG.
to about 100,000 .ANG. in average critical dimension and with micropores ranging in size from about 4 .ANG. to about 50 .ANG. in average critical dimension, and (c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1.
2. The partially pyrolyzed particles of claim 1 wherein the particles are beads or spheres of approximately the same dimensions as ion exchange resins.
3. The partially pyrolyzed particles of claim 1 wherein the surface area of the particles measured by N2 adsorption ranges between 50 and 1500M2/gram, of which the macropores contribute about 6 to about 700M2/gram as determined by mercury adsorption techniques.
4. The partially pyrolyzed particles of claim 1 wherein the particles contain micropores of molecular sieve size ranging between about 4 .ANG. and 6 .ANG. in average critical dimension.
5. The partially pyrolyzed particles of claim 1 wherein the carbon to hydrogen atom ratio is between about 20:1 and 10:1.
6. The partially pyrolyzed particles of claim 1 wherein the carbon-fixing moiety is selected from sulfonate, carboxyl, amine, halogen, oxygen, sulfonate salts, carboxylate salts and quaternary amine salts.
7. The partially pyrolyzed particles of claim 1 wherein the carbon to hydrogen atom ratio of the particles is at least 9Ø
8. A process for producing partially pyrolyzed particles of a macroporous synthetic polymer having properties suitable for use in adsorption, molecular separations, and/or catalysis and a resistance to crushing and particle sloughage greater than that of known spherical adsorbent particles or that of granular activated carbon, which comprises thermally degrading at a temperature between about 300°C and about 900°C
and in an inert gaseous atmosphere optionally containing an activating gas, a macroporous synthetic polymer containing a carbon-fixing moiety and derived from one or more ethylenically unsaturated monomers or from monomers which may be condensed to yield macroporous polymers, or mixtures thereof, for a time sufficient to drive off sufficient volatile components of the synthetic polymer to yield particles having: (a) at least 85% by weight of carbon, (b) multimodal pore distribution with macropores ranging in size from about 50 .ANG. to about 100,000 .ANG. in average critical dimension and with micropores ranging in size from about 4 .ANG. to about 50 .ANG.
in average critical dimension, and (c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1; and thereafter cooling said particles under said inert atmosphere to a temperature below that which would cause oxidation in air.
and in an inert gaseous atmosphere optionally containing an activating gas, a macroporous synthetic polymer containing a carbon-fixing moiety and derived from one or more ethylenically unsaturated monomers or from monomers which may be condensed to yield macroporous polymers, or mixtures thereof, for a time sufficient to drive off sufficient volatile components of the synthetic polymer to yield particles having: (a) at least 85% by weight of carbon, (b) multimodal pore distribution with macropores ranging in size from about 50 .ANG. to about 100,000 .ANG. in average critical dimension and with micropores ranging in size from about 4 .ANG. to about 50 .ANG.
in average critical dimension, and (c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1; and thereafter cooling said particles under said inert atmosphere to a temperature below that which would cause oxidation in air.
9. The process of claim 8 wherein the thermal degradation is conducted at a temperature between about 400°C and 800°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US55049575A | 1975-02-18 | 1975-02-18 | |
| US05/652,019 US4040990A (en) | 1975-02-18 | 1976-01-26 | Partially pyrolyzed macroporous polymer particles having multimodal pore distribution with macropores ranging from 50-100,000 angstroms |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1080198A true CA1080198A (en) | 1980-06-24 |
Family
ID=27069476
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA245,934A Expired CA1080198A (en) | 1975-02-18 | 1976-02-17 | Pyrolyzed beads of a resinous polymer |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4040990A (en) |
| CA (1) | CA1080198A (en) |
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| JPS5397987A (en) * | 1977-01-26 | 1978-08-26 | Osaka City | Itaconic acid porous weak acidic ion exchange resin and manufacturing method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL7018698A (en) | 1970-12-22 | 1972-01-25 | Porous cross-linked copolymers - from alkenic monomers, for conversion to ion-exchange resins | |
| US3816355A (en) * | 1971-12-06 | 1974-06-11 | Rohm & Haas | Macroreticular sulfonated pyridine-divinylbenzene resins |
-
1976
- 1976-01-26 US US05/652,019 patent/US4040990A/en not_active Expired - Lifetime
- 1976-02-17 CA CA245,934A patent/CA1080198A/en not_active Expired
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