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Publication numberUS3893912 A
Publication typeGrant
Publication dateJul 8, 1975
Filing dateApr 8, 1974
Priority dateApr 8, 1974
Publication numberUS 3893912 A, US 3893912A, US-A-3893912, US3893912 A, US3893912A
InventorsAbraham A Zimmerman
Original AssigneeExxon Research Engineering Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method of removing organometallic compounds from liquid hydrocarbons
US 3893912 A
Abstract
Organometallic compounds are separated from liquid hydrocarbons containing the same by contacting the liquid hydrocarbon first with a treating agent selected from the group consisting of silicon tetrachloride, cupric chloride, cupric bromide, iodine and iodine in combination with an acid and then with a suitable sorbent such as an activated charcoal. Both the initial and final contacting may be accomplished at any combination of temperature and pressure at which the hydrocarbon will remain liquid and at which all components used in the process will remain stable. Both the initial and final contacting may be accomplished in essentially any suitable fashion; however, the first treating agent will, generally, be used in combination with a suitable solvent and effecting the second contacting in a fixed bed of the sorbent is, generally, most convenient and effective.
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Description  (OCR text may contain errors)

United States Patent [1 1 Zimmerman [451 July 8,1975

[75] Inventor: Abraham A. Zimmerman, New

Providence, NJ.

[73] Assignee: Exxon Research and Engineering Company, Linden, NJ.

[22] Filed: Apr. 8, 1974 [21] Appl. No.: 458,668

[52] US. Cl 208/253; 208/251 R; 208/307; 208/278; 208/91; 208/295; 208/296 [51] Int. Cl C10g 17/00 [58] Field of Search 208/253, 251 R, 252, 99, 208/289, 290-295, 307, 278, 281, 91, 251, 296

[56] References Cited UNITED STATES PATENTS 1,769,794 7/1930 Leamon 208/307 1,814,410 7/1931 Richter et al. 208/295 1,988,114 6/1935 Egloff et al. 208/287 2,060,291 11/1936 Egloff 208/296 2,063,517 12/1936 Morrell et al.. 208/296 2,392,846 l/l946 Friedman 208/253 2,884,369 4/1959 Mattox et al..... 208/251 R 3,785,968 1/1974 Whitehurst 208/251 3,791,968 3/1974 Whitehurst et al. 208/251 3,838,043 9/1974 Crook et al 208/253 R19,879 3/1936 Lachman 208/296 OTHER PUBLICATIONS OSRD No. 3018 National Defense Research Committee of Scientific Research and Development Primary ExaminerDelbert E. Gantz Assistant Examiner-Juanita M. Nelson Attorney, Agent, or F irmWayne Hoover [5 7] ABSTRACT Organometallic compounds are separated from liquid hydrocarbons containing the same by contacting the liquid hydrocarbon first with a treating agent selected from the group consisting of silicon tetrachloride, cupric chloride, cupric bromide, iodine and iodine in combination with an acid and then with a suitable sorbent such as an activated charcoal. Both the initial and final contacting may be accomplished at any com bination of temperature and pressure at which the hydrocarbon will remain liquid and at which all components used in the process will remain stable. Both the initial and final contacting may be accomplished in essentially any suitable fashion; however, the first treating agent will, generally, be used in combination with a suitable solvent and effecting the second contacting in a fixed bed of the sorbent is, generally, most convenient and effective.

15 Claims, N0 Drawings METHOD OF REMOVING ORGANOMETALLIC COMPOUNDS FROM LIQUID HYDROCARBONS BACKGROUND OF THE INVENTION This invention relates to a process for separating organometallic compounds from liquid hydrocarbons. More particularly, this invention relates to a process for separating organo lead compounds from liquid hydrocarbons.

As is well known, there is an increasing public and governmental interest in eliminating or at least significantly reducing the amount of lead emitted to the atmosphere as the result of combustion of leaded fuels in internal combustion engines. In fact, recently passed legislation does (or will) establish emission standards which can be met only through the use of substantially lead-free fuels. The same or related legislation also creates specifications for such fuels and can impose rather harsh sanctions against those which would market such fuels but not meet the specifications therefor.

The production of lead-free of substantially lead-free fuels is, of course, well within the ordinary skill of the art. Delivery of such fuels to the consumer, however, cannot be as easily accomplished. In fact, past experience with both lead-free and low lead fuels has indicated that intentional and/or inadvertent comingling of such fuels with leaded fuels renders such ultimate delivery impossible, at least, in 100% of the cases. Such comingling could, of course, occur in the pipelines or transport tankers as well as in storage tanks at terminals or retail outlets. The need, then, for a method, short of separate transport and storage facilities, which would ensure the delivery of a substantially lead-free fuel is readily apparent.

One such method which could be used is a separation method which would permit separation of relatively minor amounts of lead from the fuel stored at a terminal or a retail outlet (after transport) or from the gasoline in a tanker or pipeline or delivery truck prior to transfer into a storage vessel. Indeed, several separation processes have, heretofore, been proposed for the separation of organo lead compounds from gasoline. Generally, these have been two-step processes wherein the organo lead compound is first converted to an insoluble or easily absorbed form and thereafter separated either by absorption, water washing, filtration and/or decanting. Often, the chemical conversion is accomplished with a Lewis acid such as stannic chloride and the separation effected with an adsorbent such as activated charcoal. These prior art methods have, however, been primarily concerned with the separation of relatively high concentrations of lead (greater than 1 gram lead per gallon of gasoline) from relatively small volumes of gasoline and are not well suited to use for theseparation of relatively small concentrations of lead (less than 0.5 grams lead per gallon of gasoline) from comparatively large volumes of gasoline. In this regard, it should be noted that separation rate was a relatively minor consideration in the prior art processes with emphasis having been placed on separation capacity. In the present situation, emphasis must be placed on the absorption rate due to the large volumes which must be treated and separation capacity is a less significant factor.

In general, these prior art processes also result in an increased gum content in the treated gasoline. While this condition may, generally, be tolerated with respect to relatively small volumes of gasoline, to be used in relatively inexpensive equipment having a relatively short design life, it obviously cannot be tolerated in large volumes of gasoline to be used in modern automobile engines. The need, then, for a separation process suited to the treatment of large volumes of gasoline without increasing the gum content thereof should be readily apparent.

SUMMARY OF THE INVENTION It has now been found that the foregoing and other deficiencies of the prior art organo lead separation processes can be avoided with the process of this invention and a process well suited to the separation of relatively small concentrations of lead from relatively large volumes of liquid hydrocarbon provided thereby. It is, therefore, an object of this invention to provide an improved process for separating organo lead compounds from liquid hydrocarbons. It is another object of this invention to provide such a process wherein the separation is accomplished at a relatively high rate. It is still another object of this invention to provide such a process which may be used without increasing the gum content of the liquid hydrocarbons subjected to treatment. Still other objects and advantages will become apparent from the disclosure set forth hereinafter.

In accordance with the present invention, the foregoing and other objects and advantages are accomplished with a process wherein a liquid hydrocarbon containing one or more organo lead compounds is first contacted with one or more treating agents selected from the group consisting of silicon tetrachloride, iodine, iodine in combination with an acid, cupric chloride and cupric bromide and thereafter contacted with a suitable sorbent. As is pointed out more fully hereinafter, it is essential that the selected treating agent be used in combination with a suitable solvent although the liquid hydrocarbon may, itself, satisfy this requirement in certain cases.

DETAILED DESCRIPTION OF THE INVENTION Broadly, the method of this invention can be used to separate or remove organo lead compounds from any hydro carbon which might contain such organo lead compounds in a dissolved form. The process may, then, be used to separate organo lead compounds from normally gaseous hydrocarbons which have been made liquid as a result of increased pressure as well as solid or highly viscous hydrocarbons which had been made liquid as the result of increased temperature. The process is equally useful to separate organo lead compounds from mixtures of such hydrocarbons as well as mixtures of either one or both of these types of hydrocarbon with normally liquid hydrocarbons. The process is, however, most useful for the separation of organo lead compounds from mixtures of normally liquid hydrocarbons, which mixtures contain one or more gaseous hydrocarbons dissolved therein. Mixtures of this type include the leaded and unleaded fuels such as gasoline, jet fuel and kerosene. The method of this invention is particularly useful for the separation of organo lead compounds from conventional leaded gasolines as well as unleaded gasolines which may as a result of contamination contain relatively minor amounts of organo lead compounds.

As indicated previously, the organo lead compounds will be separated by first contacting the liquid hydrocarbon containing the same with one or more pretreating agents selected from the class consisting essentially of silicon tetrachloride, iodine, iodine in combination with an acid, cupric chloride and cupric bromide. Generally, the treating agent selected for use will first be dissolved in a suitable solvent and then contacted with the liquid hydrocarbon in any suitable fashion which will insure reasonably good contacting between the organo lead compound or compounds and the pretreating agent. The use of a separate solvent is not, however, essential to the method of the present invention, particularly, when the treating agent employed is either soluble in the liquid hydrocarbon or when the liquid hydrocarbon also contains one or more constituents which is soluble therein and in which the selected treating agent is also soluble.

As used herein, then, in reference to the pretreating agent, the recitation suitable solvent means a material not only in which the pretreating agent is soluble at the concentration employed therein but one which is, itself, soluble in the liquid hydrocarbon at the concentration in which it is added thereto. Also, the recitation as used herein is intended to include only those materials which can be separated from the liquid hydrocarbon after the pretreatment or which, if allowed to remain therein, will not adversely affect the quality or character of the liquid hydrocarbon or detract from its use for its intended purpose. Suitable solvents do, therefore, include both organic and inorganic materials which satisfy the dual solubility requirement heretofore noted. The organic solvents are, however, preferred, since, generally, these materials need not be separated from the liquid hydrocarbon after the pretreatment so as to preserve the character and quality thereof. Useful organic solvents include alcohols, ethers, ketones, and aromatic hydrocarbons such as benzene and xylene. Moreover, alcohols and particularly isopropyl alcohol, are particularly preferred. It should, however, be noted that alcohols will not generally be used with SiCl, due to undesirable reactions thereof.

As previously indicated, then, the selected pretreating agent or agents will, generally, be dissolved in a suitable solvent before the same is contacted with the liquid hydrocarbon containing the dissolved organo lead compound or compounds. The actual concentra tion of pretreating agent in solution is, however, not critical to the present invention and, indeed, essentially any concentration consistent with the aforementioned solubility requirements can be used. Notwithstanding this, however, and since organic solvents will preferably be used without subsequent separation thereof, it is also preferred that those solvents permitting the higher concentrations of pretreating agents be used and that the solutions be used at the higher concentrations so as to minimize dilution of the liquid hydrocarbon being treated. Since the alcohols, and particularly the lower monohydric alcohols containing from about I to about 6 carbon atoms therein, yield solutions containing the highest concentrations of pretreating agent or agents, these solvents are particularly preferred for all of the pretreating agents except SiCL, and isopropyl alcohol is the most preferred of this group of solvents. For SiCl the hydrocarbon solvents and particularly the aromatic hydrocarbon solvents such as xylene are particularly preferred.

Similarly, the amount of pretreating agent or agents added to the hydrocarbon is not critical, especially in these embodiments wherein a sorbent, impregnated with a material capable of converting the dissolved organo lead compounds to a different, more easily separated form, is used. In this regard, and while the inventor does not wish to be bound by any particular theory, it is believed that the pretreating agents useful in this invention react with the organo lead compounds so as to form different lead compounds which are either insoluble (and therefore readily separable) or which are more readily absorbed by the sorbentsused in the second step of the present invention. The amount actually used is, then, not critical since, in any case, some reduction will be achieved at any concentration and, indeed, when an impregnated sorbent is used, substantially complete separation of the lead compounds is possible at any concentration. Nonetheless, the method of this invention is most effective when the amount of pretreating agent actually used is between about l and 20 times that which would be required for a stoichiometric conversion to a monohalide derivative of all organo lead contained in the liquid hydrocarbon subjected to treatment.

With respect to what would constitute a stoichiometric amount of a p'retreating agent, it should be noted that when iodine or silicon tetrachloride are used as the pretreating agents and the organo lead compounds are all of the tetralkyl variety, one mole of iodine or silicon tetrachloride per mole of tetraalkyl lead compound would effect a stoichiometric conversion thereof. The molar amount of cupric chloride and/or cupric bromide required, on the other hand, would be twice the amount of silicon tetrachloride required for a comparable conversion. Finally, the amount of iodine plus an acid required will depend upon the particular acid used, and upon the molar ratio of iodine and acid actually employed. In this regard, it should be noted that any acid containing an anion which will displace an alkyl radical of the alkylated compound and thereby form a less soluble or more readily absorbed lead compound could be used in combination with the iodine. Acids containing the sulfate anion or anions derived from the halide group and, particularly hydrogen chloride, are, however, preferred. In this case, then, the molar ratio of iodine (1 to acid (l-ICl) will range between about 0.1 and i 0.5 and the molar amount of iodine plus and acid required to effect a stoichiometric conversion will usually be the same molar amount required for a corresponding conversion with silicon tetrachloride.

in general, the pretreatment step of this invention will be accomplished by contacting or mixing the lead containing hydrocarbon with pretreating agent solution at a temperaturebetween about 30 and F., although higher or lower temperatures might be used in certain cases, with agitation or other means for providing the desired degree of mixing. Generally, conversion of the organo lead compounds will be accomplished within a time period of about 3 to about 40 minutes. Longer contacting periods may, however, be required for the conversion of some lead compounds.

In general, any of the absorbents known in the prior art to be useful for separating lead compounds from liq- -uid hydrocarbons can be used in the absorption step of thepresent process. These include activated carbon, acid treated clays, silica gel, etc. Moreover, the ferric chlorideimpregnated activated carbons, disclosed in the inventors copending application Ser. No. 405,124

which was filed Oct. 10, 1973, and the cupric chloride impregnated activated carbons, disclosed in the inventors copending application Ser. No. 458,669 which was filed of even date herewith, can be used. Activated carbons, either with or withouot an impregnated metal halide, will, generally, yield best, results and are therefore preferred.

In this regard, it has been discovered that only a limited number of the commercially available activated carbons or charcoals can be used in the process of this invention to achieve the desired high degree of separation. Such activated carbons include those which are substantially amorphous; i.e., activated carbons which do not exhibit a graphitic structure or at least only slightly so, and which have high oxygen contents, high pore volumes and relatively high surface areas per unit weight. It will, of course, be appreciated that the method of preparing the activated carbon; i.e. preparation with or without chemicals, may not have any significant effect on the performance thereof in the process of this invention and activated carbons prepared by any method are considered equivalent so long as the properties thereof are within the ranges set forth hereinafter. One exception to this otherwise general rule is, however, that preparation in the presence of a relatively strong acid such as hydrochloric acid or treatment with such an acid after preparation will, generally, enhance performance. Care should, however, be taken in such treatment to avoid acid concentrations suffihigh to permit leaching thereof during the contacting process such that the acid number of the treated hydrocarbon is significantly increased.

As has been noted, supra, best results are achieved with the method of this invention when the activated carbons employed therein is substantially amorphous. This does not, however, mean that the activated carbons must be completely free of crystalline structure. In fact, it has been found that useful activated carbons may exhibit up to about wt. crystallinity or that the same may contain up to 20 wt. %-of carbon having a graphitic type structure. Such activated carbons are, therefore, considered to be within the meaning ofsubstantially amorphous as used herein. Also, the activated carbons which are useful in the method of this invention will exhibit oxygen contents within the range of about 3 to about wt. total pore volumes within the range of about 0.5 to about 1.5 ml/g; and surface areas within the range of about 200 to about 1500 m /g.

At this point it should be noted that while any activated carbon exhibiting properties within the aforedescribed ranges is operable, best results are obtained with activated carbons containing minimal amounts; i.e. less than about 5 wt. of crystalline structure. Moreover, it should be noted that when activated carbons having higher degrees of crystalline structures (within the range heretofore specified) are used, best results therewith will usually be obtained when there is also a corresponding increase in the oxygen content thereof as well as with increased total pore volumes.

As will be readily apparent, the particle size of the activated carbon is not critical to the present invention. Indeed, the method would be quite operative with any reasonable particle size provided that satisfactory means for separating the impregnated activated carbon are used. In this regard, it should be noted that essentially any of .the filtration-or centrifugation methods known in the prior art couldbe used to separate particles too small to be separated with any other means in either a batch or continuous operation. Similarly, any other means known to be effective in separating solids from liquids could be employed to effect the desired separation. It is, however, most expedient and effective to carry out the method of the present invention in such a way as to either eliminate or at least minimize the need for such solid separation and to minimize contacting time. For this reason, it is preferred to accomplish the liquid hydrocarbon-impregnated activated carbon contacting by passing the liquid hydrocarbon through a fixed bed of the impregnated, activated carbon. When this method is used, a granular type activated type carbon will be used and the particle size will, generally, range between about 0.01 and 0.15 inches.

When a ferric chloride impregnated activated carbon is used, the same will preferably be prepared in the same manner as indicated in copending application Ser. No. 405,124. As there indicated, any of the hydrous ferric chlorides known in the art may be used for form an impregnated activated carbon useful in the method of the present invention, In this regard, as is well known, the hydrous ferric chlorides may be represented by the formula FeCl 'X O wherein X may be any one of several numbers including 5, 6 and 12. These compounds may, of course, be readily prepared with methods well known in the prior art or the same may be obtained commercially from sereral sources.

The ferric chloride impregnated activated carbon useful in the method of this invention will then be prepared by first dissolving a suitable hydrated ferric chloride in water and then combining the ferric chloride solution with a suitable activated carbon. The concentration of ferric chloride in the aqueous solution as well as the amount of such solution used in combination with the activated carbon is, of course, not critical to the invention and a satisfactory impregnated product can be obtained over a relatively broad range of such conditions. Best results, however, will be obtained when the total concentration of hydrous ferric chloride in solution is sufficient to provide the desired concentration of ferric chloride on the activated charcoal and when the total amount of solution employed is sufficient to insure good wetting of the activated charoal, and hence, good distribution of the ferric chloride without providing a large excess of water which must later be removed. Generally, the aqueous hydrous ferric chloride solution and the activated charoal will be contacted in such a manner as to insure good distribution of the ferric chloride over the activated charcoal. This can, of course, be readily accomplished with any of the well known mixing techniques. After the ferric chloride solution and the activated carbon have been contacted for a sufficient period of time, excess water will be removed by drying. Again, this can be accomplished with methods well known in the prior art such as by drying at an elevated temperature in an oven and/or by contacting the impregnated activated carbon with an inert stripping gas such as nitrogen or air. It will, of course, be appreciated that the drying time and/or conditions can be controlled such that the resulting impregnated activated carbon may contain any desired concentration of water within the pores thereof.

Generally, a satisfactory ferric chloride-impregnated activated carbon can be prepared by first forming an aqueous solution of hydrous ferric chloride containing between about 5 and 15 wt. ferric chloride (on a water-free basis) and thereafter contacting between about 1 and 2 milliliters of this solution per gram of activated carbon (on a water-free basis). This contacting can be accomplished at any temperature and pressure at which the hydrous ferric chloride remains in solution and at which the solution remains liquid. Generally, the contacting will be continued for a period of time sufficient to permit a complete wetting of the activated carbon. Following this contacting, the wetted activated carbon will be dried so as to remove at least 50 wt. of the total water; i.e., the water derived from the hydrous ferric chloride as well as any that might be contained in the activated carbon and the water used to form the solution, therefrom and most generally so as to remove between about 65 and 85 wt. of such total water. Generally, the ferric chloride impregnated activated carbon which may be used in the method of this invention will contain between about 5 and wt. FeCl (on a water-free basis), between about 50 and 93 wt. activated carbons on a water-free basis, and between about 2 and wt. water.

When a copper chloride impregnated activated carbon is employed in the method of this invention, the same will be prepared in the manner disclosed in copending application Ser. No. 458,669. As there indicated, the impregnated activated carbon useful in the method of this invention may be prepared by first dissolving a cupric chloride in a suitable solvent and then combining the cupric chloride solution with a suitable activated carbon. The concentration of cupric chloride in the solution as well as the amount of such solution used in combination with the activated carbon is, of course, not critical to the invention and a satisfactory impregnated product can be obtained over a relatively broad range of such conditions. Best results, however, will be obtained when the total concentration of cupric chloride in solution is sufficient to provide the desired concentration of cupric chloride on the activated charcoal and when the total amount of solution employed is sufficient to insure good wetting of the activated charcoal, and hence, good distribution of the cupric chloride without providing a large excess of solvent which must later be removed. Generally, the cupric chloride solution and the activated charcoal will be contacted in such a manner as to insure good distribution of the cupric chloride over the activated charcoal. This can, of course, be readily accomplished with any of the well known mixing techniques. After the cupric chloride solution and the activated carbon have been contacted for a sufficient period of time, excess solvent will be removed by drying. Again, this can be accomplished with methods well known in the prior art such as by drying at an elevated temperature in an oven and- /or by contacting the impregnated activated carbon with an inert stripping gas such as nitrogen or air. It will, or course, be appreciated that the drying time and- /or conditions can be controlled such that the resulting impregnated activated carbon may contain any desired concentration of solvent within the pores thereof.

In the broadest embodiment of this invention, organo lead compounds will be separated from liquid hydrocarbons by first contacting a liquid hydrocarbon containing one or more organo lead compounds with a pretreating agent selected from the group consisting of silica tetrachloride, iodine, iodine plus an acid, cupric chloride and cupric bromide and thereafter contacting the pretreated liquid hydrocarbon with a suitable sorbent. The desired contacting in both steps may be accomplished either in a batch, semi-batch or continuous operation and as indicated, supra, essentially any absorbent particle size may be used. Where the particle size is relatively small, however, it will be necessary to separate the impregnated activated carbon from the liquid hydrocarbon with a suitable method such as filtration or centrifugation. Where the particle size is somewhat larger, however, separation might be accomplished by settling followed by decanting or again with methods such as filtration and centrifugation. Where the particle size is sufficiently large and particularly in the range previously specified, it will be possible to effect the contacting in a fixed bed of the impregnated activated carbon, in which case the liquid hydrocarbon will, effectively, be separated from the impregnated activated carbon after the desired contacting has been accomplished.

Broadly, the method of this invention may be used to treat liquid hydrocarbons containing essentially any possible concentration of dissolved organo lead compounds. Generally, however, the method will be used to treat hydrocarbons containing less than 5 grams of dissolved lead per gallon and the same will be most effective for treating liquid hydrocarbons having less than 0.5 grams of dissolved lead per gallon. In this regard, it should be noted that the effective life of the absorbent will depend upon the amount of lead and other components actually separated therewith and as is pointed out more fully, hereinafter, the method of this invention will be most effective when the liquid hydrocarbon is pretreated with at least a stoichiometric quantity of pretreating agent required for conversion of the organo lead compound to a monohalide derivative. The advantages derived from such pretreatment are, of course, most significant from a standpoint of overall separation and sorbent life.

In general, separation of the organo lead compounds will be accomplished at a satisfactory rate when sufficient sorbent is used to provide between about 10 and 200 grams of sorbent, on a water-free basis, per gram of dissolved lead in the liquid hydrocarbon subjected to treatmentJMoreover, the rate of absorption will remain satisfactory, at least in those cases where the hydrocarbon does not contain other components which might interfere with the lead separation, until the amount of lead absorbed by the sorbent is somewhere within the range of about 0.005 to 0.10 grams of lead per gram of sorbent (on a water-free basis). As will be readily apparent, then, in a batch operation separation can be effected by adding a fixed amount of the pretreating agent and asorbent to a fixed volume of liquid hydrocarbon, the amount added being determined by the amount of lead to be separated from the liquid hydrocarbon and the amount, if any, of other components which might also be reacted or absorbed or otherwise decrease the capacity of the pretreating agent and/or sorbent. In a semi-batch or continuous operation, on the other hand, contacting with a pretreating agent followed by contacting with a fixed amount of sorbent could be continued until the concentration of lead in the treated hydrocarbon exceeds the desired concentrations.

It will, of course, be appreciated that good contacting between the liquid hydrocarbon and the pretreating agent and the sorbent is important to a complete separation. Such contacting could, of course, be achieved by shaking, agitation or the like or the same might be achieved by passing the liquid hydrocarbon first through a mixing chamber or an agitated vessel and then through a fixed bed of sorbent. In this regard, it should be noted that sufficient contacting with the sorbent will be accomplished in a fixed bed when the liquid hydrocarbon is passed through a bed of sorbent having a particle size within the range heretofore specified at a rate within the range of about 2 to about gallons per hour per lb. of sorbent.

In general, the contacting between the pretreated liquid hydrocarbon and the sorbent will be accomplished at a temperature between about 30 and 120F. and a contacting time within the range of about 1 and about 5 minutes will be sufficient to effect the desired separation using the fixed bed procedure. The fact that the method of this invention can be operated at relatively low temperatures does, of course, offer a tremendous advantage since it is contemplated that the same might be used at retail outlets which would not offer convenient heating facilities. The process cannot, however, be operated at extremely low temperatures since the reaction rate and rate of diffusion into the pores of the activated carbon would become too slow.

As indicated, supra, the method of this invention can be effectively used to separate relatively large lead concentrations from liquid hydrocarbons. Large concentrations will, however, significantly reduce the useful life of the sorbent. This in turn would result in frequent replacement or regeneration thereof. For this reason, then, it may be desirable to use two or more separate pretreatments, when treating a liquid hydrocarbon containing more than about 0.5 g. Pb/gal., before contacting the pretreated liquid with sorbent so as to maximize the life of the sorbent. In this embodiment of the invention, each of the separate pretreatments would be completed in the same manner and, generally, each pretreatment would be followed by a filtration so as to remove suspended solids. When the lead concentration is below about 0.5 grams per gallon and preferably below about 0.3 grams per gallon, a single pretreatment followed by contacting with a suitable sorbent will, generally, yield 21 treated hydrocarbon having less than 0.05 g Pb/gal. thereof.

With respect to the pretreatment of the lead containing hydrocarbon, cupric chloride has been found most advantageous as the pretreating agent. This and the other pretreating agents will generally be used in accordance with techniques known or obvious from related processes and such use need not be described in detail herein. Nevertheless, it should be noted that any one of these compounds or a mixture of any one or more thereof will, generally, be dissolved in a suitable solvent and combined with the liquid hydrocarbon containing dissolved lead at a temperature between about 30 and about lF. for a period of time sufficient to effect the desired conversion of the soluble lead compounds. The conversion products thus formed will then be separated with a suitable method such as water washing, decanting, filtration and/or centrifugation. It'will, of course, be appreciated that the amount of pretreating agent employed is not critical, but the amount actually used will generally exceed the stoichiometric amount required for complete conversion of the soluble lead compounds present in the treated hydrocarbons to a monohalide derivative and may range as high as 20 times that amount.

In this regard, it should, however, be noted that when large excesses are used, it may be necessary to subsequently separate the excess pretreating agent from the liquid hydrocarbon and, indeed, this will, generally, be accomplished via filtration followed by absorption with any of the sorbents herein indicated as useful. Such absorption may, however, reduce the effective capacity of the sorbent and should, therefore, be minimized. For these reasons, then, it is preferred that the amount of pretreating agent actually used be a minimum which is consistent with effective separation. Generally, this will be within the range of about 2 to about 10 times the stoichiometric amount required for the conversion of a tetraalkyl to a monohalide derivative, and, most preferably, the pretreating agent will be used in an amount within the range of about 3 to about 6 times this stoichiometric amount.

As indicated supra, the method of the present invention can be used to separate dissolved organo lead compounds from any liquid hydrocarbon. The process is particularly useful, however, for the separation of tetraalkyl lead compounds such as tetraethyl lead and tetramethyl lead from mixtures of liquid hydrocarbons such as gasoline, jet fuel and kerosene. The method of this invention is particularly useful for the separation of minor concentrations of such lead compounds from liquid hydrocarbon mixtures to be offered and sold as unleaded gasolines.

PREFERRED EMBODIMENT In a preferred embodiment, anhydrous cupric chloride dissolved in isopropyl alcohol at a concentration within the range from about I to about 5 wt. will be used in combination with an activated carbon which is substantially free of graphitic type carbon (less than about 5 wt to separate tetraalkyl leads, and particularly tetraethyl and tetramethyl leads or equilibrated mixes thereof from gasoline. The activated carbon, in addition to being substantially free of graphitic type carbon, will exhibit a pore volume within the range from about 0.8 to about 1.2 ml/g., an oxygen content within the range from about 5 to about 20 wt. and a surface area between about 500 and 1000 m /g.

In the preferred embodiment, the lead concentration in the gasoline will be less than 0.5 g./gallon and in a most .preferred embodiment the lead concentration will be less than 0.3 g/gallon. Moreover and as indicated, supra, the lead containing gaoline will first be pretreated by contacting the same with a solution of cupric chloride in isopropanol. The pretreatment will be accomplished by mixing the pretreating agent with the leaded gasoline in an amount ranging between about 2 and about l0,times that required for stoichiometric conversion of the tetraalkyl lead contained therein and then subjecting the mixture to agitation. The pretreatment will be accomplished at a temperature between about 40 and F. under conditions of intimate contacting for a period of time between about 5 and 20 minutes. The pretreated gasoline will then be filtered and the filtrate then contacted with an activated carbon exhibiting properties within the range heretofore specified. The contacting with the activated carbon will be accomplished in a fixed bed thereof, the activated carbon having an average particle size within the range of about 0.015 to about 0.06 inches and at a flow rate between about 4 and about 8 gallons (gasoline) per hour per pound of impregnated activated carbon. Generally,

the actual contacting time between the filtrate and carbon will be within the range of about 1 to about 3 minutes.

It is believed that the present invention will become even more apparent from the following examples which illustrate the broadest embodiment thereof, a preferred embodiment thereof and a most preferred embodiment thereof. These examples are not, however, intended to limit the invention in any way.

EXAMPLE 1 Two liters of gasoline containing 0.18 g. Pb/gal. thereof, but no light or heavy cat naphthas, was combined with 8 ml of an isopropanol solution of CuCl containing 3.8 wt. CuCl The isopropanol solution was added to small batches of the gasoline with stirring such that the average contact time was about /2 hour. The contacting was accomplished at a temperature of 75F. The thus treated mixture was then filtered by passing the same through a filter to separate any precipitated solids. The filtrate was then passed through a fixed bed of activated carbon (10 g) such that the average contact time was about 2 minutes. The activated carbon had a total pore volume of 1.1 ml/g, contained 16.5 wt. O 5 wt. H O, exhibited a surface area of 640 m lg and was substantially amorphous or nongraphitic. The particle size of the activated carbon was such that the same passed through a mesh (U.S.) screen but was retained on a 40 mesh (U.S.) screen. After completion of the pretreatment and adsorption steps, the treated gasoline was filtered so as to separate any suspended solids therein. The treated gasoline was, then, analyzed for lead content and found to contain 0.02 g Pb/gal.

EXAMPLE 2 Two liters of gasoline identical with that used in Ex ample l was first combined with 12 grams of a solution containing 1.5 wt. l and 1.8 wt. HCl at a temperature of 75F., in small batches, and agitated briefly with an average contact time of about 30 minutes. Following this pretreatment the gasoline was filtered to separate suspended solids and passed through a bed of 10 g. of activated carbon identical to that used in Example 1 at a temperature of 75F. such that the average contacting time was about 2 minutes. Again, the contacting was accomplished by passing the gasoline through a fixed bed of the activated carbon and the treated gasoline was filtered thereafter to separate any suspended solids remaining therein. Following this contacting, the treated gasoline was then analyzed for dissolved lead content As a result of these tests, it was found that the same contained 0.04 grams Pb/gallon.

EXAMPLE 3 Two additional liters of gasoline identical with that used in Examples 1 and 2 was first combined with 5.4 grams of a benzene solution containing 12.5 wt. silicon tetrachloride at a temperature of 75F. in small batches, and agitated briefly with an average contact time of 30 minutes. Following this pretreatment the 2 liters of gasoline were filtered and then passed over 10 g. of activated carbon identical to that used in Exampics 1 and 2 at a temperature of 75F. such that the average contacting time was about 2 minutes. The treated gasoline was then filtered. Following this treatment, the

gasoline was analyzed for lead content and found to contain 0.03 grams Pb/gallon.

EXAMPLE 4 Two liters of gasoline containing 0.07 g. Pb/gal. thereof and 25 wt. light and heavy cat naphthas was combined in small batches with 12 ml. of an isopropanol solution of CuCl containing 2.2 wt. CuCl and the resulting mixture subjected briefly to mild agitation at a temperature of F. The thus treated mixture was then filtered by passing the same through a 5;]. filter to separate any precipitated solids. The filtrate was then passed through a fixed bed of activated carbon (10 g) such that the average contact time was about 2 minutes. The activated carbon had a total pore volume of 1.1 ml/g, contained 16.5 wt. O 5 wt. H O, exhibited a surface area of 640 m /g was amorphous or nongraphitic. The particle size of the activated carbon was such that the same passed through a 20 mesh (U.S.) screen but retained on a 40 mesh (U.S.) screen. After completion of the pretreatment and absorption steps, the treated gasoline was filtered so as to separate any suspended solids therein. The treated gasoline was, then, analyzed for lead content and found to contain 0.02 g Pb/gal.

EXAMPLE 5 Two liters of gasoline identical with that used in Example 4 was first combined with 12 ml of a solution containing 2 wt. l and 1 wt. HCl at a temperature of 75F. and briefly agitated. Following this pretreatment the gasoline was filtered to separate suspended solids and passed through a bed of 10 g activated carbon identical to that used in Example 4 at a temperature of 75F. such that the average contacting time was about 2 minutes. Again, the contacting was accornplished by passing the gasoline through a fixed bed of the activated carbon and the treated gasoline was filtered thereafter to separate any suspended solids re maining therein. Following this contacting, the treated gasoline was then analyzed for dissolving lead content. As a result of these tests, it was found that the same contained .0l grams Pb/gallon."

EXAMPLE 6 Two additional liters of gasoline identical with that used in Example 4 was first combined with 5 ml of a xylene solution containing 7 wt. silicon tetrachloride at a temperature of 75F. and briefly agitated. Following this pretreatment the 2 liters of gasoline was filtered and then passed over 10 g of activated carbon identical to that used in Example 4 at a temperature of 75F. such that the average contacting time was about 2 minutes. The treated'gasoline was then filtered. Following this treatment, the gasoline was analyzed for lead content and found to contain 0.015 grams Pb/gallon.

EXAMPLE 7 Four liters of gasoline containing 0.09 g. Pb/gal. thereof and 25% light and heavy cat naphthas was combined with 12 ml of an isopropanol solution of CuCl containing 2.5 wt. CuCl and the resulting mixture subjected to mild agitation as described in Example 1.

age contact time was about 2 minutes. The activated carbon had a total pore volume of 1.1 ml/g, contained 16.5 wt. O 5 wt. H O, exhibited a surface area of 640 m /g and was amorphous or non-graphitic. The particle size of the activated carbon was such that the same passed through a 20 mesh (U.S.) screen but was retained on a 40 mesh (U.S.) screen. After completion of the pretreatment and absorption steps, the completion of the pretreatment and absorption steps, the treated gasoline was filtered so as to separate any suspended solids therein. The treated gasoline was, then, analyzed for lead content and found to contain 0.03 g Pb/gal.

EXAMPLE 8 Two liters of gasoline containing 0.18 g. Pb/gal. thereof but no light or heavy cat naphthas was combined with 16 ml of an isopropanol solution of CuCl containing 3.8 wt. CuC1 and the resulting mixture subjected to mild agitation as described in Example l. The thus treated mixture was then filtered by passing the same through a Su filter to separate any precipitated solids. The filtrate was then passed through a fixed bed of activated carbon (.10 g) such that the average contact time was about 2 minutes. The activated carbon had a total pore volume of 1.1 ml/g. contained 16.5 wt. O 5 wt. H O, exhibited a surface area of 640 m /g and was amorphous or non-graphitic. The particle size of the activated carbon was such that the same passed through a 20 mesh (U.S.) screen but was retained on a 40 mesh (U.S.) screen. After completion of the pretreatment and absorption steps, the treated gasoline was filtered so as to separate any suspended solids therein. The treated gasoline was, then, analyzed for lead content and found to contain .01 g Pb/gal.

EXAMPLE 9 Four liters of gasoline containing 0.08 g. Pb/gal. thereof and 25 Wt. light and heavy cat naphthas was combined with 24 ml of an isopropanol solution of 'CuCl '2H O containing 3 wt. CuC1 -2H O and the resulting mixture subjected to mild agitation in the same manner and at the same conditions used in Example 1. The thus treated mixture was then filtered by passing the same through a 5p. filter to separate any precipitated solids. The filtrate was then passed through a fixed bed of activated carbon (10 g) identical that used in Example 1 such that the average contact time was about 1 minute. The thus treated gasoline contained 0.06 g. Pb/gal.

EXAMPLE 10 An activated carbon impregnated with hydrous cupric chloride was prepared by first dissolving 6.0 gram of CuCl- '2H O in 3.0 grams of water and 30.0 g. of methanol and then combining this solution with 50.0 grams of granular activated carbon containing 5 wt. water. The particle size of the granular carbon was such that the same all passed througha 20 mesh (U.S.) screen and was retained on a 40 mesh (U.S.) screen. The activated carbon had a total pore volume of 1.1 ml/g., contained 16.5% oxygemhad a surface area of 640 m /g and was essentially amorphous or nongraphitic. The aqeuous methanolic cupric chloride solution and the activated carbon were combined at a temperature of 75F. and the combined mixture was stirred until the activated carbon'was throughly wetted.

The'combined mixture was then dried with nitrogen gas at a-temperature of F. for a period of 2.5 hours. The resulting activated carbon contained 8 wt. CuCl 1.5 wt. methanol, 8.5 wt. H Oand 82% carbon. Ten grams of the impregnated activated carbon thus prepared were placed in a fixed bed and contacted with four liters of gasoline containing 0.09 grams Pb/gallon at 75F., such that the average contact time was about 1 minute.

During the contacting, the flow of gasoline was sufficient as to assure the desired degree of contacting between the lead and the activated carbon. After completion of the contacting, the treated gasoline was filtered to separate any suspended solids remaining therein. The treated gasoline was then analyzed and found to contain 0.035 grams Pb/gallon.

EXAMPLE 1 1 Four liters of gasoline identical with that used in Example 10 was first contacted with 0.5 grams cupric chloride (2% solution in isopropanol) at a temperature of 75F. for an average of 30 minutes in small batches. In this Example, the gasoline was initially stirred during this contacting period. Following this pretreatment the gasoline was filtered to separate suspended solids and passed through a bed comprising 10 grams of the hydrous cupric chloride impregnated activated carbon prepared in Example 10 at a temperature of 75F. Again, the contacting was accomplished by passing the gasoline through a fixed bed of the sorbentand the treated gasoline was filtered thereafter to separate any suspended solids remaining therein. Following this contacting, the treated gasoline was then analyzed for dissolved lead content. As result of these tests, it was found that the same contained 0.015 grams Pb/gallon.

EXAMPLE 12 Two liters of gasoline containing 0.1 l g. of an equilibrated mix of tetraethyl lead and tetramethyl lead/gal. thereof, but no light or heavy cat naphthas, was combined in small batches with 8 m] of an isopropanol solution of CuCl; containing 2 wt. CuC1 and the resulting mixture subjected, briefly, to mild agitation at a temperature of 75F. The thus treated mixture was then filtered by passing the same through a 5 p. filter to separate any precipitated solids. The filtrate was then passed througha fixed bed of activated carbon (10 g) such that the average contact time was about 2 minutes. The activated carbon had a total pore volume of 1.1 ml/g, contained 16.5 wt. O 5 wt. H O, exhibited a surface area of 640 m /g and was amorphous or non-graphitic. The particle size of the activated carbon was such that, the same passed through a 20 mesh (U.S.) screen but was retained on a 40 mesh (U.S.) screen. After completion of the pretreatment and absorption steps, the treated gasoline was filtered so as to separate any suspended solids therein. The treated gasoline was, then, analyzed for lead content and found to contain 0.05 g. Pb/gal.

EXAMPLE 13 Two liters of gasoline containing 0.1 l g. tetramethyl lead/gal. thereof, but no light or heavy cat naphthas, was combined in small batches with 10 ml of an aqueous isopropanol solution of 1 and HCl containing 2 wt. l and 1 wt. HCl and the resulting mixture subjected briefly to mild agitation at a temperature of 75F. The thus treated mixture was then filtered by passing the same through a p. filter to separate any precipitated solids. The filtrate was then passed through a fixed bed of ferric chloride impregnated activated carbon g) such that the average contact time was about 2 minutes. The activated carbon had a total pore volume of 1.1 m lg. contained 16.5 wt. O 5 wt. H O, exhibited a surface area of 640 m /g and was amorphous or non-graphitic. It contained 13 ferric chloride and 19% H O. The particle size of the impregnated activated carbon was such that the same passed through a 20 mesh (U.S.) screen but was retained on a 40 mesh (U.S.) screen. After completion of the pretreatment and absorption steps, the treated gasoline was filtered so as to separate any suspended solids therein. The treated gasoline was, then, analyzed for lead content and found to contain 0.02 g. Pb/gal.

EXAMPLE 14 Four liters of gasoline identical to that used in Example 9 were contacted with 24 ml of an isopropanol solution containing 2.5 wt. CuCl in the same manner and under the same conditions as were used in Example 1. The pretreated gasolin was then filtered and passed over 10 g. of activated carbon identical to that used in Example 1. The treated gasoline contained 0.03 g. Pb/gal.

EXAMPLE Example 14 was repeated except that the gasoline used was first predried with silica gel so as to remove of the H 0 originally present therein. The treated gasoline from this Example, however, contained only 0.024 g. Pb/gal. The results obtained in Examples 9, 14 and 15 thus suggest that improved results are obtained by reducing the water content of the system.

EXAMPLE 16 The run of Example 14 was repeated except that 20 ml of an isopropanol solution containing 3 wt. CuBr was substituted for the 24 ml of CuCl solution. The thus treated gasoline contained 0.04 g Pb/gal.

EXAMPLE 17 Two liters of gasoline identical to that used in Example l were pretreated with 7 ml of a benzene solution containing 3 wt. 1 in substantially the same manner and at the same conditions described in Example 1. The pretreated gasoline was then filtered and passed over an activated carbon bed identical to that used in Example 1 and at the same conditions used therein. The thus treated gasoline contained 0.05 g Pb/gal.

As will be readily apparent from the foregoing Examples, the method of the present invention is effective in separating tetraalkyl lead compounds from gasoline. As will also be readily apparent, the method of this invention is effective over a relatively broad range of lead concentrations.

While the present invention has been described and illustrated by reference to particularly preferred embodiments thereof, it will be appreciated that the same lends itself to several variations which would be obvious to those of ordinary skill in the art. Reference should, therefore, be made solely to the appended claims to determine the scope of the present invention.

Having thus described and illustrated the present invention what is claimed is:

l. A method for separating an organolead compound from liquid hydrocarbons comprising the steps of first contacting a liquid hydrocarbon having an organolead compound dissolved therein with a pretreating agent selected from the group consisting of silicon tetrachloride, iodine, cupric chloride and cupric bromide and thereafter contacting the pretreated hydrocarbon with an adsorbent useful for separating lead compounds from liquid hydrocarbons selected from the group consisting of activated carbon, acid treated clays and silica gels, and then recovering a liquid hydrocarbon having a reduced dissolved lead content therein.

2. The method of claim 1 wherein the pretreating agent is first dissolved in a suitable solvent and thereafter combined with said liquid hydrocarbon.

3. The method of claim 2 wherein the adsorbent is an activated carbon which is substantially amorphous and has an oxygen content within the range of about 3 to about 25 wt.

4. The method of claim 3 wherein said activated carbon contains less than about 5 wt. crystalline structure carbon; has an oxygen content within the range of about 10 to about 20 wt. has a total pore volume within the range of about 0.8 to about 1.2 ml/g; and exhibits a surface area within the range of about 200 to.

about 1000 m /g.

5. The method of claim 2 wherein the contacting with said pretreating agent is accomplished at a temperature between about 30 and about F.

6. The method of claim 2 wherein the contacting with the adsorbent is accomplished in a fixed bed and is continued for a period of time between about 1 and about 5 minutes.

7. The method of claim 2, wherein the liquid hydrocarbon contains less than about 0.5 g Pb/gallon.

8. A method for separating a dissolved organo lead compound from a liquid hydrocarbon comprising:

1. first contacting a liquid hydrocarbon containing a dissolved organo lead compound therein with a pretreating agent selected from the group consisting of silicon tetrachloride, iodine, cupric chloride and cupric bromide and mixtures thereof;

2. thereafter contacting said liquid hydrocarbon with an activated carbon; and

3. recovering a liquid hydrocarbon having a reduced dissolved lead content therein.

9. The process of claim 8 wherein the amount of pretreating agent used is between about 1 and about 20 times the stoichiometric amount required to convert all of the dissolved lead contained in the liquid hydrocarbon to a monohalide derivative.

10. The method of claim 8 wherein said liquid hydrocarbon is first contacted with said treating agent at a temperature within the range of about 30 and about 120F. and thereafter contacted with an activated carbon at a temperature between about 30 and about 120F.

11. The method of claim 10 wherein said liquid hydrocarbon is filtered after being contacted with said pretreating agent and before the same is contacted with said activated carbon.

12. The method of claim 11 wherein the activated carbon is substantially amorphous and has an oxygen content within the range of about 3 to about 25 wt.

13. The method of claim 11 wherein said activated carbon contains less than about 5 wt. crystalline structure carbon; has an oxygen content within the range of about 10 to about 20 wt. has a total pore hol before being combined with said liquid hydrocarvolume within the range of about 0.8 to about 1.2 ml/g; hon

and exhibitsa surface area within the range of about to about 1000 mzlg. 15. The method of claim 14 wherein said lower alco- 14; The method of claim 8 wherein said pretreating is isopropyl alcoholagent is CuCl and the same is dissolved in a lower alco-

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Referenced by
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US3998725 *Apr 30, 1975Dec 21, 1976Exxon Research And Engineering CompanyContacting with alumina-silica, cupric chloride, water and an amine
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Classifications
U.S. Classification208/253, 208/295, 208/307, 208/91, 208/251.00R, 208/278, 208/296
International ClassificationC10G29/12
Cooperative ClassificationC10G29/12, C10G27/02
European ClassificationC10G27/02, C10G29/12