GB2187756A

GB2187756A - Catalyst for hydrogenation of unsaturated hydrocarbons with hydrogen and process for preparing same

Info

Publication number: GB2187756A
Application number: GB08605808A
Authority: GB
Inventors: Vladimir Mikhailovich Gryaznov; Alexandr Petrovich Mischenko; Viktor Sergeevich Smirnov; Maria Evgrafovna Sarylova; Anatoly Borisovich Fasman
Original assignee: Institut Neftekhimicheskogo Sinteza Imeni A V Topchieva; AV Topchiev Institute of Petrochemical Synthesis
Current assignee: Institut Neftekhimicheskogo Sinteza Imeni A V Topchieva; AV Topchiev Institute of Petrochemical Synthesis
Priority date: 1986-03-10
Filing date: 1986-03-10
Publication date: 1987-09-16
Anticipated expiration: 2006-03-10
Also published as: FR2595092B1; GB2187756B; DE3609263A1; GB8605808D0; JPS62204845A; FR2595092A1

Abstract

A catalyst suitable for hydrogenation of unsaturated hydrocarbons with hydrogen comprises a membrane made from an alloy of 80-95% by mass of palladium and 5-20% by mass of ruthenium or rhodium and consisting of a non-porous layer and a porous layer positioned on one side or both sides of said non-porous layer. The catalyst may be prepared by a process in which copper or mercury is applied on one or both sides, of the surface of a membrane made from the above mentioned alloy, the thickness ratio of the layer of copper or mercury to the membrane is of from 1:10 to 1:100 respectively; the membrane with the deposited there onto copper is maintained at a temperature within the range of from 300 to 800 DEG C, the membrane with mercury deposited thereon is maintained at a temperature of from -10 to 150 DEG C, whereafter copper or mercury is chemically recovered from the membrane.

Description

SPECIFICATION Catalyst for hydrogenation of unsaturated hydrocarbons with hydrogen and process for preparing same The present invention relates to the preparation of catalysts and, more particularly, to catalysts for hydrogen hydrogenation of unsaturated hydrocarbons such as olefines and dienes and to processes for preparing same.

Known in the art are metallic catalysts with a well-developed surface comprising porous granules of a carrier (alumina, silica gel, carbon) supporting a catalytically active metal. Also known are metallic catalysts with a well-developed surface (skeleton catalyst) /cf. C.N.Setterfield, "Heterogeneous Catalysts in Practice", McGraw-Hill Inc., New York 1980/.

The prior art processes for the preparation of the above-mentioned catalysts with a highly developed surface comprise deposition of a catalytically active metal in a highly dispersed form onto a granulated carrier. Furthermore, metallic catalysts with a well-developed surface (skeleton catalysts) are produced, for example, by leaching of some alloys of catalytically active metals with aluminium, silicon and the like (see the opt.cit.publication).

The above-mentioned catalysts do not feature a selective premevability for hydrogen. They are not durable which results in their mechanical wear during operation. It is impossible to make membranes therefrom.

Known in the art is a membrane catalyst with a highly developed surface manufactured as a foil or a tube with palladium black or other metal black deposited on their surface. The foil or the tube is made of palladium or an alloy thereof with silver or nickel (cf. V.M.Gryaznov, V.S.Smirnov, L.K.lvanova, A.P.Mischenko. Doklady AN SSSR, 1970, vol. 190, p. 144).

The process for the manufacture of this membrane catalyst consists in a chemical or electrochemical deposition of palladium black or of another catalytically active metal (such as nickel) black onto the surface of a membrane made as a foil or a tube from a palladium alloy, for example with silver (see the above publication).

However, the prior art process does not ensure a durable coating of the membrane with black of palladium or of another metal. Furthermore, the use of another catalytically active metal frequently results in a reduced permeability of the membrane catalyst for hydrogen, since a considerable portion of the surface of the membrane of the palladium alloy becomes inaccessible for molecules of hydrogen and the organic substance. Upon a long-time operation in a medium of hydrogen, air and hydrocarbons the layer of black is destroyed and stripped-off.

Also known is a catalyst for hydrogen hydrogenation of unsaturated hydrocarbons comprising a substrate made from a structural metallic material with a porous layer of a catalytically active material such as nickel, palladium or platinum deposited on its surface (cf. USSR Inventor's Certificate No. 218830, Int. Pat. Cl. B 01 J 01 25/00, Bulletin of Inventions No. 24, 1967).

A process for producing this catalyst comprises deposition of a layer of a catalytically active metal on the surface of a substrate, followed by coating thereof with a layer of a catalytically inactive metal such as aluminium or zinc, maintaining at a temperature within the range of from 300 to 1,000 C to ensure a mutual diffusion of the catalytically active and catalytically inactive metals, followed by a chemical recovery of aluminium or zinc from the catalytically active metal by leaching with sodium hydroxide or potassium hydroxide. The layer thickness of the catalytically inactive metal is equal too or by 10 times greater than that of the active metal (see the above mentioned publication).

This prior art process, however, does no make it possible to produce a membrane catalyst whereupon hydrogenation processes occur with the use of active (elemental) hydrogen diffusing through the membrane. On the catalyst produced by the above process such processes occur with the use of molecular hydrogen at a competiting adsorption of hydrogen and the unsaturated hydrocarbon, thus resulting in a reduced rate of hydrogenation and lowered selectivity of the process.

It is an object of the present invention to provide a catalyst with a highly developed porous surface, but without through pores, having an increased selective permeability for hydrogen and a high mechanical strength of the porous layer and to provide a process for the preparation of a catalyst featuring the above-specified properties.

This object is accomplished by the provision of a palladium-based catalyst for hydrogen hydrogenation of unsaturated hydrocarbons, wherein according to the present invention the catalyst comprises a membrane made of an alloy of 80-98% by mass of palladium and 5-20% by mass of ruthenium or rhodium and consisting of a non-porous layer and a porous layer disposed on one of both sides of the non-porous layer, the porous surface area being ranged from 150 to 820 cm2 of pores per cm2 of the membrane surface and the thickness ratio of the porous layer to the non-porous one being from 1:5 to 1:1,000 respectively.

This object is also accomplished by a process for preparing the catalyst by depositing a catalytically inactive metal onto a catalytically active metal, maintaining these metals at a temper ature ensuring their mutual diffusion, followed by a chemical recovery of the catalytically inactive metal from the catalytically active metal, wherein according to the present invention the catalytically active metal is used as a membrane from an alloy consisting of 80-95% by mass of palladium and 5-20% by mass of ruthenium or rhodium; as the catalytically inactive metal copper or mercury is used which is applied to the membrane surface on one or both sides thereof at a thickness ratio of the catalytically inactive metal to the membrane of from 1:10 to 1:100; in the case of using copper as the catalytically inactive metal the membrane with copper deposited thereonto is maintained at a temperature within the range of from 300 to 800"C and copper is chemically removed from the membrane by treating thereof with trichloroacetic acid; in the case of using mercury as the catalytically inactive metal the membrane with mercury deposited thereonto is maintained at a temperature of from - 10 to 150"C and chemical removal of mercury from the membrane is effected by treating the membrane with a 40-60% aqueous solution of iron (III) chloride or with a 20-30% aqueous solution of nitric acid.

The process according to the present invention makes it possible to produce a membrane catalyst without through pores, having a highly developed porous surface (up to 800 cm2 of pores per cm2 of the membrane surface), thus enhancing the catalyst productivity during the process of hydrogenation of unsaturated hydrocarbons owing to the use of elemental hydrogen.

The selective permeability for hydrogen is also increased considerably. Thus, at room temperature (18-25"C) the hydrogen permeability of a membrane catalyst produced by the process according to the present invention is by 5-10 times higher than that of the prior art membrane catalyst; this enables the use of the membrane catalyst prepared by the process according to the present invention in a process of hydrogenation of unsaturated hydrocarbons with hydrogen at low temperatures (20-40"C). Further more, the catalyst produced by the process according to the present invention has a high mechanical strength of the porous layer which does not break during operation and regeneration of the membrane catalyst.

As it has been already mentioned hereinabove, as the catalytically active metal an alloy is used which consists of 80-95% by mass of palladium and 5-20% by mass ruthenium or rhodium. It is undesirable to use an alloy with a content of palladium less than 80% by mass, since permeability for hydrogen of such alloys is very small, whereas at a content of palladium of above 95% the alloys become unstable in the atmosphere of hydrogen and get readily destroyed.

It is also inadvisable to lower the area of the porous surface of the membrane catalyst below 150 cm2 of pores per cm2 of the membrane surface, since such membrane catalyst has but a low activity. At a value of the porous surface area above 820 cm2 of pores per cm2 of the membrane surface the porous layer becomes to crumble.

An increased- thickness ratio of the porous layer to the non-porous one of a value above 1:5 results in a reduced mechanical strength of the membrane catalyst. A lowered thickness ratio of the above-mentioned layers to a value below 1:1 ,000 is neither expedient, since the resulting membrane catalyst has but a low activity.

It is inadvisable to use the thickness ratio of the catalytically inactive layer to the membrane above 1:10, since a higher content of the catalytically inactive metal results in the formation of through pores in the membrane. The thickness ratio of less than 1:100 results in a slight loosening of the membrane surface which does not enable the preparation of a highly active hydrogenation catalyst.

The temperature of the membrane residence with the layer of copper above 800"C is undesirable, since at high temperatures a deep diffusion of copper into the superficial layer of the palladium alloy takes place which does not make it possible to fully remove copper upon a subsequent treatment with trichloroacetic acid and this residual copper provides a detrimental effect on activity of the membrane catalyst. Below 300"C the diffusion of copper into the palladium alloy gets very slowed-down and a porous layer is not formed upon dissolution of copper with the acid.

The temperature of treatment of the membrane with a layer of mercury is limited by the range of - 10 to 150"C by the same considerations as in the case of a membrane with a layer of copper.

To dissolve copper which has diffused into the membrane trichloroacetic acid is used. This solvent, while reacting with copper, does not interact with catalytically active palladium, ruthenium and rhodium which makes it possible to obtain a membrane catalyst with a porous structure of its surface.

Nitric acid with a concentration of below 20% sparingly dissolves mercury, wherefore it is inadvisable to use diluted solution of nitric acid, whereas at a concentration of nitric acid above 30% palladium as well as ruthenium and rhodium incorporated in the catalyst start to dissolve.

Similar considerations define the choice of concentrations of the aqueous solution of iron (III) chloride.

The membrane catalyst for hydrogenation comprises a membrane shaped as a foil, a plate or a tube. This membrane is made from an alloy of palladium with ruthenium or rhodium and consists of a porous layer and a non-porous layer; the porous layer can be disposed on both sides of the non-porous layer and on one side thereof. In the latter case the hydrogenation process is carried out on the side of the porous layer. The thickness ratio of porous and nonporous layers ranges from 1:5 to 1:1,000 respectively. The porous surface area is 150 to 820 cm2 of pores per cm2 of the membrane catalyst surface.

The membrane catalyst according to the present invention is prepared in the following manner.

First of all, onto a clear surface of a membrane shaped, for example, as a foil a plate or a tube from an alloy of palladium with ruthenium or rhodium a thin layer of copper or mercury is applied on one or both sides at a thickness ratio of the layer of the catalystically inactive metal to the membrane of from 1:10 to 1:100. Copper can be applied onto the membrane by, for example, vacuum atomization, electroplating, diffusion welding; mercury should be preferably deposited by dipping or casting. The membrane with copper or mercury applied thereonto is maintained at a specific temperature (within the range of from 300 to 800"C in the case of copper and from - 10 to 1 50"C in the case of mercury) and then placed into an appropriate solvent.In the case of copper use is made of trichloroacetic acid, in the case of mercury-of a 40-60% aqueous solution of iron (III) chloride or a 20-30% aqueous solution of nitric acid.

After drying a membrane catalyst with a porous layer is obtained.

The membrane catalyst produced in the above-described manner is tested for hydrogen permeability by the direct-flow method using a thermal-conductivity cell-katharometer.

To carry out a process of hydrogenation of unsaturated hydrocarbons such as 1 ,3-pentadiene, pentene, cyclopentadiene, the membrane catalyst according to the present invention is placed into a reactor in such a manner that it partitions the inner space of the reactor into two chambers. Into one chamber hydrogen is supplied, into the other the compound to be hydrogenated. Hydrogen diffuses into the second chamber through the membrane catalyst in an active elemental form and reacts with the substance being hydrogenated on the porous surface of the membrane catalyst with the formation of the desired product. The catalyst composition is determined chomatographically. The thickness of the porous and non-porous layers of the catalyst is determined by means of an electron microscope.

For a better understanding of the present invention some specific examples illustrating its particular embodiments are given -hereinbelow.

Example 1.

A 100m foil made from an alloy consisting of 90.2% by mass of palladium and 9.8% by mass of ruthenium is degreased, rinsed with distilled water and a layer of copper with the thickness of 2item is applied onto both sides of the foil by way of vacuum atomization.

The foil with the layers of copper applied thereonto is heated to the temperature of 800"C, whereafter it is kept at this temperature for 3 hours. Then the foil is cooled, placed into trichloroacetic acid and kept therein until copper is fully recovered. A membrane catalyst is thus obtained which is shaped as a foil from the above-mentioned alloy and consists of a 95jim nonporous layer and superficial porous layers each having 2/tm thickness. The porous surface area measured by the BET (Brunauer S., Emmett P.H., Teller E.) method is equal to 820 cm2 of pores per cm2 of the membrane surface.

The permeability for hydrogen of the membrane catalyst (J) produced as described in Example 1 and permeability for hydrogen of the initial foil (without the treatment according to the present invention) are shown in Table 1 hereinbelow.

TABLE 1 Temperature, "C 200 300 350 400 Permeability for hydrogen of the membrane catalyst, J x 104 cm2s 'MPa 0-5 4.42 10.2 14.2 16.6 Permeability for hydrogen of the initial foil, J x 104, cm2 s-1 MPa 05 2.14 5.1 6.8 8.95 As it is seen from the above data, the membrane permeability for hydrogen after the treatment according to the present invention is increased by 2 times.

Example 2 A 50,um foil from an alloy consisting of 80% by mass. of palladium and 20% by mass of rhodium is coated on both sides with copper layers of 0.5 Am thickness each as described in the foregoing Example 1. The foil with copper layers applied thereonto is heated to the temperature of 300 C and maintained at this temperature for 3 hours. The copper is removed from the membrane by dissolution in trichloroacetic acid. A membrane catalyst similar to that of Example 1 is obtained with the thickness of each of the porous layers equal to 0.2 m at the thickness-of the non-porous layer of 49,um. The area of the porous surface of the membrane catalyst is equal to 410 cm2 per cm2 of the membrane surface.The permeability for hydrogen of the membrane catalyst at the temperature of 350 C is equal to 15.1 x 10-4 cm2 s-1 MPa-05.

Example 3 The external surface of a tube with the outside diameter of 1.2 mm and wall thickness of 100,um made from an alloy of the same composition as in Example 1 hereinbefore is coated with a layer of copper of-1,um thickness.-The tube with the copper layer deposited thereon is maintained for two hours at the temperature of 550"C. After removing copper by treatment with trichoroacetic acid a membrane catalyst is- obtained in the shape of a tube with the wall thereof made from the above-mentioned alloy and consisting of an inner non-porous layer of 99m thickness and an outside porous layer of 1,um thickness. The area of the porous surface of the membrane catalyst is 620 cm2 of the membrane surface.The permeability for hydrogen at the temperature of 350 C is-equal to 7.5x10--4 cm2 s 1 MPa 05.

Example 4 Onto a 100,um foil from an alloy consisting of 90.2% by mass of palladium and 9.8% by mass of ruthenium a copper foil of Sijm thickness is applied and subjected to compression under the pressure of 0.2MPa at the temperature of 300"C for 10 hours. The two metals are thus bonded to one another by diffusion welding. After cooling of the bimetal foil copper is removed by dissolving thereof in trichlordacetic acid: A membrane catalyst is obtained in the form of a foil made from the above-mentioned foil-and consisting of a non-porous layer with the thickness of 98 m and a porous layer of 2,zim thickness. They are of the porous surface of the membrane catalyst is equal to 740 cm2 of pores per cm2 of the membrane surface.The hydrogen permeability of the catalyst at the temperature of 200 C is equal to 5.7 x 10 4 cm2 s 1 MPa 05 and that at the temperature of 300 C is 11 1,0 x 10 4 cm2 s 1 MPa 05.

Example 5 On both sides of a 100Xtm foil made from an alloy consisting of 90.2% by mass of palladium and 9.8% by mass of ruthenium mercury layers of 4itm thickness each are applied. The foil with the layers of mercury applied thereonto is maintained at the temperature of 60 C for 5 hours, whereafter it is placed into a- boiling 60% aqueous solution of iron (III) chloride, kept in this solution till a complete dissolution of mercury and washed with distilled water until no reaction on chlorine ion is observed.After such treatment a membrane catalyst is obtained as a foil made from the above-mentioned alloy and consisting of a non-porous layer of 92jim thickness and superficial porous layers positioned on both sides of the non-porous layer and having thickness of 4 cm each. The area of the porous surface of the membrane catalyst is 520 cm2 of pores per cm2 of pores per cm2 of the membrane surface.

Table 2 shows the data on hydrogen permeability for the catalyst produced according to Example 5.

Table 2 Temperature, 200 300 350 400 Permeability for hydrogen, J x 104, cm2 s l MPa 05 4.2 9.1 12.4 14.7 Example 6 Onto a 1000ism plate from an alloy consisting of 92% by mass of palladium and 8% by mass of rhodium layers of mercury of Sjtm thickness each are applied according to the procedure described in Example 5 hereinabove. The plate with the layers of mercury applied thereonto are maintained at the temperature of - 100C for 3 days. Then mercury is recovered from the plate, treated with a 40% aqueous solution of iron (III) chloride upon boiling. A membrane catalyst is thus obtained as a plate made from the above-mentioned alloy and consisting of a non-porous layer of 999,um thickness and superficial porous layers positioned on both sides of the nonporous layer and having thickness of 0.5,zm each. The value of the porous surface of the membrane catalyst is equal to 150 cm2 of pores per cm2 of the membrane surface; hydrogen permeability at the temperature of 350"C is equal to 12.9x 10-4cm2s-'MPa-05.

Example 7 On both sides of a 100,umthick foil made from an alloy consisting of 94% by mass of palladium and 6% by mass of ruthenium layers of mercury of 8,um each are applied by the method of casting. The foil with the deposited thereonto layers of mercury is maintained at the temperature of 150"C for one hour. Thereafter mercury is removed by treating the membrane with a 50% aqueous solution of iron (III) chloride. A membrane catalyst is thus obtained as a foil from the above-mentioned alloy and consisting of a non-porous layer of 98Am thickness and superficial porous layers positioned on both sides of the non-porous layer and having thickness of 1,um each.The area of the porous surface of the membrane catalyst is 280 cm2 of pores per cm2 of the membrane surface; hydrogen permeability at the temperature of 350"C is equal to 14.1 x 10-4 cm2 s-1MPa-05.

Example 8 A membrane catalyst is prepared from an alloy consisting of 95% by mass of palladium and 5% by mass of rhodium as described in the foregoing Example 7, but mercury is removed by placing the foil, after the thermal treatment at 150"C, into aqueous solutions of nitric acid having different concentrations.

The thickness values of the non-porous layer and porous ones, the porous surface area and hydrogen permeability (at the temperature of 350"C) of the resulting membrane catalyst in relationship with the concentration of the employed nitric acid are shown in Table 3 hereinbelow.

TABLE 3 Concentration of the aqueous solution of nitric acid, % 20 25 30 Thickness of each porous layer, gtm 2 3.5 5 Thickness of the non-porous layer, jtm 85 70 50 Area of the porous surface, cm2 of pores/cm2 310 450 480 Hydrogen permeability, Jx104, cm2s a MPa 05 12.6 14.8 13.2 Example 9 Onto both sides of a 900/xmthick plate made from an alloy having the same composition as in Example 1 hereinbefore players of mercury of 5Xlm each are applied by dipping. The plate with the thus applied layers of mercury is kept at the temperature of 10 C for 24 hours. After this residence the plate is placed into a 20% aqueous solution of nitric acid for one hour.A membrane catalyst is thus obtained in the form of a plate made from the above-mentioned alloy and consisting of a non-porous layer of 900/flu thickness and superficial porous layers positioned on both sides of the non-porous layer and having a thickness of 0.45 itm each.

The area of the porous surface is 250 cm2 per cm2 of the membrane catalyst surface, the hydrogen permeability at the temperature of 350"C is equal to 13.4x 10 4 cm2 s 1 MPa 0-5.

Example 10 Onto both sides of a 10/cm foil produced from an alloy of the same composition as in Example 1 layers of mercury of 10/cm thickness each are applied. The foil with the layers of mercury deposited thereonto is kept at the temperature of 145"C for one hour. After cooling the foil is placed into a 60% aqueous solution of iron (III) chloride and kept at reflux. A membrane catalyst is thus obtained in the form of a foil made from the above-mentioned alloy and consisting of a non-porous layer of 96 zm thickness and superficial porous layers positioned on both sides of the non-porous layer and having thickness of 2 xm each.The area of the porous surface is equal to 540 cm2 or pores per cm2 of the membrane catalyst surface; the permeability for hydrogen at the temperature of 300"C is 7.9x10-4 cm2 s-1 MPa-05.

As it is seen from the above Examples, the permeability for hydrogen of the membrane catalyst is significantly (by 1.5 to 2 times) increased as compared to that of the initial foil. This makes it possible to enhance productivity of the membrane catalyst in the reaction of hydrogenation of unsaturated hydrocarbons.

Given hereinbelow are Examples 11 through 16 which illustrate the process of hydrogenation of unsaturated hydrocarbons on the membrane catalyst according to the present invention prepared as -described in Examples 1, 2, 3, 5 and 8 hereinbefore and on the prior art membrane catalyst produced by the process described in Doklady AN SSSR, 1970, vol.190, p. 144 by V.M. Gryaznov, V.S. Smirnov, L.K. Ivanova, A.P. Mischenko.

Example ii The investigation of catalytical properties of the membrane catalyst prepared according to Example 3 and shaped as a tube is carried out by hydrogenating 1 ,3-pentadiene in a reactor separated into two chambers by the above-mentioned membrane catalyst. Into one chamber formed by the tube cavity hydrogen is fed at therate of 30 ml/min, while into another chamber formed by the reactor wall and the outside surface of the tube a mixture of 1 ,3-pentadiene with argon is supplied at the rate of 10 ml/min under the pressure of 1,3-pentadiene vapours of 10 mm Hg.

The catalysate compositions obtained at different hydrogenation temperatures are shown in Table 4 hereinbelow.

TABLE 4 Temper- Catalysate composition, mol % ature, 0 C pentane 1-pentene 2-pentene 1,3-pentadiene 60 63.0 - 1.1 35.9 100 77.9 0.1 12.0 10.0 180 82.5 1.3 2.2 14.0 Example 12 The investigation of catalytical properties of a membrane catalyst prepared according to Example 5 hereinbefore as a foil is carried out by hydrogenation of 1,3-pendadiene in a reactor partitioned into two chambers by means of the above-mentioned catalyst. Into one chamber hydrogen is supplied at the rate of 30 ml/min, while into another chamber vapours of 1,3pentadiene are fed in a current of argon at the rate of 30 ml/min under the pressure of the hydrogen vapours of 15 mm Hg.

The catalyst compositions obtained at different hydrogenation temperatures are shown in Table 5 hereinbelow.

TABLE 5 Temperature, Catalysate composition, mol. % "C pentane 1-pentene 2-pentene 100 11.3 15.9 72.8 110 1-3.1- 16.8 70.1 150 20.9 6.4 72.7 Example 13 The investigation of catalytical properties of the membrane catalyst produced according to Example 2 hereinbefore in the form of a foil is carried out by hydrogenation of 1 ,3-pentadiene in a reactor partitioned into two chambers by means of the above-mentioned catalyst. Into one chamber hydrogen is supplied at the rate of 30 ml/min, while into another chamber vapours of 1 ,3-pentadiene are fed in a current of argon at the rate of 30 ml/min under the pressure of the hydrocarbon vapours of 15 mm Hg.

The catalyst compositions obtained in the process of hydrogentation carried out at different temperatures are shown in Table 6 hereinbelow.

TABLE 6 Temperature, Catalysate composition, mol. % "C pentane 1-pentene 2-pentene 100 14.9 9.6 75.5 110 32.0 4.0 64.0 150 25.0 5.4 69.6 Example 14 Comparative A membrane catalyst is used which is shaped as a foil from an alloy consisting of 94.2% by mass of palladium and 5.8% of nickel prepared by the prior art process described in the publication by V.M. Gryaznov, V.S. Smirnov, L.K. Ivanova, A.P. Mischenko, Doklady AN SSSR, 1970, vol. 190, p. 144.

The study of catalytical properties of this membrane catalyst is carried out by hydrogenation of 1 ,3-pentadiene in a reactor partitioned into two chambers by the above-mentioned catalyst.

Into one chamber hydrogen is supplied at the rate of 30 or 75 ml/min, while- into the other chamber vapours of 1 ,3-pentadiene are fed in a current of argon at the rate of 10 ml/min under the pressure of the hydrocarbon varpous of 10 mm Hg. The catalysate compositions formed at different temperatures of the hydrogenation process and rates of hydrogen supply are shown in Table 7 hereinbelow.

Table 7

Rate of Temper- Catalysate composition. mol t hydrogen ature.

supply. C pentane 1-pentene 2-pentene 1,3-penta ml/min diene 30 100 1.0 13.0 36.0 50.0 150 1.9 23.3 49.7 25.1 75 100 1.0 15.0 26.0 58.0 From the data shown in Tables 4, 5, 6 and 7 it is seen that the depth of hydrogenation on the membrane catalyst produced by the process according to the present invention is considerably greater than on the membrane catalyst prepared by the prior art process which makes it possible to increase the load on a unit surface area of the reaction surface of the catalyst and to intensify the process of hydrogenation.

Example 15 The study of catalytical properties of a membrane catalyst produced as a foil according to Example 1 hereinbefore is carried out by hydrogenation of cyclopentadiene in a reactor partitioned into two chambers by means of the above-mentioned membrane catalyst. Into one chamber hydrogen is fed at the rate of 75 ml/min, whereas into another chamber vapours of cyclopentadiene in a current of argon at the rate of 60 ml/min under the pressure of the hydrocarbon vapours of 180 mm Hg.

The catalysate compositions obtained at different temperatures of the hydrogenation process are shown in Table 8.

TABLE 8 Tempera- Catalysate composition, mol. % ature, "C cyclopentane cyclopentene cyclopentadiene 40 8.0 92.0 60 14.2 85.8 100 53.4 46.1 0.5 150 55.1 40.2 4.7 200 16.3 62.3 21.4 At a temperature within the range of from 40 to 60"C cyclopentadiene is fully hydrogenated with the predominant formation of cyclopentene which is a starting monomer for the production of synthetic rubber.

Example 16 The investigation of catalytical properties of a membrane catalyst produced according to Example 8 using a 25% aqueous solution of nitric acid for the removal of mercury is carried out by way of hydrogenation of 1-pentene in a reactor partitioned into two chambers by means of the above-mentioned catalyst. Into one chamber hydrogen is fed at the rate of 100 ml/min, into the other -vapours of 1-pentene in a current of argon at the rate of 50 ml/min under the pressure of the hydrocarbon vapours of 400 mm Hg.

The catalysate compositions obtained at different temperatures of the hydrogenation process are shown in Table 9.

Table 9 Tempera- Catalysate composition, mol. % ature, OC pentane 2-pentene 1-pentene 20 99.8 - 0.2 40 97.0 2.1 0.9 60 90.1 7.2 2.7 100 85.4 11.5 3.1 150 55,7 29.4 14.9 As it is seen from the above-given Examples 12, 13, 15 and 16,-hydrogenation of unsaturated hydrocarbons on the membrane catalyst according to the present invention within a temperature range of from 20 to 100"C proceeds substantially completely thus enabling preparation of the desired products necessitating no further separation from the initial reagent.

Therefore, the membrane catalyst according to the present invention makes it possible to carry out the process of hydrogenation of hydrocarbons within a broad temperature range (from 20 to 200"C) at a high degree of conversion (up to 100%) of the starting hydrocarbons and with a greater selectivity to give products which comprise valuable raw materials in the manufacture of synthetic rubbers.

The process for the preparation of a hydrogenation catalyst according to the present invention makes it possible to obtain a membrane catalyst selectively permeable for hydrogen and exemptied from through pores, thus enabling hydrogenation of unsaturated hydrocarbons with a highly active elemental hydrogen at a high degree- of conversion and selectivity.

Owing to the use of the process according to the present invention a membrane catalyst is obtained which has a porous layer having common crystal structure with the non-porous layer thereof, thus ensuring high mechanical strength of the porous layer and its resistance in the process of hydrogenation in the atmosphere of hydrogen and hydrocarbons, as well as in regeneration with air.

Claims

1. A catalyst suitable for hydrogenation of unsaturated hydrocarbons with hydrogen comprising a membrane made from an alloy of 80-95% by mass of palladium and 5-20% by mass of ruthenium or rhodium and consisting of a non-porous layer and a porous layer positioned on one side or both sides of said non-porous layer.

2. A catalyst according to claim 1 wherein the area of the porous surface is equal to 150-820cm2 of pores per cm2 of the membrane surface.

3. A catalyst according to claim 1 or 2 wherein the thickness ratio of the porous layer to the non-porous layer is 1:5 to 1:1000 respectively.

4. A catalyst for hydrogenation of unsaturated hydrocarbons with hydrogen according to claim 1, substantially as described in the specification and examples 1 to 10 hereinbefore.

5. A process for preparing a catalyst according to claim 1, consisting in that onto the surface of membrane of an alloy consisting of 80-95% by mass of palladium and 5-20% by mass of ruthenium or rhodium, copper or mercury is applied on one or both sides, the thickness ratio of the layer of copper or mercury to the membrane is of from 1:10 to 1:100 respectively, the membrane with the deposited thereonto copper is maintained at a temperature within the range of from 300 to 800"C, the membrane with mercury deposited thereonto is maintained at a temperature of from -10 to 1 50"C, whereafter copper or mercury is chemically recovered from the membrane.

6. A process according to the claim 5 wherein copper is removed from the membrane by treatment with trichloroacetic acid.

7. A process according to claim 5 wherein mercury is removed from the membrane by treatment with a 40-60% aqueous solution of iron (III) chloride or a 20-30% aqueous solution of nitric acid.

8. A process for preparing a catalyst for hydrogenation of unsaturated hydrocabons with hydrogen according to claim 5 substantially as described in the specification and examples 1 to 10 hereinbefore.

9. The use of a catalyst according to claim 1 in the hydrogenation of an organic compound.