US3679773A

US3679773A - Dehydrogenation-type reactions with group viii catalysts

Info

Publication number: US3679773A
Application number: US769751A
Authority: US
Inventors: Stephen M Kovach; Ronald A Kmecak
Original assignee: Ashland Oil Inc
Current assignee: Ashland LLC
Priority date: 1968-10-22
Filing date: 1968-10-22
Publication date: 1972-07-25
Anticipated expiration: 1989-07-25

Abstract

A process for the dehydrocyclization of paraffinic hydrocarbons or the dehydrogenation of low molecular weight paraffins to produce hydrogen and mono-olefins, including, contacting the organic materials with a catalyst of an active metal from Group VIII of the Periodic System, such as platinum, palladium, ruthenium and nickel, in amounts of about 0.5 to 5 percent of the finished catalyst and a promoter from the rare earth metal Group of the Periodic System, such as cerium and thorium, in an amount of 1 to 10 percent of the finished catalyst, both deposited on an inert oxide support, such as gamma-type aluminas, silica-alumina, silica-magnesia, etc., at a temperature between about 550* and 1,250*F, a pressure of 0.01 to 2,600 mm. of mercury absolute, and a liquid hourly space velocity of 0.1 to 10. A promoting amount of a second metal selected from the group consisting of alkali metals and alkaline earth metals may also be deposited on the carrier. The hydrogen produced by the dehydrogenation of paraffins is also separated from the olefins and contacted with coal liquids in the presence of the above catalyst or a hydrogenation catalyst and under hydrogenation conditions to increase the saturation of the coal liquids.

Description

United States Patent Kovach et a1.

July 25, 1972 [72] lnve'ntors: Stephen M. Kovach; Ronald A. Kmecak,

both of Ashland, Ky.

[73] Assignee: Ashland Oil, Inc., Houston, Tex.

[22] Filed: Oct. 22, 1968 211 Appl. No.: 769,751

[52] US. Cl ..260/683.3, 208/10, 208/49,

252/457, 252/459, 252/460, 252/462, 260/673.5 [51] Int. Cl ..C07c 5/18, C07c 11/04 [58] Field of Search ..260/683.3, 673.5; 252/462 [56] References Cited UNITED STATES PATENTS 1,271,013 7/1918 Bosch et al. ..260/683.3 2,651,598 9/1953 Ciapetta ..260/673 5 2,780,584 2/1957 Doumani 260/6735 3,503,867 3/1970 Ludlam et a1.. ..208/10 2,814,599 11/1957 Le Francois et al. ..260/683 3 3,435,090 3/1969 Abell et a1. ..260/683.3 3,299,156 1/1967 Ashley et a1. ..260/673.5

Primary Examiner-Delbert E. Gantz Assistant Examiner-G. E. Schmitkons Attorney-Walter H. Schneider [57] ABSTRACT A process for the dehydrocyclization of paraffinic hydrocarbons or the dehydrogenation of low molecular weight paraffins to produce hydrogen and mono-olefins, including, contacting the organic materials with a catalyst of an active metal from Group Vlll ofthe Periodic System, such as platinum, palladium, ruthenium and nickel, in amounts of about 05 to 5 percent of the finished catalyst and a promoter from the rare earth metal Group of the Periodic System, such as cerium and thorium, in an amount of 1 to 10 percent of the finished catalyst, both deposited on an inert oxide support, such as gamma-type aluminas, silica-alumina, silica-magnesia, etc., at a temperature between about 550 and 1,250F, a pressure of 0.01 to 2,600 mm. of mercury absolute, and a liquid hourly space velocity of 0.1 to 10. A promoting amount of a second metal selected from the group consisting of alkali metals and alkaline earth metals may also be deposited on the carrier. The hydrogen produced by the dehydrogenation of paraffins is also separated from the olefins and contacted with coal liquids in the presence of the above catalyst or a hydrogenation catalyst and under hydrogenation conditions to increase the saturation of the coal liquids.

10 Claims, No Drawings DEHYDROGENATION-TYPE REACTIONS WITH GROUP VIII CATALYSTS BACKGROUND OF THE INVENTION The present invention relates to a method for effecting reactions involving the dehydrogenation of organic materials. In a more specific aspect, the present invention relates to a method for the dehydrogenation and dehydrocyclization of hydrocarbon materials.

Numerous processes have been developed for the dehydrogenation of organic materials and, particularly, for the dehydrogenation and dehydrocyclization of non-aromatic hydrocarbons.

Among the dehydrocyclization type reactions are those involving the treatment of a variety of feedstocks containing normal paraffins. In these instances, normal paraffins, such as n-hexane and n-heptane, or mixtures thereof, are dehydrogenated and cyclized to produce aromatic hydrocarbons. This type reaction may also be applied to hydrocarbon mixtures containing normal paraffins, such as primary flash distillates and the products of the well-known reforming process in which a naphtha fraction is contacted at elevated temperature and pressure and in the presence of hydrogen with a dehydrogenation catalyst, for example a catalyst consisting essentially of platinum and alumina with or without combined halogen to produce a gasoline fraction ofincreased octane number. The dehydrocyclization reactions are, of course, primarily confined to the treatment of materials having five carbon atoms and higher.

The dehydrogenation type of reaction without cyclization also is primarily applied to paraffinic hydrocarbons. However, in this case, the hydrocarbon feed is normally a hydrocarbon having five or less carbon atoms per molecule. Specifically, in this latter case, the petroleum industry now produces a wide variety of hydrocarbon streams for use as fuels and chemicals. Two of the more important chemicals are olefins which are utilized as chemical intermediates and hydrogen which is used for the production and processing of petrochemicals and fuels. At the present time, most of the unsaturated light hydrocarbons are obtained as by-products of cracking processes. While this is a relatively cheap source of light olefins, the purity of the product does not generally meet requirements where high purity is needed. One possible means of obtaining relatively pure, unsaturated hydrocarbons is by the dehydrogenation of the corresponding saturated hydrocarbons. This is a relatively simple operation. Large quantities of the raw material can be obtained at a reasonable price. Several processes have been developed for light paraffin dehydrogenation. These generally include cyclic, adiabatic, fixed-bed regenerative processes requiring short cycle times due to coke deposition on the catalyst. Therefore, for continuous operation, a minimum of three reactors is required with one reactor on-stream, one being regenerated, and one on standby. Multiples of this system can be utilized to increase olefin production. Another method for producing unsaturates is the pyrolysis of hydrocarbons. This is a process which is used almost exclusively for the production of acetylene, ethylene, and propylene. One drawback of this system is the high temperature required and the low purity of the hydrogen product stream. Yet another method which has been developed entails the dehydrogenation of paraffins over precious metal catalysts. However, conversions are very low, about percent, and olefin separation must be effected by aromatic alkylation. The production of hydrogen for the petroleum-petrochemical industry is generally through catalystic reforming of naphthas or the steam reforming of light hydrocarbons. The hydrogen available from catalystic reforming is rather limited and in short supply, so that more and more, producers are resorting to steam reforming of light hydrocarbons to satisfy the massive hydrogen requirements oftoday's operations.

Hydrogen requirements are also extremely high in processes for the treatment of liquids derived from coal. For example, coal liquids may be obtained from coal in solid form by carbonization or pyrolysis of the solid coal to produce coal tar products and the solvent extraction of coal solids with solvents, such as tetralin, decalin and the like, to produce a solvent extract. It is therefore highly desirable that an integrated process for the production of substantial volumes of hydrogen and the saturation and upgrading of coal liquids with such hydrogen be provided.

It is therefore an object of the present invention to provide a process for effecting reactions involving the dehydrogenation of organic materials. Another object of the present invention is to provide an improved process for effecting reactions involving the dehydrogenation or dehydrocyclization of organic materials. Yet another object of the present invention is to provide an improved process for the saturation of highly unsaturated organic materials derived from solids. Another and further object of the present invention is to provide an integrated process for the saturation of coal liquids including dehydrogenating paraffinic hydrocarbons to produce monoolefins and hydrogen, separating the hydrogen from the monoolefins and contacting the coal liquid with said hydrogen under hydrogenation conditions. It is also an object of the present invention to provide an improved process for the production of olefins and hydrogen. Yet another object of the present invention is to provide an improved process for the production of olefins and hydrogen by the dehydrogenation of paraffins. A further object of the present invention is to provide an improved process for the production of olefins and hydrogen by the dehydrogenation of paraffins which utilizes a novel catalyst system. A further object of the present invention is to provide an improved process for the conduct of dehydrogenation-type reactions which utilizes a catalyst capable of high conversion rates. Another and further object of the present invention is to provide an improved process for the conduct of dehydrogenation-type reactions which utilizes a catalyst of high selectivity. Still another object of the present invention is to provide an improved process for the conduct of dehydrogenation-type reactions which utilizes a catalyst having a low coking rate. These and other objects and advantages of the present invention will be apparent from the following detailed description.

SUMMARY OF THE INVENTION Briefly, in accordance with the present invention, dehydrogenation-type reactions are conducted by contacting the feed material with a Group VIII metal and a rate earth metal, both deposited on an inert oxide support. The invention also provides for an integrated process for the dehydrogena tion of paraffinic hydrocarbons to produce mono-olefins and hydrogen, the separation of hydrogen from the mono-olefins and the saturation of coal liquids with such hydrogen.

Suitable feedstocks for use in the dehydrocyclization of non-aromatic hydrocarbons include those previously mentioned, such as, n-hexane and n-heptane and mixtures of these, as well as hydrocarbon mixtures containing normal parafi'ms, such as, distillates and products of reforming operatrons.

The dehydrocyclization operation may be carried out at temperatures varying all the way from 550 to about 1,150 F, at pressures between about 0.01 and 2,600 mm. mercury absolute, and at liquid hourly space velocities of from 0.1 to 10.

Suitable feedstocks for use in the dehydrogenation include ethane, propane, normal butane, iso-butane, normal pentane, iso-pentane, etc.

Processing conditions for the dehydrogenation reaction are dependent upon the feedstock employed. Generally, temperatures between about 900 and 1,250 F, pressures between about and 2,500 mm. mercury absolute, and liquid hourly space velocities from about 0.] to l0 may be employed. More specifically, if ethane is the feedstock, the temperature should be between about l,l00 and l,250 F. Where C to C paraffins are the feedstock, a temperature of 900 to l,l50 F should be used.

The separation of the mono-olefins and hydrogen produced in the dehydrogenation reaction may be effected by selective adsorption and other known separation techniques. The separated hydrogen is then contacted with liquid materials of a highly unsaturated nature such as coal liquids derived from solid coal. For example, it is known that solid coal can be.

crushed or ground and subjected to carbonization or pyrolysis at elevated temperatures to produce liquids known as coal tar liquids. It is also known that crushed or pulverized coal can be contacted with a suitable solvent, at slightly elevated temperatures, such as tetralin, decalin and other hydrogen transfer solvents, to thereby produce a solvent extract which resembles coal tar liquids or heavy petroleum crudes. Both of these crude materials, particularly the solvent extracts, are highly unsaturated mixtures containing substantial volumes of cyclic compounds, which must be saturated to some extent before they can be further processed to produce fuels and chemicals. Such saturation is effected'in accordance with the present invention by contacting the coal liquids with the hydrogen separated from the mono-olefins and recovering the hydrogenated coal liquids. The hydrogenated coal liquids then resemble in substantially all respects. except for aromaticity, hydrocarbon liquids derived from petroleum crude oils; and, accordingly, they may be processed in accordance with conventional refinery practices for the conversion of petroleum oils.

The hydrogenation of the coal liquids may be carried out in the presence of the same catalysts employed for the dehydrogenation reaction. However, any known hydrogenation catalysts may also be employed, such as Group VIII metals, for example, platinum, palladium, rhodium and nickel and cobalt and Group V] metals, such as molybdenum or tungsten or various combinations of these metals, deposited on a carrier such as alumina or silica. Hydrogenation conditions may include temperatures from about 450 to 800 F, preferably about 500 to 800 F, pressures of about 400 to 10,000 psig., liquid hourly space velocities from about 0.1 to 10, and hydrogen-to-hydrocarbon mole ratios from about I to 20 to l.

The novel catalysts of the present invention include an active metal from Group VIII of the Periodic System, and specifically, platinum, palladium, rhodium, ruthenium, or nickel in a concentration of about 0.5 to 5 percent by weight based on the finished catalyst. The promoter ofthe present invention includes a rare earth metal, such as cerium or thorium in a concentration of about 1 to l percent by weight based on the finished catalyst product. The promoter is preferably in its oxide form. Both of these materials are deposited on an inert oxide support, preferably an alumina ofa gamma type, such as the bayerite, beta, etc., and boehmite crystalline forms. Other suitable supports of this character may also be used, such as other aluminas, silica-alumina, silica, silica-magnesia, alumina-magnesia, silica-zirconia, etc.

if desired, a second promoter selected from the group consisting of alkali metals, such as, potassium, rubidium, cesium, etc., and alkaline earth metals, such as magnesium, calcium and strontium, may also be deposited on the carrier. The total amount of promoting agents is preferably with the l to [0 percent limit previously mentioned. lt is also preferred that this promoter be in its oxide form on the finished catalyst.

The catalysts may be prepared by techniques well known in the art. For example, such preparation includes known impregnation techniques. One can employ extrudates or pellets for impregnation or powders followed by pelletization or extrusion to yield the finished catalyst. The active metal and the promoter are added through the use of water-soluble salts, such as their halides, nitrates, sulfates, acetates, etc. Easily hydrolyzed salts can be kept in solution without decomposition by employing the appropriate inorganic acids. Wellknown procedures for drying and calcination of the catalysts may also be employed, such as vacuum drying and calcination in oxidative, neutral and reductive atmospheres, utilizing calcination temperatures of about 800 to 1,200 F.

The following example illustrates the conduct of the present process:

Dehydrogenation of Paraffins Catalyst Identity l Pd ZQIH' When reference is made herein to the Periodic System of elements, the particular groupings referred to are as set forth in the Periodic Chart of the Elements in "The Merck Index," Seventh Edition, Merck & Co., Inc., 1960.

We claim:

1. A process for dehydrogenating hydrocarbons predominating in aliphatic, paraffinic hydrocarbons having up to five carbon atoms per molecule comprising; contacting the hydrocarbons with a catalyst consisting essentially of both about 0.5 to 5 percent by weight of one metal ofGroup Vlll of the Periodic System and about 1.0 to l0 percent by weight of an oxide of a rare earth metal selected from the group consisting of cerium and thorium, both impregnated on a gamma alumina support, under conditions sufficient to effect said hydrogen transfer reaction, including, a temperature of about 550 to l,230 F, a pressure ofabout 0.0! to 2,500 mm ofmercury and a liquid hourly space velocity of about 0.1 to 10.

2. A process in accordance with claim I wherein the dehydrogenation temperature is between about 900 and 1 ,250 F.

3. A process in accordance with claim 2 wherein the paraffinic hydrocarbon is ethane and the temperature isbetween about l,100 and 1,250 F.

4. A process in accordance with claim 2 wherein the hydrocarbons contain three to five carbon atoms per molecule and the temperature is between about 900 and l, 1 50 F.

5. A process in accordance with claim 1 wherein the paraffinic hydrocarbons are converted to hydrogen and olefins, the

hydrogen and olefins are separated and coal liquids are contacted with the hydrogen in the presence of a hydrogenation catalyst and under conditions sufficient to hydrogenate at least a portion of said coal liquids.

6. A process in accordance with claim 5 wherein the hydrogenation catalyst is a catalyst of the same character as the dehydrogenation catalyst.

7. A process in accordance; with claim 1 wherein the Group VIII metal is a metal selected from the group consisting of noble metals and nickel. A

8. A process for dehydrogenating hydrocarbons predominating in aliphatic, paraffmic hydrocarbons having up to five carbon atoms per molecule comprising; contacting the hydrocarbons with a catalyst consisting essentially of about 0.5 to 5 percent by weight of one metal of Group VIII of the Periodic System, about 1.0 to 10 percent by weight of an oxide of a rare earth metal selected for the group consisting of cerium and thorium, and a second promoter of about I to 10 percent by weight of an oxide of a metal selected from the group consisting of alkali metals, alkaline earth metals and mixtures thereof, all impregnated on a gamma alumina support, under conditions sufficient to effect said dehydrogenation, including a temperature of about 550 to 1,230 E, a pressure of about 0.01 to 2,500 mm of mercury and a liquid hourly space velocity of about 0.1 to 10.

9. A process in accordance with claim 8 wherein the second promoter is an alkali metal.

10. A process in accordance with claim 8 wherein the 5 second promoter is an alkaline earth metal.

Claims

2. A process in accordance with claim 1 wherein the dehydrogenation temperature is between about 900* and 1,250* F.
3. A process in accordance with claim 2 wherein the paraffinic hydrocarbon is ethane and the temperature is between about 1, 100* and 1,250* F.
4. A process in accordance with claim 2 wherein the hydrocarbons contain three to five carbon atoms per molecule and the temperature is between about 900* and 1,150* F.
5. A process in accordance with claim 1 wherein the paraffinic hydrocarbons are converted to hydrogen and olefins, the hydrogen and olefins are separated and coal liquids are contacted with the hydrogen in the presence of a hydrogenation catalyst and under conditions sufficient to hydrogenate at least a portion of said coal liquids.
6. A process in accordance with claim 5 wherein the hydrogenation catalyst is a catalyst of the same character as the dehydrogenation catalyst.
7. A process in accordance; with claim 1 wherein the Group VIII metal is a metal selected from the group consisting of noble metals and nickel.
8. A process for dehydrogenating hydrocarbons predominating in aliphatic, paraffinic hydrocarbons having up to five carbon atoms per molecule comprising; contacting the hydrocarbons with a catalyst consisting essentially of about 0.5 to 5 percent by weight of one metal of Group VIII of the Periodic System, about 1.0 to 10 percent by weight of an oxide of a rare earth metal selected for the group consisting of cerium and thorium, and a second promoter of about 1 to 10 percent by weight of an oxide of a metal selected from the group consisting of alkali metals, alkaline earth metals and mixtures thereof, all impregnated on a gamma alumina support, under conditions sufficient to effect said dehydrogenation, including a temperature of about 550* to 1,230* F., a pressure of about 0.01 to 2,500 mm of mercury and a liquid hourly space velocity of about 0.1 to 10.
9. A process in accordance with claim 8 wherein the second promoter is an alkali metal.
10. A process in accordance with claim 8 wherein the second promoter is an alkaline earth metal.