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Publication numberUSRE37663 E1
Publication typeGrant
Application numberUS 09/206,233
Publication dateApr 16, 2002
Filing dateDec 7, 1998
Priority dateAug 14, 1993
Fee statusPaid
Also published asCA2129379A1, CA2129379C, DE69420799D1, DE69420799T2, DE69432823D1, DE69432823T2, EP0638534A1, EP0638534B1, EP0937697A2, EP0937697A3, EP0937697B1, US5593935
Publication number09206233, 206233, US RE37663 E1, US RE37663E1, US-E1-RE37663, USRE37663 E1, USRE37663E1
InventorsStanislaw E. Golunski, John W. Hayes
Original AssigneeJohnson Matthey Public Limited Company
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Catalysts
US RE37663 E1
Abstract
The dehydrogenation of an alkane to an alkene, especially isobutane to isobutene, is carried out in admixture with oxygen and in the absence of added steam over a dehydrogenation and oxidation catalyst comprising a platinum group metal deposited upon a support. A catalyst comprising platinum deposited on a support which is a mixture of tin oxide and zirconium oxide possesses good activity for the dehydrogenation of an alkane, especially carried out in this way.
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Claims(21)
We claim:
1. A catalyst for alkane dehydrogenation, comprising by weight 0.1 to 3% platinum, calculated as metal, 6 to 60% tin oxide, and 37 to 94.9% zirconium oxide, the platinum deposited upon a support which is a mixture of the tin oxide and the zirconium oxide.
2. A catalyst according to claim 1, containing 10 to 60% by weight of the tin oxide.
3. A catalyst according to claim 1, wherein the support contains substantially no alumina.
4. A catalyst according to claim 1, consisting essentially of 0.1 to 3% by weight of platinum, calculated as metal, 10 to 60% by weight of tin oxide, 37 to 94.9% zirconium oxide, and at least one member selected from the group consisting of stabilisers and promoters.
5. A catalyst according to claim 1, wherein the support comprises SnO2 and ZrO2 in a weight ratio of approximately 1:4.
6. A catalyst according to claim 5, comprising approximately 1% by weight of platinum, impregnated onto a co-precipitate of SnO2 and ZrO2 in a weight ratio of approximately 1:4.
7. A catalyst according to claim 1, wherein the catalyst has substantially an absence of alumina.
8. A catalyst according to claim 1, wherein the catalyst contains 15-30% by weight of tin oxide.
9. A catalyst according to claim 1, wherein the catalyst contains 70-85% by weight zirconium oxide.
10. A catalyst according to claim 1, wherein the catalyst has a weight ratio of the tin oxide to the zirconium oxide of 1:3-9.
11. A catalyst according to claim 1, wherein the catalyst has a weight ratio of the tin oxide to the zirconium oxide of 1:3-5.
12. A catalyst for alkane dehydrogenation comprising a catalytically effective amount of platinum, 6 to 60% tin oxide, and 37 % to 94.9 % zirconium oxide, the platinum being deposited on a support comprising a mixture of the tin oxide and the zirconium oxide.
13. A catalyst support consisting of 6 to 60% tin oxide and 37 % to 85 % zirconium oxide.
14. A catalyst for alkane dehydrogenation, comprising a catalytically effective amount of platinum, 6 to 60% tin oxide, and 37 % to 94.9 % zirconium oxide, the platinum being deposited on a support comprising a mixture of the tin oxide and the zirconium oxide, made by a process comprising the steps of:
making the support by a co-precipitation process comprising adding NaOH to a mixture of tin and zirconium salts in aqueous solution, and drying and calcining the NaOH-containing mixture to which NaOH was added, wherein the dried and calcined mixture comprises 6 to 60 % tin oxide and at least 37 % zirconium oxide; impregnating the calcined mixture with an aqueous solution of a platinum salt; and drying and calcining the impregnated mixture.
15. A catalyst of claim 1, wherein the catalyst comprises 37 to 85% zirconium oxide.
16. A catalyst of claim 1, wherein the catalyst comprises 37 to 85% zirconium oxide.
17. A catalyst support of claim 13, wherein the catalyst support consists of tin oxide and zirconium oxide in a weight ratio of approximately 1:3-9.
18. A catalyst support, wherein the catalyst support consists essentially of 30-15% tin oxide and 70-85 % zirconium oxide.
19. A catalyst support of claim 18, wherein the catalyst support substantially lacks alumina.
20. A catalyst support of claim 18, wherein the catalyst support consists essentially of 20% tin oxide and 80 % zirconium oxide.
21. A catalyst of claim 14, wherein the catalyst comprises SnO2 and ZrO 2 in a weight ratio of approximately 1:3-9.
Description

This application and Ser. No. 09/240,150 are copending reissue applications of the same original patent.

The present invention concerns improvements in catalysts and in catalytic processes. More especially it concerns catalysts and processes for dehydrogenation of alkanes.

It is known to dehydrogenate isobutane to isobutene using direct dehydrogenation at low space velocity (GHSV=100-1000 hr−1). The conventional industrial process has several inherent disadvantages:

(a) it is an endothermic reaction, requiring high thermal input;

(b) the yield of isobutene is equilibrium limited; and

(c) at temperatures favouring high yields of isobutene, the rate of catalyst de-activation is also high.

Improvements to the conventional process have included the addition of either steam (eg U.S. Pat. No. 4,926,005 and 4,788,371) or hydrogen (eg U.S. Pat. No. 4,032,589) to the gas feed. The function of the hydrogen is as a diluent, and to reduce the deposition of carbon on the catalyst. The steam improves thermal conduction through the catalyst bed and reduces the deposition of carbon on the catalyst, and hence it too has been used as a diluent. The catalysts used in industry include platinum on alumina, platinum on tin oxide and chromium oxide-based catalysts. There remains a need for an improved process for the dehydrogenation of alkanes, especially for the dehydrogenation of isobutane, which is a starting material for MTBE (methyl-tert-butyl-ether) production. The conventional processes require high inputs of energy and the capital cost of a catalytic reactor designed to supply large amounts of heat is particularly high. Moreover, conventional processes demonstrate rapid catalyst deactivation, so that expensive and complex catalyst regeneration has to be designed into the equipment and the process.

The present invention provides an improved process and novel catalyst for alkane dehydrogenation.

Accordingly, the invention provides a process for the dehydrogenation of an alkane to form an alkene, comprising passing a feedstock comprising said alkane in the gas phase in admixture with oxygen and in the absence of added steam over a dehydration and oxidation catalyst comprising a platinum group metal deposited upon a support.

The invention provides also a catalyst for alkane dehydrogenation, comprising platinum deposited upon a support which is a mixture of tin oxide and zirconium oxide. The invention also provides a process for the dehydrogenation of an alkane to form an alkene, comprising passing a feedstock comprising said alkane in the gas phase over this catalyst.

The present processes and catalyst are advantageous over the known processes and catalyst by reason of one or more of such features as higher yield of the alkene, higher selectivity to the alkene, lower operating temperature, lower heat input, a simpler system and lower catalyst deactivation.

There is much prior an art on the dehydrogenation of alkanes to alkenes, (though a scant amount on the oxidative dehydrogenation of alkanes to alkenes), yet the present improvements were not realised before. As explained in the U.S. specification 4,788,371 mentioned above, the dehydrogenation of hydrocarbons is endothermic. In a system employing a dehydrogenation catalyst only, it is typically necessary to add superheated steam at various points in the process or to intermittently remove and reheat the reaction stream between catalyst beds. In an improvement, processes were developed which utilised a two-catalyst system with distinct beds or reactors of dehydrogenation or selective oxidation catalysts. The purpose of the selective oxidation catalysts was to selectively oxidise the hydrogen produced as a result of the dehydrogenation with oxygen that had been added to the oxidation zone to generate heat internally in the process. The heat generated would typically be sufficient to cause the reaction mixture to reach desired dehydrogenation temperatures for the next dehydrogenation step. The US specification explains that in its invention one specific catalyst can be used to accomplish both the dehydrogenation and oxidation reactions. It discloses a process for the steam dehydrogenation of a dehydrogenatable hydrocarbon with oxidative reheating which comprises contacting a dehydrogenatable hydrocarbon comprising C2-C15 paraffins and steam at a steam to hydrocarbon molar ratio of from 0.1:1 to 40:1, at a pressure from 0.1 to 10 atmospheres, a temperature of from 400 to 900 C., and a liquid hourly space velocity of from 0.1 to 100 hr−1 with a catalyst in the first reaction zone of a reactor containing a plurality of reaction zones and introducing an oxygen-containing gas into the second, and every other reaction zone of the plurality of reaction zones such that the total rate of the oxygen-containing gas introduced into the reaction zone ranges from 0.01 to 2 moles of oxygen per mole of C2-C15 paraffin feed wherein the catalyst is comprised of from 0.1 to 5 weight % platinum, and from 0.01 to 5 weight% potassium or cesium or mixtures thereof on an alumina support having a surface area of from 5 to 120 m2/g and recovering the products of the reaction. Though the specification mentions the possibility of a single reaction zone within a single reactor with single inlet and outlet parts, all co-feeds entering the inlet of the reactor and products and by-products leaving the system through the reactor outlet part, there is no Example illustrating this concept. Moreover, the present broad process involving passing an alkane in admixture with oxygen over a dehydrogenation and oxidation catalyst is not a steam dehydrogenation; instead, it is carried out in the absence of added steam (though some steam is formed by reaction of the oxygen with hydrogen which is present).

FIG. 3 shows a schematic diagram of a reactor 10 for performing this process. As shown in FIG. 3, the present broad process involves passing an alkane stream 10 in admixture with oxygen over the dehydrogenation and oxidation catalyst in the reactor 20 to result in a product stream 30. In this aspect of the present invention, we have discovered that oxygen in the absence of added steam is advantageously admixed with the alkane and passed over the catalyst, so that heat produced by the exothermic reaction of the oxygen with hydrogen which is present provides, partially or fully, the heat required by the endothermic dehydrogenation. The hydrogen required for the reaction with the oxygen can be introduced into the reaction zone, but this is not preferred. Advantageously, the hydrogen is hydrogen produced by the dehydrogenation of the alkane to alkene, so as to shift the equilibrium in favour of the alkene. Preferably, the amount of oxygen is such that the dehydrogenation is carded carried out under adiabatic conditions, so that no heat is supplied (or removed) from the reaction. Especially preferred is the amount of oxygen being such that the endothermic dehydrogenation is balanced by the exothermic reaction of the oxygen with hydrogen which is present so that the temperature remains constant (this situation is referred to herein as thermally neutral conditions). Thus, the optimum temperature for yield, life of catalyst etc can be maintained, eg so that at least 95% selectivity to the alkene is obtained.

The amount of oxygen is desirably less than the amount of the alkane, on a molar basis, and preferably less than half the amount of the alkane on this basis. For example, employing isobutane as the alkane, it is preferred that the amount of oxygen be below that indicated by the stoichiometry of the reaction equation:

C4H10+0.5O2→C4H8+H2O.

The optimum amount of oxygen will vary with the desired operating temperature, and as a guide we would predict that the maximum amount of oxygen for highly selective, thermally neutral, dehydrogenation of isobutane be 5% at 450 C., 7.5% at 500 C. and 9% at 550 C., based on the combined volumes of isobutane and oxygen.

The present oxidative dehydrogenation is usually carried out at a temperature from 350 to 550 C., for instance at a temperature from 350 to 480 C., for example when the platinum group metal comprises platinum and the support comprises alumina.

The oxidative dehydrogenation is preferably carried out under relatively high space velocities, such as an alkane, and especially a total, gas hourly space velocity (GHSV) of 1000 to 5000 hr−1, for example for isobutane.

The operating pressure is conveniently atmospheric, but the dehydrogenation can be operated at above or below atmospheric pressure. If desired, diluent gases can be used, although hydrogen is not recommended as explained above; in addition, it would be an added process cost.

The alkane which is dehydrogenated is preferably raw material, not alkane which has already been partially dehydrogenated.

The oxygen can be employed as such but conveniently it is employed as a component of an oxygen-containing gas, particularly air.

The platinum group metal dehydrogenation and oxidation catalyst can be such a catalyst known in the art. The platinum group metal (ruthenium, rhodium, palladium, osmium, iridium and platinum) is preferably platinum. The catalyst preferably contains 0.1 to 3% by weight of the platinum group metal, eg platinum. The support can be for example alumina, silica, magnesia, titania, zirconia or a mixture or joint oxide (eg an alumina silicate) thereof, or a Group IIA or IIB (eg zinc) aluminate spinel. Groups IIA and lIB are as given in the inside front cover of the CRC Handbook of Chemistry and Physics, 60th edition, CRC Press, 1980. Commonly, the support comprises (ie consists of or includes) alumina. For instance, the catalyst contains as support 10-99.9% by weight of alumina. Promoters can be employed with the platinum group metal. Preferred as promoter is tin oxide. The promoter, when present, is usually employed as 0.1-5% by weight of the catalyst. The catalyst can be obtained in conventional ways, for example by impregnating the support with a precursor of the platinum group metal and a precursor of any co-promoter, and calcining.

A particularly advantageous catalyst for the present oxidative dehydrogenation of an alkane in the absence of added steam, though it can be used advantageously for the oxidative dehydrogenation in the presence of added stem steam, and indeed for the direct dehydrogenation, is a novel catalyst. This catalyst for alkane dehydrogenation comprises platinum deposited upon a support which is a mixture of tin oxide and zirconium oxide. The catalyst contains a catalytically effective amount of the platinum. Usually the catalyst contains 0.1 to 3% by weight of platinum, calculated as metal. Additional catalytically active components can be present, though preferably the catalytically active component consists essentially of platinum. The catalyst contains a supporting amount of the mixture of tin oxide and zirconium oxide. Additional support components can be present. The common support component alumina, however, has been found to be disadvantageous. Preferably, therefore, the catalyst contains substantially no alumina. It is preferred that the support consists essentially of the mixture of tin oxide and zirconium oxide. Usually the catalyst contains 6-60, preferably 10-60, especially 15-30, % by weight of the tin oxide (measured as tin oxide). Usually the catalyst contains 37-94.9, preferably 70-85, % by weight of the zirconium oxide. The weight ratio of the tin oxide to the zirconium oxide is preferably 1:3-9, especially 1:3-5. In a preferred embodiment, the catalyst comprises 0.1 to 3% by weight of platinum, calculated as metal, 10 to 60% by weight of tin oxide, the balance being zirconium oxide. A particular catalyst has a support comprising SnO2 and ZrO2 in a weight ratio of approximately 1:4. One preferred embodiment of the catalyst of the invention is prepared by impregnating 1% (by weight, calculated as metal) of a platinum salt or compound onto a co-precipitate of SnO2 and ZrO2 in a weight ratio of 1:4.

The catalyst of the invention may comprise in addition other components such as promoters and/or stabilisers. The catalyst may be in the form of pellets or other shapes, for example produced by pelletisation or extrusion, or may be supported on high surface area monoliths such as ceramic or metal honeycomb monoliths.

The mixture of SnO2 and ZrO2 may be formed in a variety of ways and there may be a chemical interaction or compound formation between the components which is as yet not fully understood. The preferred method of preparation is by co-precipitation; suitably by adding NaOH to a mixture of tin and zirconium salts in aqueous solution. The mixture may then be dried and calcined, especially to yield a powdered material with moderately high surface area (typically 95 m2g−1) and narrow pore-size distribution (most of the pores having a radius of about 2 nm), before impregnation with an aqueous solution of a platinum salt. The impregnated catalyst is suitably dried and calcined again.

The invention further provides a process for the dehydrogenation of alkanes to form alkenes, comprising passing a feedstock comprising said alkane in the gas phase over a catalyst according to the invention. Advantages of the present catalyst and process are indicated in the Examples hereafter. In particular, the invention provides the use of the catalyst in the oxidative dehydrogenation of an alkane, whereby extended durability before regeneration is achieved.

The process employing the novel catalyst is particularly advantageous when operated as an oxidative dehydrogenation reaction. That is, the invention includes a process for the oxidative dehydrogenation of alkanes to form alkenes, comprising passing a feedstock comprising said alkane in the gas phase in admixture with oxygen over a catalyst according to the invention. The oxygen can be employed as such, but conveniently it is employed as a component of an oxygen-containing gas, particularly air.

The oxidative dehydrogenation using the novel catalyst can be carried out mutatis mutandis as described above for oxidative dehydrogenation in the absence of added steam using catalysts in general. For instance, the oxidalive dehydrogenation, with or without added steam, using the novel catalyst is preferably carded out under relatively high space velocities, such as an alkane, and preferably a total, GHSV of 1000 to 5000 hr−1, for example for isobutane.

Preferably, the oxidative dehydrogenation using the novel catalyst is operated under adiabatic conditions, especially thermally neutral conditions. The amount of free oxygen in the feedstock is preferably, therefore, controlled to achieve this under the other operating conditions chosen. In particular, the amount of oxygen required increases with increasing temperature. It has been found that operation under adiabatic conditions offers the opportunity to overcome many of the disadvantages of direct dehydrogenation. In preferred embodiments, the process of the invention:

i) provides heat within the catalyst bed by reacting exothermically with some of the hydrogen being formed;

ii) by consuming hydrogen, can shift the equilibrium in favour of the desired products; and

iii) suppresses two of the major causes of catalyst deactivation, that is over-reduction of the catalyst and carbon deposition.

The concentration of oxygen should be carefully controlled at adiabatic conditions, and it is believed that the amount of oxygen should be maintained below stoichiometric relative to the amount of hydrogen present. There are two primary reasons for requiring that the amount of oxygen be carefully controlled, firstly to avoid unwanted products being produced, either from partial or deep oxidation, and secondly to prevent excessive temperature excursions caused by large exotherms.

Desirably, the oxidative dehydrogenation reaction using the novel catalyst is carried out at a temperature of from 350 to 550 C., more preferably in the range 400 to 530 C., especially 440 to 510 C. The operating pressure is conveniently atmospheric, but the process may be operated at above or below atmospheric pressure. If desired, diluent gases may be used, although hydrogen is not recommended since it would be consumed and be an added process cost.

Although the present invention, whether involving the novel catalyst or not, is described herein with particular reference to the oxidative dehydrogenation of isobutane, the invention should not be considered as limited thereto, and may be applied to alkanes in general, and the novel catalyst may also find application in direct dehydrogenation. Nonetheless, it is believed that the greatest benefits arise in oxidative dehydrogenation. The alkane is usually of 2-15, preferably 2-5, particularly 3 or 4, carbon atoms. The alkane can be linear, though preferably it is branched.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated by the accompanying two drawings FIGS. 1 and 2, which each represent two graphs showing yield data and which are described in the Examples hereafter. FIG. 3 is a schematic diagram of a reactor apparatus of the present invention.

The invention will now be described with reference to the following Examples.

In the prior art, the Pt and Sn are usually supported on Al2O3, with the loading of Sn being ≦5% measured as tin (see J C Hayes, U.S. Pat. No. 4,003,852). Although there are some references to the use of ZrO2 (E Clippinger and B F Mulaskey, U.S. Pat. No. 3,864,284; G J Antos, U.S. Pat. No. 4,003,826; J C Hayes, U.S. Pat. No. 4,003,852), its function has been claimed to be simply that of a physical support.

EXAMPLE 1 AND COMPARATIVE EXAMPLE 1

Pt-Sn/Al2O3 is a known hydrocarbon-conversion catalyst, which is effective for reactions such as reforming (see T-H Chao et al U.S. Pat. No. 5,128,300) and direct dehydrogenation (see J W Jenkins, U.S. Pat. No. 3,511,888) of C2-C20 alkanes. A catalyst with the nominal composition (by mass) of 1%Pt-1%Sn/Al2O3 was prepared (following the method described by F C Wilhelm, U.S. Pat. No. 3,998,900) by co-impregnating γ-Al2O3 with an aqueous mixture of hydrogen hexachloroplatinate(IV) (chloroplatinic acid) and acidified tin(II) chloride. The resultant material was dried (110 C.; air;, 24 hr) and calcined (500 C.; air; 2 hr). As is conventional, small amounts of tin oxide are measured and written as Sn and larger amounts, eg 10%, are measured and written as SnO2.

A packed bed (1 cm3) of powdered sample (<150 μm particle diameter) was tested in an adiabatic reactor. For measurements of direct-dehydrogenation activity at 450 C., in Comparative Example 1, a gas-feed of undiluted isobutane was used at a flow-rate of 50 cm3 min−1 (GHSV=3000 hr−1; MHSV=6 dm3 hr−1gcat −1). The molar conversion (% isobutane converted to all products) and selectivity (number of moles of isobutane converted to isobutene divided by number of moles of isobutane converted to all products) were recorded as a function of time at selected furnace/gas-inlet temperatures; the molar yield was calculated from the relationship: Yield / % = conversion / % selectivity / % 100

Oxidative dehydrogenation was carded carried out, in Example 1, by adding just enough air to the gas-feed to ensure thermally-neutral operation (ie i.e., bed temperature=furnace/gas-inlet temperature). The space velocity of the isobutane was the same, therefore, as during direct dehydrogenation. Again, the molar conversion and selectivity were recorded as a function of time.

In both modes of operation (direct dehydrogenation and oxidative dehydrogenation), the catalyst showed very high selectivity (≧95%) toward isobutene formation. Only during the first 5 minutes of testing was there any sign of an undesired cracking product (propene). In the oxidative mode, the amount of CO2 formed was just above the detection limit of the GC analyser, no CO was detected.

As shown in Table 1, the direct-dehydrogenation activity declined noticeably during the first 60 minutes; thereafter, the de-activation was very gradual. The initial loss in activity coincided with the bed temperature decreasing to a new stable value, as the endothermic reaction reached steady-state.

TABLE 1
(Comparative Example 1)
Direct Dehydrogenation over 1% Pt-1% Sn/Al2O3
Isobutene Yield/%
Elapsed Time/min 450 C.
2 16.3
25 15.4
55 15.2
120 15.1
300 14.7
1800
—: not recorded

When the catalyst was tested in the oxidalive mode, at 450 C. and 500 C., the reaction became thermally neutral when the oxygen concentration reached ca 3 or 4% at 450 C., and ca 5.5% at 500 C. The initial activity at 450 C. was higher than for direct dehydrogenation (compare Tables 1 and 2). The isobutene yield is higher at 500 C. than at 450 C.

TABLE 2
(Example 1)
Oxidative dehydrogenation over 1% Pt-1% Sn/Al2O3
Isobutene Yield/%
Elapsed Time/min 450 C. 500 C.
2 24.6 27.8
25 18.7 24.6
55 18.0 23.0
100 21.6
180 16.4 19.2
300 15.5 16.5
400 14.9

EXAMPLE 2

The catalyst described in Example 1 and Comparative Example 1 was used to dehydrogenate isobutane at 450 C., under the conditions described in Comparative Example 1. The yield of isobutene was allowed to decline to 15%, before air was added to the gas-feed. The activity of the catalyst was then measured as a function of gas-feed composition (Table 3).

TABLE 3
Oxidative dehydrogenation of isobutane over
1% Pt-1% Sn/Al2O3 at 450 C.
% Air in Bed Temperature Isobutane Isobutene
Gas-Feed C. Conversion % Selectivity %
70 498 24.0 70
65 488 21.8 78
55 478 20.0 84
45 468 20.8 85
35 460 19.5 90
20 450 18.0 95

At high air concentrations, the catalyst bed temperature exceeded the furnace temperature and the major products were isobutene and carbon dioxide. As the concentration of air was lowered, the bed temperature decreased and the selectivity to isobutene improved. An optimum gas-composition was eventually achieved, which resulted in the bed temperature remaining at 450 C., whilst very little carbon dioxide was formed.

EXAMPLE 3

1%Pt-1%Sn/ZrO2 (nominal composition, by mass) was prepared by the method described in Example 1 and Comparative Example 1, except that zirconia was substituted for γ-Al2O3. The catalyst was subjected to the same tests (at isobutane-GHSV=3000 hr−1) as described in Example 1 and Comparative Example 1, except that both oxidative and direct dehydrogenation were carried out at 500 C. as well as 450 C.

TABLE 4
Direct Dehydrogenation Over 1% Pt-1% Sn/ZrO2
Isobutene Yield/%
Elapsed Time/min 450 C. 500 C.
2 15.7 29.2
25 15.2 25.7
60 15.1 25.4
240 14.5 23.6
500 22.4
1150 13.4
1380 13.4 19.0
1500 13.4 18.6

The marked improvement at 500 C. can be seen.

In the oxidative mode, there was again a marked improvement at 500 C. compared to use at 450 C. At 500 C., the zirconia-containing catalyst showed improved durability over the 1%Pt-1%Sn/Al2O3 catalyst (Tables 2 and 5), with the isobutene yield exceeding 20% during the first 185 min of testing (compared to 150 min for Pt-Sn/Al2O3).

TABLE 5
Oxidative Dehydrogenation Over 1% Pt-1% Sn/ZrO2
Isobutene Yield/%
Elapsed Time/min 450 C. 500 C.
2 19.6 31.6
25 18.3 29.0
55 17.8 26.5
120 15.2 23.1
180 14.6 20.0
300 14.0 18.0

EXAMPLE 4 AND COMPARATIVE EXAMPLE 2

1%Pt-1%Sn/10%ZrO2-Al2O3 (nominal composition, by mass) was prepared by the method described in Example 1 and Comparative Example 1, except that ZrO2-Al2O3 was substituted for Al2O3. The mixed-oxide was made by impregnating γ-Al2O3 with an aqueous solution of zirconium nitrate, before drying (110 C.; air; 24 hr) and calcining (500 C.; air; 2 hr).

The good durability gained by using ZrO2 (in Example 3) was lost by adding Al2O3. During oxidative testing (Example 4) at 500 C. under identical conditions to those of Example 3, the yield of isobutene dropped from 30.0% to 15.0% in the course of the first 85 min. This shows the deleterious effect of alumina; the catalyst does not have the present supporting amount of the mixture of tin oxide and zirconium oxide.

EXAMPLE 5

1%Pt/10%SnO2-ZrO2 (nominal composition, by mass) was prepared by co-precipitating SnO2 and ZrO2 from an aqueous mixture of tin(IV) chloride and hydrated zirconium oxychloride, using aqueous sodium hydroxide as the precipitant. The precipitate was washed thoroughly, before being dried (110 C.; air; 24 hr) and calcined (500 C.; air; 2 hr). The resultant mixed-oxide was impregnated with aqueous dinitrodiammine platinum(II), before the above drying and calcination steps were repeated. The catalyst was tested under the conditions described in Example 3.

The increased loading of Sn was not beneficial to direct dehydrogenation, but resulted in improved durability during oxidative dehydrogenation (compare Tables 5 and 6). At 500 C., the isobutene yield exceeded 20% during the first 210 minutes (compared to 185 minutes for 1%Pt-1%Sn/ZrO2).

TABLE 6
Oxidative Dehydrogenation Over 1% Pt/10% SnO2—ZrO2
Isobutene Yield/%
Elapsed Time/min 450 C. 500 C.
2 17.1 28.2
25 18.4 28.7
55 18.2 27.6
120 16.5 24.2
180 14.8 21.3
240 18.7

EXAMPLE 6

1%Pt/20%SnO2-ZrO2 (nominal composition, by mass) was prepared by the method described in Example 5, and tested under the conditions described in Example 3. Again, the clearest benefit derived from the high tin loading was apparent in the oxidative mode, both at 450 C. and 500 C., when the rate of deactivation was even further reduced (compare Tables 5, 6 and 7). In particular, the durability at 450 C. (as measured by the duration of yield ≧15%) exceeded 24 hr (compared to 6 hr for 1% Pt-1%Sn/Al2O3); see FIG. 1.

TABLE 7
Oxidative dehydrogenation over 1% Pt/20% SnO2—ZrO2
Isobutene Yield/%
Elapsed Time/min 450 C. 500 C.
2 19.0 38.7
25 18.8 31.4
55 18.6 29.0
180 18.0 24.0
300 17.6 20.8
400 18.8
1260 15.1
1500 14.9

EXAMPLE 7

A fresh sample of 1%Pt/20%SnO2-ZrO2 (as described in Example 6) was treated under oxidative conditions, but at half the space velocity used in Examples 1-6 and Comparative Examples 1 and 2.

At this lower space velocity (isobutane-GHSV=1500 hr−1), the catalyst de-activated more gradually. As FIG. 2 shows, its initial activity at 500 C. was similar to that observed in Example 6, but the yield still exceeded 25% after 5 hours (the time taken for the yield to fall below 20% at isobutane-GHSV =3000 hr−1).

COMPARATIVE EXAMPLE 3

1%Pt/SnO2 (nominal composition, by mass) was prepared by impregnating SnO2 with an aqueous solution of tetraammineplatinum(II) hydroxide, before drying (110 C.; air; 24 hr) and calcining (500 C.; air; 2 hr). It was tested under the conditions described in Example 3. This material was a very poor catalyst for both direct dehydrogenation (2.0% maximum yield at 450 C.) and oxidative dehydrogenation (3.2% maximum yield at 450 C.).

EXAMPLE 8

The ability of 1%Pt/20%SnO2-ZrO2 (as described in Example 6) to dehydrogenate linear alkanes was tested by following the procedures given in Example 3, but replacing the isobutane reactant with normal butane. During direct dehydrogenation, the initial total yield of unsaturated products was 26% (product selectivity: 32% 1-butene, 27% cis 2-butene, 38% trans 2-butene, 2% butadiene), but declined to 14% in the space of 3 hours. On switching to the oxidative mode, without first regenerating the catalyst in any way, the total yield recovered, reaching a maximum of 29% before declining slowly (down to 25% after a further 2 hours); the product distribution was very similar to that observed during direct dehydrogenation.

EXAMPLE 9

The sequence of tests described in Example 8 was repeated using propane as the alkane reactant. During direct dehydrogenation, the initial yield of propene was 19%; after 3 hours, it had declined to 12% On switching to the oxidative mode, the yield was restored to 19%. Thereafter, it declined slowly to 17% during the next 4 hours.

The invention is further illustrated by the yield data given graphically for various catalysts in the accompanying FIGS. 1 and 2.

FIG. 1:

Oxidative dehydrogenation of isobutane (GHSV=3000 hr−1) at 450 C., over

(a) 1%Pt/20%SnO2-ZrO2;

(b) 1%Pt-1%Sn/Al2O3.

FIG. 2:

Oxidative dehydrogenation of isobutane at 500 C., over

(a) 1%Pt/20%SnO2-ZrO2;

(b) 1%Pt/20%SnO2-ZrO2;

(c) 1%Pt-1%Sn/ZrO2;

(d) 1%Pt-1%Sn/Al2O3.

For (a), GHSV=1500 hr−1; (b)-(d); GHSV=3000 hr−1

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2408140Sep 18, 1944Sep 24, 1946Shell DevDehydrogenation catalyst
US3437703May 5, 1966Apr 8, 1969Foster Grant Co IncCatalytic dehydrogenation process and compositions
US3511888Feb 8, 1968May 12, 1970Shell Oil CoParaffin conversion catalyst and process
US3637527Jul 23, 1969Jan 25, 1972Chevron ResPreparation of multicomponent catalysts
US3668147Nov 19, 1968Jun 6, 1972Nitto Chemical Industry Co LtdMultiple promoted iron oxide-antimony oxide catalysts for oxidation of olefins
US3670044Jul 18, 1969Jun 13, 1972Phillips Petroleum CoCatalytic dehydrogenation process
US3745112Nov 23, 1971Jul 10, 1973Universal Oil Prod CoPlatinum-tin uniformly dispersed hydro-carbon conversion catalyst and process
US3790473Nov 6, 1972Feb 5, 1974Universal Oil Prod CoTetrametallic hydrocarbon conversion catalyst and uses thereof
US3864284Jun 1, 1973Feb 4, 1975Chevron ResPlatinum-tin catalyst on an alumina carrier
US3911039Jan 23, 1974Oct 7, 1975Standard Oil Co OhioProcess for the preparation of botadiene from N-butene
US3939220 *Jan 18, 1974Feb 17, 1976Universal Oil Products CompanyDehydrogenation method and multimetallic catalytic composite for use therein
US3957688Nov 15, 1973May 18, 1976Phillips Petroleum CompanyCatalytic dehydrogenation process
US3972184Oct 25, 1974Aug 3, 1976Ethyl CorporationCatalytic treatment of exhaust gas responsive to engine temperature
US3998900Aug 27, 1974Dec 21, 1976Universal Oil Products CompanyDehydrogenation of hydrocarbons with a multimetallic catalytic composite
US4003826Oct 28, 1975Jan 18, 1977Uop Inc.Hydrocarbon conversion with an acidic multimetallic catalytic composite
US4003852Jan 8, 1976Jan 18, 1977Uop Inc.Nonacidic multimetallic dehydrogenation catalyst
US4032589Mar 17, 1975Jun 28, 1977Chevron Research CompanyDehydrogenation catalyst and process
US4070413Oct 28, 1976Jan 24, 1978Uop Inc.Dehydrogenation of saturated hydrocarbons
US4149998Feb 23, 1977Apr 17, 1979Exxon Research & Engineering Co.Supported metal interaction catalysts
US4152246Jul 18, 1977May 1, 1979Compagnie Francaise De RaffinageCatalyzed processes for the hydrotreatment of hydrocarbons
US4152365Mar 17, 1975May 1, 1979Phillips Petroleum CompanySelective hydrogenation of polyenes
US4418237May 21, 1982Nov 29, 1983Uop Inc.Dehydrogenation of dehydrogenatable hydrocarbons
US4423407Feb 27, 1981Dec 27, 1983Dart Industries Inc.Apparatus and method for measuring the concentration of gases
US4431750 *May 19, 1982Feb 14, 1984Phillips Petroleum CompanyPlatinum group metal catalyst on the surface of a support and a process for preparing same
US4469816Dec 14, 1982Sep 4, 1984Allied CorporationPalladium on alumina aerogel catalyst composition and process for making same
US4486547Jun 2, 1983Dec 4, 1984Uop Inc.Indium-containing dehydrogenation catalyst
US4492769Jul 25, 1983Jan 8, 1985Pro-CatalysePollution control catalyst for internal combustion engine exhaust system/catalytic converter and process for its preparation
US4613715Jul 12, 1985Sep 23, 1986Phillips Petroleum CompanyOxygen addition to a steam-active dehydrogenation reactor
US4617794Jun 3, 1985Oct 21, 1986Kabushiki Kaisha Toyota Chuo KenkyushoExhaust gas purifying method and apparatus for internal combustion engines
US4708946May 21, 1986Nov 24, 1987Nippon Shokubai Kagaku Kogyo Co., Ltd.Catalyst for purifying exhaust gas
US4717779Aug 6, 1986Jan 5, 1988Uop Inc.Dehydrogenation of dehydrogenatable hydrocarbons
US4727216Jul 21, 1986Feb 23, 1988Chevron Research CompanyDehydrogenation of isobutane over a zeolitic catalyst
US4786625Dec 11, 1987Nov 22, 1988Uop Inc.Dehydrogenation catalyst compositon
US4788371Dec 30, 1987Nov 29, 1988Uop Inc.Catalytic oxidative steam dehydrogenation process
US4808394Sep 8, 1987Feb 28, 1989Phillips Petroleum CompanyCatalytic oxidation of carbon monoxide
US4902848Jul 1, 1988Feb 20, 1990UopProcess for the dehydrogenation of hydrocarbons
US4902849Feb 6, 1989Feb 20, 1990Phillips Petroleum CompanyDehydrogenation process
US4914075Dec 5, 1988Apr 3, 1990UopDehydrogenation catalyst composition
US4926005May 17, 1989May 15, 1990Phillips Petroleum CompanyDehydrogenation process
US4940826Feb 6, 1989Jul 10, 1990British Petroleum Company P.L.C.Process for the production of mono-olefins by the catalytic oxidative dehydrogenation of gaseous paraffinic hydrocarbons having two or more carbon atoms
US5082820 *Nov 27, 1989Jan 21, 1992Nippon Shokubai Kagaku Kogyo Co., Ltd.Carrier for gas-treating catalyst, method for production thereof and gas-treating catalyst incorporating said carrier therein
US5113023Jul 16, 1990May 12, 1992Phillips Petroleum CompanyRemoval of linear internal olefins from steam active dehydrogenation recycle stream
US5128300Sep 25, 1991Jul 7, 1992UopReforming catalyst with homogeneous metals dispersion
US5217692Jun 10, 1991Jun 8, 1993E.T.R. Elektronik Technologie Rump GmbhGas sensor arrangement
US5220091Feb 26, 1992Jun 15, 1993Phillips Petroleum CompanyAlkane dehydrogenation
US5234883Mar 18, 1992Aug 10, 1993Degussa AktiengesellschaftCatalyst for hardening fatty acids and process for its preparation
US5283041 *Aug 13, 1992Feb 1, 1994Engelhard CorporationCatalytic incineration of organic compounds
US5290589Aug 12, 1991Mar 1, 1994Ensci, Inc.Process for coating a substrate with iron oxide and uses for coated substrates
US5302350Jan 26, 1993Apr 12, 1994Fci - Fiberchem, Inc.Specific and reversible carbon monoxide sensor
US5439859Apr 27, 1992Aug 8, 1995Sun Company, Inc. (R&M)Process and catalyst for dehydrogenation of organic compounds
CA1319928A Title not available
EP0102067A2Aug 26, 1983Mar 7, 1984Kabushiki Kaisha ToshibaCO gas detecting device and circuit for driving the same
EP0127942A1Apr 27, 1984Dec 12, 1984Asahi Kasei Kogyo Kabushiki KaishaProcess for the preparation of acrylonitrile or methacrylonitrile
EP0228792A1Nov 13, 1986Jul 15, 1987Arco Chemical Technology Inc.Dehydrogenation of isobutane
EP0266875A1Sep 9, 1987May 11, 1988Hitachi, Ltd.Method of catalytic combustion using heat-resistant catalyst
EP0332289A2Feb 2, 1989Sep 13, 1989The British Petroleum Company P.L.C.A process for the production of mono-olefins by the catalytic oxidative dehydrogenation of gaseous paraffinic hydrocarbons having two or more carbon atoms
EP0337730A1Apr 11, 1989Oct 18, 1989Catalysts and Chemicals Inc, Far EastHeat resistant noble metal catalyst and method of producing the same
EP0507590A1Apr 3, 1992Oct 7, 1992Nippon Shokubai Co., Ltd.Catalyst for purifying exhaust gas
GB1550274A Title not available
GB2011088A Title not available
GB2013901A Title not available
GB2019240A Title not available
GB2024263A Title not available
Non-Patent Citations
Reference
1Catalysis, edited G. C. Bond and G. Webb, The Royal Society of Chemistry, London (1982), pp. 273-307, no month.
2Inside front cover of CRC Handbook of Chemistry and Physics, 67th ed., CRC Press 1986 (Periodic Table of Elements).
3Inside front cover of the CRC Handbook of Chemistry and Physics, 60th Edition, CRC Press 1980 (Periodic Table of the Elements).
4J. CHEM. SOC. FARADAY TRANS., 1992 88(4), Phase Cooperation between the ZnFe2O4 and alpha-Fe2O3 Phases of Ferrite Catalysts in the Oxidative Dehydrogenation of n-Butenes, Zhang et al., pp. 637-644, no month.
5J. CHEM. SOC. FARADAY TRANS., 1992 88(4), Phase Cooperation between the ZnFe2O4 and α-Fe2O3 Phases of Ferrite Catalysts in the Oxidative Dehydrogenation of n-Butenes, Zhang et al., pp. 637-644, no month.
6JOURNAL OF CATALYSTS, Bismuth Molybdate Catalysts. Preparation, Characterization and Activity of Different Compounds in the Bi-Mo-O System, Batist et al., 25, (1972), pp. 1-11, no month.
7Official Letter from Norwegian Patent Office with English Translation.
8Successful Design of Catalysts, "Fine Structure of Novel Gold Catalysts Prepared by Coprecipitation', edited by T. Inui, published by Elsevier Science Publishers B.V., Amsterdam (1988) pp. 33-42, no month.
9Successful Design of Catalysts, ‘Fine Structure of Novel Gold Catalysts Prepared by Coprecipitation’, edited by T. Inui, published by Elsevier Science Publishers B.V., Amsterdam (1988) pp. 33-42, no month.
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US7737078 *Dec 1, 2005Jun 15, 2010Toyota Jidosha Kabushiki KaishaCatalyst for purifying exhaust gas
US7820588 *Dec 1, 2006Oct 26, 2010Ford Global Technologies, LlcCarbon monoxide catalyst
US7985709 *Sep 28, 2004Jul 26, 2011The United States Of America As Represented By The Administrator Of The National Aeronautics And Space AdministrationMethodology for the effective stabilization of tin-oxide-based oxidation/reduction catalysts
US20130216470 *Aug 22, 2011Aug 22, 2013Bayer Intellectual Property GmbhCatalyst and method for the production of chlorine by gas phase oxidation
Classifications
U.S. Classification502/339, 502/352, 502/349, 502/325
International ClassificationC07C5/333, C07B35/04, C07B61/00, C07C11/02, C07C11/09, B01J23/40, C07C5/48, B01J23/62, B01J37/03, B01J21/06, C07C5/32
Cooperative ClassificationC07C2523/42, B01J23/626, C07C2523/14, C07C2521/06, C07C5/325, B01J37/03, C07C5/48, C07C5/3337, B01J21/066, C07C2523/62
European ClassificationB01J21/06W, C07C5/333D2, C07C5/48, C07C5/32B4B, B01J37/03, B01J23/62H4
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