Abstract: A facility for converting an olefinic C4 cut to isobutene and propylene comprising, in succession: 1) a zone 1 for selective hydrogenation of olefins in the olefinic C4 cut with simultaneous isomerisation of butene-1 to butene-2, said zone comprising at least one device for introducing the olefinic C4 cut to be converted, at least one device for removing an effluent, and at least one device for introducing hydrogen, said zone also comprising at least one catalyst bed; 2) a separation zone, comprising at least one device for introducing the effluent from zone 1 directly connected to said at least one device for removing an effluent, at least one device for removing a first fraction comprising isobutene and butene-1, and at least one device for removing a second fraction comprising butene-2 and n-butane, wherein the second fraction comprises at most 1% by weight of isobutene and at most 1% by weight of butene-1; 3) a metathesis zone for metathesis of butene-2 with ethylene to produce propylene, wherein the m

Abstract: Hydrogenation of a liquid cut containing hydrocarbons, in particular unsaturated molecules containing at least two double bonds or at least one triple bond, is described wherein the unsaturated molecules are at hydrogenated to less unsaturated molecules containing at least one double bond, in at least one reactor comprising at least two distinct beds of at least one hydrogenation catalyst, and wherein a gas phase containing hydrogen is introduced, a portion thereof being mixed with said cut upstream of the first catalyst bed and a portion thereof being introduced upstream of the subsequent beds contained in said reactor.

Abstract: A process for separating ethane and ethylene from a hydrocarbon steam-cracking effluent is described. Effluent (1) is absorbed in an absorption column by a cooled solvent (9). At the bottom of the column, the liquid phase that contains the solvent and the C2+ hydrocarbons is recovered and hydrogenated (15). The hydrogenation effluent that contains the solvent is introduced into a first distillation column (16). Ethane-ethylene mixture (17) is drawn off laterally from the column, and a phase (19) that contains the solvent and hydrocarbons with at least 3 carbon atoms is drawn off at the bottom of the column. This phase (19) is separated in a second distillation column (22), and C3+ hydrocarbons and, at the bottom of the column, regenerated solvent (26) that is cooled and that is recycled (9, 52) in the absorption column are collected.

Abstract: The present invention provides a process for selectively hydrogenating C2-C10 greater unsaturated hydrocarbons (acetylenes and diolefins) at the upstream side of a front depropanizer or front deethanizer in an olefin production plant. After passing through a mixed phase hydrogenation reactor to selectively hydrogenate, the olefin plant process stream passes to a front depropanizer or front deethanizer. The process according to the present invention is able to selectively hydrogenate C2-C10 greater unsaturated hydrocarbons (including acetylene), to reduce the number of equipments, the amount of equipment fouling and the energy consumption.

Abstract: The present invention provides an improved selective hydrogenation process for removing C10-C16 diolefins in the product from dehydrogenation of C10-C16 paraffins to mono-olefins, which process includes bringing the mixture stream of paraffins and olefins containing C10-C16 mono-olefins and C10-C16 diolefins into contact with a specific hydrogenation catalyst in a plurality of hydrogenation reactors connected in series under the reaction conditions for hydrogenation. Hydrogen is injected into each reactor respectively. To convert the diolefins in the mixture stream of paraffins and olefins into mono-olefins, &ggr;-alumina having a specific surface area of 50-300 m2/g and a pore volume of 0.2-2.0 cm3/g is used as the supporter of the hydrogenation catalyst, palladium is supported on the supporter as the main catalyst element and an element selected from silver, gold, tin, lead or potassium is supported on the supporter as the promoter.

Abstract: A process is provided for the selective hydrogenation of dienes from a mixed hydrocarbon stream. The catalyst contains nickel in an amount between approximately 5 and 15 weight percent and, alternatively, may contain nickel oxide and molybdenum oxide in an amount between approximately 3 to 6 and 12 to 25 weight percent, respectively. The catalyst metals are on an aluminum oxide support. The process does not require any activation or pre-treatment of the catalyst. No sulfur is added to the reaction zone and the catalyst is not adversely affected by the presence of up to 0.20% by weight of sulfur in the feed stream. According to the process, conjugated dienes are reduced by at least 80 to 90%.

Abstract: The method of producing high purity isooctane useful as a gasoline blending component from diisobutylene or isooctane contaminated with minor amounts of oxygenated impurities which comprises converting the impurities at conditions of elevated temperature and pressure to hydrocarbon and water and recovering the purified diisobutylene or isooctane stream.

Abstract: The process of the invention is a process for selective hydrogenation of a hydrocarbon feed containing hydrogen and C2+ hydrocarbons, characterized in that it comprises at least one step for separating a fraction of the hydrogen contained in the feed by means of a membrane (step a)) and a step for selective hydrogenation of the effluent from step a) in a reactive column (step b)).

Abstract: The present invention provides an improved method for deep selective hydrogenation for use in recovering high purity olefins from cracked gas effluents or other paraffin/olefin gaseous mixtures by use of a chemical absorption process.

Abstract: A novel catalyst comprises at least one support and at least one metal from group VIII or the periodic table e.g. palladium and is characterized in that the metal particles deposited on the support are not isolated from each other, e.g. at least 50% of the particles have a point of contact with one other particle.

Abstract: An apparatus and process for treating a complex mixture of hydrocarbons containing undesirable olefinic compounds to remove the mono olefins and diolefins in two stages and separate a desirable key component from the mixture, by first treating the key component in a reactive distillation column under mild conditions to hydrogenate diolefins then separating the diolefin-depleted key component and any lighter materials from the heavier components and sending the diolefin-depleted key component and lighter materials to a second reactive distillation column where the lights are removed overhead and the diolefin-depleted key component is hydrogenated under more severe conditions to remove the mono olefins.

Abstract: A catalyst which contains, in its active composition, from 0.05 to 1.0% by weight of at least one metal or compound of a metal of the 10th group of the Periodic Table of the Elements and from 0.05 to 1.0% by weight of at least one metal or compound of a metal of the 11th group of the Periodic Table of the Elements, with the weight ratio of the metal of the 11th group to the metal of the 10th group being from 0.95 to 1.05, and, as support, an SiO2 -containing catalyst support having a BET surface area of from 2 to 400 m2/g, wherein at least 20% of the total pore volume of the catalyst is made up by pores having a diameter greater than 100 nanometers, can be used in processes for removing alkynes, dienes and/or monounsaturated hydrocarbons from streams of materials.

Abstract: A process for the selective hydrogenation of trace quantities of acetylene compounds contained in a stream of diolefins to achieve extended on-stream performance by simultaneously contacting the selective catalyst with a diolefin feed, hydrogen and a polymer solvent.

Abstract: A process for selective hydrogenation of unsaturated compounds such as acetylenic compounds or diolefins is carried out in the presence of a catalyst comprising at least one support, at least one metal from group VIII of the periodic table and at least one additional element M selected from the group formed by germanium, tin, lead, rhenium, gallium, indium, gold, silver and thallium. The process is characterized in that the catalyst is prepared using a process in which said metal M is introduced in an aqueous solvent, in the form of at least one organometallic compound comprising at least one carbon-M bond.

Abstract: A particulate selective hydrogenation catalyst for hydrogenating unsaturated diolefinic hydrocarbons to &agr;-olefinic hydrocarbons at rates which are at least 1.5 times higher than the rate of hydrogenation of &agr;-olefinic hydrocarbons to saturated compounds contains palladium distributed at the periphery of particles (spherules or extrudates), and at least one element selected from tin and lead. Further, the tin and/or lead is advantageously distributed at the periphery of the spherules or extrudates.

Abstract: A composition and a process for using the composition in a selective hydrogenation of a highly unsaturated hydrocarbon such as, for example, an alkyne or diolefin, to a less unsaturated hydrocarbon such as, for example, an alkene or a monoolefin, are disclosed. The composition comprising palladium, a selectivity enhancer and an inorganic support wherein the palladium and selectivity enhancer are each present in a sufficient amount to effect the selective hydrogenation of a highly unsaturated hydrocarbon. Optionally, the composition can comprise silver. Also optionally, the palladium is present as skin distributed on the surface of the support. The composition can further comprise an alkali metal-containing compound such as, for example, potassium fluoride.

Abstract: A catalyst composition and process for preparing such catalyst composition which can be useful in contacting a hydrocarbon-containing fluid which contains a highly unsaturated hydrocarbon such as 1,3-butadiene, in the presence of hydrogen, with such catalyst composition in a hydrogenation zone under a hydrogenation condition effective to hydrogenate such highly unsaturated hydrocarbon to a less unsaturated hydrocarbon such as n-butene is disclosed. Such process for preparing a catalyst composition includes (1) combining a zeolite, a Group VIB metal, and an inorganic support to form a modified zeolite; (2) calcining such modified zeolite under a calcining condition to produce a calcined, modified zeolite; and (3) contacting such calcined, modified zeolite with a carburizing agent under a carburizing condition to provide such catalyst composition.

Abstract: A process for the selective hydrogenation of trace quantities of acetylene compounds contained in a stream of diolefins to achieve extended on-stream performance by contacting an off-line selective hydrogenation reaction zone containing selective catalyst with hydrogen and a polymer solvent.

Abstract: A method for improving the operation of a propane-propylene splitter in a process for the dehydrogenation of propane wherein the propane is dehydrogenated to produce a stream containing propylene and trace quantities of methyl acetylene and propadiene compounds and which stream is selectively hydrogenated to selectively saturate at least a majority of the trace quantities of methyl acetylene and propadiene compounds. The resulting effluent from the selective hydrogenation zone is fractionated in a propane-propylene splitter to produce a high-purity propylene product stream, an unconverted propane stream which is introduced to the dehydrogenation zone and a small slip stream or side-cut containing methyl acetylene and propadiene compounds which is introduced into the selective hydrogenation zone.

Abstract: A process is provided for the selective hydrogenation of at least one organic compound having at least one unsaturated group, by bringing the at least one organic compound into contact with a hydrogen-containing gas in the presence of a catalyst, wherein the catalyst comprises an active material which is applied to a solid electrolyte to which, in turn, a metallic substrate is connected in such a way that a current flows through the solid electrolyte, so that the active material can be kept at a constant potential and a voltage is applied to

Abstract: A process and apparatus for treating raw gasoline from catalytic cracking to obtain gasoline with the qualities required for use as motor fuel comprises selective hydrogenation followed by stabilization and optional cooling of the effluent, then sweetening followed by degassing to obtain a dedienized, stabilized and sweetened gasoline. The hydrogenation catalyst preferably comprises 0.1-1% of palladium deposited on a support, sweetening is preferably carried out on a solid catalyst containing an aluminosilicate of an alkali metal (for example sodalite), a metal chelate and activated charcoal. The product from this process can be placed directly in the gasoline pool or, advantageously, fractionated to obtain one or more cuts which can be used as feeds for etherification.

Abstract: A process for the selective hydrogenation of the diolefins and acetylenic compounds in a olefin rich aliphatic hydrocarbon streams is disclosed wherein the selective hydrogenation is carried out at 40 to 300° F. under low hydrogen partial pressure in the range of about 0.1 psi to less than 70 psia at 0 to 350 psig in a distillation column reactor containing a hydrogenation catalyst which serves as a component of a distillation structure, such as supported PdO encased in tubular wire mesh. Essentially no hydrogenation of the olefins occurs.

Abstract: A catalyst for removing olefins from aromatic compounds or mixtures of aromatic compounds wherein the catalyst is a naturally acidic smectite clay containing exchangeable cations wherein the naturally acidic smectite clay has a cation exchange capacity of 40 to 80 meq./100 g. and wherein the exchangeable cations include 5 to 70 meq./100 g. of Al.sup.3+ cations, a process for the preparation of this catalyst including treating a naturally acidic smectite clay with an aluminum salt solution wherein the salt solution includes Al.sup.3+ ions at a concentration of at least 10 meq./100 g. of the catalyst, and a process for the removal of olefins from aromatic compounds or mixtures of aromatic compounds using the above-described catalyst.

Abstract: A supported hydrogenation catalyst composition is disclosed which comprises palladium, an inorganic support such as alumina, and a selectivity enhancer selected from the group consisting of silver, phosphorus, sulfur, and combinations of two or more thereof. Also disclosed is a selective hydrogenation process in which highly unsaturated hydrocarbons such as diolefins and/or alkynes are hydrogenated with hydrogen to less unsaturated hydrocarbons such as monoolefins.

Abstract: A process is disclosed for generating pure aromatic compounds from a reformed gasoline which contains aromatic compounds, olefins, diolefin, and triolefins, which comprises the steps of:(a) selectively hydrogenating the olefins, diolefins and triolefins in the reformed gasoline to obtain a mixture of hydrogenated, non-aromatic compounds and aromatic compounds; and(b) separating the aromatic compounds from the hydrogenated, non-aromatic compounds in the mixture formed during step (a) by either extractive distillation, liquid--liquid extraction or both to obtain the pure aromatic compounds.

Abstract: In the process for the selective hydrogenation of dienes in diene-containing feed streams, a diene-containing feed stream is hydrogenated over a nickel-containing precipitated catalyst at from 40 to 100.degree. C., a pressure of from 3 to 20 bar and a WHSV (weight hourly space velocity) of from 1 to 10 kg/(l.times.h) in the presence of free hydrogen.

Abstract: Process flow sequences for the reduction of equipment fouling in the fractional distillation of light end hydrocarbon components, such as those produced by pyrolysis or steam cracking, wherein conventional multiple hydrogenation unit configurations are replaced with upstream hydrogenation unit configurations. The upstream hydrogenation units of the invention are located at either side draws or in the reboiler circuit of deethanizers, in front-end demethanizer and front-end deethanizer sequences, or depropanizers, in front-end depropanizer sequences and obviate the need for most of the conventionally used hydrogenation units downstream.

Abstract: A palladium-base catalyst can selectively hydrogenate highly unsaturated hydrocarbon compounds contained in small amounts in an olefin compound prepared by steam cracking or the like of naphtha without causing hydrogenation of the olefin as a side reaction and the precipitation of a carbonaceous material. The catalyst comprises palladium and alumina, and the exposed face of each palladium crystallite is mainly accounted for by (100) and (110) faces. Further, in the desorption of absorbed hydrogen by heating, desorption peaks are observed in the temperature ranges of 40 to 90.degree. C. and of 120 to 170.degree. C. and the ratio of hydrogen desorption amount of the former to the latter is (4:6) to (3:7).

Abstract: The present invention concerns a process for the production of isobutene and propylene by metathesis of an olefinic C.sub.4 cut. The process comprises three successive steps: 1) selective hydrogenation of butadiene with isomerisation of butene-1 to butene-2; 2) separation by distillation to produce isobutene overhead, leaving a butene-2 bottom cut; 3) metathesis of the butene-2 cut with ethylene. The advantage of this process is that polymerisation quality propylene can be produced very selectively, in contrast to other processes such as dehydrogenation of propane or other cracking processes.

Abstract: A process for the treatment of a feed comprising at least hydrocarbons containing at least 3 to 10 carbon atoms per molecule, including acetylenic and diolefinic hydrocarbons, comprises passing the feed into a distillation zone associated with a selective hydrogenation reaction zone comprising at least one catalytic hydrogenation bed which is internal to or external of the distillation zone, in which hydrogenation of at least a portion of the acetylenic and diolefinic hydrocarbons contained in the feed is carried out in the presence of a gas stream rich in hydrogen. The process is particularly suitable for the treatment of products from catalytic cracking.

Abstract: A catalyst is described for selective gas phase hydrogenation of acetylenic compounds containing 2 or 3 carbon atoms to the corresponding ethylenic compounds. The catalyst, in the form of spherules or extrudates, comprises palladium, at least one metal from group IB, optionally at least one alkali or alkaline-earth metal, and alumina, in which at least 80% of the palladium and at least 80% of the element from group IB are present in a volume at the periphery of the catalyst defined between a spherical or cylindrical surface with radius r.sub.1 corresponding to the average radius of the spherules or extrudates of the catalyst and a spherical or cylindrical surface with radius r.sub.2 at least equal to 0.8 r.sub.1, the catalyst having a group IB metal/palladium ratio of 0.4 to 3 by weight. Further, it is advantageous for this catalyst that at least 30% of the metal particles contain both palladium and silver.

Abstract: For the treatment of a feed comprising a major portion of olefinic hydrocarbons containing 4 carbon atoms per molecule, including isobutene, 1-butene and 2-butenes in a ratio which substantially corresponds to the thermodynamic equilibrium, in which the feed is treated in a distillation zone comprising a stripping zone and a rectification zone associated with at least one hydroisomerization reaction zone, the hydroisomerization reaction zone being at least partially internal to the distillation zone and comprising at least one catalytic bed, in which hydroisomerization of at least a portion of 1-butene is carried out in the presence of a hydroisomerization catalyst and at least one gas stream comprising hydrogen, such that an effluent rich in isobutene leaves the distillation zone overhead and an effluent rich in 2-butenes leaves the bottom, the process being characterized in that each catalytic bed in the internal portion of the hydroisomerization zone is traversed by an ascending co-current of the gas strea

Abstract: The gas-phase hydrogenation of a feed containing at least 50% by weight of at least one C.sub.6 -C.sub.20 -olefin with a gas containing at least hydrogen over a catalyst is carried out by a process in which the feed is introduced as a liquid into the gas.

Abstract: Compensation for catalyst activity decline in multi-bed selective hydrogenation of acetylenes in the presence of olefins by providing inter-bed heating so that the product from the first bed is heated before it is fed to the second bed, and the temperature at which the product from the first bed is fed to the second bed is increased as the catalyst activity declines. In a modification, when the catalyst is fresh, the product from the first bed is cooled before it is fed to the second bed, but, as the catalyst activity declines the temperature at which the product from the first bed is fed to the second bed is increased, so that after a period of use the product from the first bed is heated before it is fed to the second bed.

Abstract: Catalytic cracking gaseolines are treated by: (a) fractionating the raw gasoline cut into two cuts; (b) optional selective diene hydrodenation of the light cut, then mild hydrotreatment and stripping; (c) sweetening the light cut which is conducted before the mild hydrotreatment step by contact with a supported catalyst containing 0.1-1% by weight of palladium, or after the mild hydrotreatment step and which is then an extractive sweetening step, or with a catalyst having an alkaline base optionally incorporated and also an oxidizing agent. The heavy gaseoline fraction is optionally desilphurized in a hydrotreatment unit. The desulpurized and sweetened light gaesoline can be added to the gasoline pool either directly or mixed with the desulphurized heavy gaseoline cut.

Abstract: A process for the alkylation of benzene contained in a mixed refinery stream is disclosed wherein the refinery stream is first subjected to hydrogenation of higher olefins prior to alkylation of the benzene with selected types and quantities of lower olefins. Streams containing sulfur compounds may be pretreated by hydrodesulfurization. All of the process steps are advantageously carried out in distillation column reactors to take advantage of that mode of operation.

Abstract: A method for producing a cyclopentane product which comprises the following steps: (a) cracking dicyclopentadiene to form a cyclopentadiene-rich stream and a higher boiling liquids stream; (b) separating the cyclopentadiene-rich stream from the higher boiling liquids stream; (c) diluting the cyclopentadiene-rich stream with recycled saturates such that the cyclopentadiene content is limited to between about 5-50%; (d) conducting a first hydrogenation of the cyclopentadiene-rich stream in the presence of hydrogen and a first catalyst, and at a temperature (i.e., preferably between about 26 to 94.degree. C., more preferably in the range between about 37 to 66.degree. C.

Abstract: Integrated process for the production of butene-1 which comprises feeding a C.sub.4 hydrocarbon stream to a separation unit of butene-1 and recycling the remaining stream to the same unit after treatment in a bond isomerization section to convert the remaining butenes-2 into butene-1, a molecular sieve separation unit is inserted in the cycle operating with the hydrocarbons in a vapour phase, for the purge of the paraffins.

Abstract: Catalytic composition effective in the selective hydrogenation of olefinic double bonds prepared by the reaction between:(A) at least one bis(cyclopentadienyl)Titanium derivative having the general formula (I) (C.sub.5 H.sub.5).sub.2 Ti(R) (R.sub.1) wherein R and R.sub.1, the same or different, are halogens; the above compound (I) being solid or dispersed in one or more non-solvent diluents;(B) at least one organo derivative having general formula (II) M(R.sub.2) (R.sub.3) wherein M is selected from Zinc and Magnesium, and R.sub.2 and R.sub.3, the same or different, are selected from C.sub.1 -C.sub.16 alkyls;(C) at least one modifier.

Abstract: The present invention provides a process and system for the removal of butadiene from a cracked gas stream prior to entering a front end hydrogenation reactor in an olefin production facility.

Abstract: In an olefins plant for the production and recovery of ethylene and propylene, the hydrogenation of the C.sub.2 acetylenes, the C.sub.3 acetylenes and dienes and the C.sub.4 and heavier acetylenes, dienes and olefins and the selective separation of the resulting products is carried out by the use of various arrangements of one or more reaction distillation columns. These columns contain a hydrogenation catalyst in enriching and stripping sections and concurrently perform a catalytic hydrogenation reaction and a distillation function.

Abstract: A process for the production of C.sub.8 alkene isomers by the oligomerization of light olefins to heavier olefins is improved by the addition of heavy paraffins to the oligomerization zone. The recycle of the heavy paraffins improves the selectivity of the oligomerization for C.sub.8 olefin isomers that have a high octane number when saturated and reduces catalyst fouling. The saturated octane number of the resulting C.sub.8 isomers is particularly improved when the oligomerization zone is operated at reduced temperature conditions.

Abstract: A process for the alkylation of benzene contained in a mixed refinery stream is disclosed wherein the refinery stream is first subjected to hydrogenation of higher olefins prior to alkylation of the benzene with selected types and quantities of lower olefins. Streams containing sulfur compounds may be pretreated by hydrodesulfurization. All of the process steps are advantageously carried out in distillation column reactors to take advantage of that mode of operation.

Abstract: A process for the selective hydrogenation in the gas phase of acetylene compounds containing 2 or 3 carbon atoms to the corresponding ethylene compounds is described. The process uses a catalyst in the form of spherules or extrudates containing palladium, at least one group IB metal, optionally at least one alkaline or alkaline-earth metal and alumina, in which at least 80% of the palladium and at least 80% of the group IB element are present in a volume at the periphery of the catalyst defined between a spherical or cylindrical surface of radius r.sub.1 corresponding to the average spherule or extrudate diameter and a spherical or cylindrical surface of radius r.sub.2 at least equal to 0.8r.sub.1. More particularly, the catalyst comprises an alumina, palladium in a proportion of 0.01% to 0.5% by weight, and group IB metal in a proportion of 0.001 to 0.02% by weight, with a weight ratio of group IB metal/palladium of 0.05 to 0.25.

Abstract: A process is provided for the production of a gasoline blending fraction rich in isooctane by the dimerization of isobutylene using tertiary butyl alcohol modifier and isoalkane diluent; advantageously the isobutylene is derived from the dehydration of tertiary butyl alcohol and the isoalkane used as diluent in the dimerization is the product formed by hydrogenation of the oligomerization product.

Abstract: A process for the removal of vinylacetylene, ethylacetylene and 1,2-butadiene from C.sub.4 aliphatic hydrocarbon streams comprising, concurrently: (1) feeding hydrogen and a hydrocarbon stream comprising C.sub.4 hydrocarbons including butanes, butenes, butadienes and vinylacetylene to a distillation column reactor containing a bed comprising a hydrogenation catalyst of the type characterized by platinum, palladium or rhodium which is prepared as a distillation structure to selectively hydrogenate a portion of the vinylacetylene and the 1,2-butadiene and (2) fractionally distilling the reaction mixture to remove a heavier fraction and removing a fraction overhead comprising substantially all of the C.sub.4.

Abstract: A process is provided for simultaneous selective hydrogenation of diolefins and nitriles from a hydrocarbon feedstock, wherein hydrogenation is carried out using a catalyst in one reactor zone while partially deactivated catalyst in another reactor zone is regenerated.

Abstract: A supported hydrogenation catalyst composition is disclosed which comprises a palladium component, at least one alkali metal iodide such as, for example, potassium iodide and an inorganic support material such as alumina. Also disclosed is selective hydrogenation process in which diolefins and/or alkynes are hydrogenated with hydrogen to this corresponding monoolefins.

Abstract: A light hydrocarbon stream, such as a C.sub.3 -C.sub.5 stream recovered from an FCC unit, is catalytically treated for the selective hydrogenation of dienes and for the removal of mercaptans by thioetherification. The effluent of the reaction zone is fractionated to remove light ends and thioethers in a dual section fractionation zone, with the interconnection of the sections facilitating a reduction in capital and operating costs.

Abstract: A silica-supported catalyst suitable for the selective hydrogenation of acetylene in hydrocarbonaceous streams, comprising from 0.001 to 1% by weight, based on the supported catalyst, of palladium and from 0.005 to 5% by weight, based on the supported catalyst, of at least one promoter metal of groups 1 and 2 of the periodic table, obtainable by impregnating a silica support with a solution comprising at least one promoter metal, drying the impregnated support, impregnating with a palladium-including solution, drying and calcining.