Abstract: A process for the selective hydrogenation of polyunsaturated compounds containing at least 2 carbon atoms per molecule, contained in a hydrocarbon feedstock having a final boiling point below or equal to 300° C. in the presence of a catalyst comprising an alumina support and an active phase comprising nickel, said active phase not comprising a metal from Group VIB, said catalyst being prepared by a process comprising at least: i) a step of bringing said support into contact with at least one solution containing at least one nickel precursor; ii) a step of bringing said support into contact with at least one solution containing at least one organic compound comprising at least one carboxylic acid function; iii) a step of drying said impregnated support at a temperature below 250° C.; steps i) and ii) being carried out separately, in any order.

Abstract: A process for the hydrotreatment of a feed obtained from renewable sources in which the total stream of feed F is divided into a number of different part-streams of feed F1 to Fn equal to the number of catalytic zones n, where n is 1 to 10. The mass flow rate of hydrogen sent to the first catalytic zone represents more than 80% by weight of the total mass flow rate of hydrogen used. The effluent from the reactor outlet undergoes at least one separation step. A portion of the liquid fraction is recycled to the catalytic zones in a manner such that the local recycle ratio for each of the beds is 2 or less, and the local dilution ratio over each of the beds is less than 4.

Abstract: A process for hydrotreatment of a feed from renewable sources such as vegetable oils for the production of paraffinic hydrocarbons comprising pre-treatment by crystallisation and/or precipitation allowing the elimination of insoluble inorganic impurities under hydrotreatment conditions. The flow of the total feed is divided up into a certain number of different, part flows equal to the number of catalytic zones in the reactor, and the different part flows are injected in the successive catalytic zones in increasing proportions to produce an effluent containing paraffinic hydrocarbons.

Abstract: A process for hydrotreatment of a feed from renewable sources such as vegetable oils for the production of paraffinic hydrocarbons comprising a pre-treatment step by crystallization and/or precipitation and pre-hydrogenation of the feed under hydrogen allowing the elimination of insoluble inorganic impurities under hydrotreatment conditions and improved exothermal management of the reaction. The effluent is separated to a gas fraction and a liquid fraction containing paraffinic hydrocarbons, a portion of said liquid fraction is recycled.

Abstract: A liquid/gas reactor includes a bulk catalyst bed and means for supplying fresh feed and recycled at least partially converted liquid product stream to the bulk catalyst bed. The reactor also includes means for collecting an at least partially converted liquid product stream from the bulk catalyst bed and recycling at least a portion thereto. A minor catalyst bed extends substantially vertically through the bulk catalyst bed. Means for supplying recycled at least partially converted product stream only to the minor catalyst bed is also provided. A separating wall is disposed between the bulk catalyst bed and the minor catalyst bed.

Abstract: Process for the continuous hydrogenation of triglyceride containing raw materials in a fixed bed reactor system having several catalyst beds arranged in series and comprising at least one hydrogenation catalyst comprising an active phase constituted by a nickel and molybdenum element. The raw material feed, hydrogen containing gas and diluting agent are passed together through the catalyst beds at hydrogenation conditions. The raw material feed stream as well as the stream of hydrogen containing gas are divided into an equal number of different partial streams. These are each passed to one catalyst bed in such a manner that the weight ratio of diluting agent to raw material feed is essentially the same at the entrance of all catalyst beds and does not exceed 4:1. The claimed process is preferably conducted at low temperatures and allows the utilization of existing units due to the low recycle ratio.

Abstract: Disclosed is a process for the removal of sulfur from a fuel gas stream that additionally contains diolefins and oxygen as well as organic sulfur compounds by pretreating the fuel gas stream in a pretreatment reactor in order to significantly reduce the amounts of any diolefins and oxygen contained therein prior to the hydrodesulfurization in a hydrotreater reactor wherein organic sulfur compounds are converted to hydrogen sulfide. The hydrogen sulfide formed is removed from the hydrotreated gas stream by use of an absorption treatment method, such as amine treatment, to yield a treated fuel gas stream having a reduced concentration of hydrogen sulfide and an overall sulfur content that is low enough to meet stringent sulfur regulation requirements.

Abstract: The present invention discloses a process for the selective hydrogenation of phenylacetylene in the presence of styrene conducted in a combined bed, which process comprises under hydrogenation reaction conditions, passing a hydrocarbon fraction feedstock containing phenylacetylene and styrene through a combined bed reactor containing a catalyst A and a catalyst B to contact the feedstock with the catalyst A and the catalyst B in turn, wherein the catalyst A is a nickel-based catalyst, the catalyst B is at least one selected from the group consisting of palladium-based catalysts and copper-based catalysts, and a weight ratio of the catalyst A loaded to the catalyst B loaded is from 0.5:1 to 5:1.

Abstract: Process for treatment of a feedstock, such as hydrocarbons that comprise at least 4 carbon atoms per molecule and that comprise at least one unsaturated compound including benzene, such that said feedstock is treated in a distillation zone, associated with a hydrogenation reaction zone, at least in part outside of the distillation zone, and an isomerization zone, so as to discharge—at the top of the distillation zone and at the bottom of the distillation zone—an effluent that is low in unsaturated compounds, whereby said process comprises the treatment of at least a second feedstock, comprising at least one unsaturated compound including benzene, at least partially directly injected into the hydrogenation zone that is outside of the distillation zone.

Abstract: A process has been developed for producing fuel from renewable feedstocks such as plant and animal oils and greases. The process involves treating a first portion of a renewable feedstock by hydrogenating and deoxygenating in a first reaction zone and a second portion of a renewable feedstock by hydrogenating and deoxygenating in a second reaction zone to provide a diesel boiling point range fuel hydrocarbon product. If desired, the hydrocarbon product can be isomerized to improve cold flow properties. A portion of the hydrocarbon product is recycled to the first reaction zone to increase the hydrogen solubility of the reaction mixture.

Abstract: A process and apparatus are disclosed for hydrocracking hydrocarbon feed in a hydrocracking unit and hydrotreating a diesel product from the hydrocracking unit in a hydrotreating unit. The hydrocracking unit and the hydrotreating unit share the same recycle gas compressor. A make-up hydrogen stream may also be compressed in the recycle gas compressor. A warm separator separates recycle gas and hydrocarbons from diesel in the hydrotreating effluent, so fraction of the diesel is relatively simple. The warm separator also keeps the diesel product separate from the more sulfurous diesel in the hydrocracking effluent, and still retains heat needed for fractionation of lighter components from the low sulfur diesel product.

Abstract: Provided herein are olefinic feedstocks derived from conjugated hydrocarbon terpenes (e.g., C10-C30 terpenes), methods for making the same, and methods for their use.

Abstract: A method for preparing a phenylcyclohexane of formula I by hydrogenation of a biphenyl of formula II with hydrogen in the presence of Raney nickel, where R1 and R2 both have the same meaning in formulas I and II and independently of one another are hydrogen atoms, C1- to C10-alkyl groups or phenyl groups, wherein the hydrogenation takes place in the presence of 0 to 20 parts by weight of water to 100 parts by weight of Raney nickel.

Abstract: A liquid/gas reactor includes a bulk catalyst bed and means for supplying fresh feed and recycled at least partially converted liquid product stream to the bulk catalyst bed. The reactor also includes means for collecting an at least partially converted liquid product stream from the bulk catalyst bed and recycling at least a portion thereto. A minor catalyst bed extends substantially vertically through the bulk catalyst bed. Means for supplying recycled at least partially converted product stream only to the minor catalyst bed is also provided. A separating wall is disposed between the bulk catalyst bed and the minor catalyst bed.

Abstract: An apparatus is disclosed for hydrocracking hydrocarbon feed in a hydrocracking unit and hydrotreating a diesel product from the hydrocracking unit in a hydrotreating unit. The hydrocracking unit and the hydrotreating unit shares the same recycle gas compressor. A warm separator separates recycle gas and hydrocarbons from diesel in the hydrotreating effluent, so fraction of the diesel is relatively simple. The warm separator also keeps the diesel product separate from the more sulfurous diesel in the hydrocracking effluent, and still retains heat needed for fractionation of lighter components from the low sulfur diesel product.

Abstract: An apparatus and process is disclosed for hydroprocessing hydrocarbon feed in a hydroprocessing unit and hydrotreating a second hydrocarbon. The hydrotreating effluent is mixed with hydroprocessing effluent and together fractionated.

Abstract: This invention has as its object a process for selective hydrogenation of an unsaturated olefinic feedstock that comprises 3 or 4 carbon atoms, using at least two switchable fixed-bed reactors, each containing at least one catalytic bed and in which said feedstock successively passes through all of the reactors, and in which, each time that one of the reactors is deactivated, the point of introduction of the feedstock is moved downstream.

Abstract: An apparatus is disclosed for converting heavy hydrocarbon feed into lighter hydrocarbon products. The heavy hydrocarbon feed is slurried with a particulate solid material to form a heavy hydrocarbon slurry and hydrocracked in a slurry hydrocracking unit to produce vacuum gas oil (VGO) and pitch. A first vacuum column separates VGO from pitch, and a second vacuum column further separates VGO from pitch. As much as 15 wt-% of VGO can be recovered by the second vacuum column and recycled to the slurry hydrocracking unit. A pitch composition is obtained which can be made into particles and transported without sticking together.

Abstract: Systems and methods are provided for hydroprocessing a petroleum fraction, such as a bottoms fraction from a fuels hydrocracking process, to generate a lubricant base oil. A fuels hydrocracking process typically has less stringent requirements for the sulfur and nitrogen content of a feed as compared to a lubricant base oil. Additionally, depending on the nature of the feed for the fuels hydrocracking process, the bottoms fraction may contain a relatively high level of aromatics compounds. The aromatic content of such a petroleum fraction can be reduced using a aromatic saturation stage with multiple catalyst beds, or alternatively using a reactor (or reactors) with multiple aromatic saturation stages. The catalysts in the various beds or stages can be selected to provide different types of aromatic saturation activity. An initial bed or stage can provide activity for saturation of 1-ring aromatics in the petroleum fraction.

Abstract: Selective hydrogenation of a polyunsaturated hydrocarbon feed containing at least 2 carbon atoms per molecule and having an end point of 250° C. or less, by contacting said feed with a catalyst having an active phase of at least one metal from group VIII deposited on a support formed by at least one oxide, said catalyst being prepared using a process involving at least: i) contacting said support with at least one solution containing at least one precursor of metal from group VIII; ii) contacting said support with at least one organic compound formed from at least one cyclic oligosaccharide composed of at least 6?-(1,4)-bonded glucopyranose subunits; iii) calcining to obtain metal from group VIII in oxide form; i) and ii) possibly being carried out separately, in any order, or simultaneously.

Abstract: This invention describes a process for hydrogenation of an aromatic feedstock that as a catalytic composition uses a suspension of metal nanoparticles of a mean size of between 1 and 20 nanometers in at least one non-aqueous ionic liquid, whereby said suspension also contains at least one nitrogen-containing ligand, in which said metal nanoparticles comprise a transition metal in the zero-valence state, whereby the transition metal is selected from the groups 8, 9, 10 and 11 of the periodic table and in which said nitrogen-containing ligand comprises 1 to n nitrogen atoms, whereby n is an integer of between 1 and 20.

Abstract: A process has been developed for producing fuel from renewable feedstocks such as plant and animal oils and greases. The process involves treating a first portion of a renewable feedstock by hydrogenating and deoxygenating in a first reaction zone and a second portion of a renewable feedstock by hydrogenating and deoxygenating in a second reaction zone to provide a diesel boiling point range fuel hydrocarbon product. If desired, the hydrocarbon product can be isomerized to improve cold flow properties. A portion of the hydrocarbon product is recycled to the first reaction zone to increase the hydrogen solubility of the reaction mixture.

Abstract: Apparatuses for processing a hydrocarbonaceous feedstock flows are provided. In one aspect, the method includes providing two or more hydroprocessing stages disposed in sequence, each hydroprocessing stage having a hydroprocessing reaction zone with a hydrogen requirement and each stage in fluid communication with the preceding stage. A hydrogen source is provided substantially free of hydrogen from a hydrogen recycle compressor. The hydrocarbonaceous feedstock flow is separated into an portions of fresh feed for each hydroprocessing stage, and the first portion of fresh feed to the first hydroprocessing stage is heated. The heated first portion of fresh feed is supplied with hydrogen from the hydrogen source in an amount satisfying substantially all of the hydrogen requirements of the hydroprocessing stages to a first hydroprocessing zone. The unheated second portion of fresh feed is admixed with effluent from previous stage to quench the hot reactor effluent before entering a second stage.

Abstract: An apparatus is disclosed for converting heavy hydrocarbon feed into lighter hydrocarbon products. The heavy hydrocarbon feed is slurried with a particulate solid material to form a heavy hydrocarbon slurry and hydrocracked in a slurry hydrocracking unit to produce vacuum gas oil (VGO) and pitch. A first vacuum column separates VGO from pitch, and a second vacuum column further separates VGO from pitch. As much as 15 wt-% of VGO can be recovered by the second vacuum column and recycled to the slurry hydrocracking unit. A pitch composition is obtained which can be made into particles and transported without sticking together.

Abstract: This invention covers a process for dimerizing of isobutylene to Iso-octene and unique configuration is being disclosed, where the Feed is diluted to low level with recycle which has essentially no Iso-octene, dual catalyst system, new selectivator (IPA) and successive catalyst stages if needed to enhance the conversion. The process is very selective and provides higher isobutylene conversion. Additionally the invention also covers the hydrogenation of olefins to Paraffin, Iso-octene to Iso-octane product under moderate conditions and with dual or single catalyst system.

Abstract: An apparatus is disclosed for hydroprocessing two hydrocarbon streams at two different pressures. A hydrogen stream is compressed and split. A first split compressed stream is further compressed to feed a first hydroprocessing unit that requires higher pressure for operation. A second split compressed stream is fed to a second hydroprocessing unit that requires lower pressure. Recycle hydrogen from the second hydroprocessing unit is recycled back to the compression section.

Abstract: An apparatus is disclosed for hydroprocessing two hydrocarbon streams at two different pressures. A hydrogen stream is compressed and split. A first split compressed stream is further compressed to feed a first hydroprocessing unit that requires higher pressure for operation. A second split compressed stream is fed to a second hydroprocessing unit that requires lower pressure. Recycle hydrogen from the second hydroprocessing unit is recycled back to the compression section.

Abstract: A process for the conversion of biomass to a liquid fuel is presented. The process includes the production of diesel and naphtha boiling point range fuels by hydrotreating and hydrocracking of lignin in the biomass in a one step process.

Abstract: A C4-olefin mixture having a 1,3-butadiene content of from 100 to 500 ppm and a content of 1,2-dienes of less than 10 ppm is described. The present invention further provides a process for preparing this C4-olefin mixture and provides for its use in a metathesis reaction for preparing 2-pentene and/or 3-hexene.

Abstract: A process for the desulfurization of a fluid catalytically cracked naphtha wherein the valuable olefins are retained and recombinant mercaptans are prevented from forming, resulting in a low sulfur naphtha. Embodiments disclosed herein may allow for more flexibility in varying the end point of the naphtha used in gasoline blending.

Abstract: Processes and systems for stabilization and subsequent hydrogenation of an immiscible olefin are described. In certain embodiments, the hydrogenation is conducted in a fixed bed reactor in presence of a hydrogenation catalyst.

Abstract: The present invention provides a hydrogenation method capable of converting cracked kerosene into the raw materials for petrochemical cracking having a high thermal decomposition yield by a hydrogenation reaction. The present invention is a petrochemical process for producing at least any of ethylene, propylene, butane, benzene or toluene by carrying out a thermal decomposition reaction at least using naphtha for the main raw material, wherein cracked kerosene produced from a thermal cracking furnace is hydrogenated using a Pd or Pt catalyst in a two-stage method consisting of a first stage (I), in which a hydrogenation reaction is carried out within the range of 50 to 180° C., and a second stage (II), in which a hydrogenation reaction is carried out within the range of 230 to 350° C., followed by re-supplying all or a portion of these hydrogenated hydrocarbons to a thermal cracking furnace.

Abstract: A reactor, which is capable of accommodating a reaction in which at least three phases are present and at least one gaseous starting material and at least one liquid starting material are reacted in cocurrent over a fixed-bed catalyst to give one or more product(s), contains at least one first zone in which a catalyst is present as a fixed bed; and at least one second zone whose size corresponds to a reactor cross section and which is separated from the at least one first zone by a distributor plate provided with at least one hole and in which at least one liquid and at least one gaseous starting material enter the reactor. The distributor plate is provided with at least one static mixer which is located in the at least one hole on at least one side of the distributor plate.

Abstract: The present invention relates to a process for the hydrogenation of olefins. The process comprises hydrogenation of a feed stock comprising more than 90 wt-% of olefins, carried out in a hydrogenation reactor comprising at least two reaction stages, wherein the feed stock is hydrogenated in the first reaction stage equipped with a cooling circuit and comprising a first and an optional second catalyst bed, and the effluent from the first reaction stage is hydrogenated in the final reaction stage comprising one or more catalyst beds and optionally equipped with a cooling circuit, the process is operated in trickling or pulse flow mode in a three phase reactor with a fixed catalyst bed and at least one catalyst of same or different type is used in each stage, the catalyst having different particle size and/or optionally different shape in at least two stages.

Abstract: A C4-olefin mixture having a 1,3-butadiene content of from 100 to 500 ppm and a content of 1,2-dienes of less than 10 ppm is described. The present invention further provides a process for preparing this C4-olefin mixture and provides for its use in a metathesis reaction for preparing 2-pentene and/or 3-hexene.

Abstract: A process for the selective hydrogenation of alpha-methyl-styrene (AMS) to cumene in a two catalyst system is disclosed. A crude cumene feed stream containing up to 10% AMS by weight is supplied to the first reaction zone 112 and mixed with hydrogen in a first catalyst bed 118 containing a nickel catalyst, converting from 70 to 95 percent of the AMS to cumene. Cumene and remaining AMS are separated from hydrogen in a liquid take off tray 120. The first reaction zone 112 effluent is supplied to a second reaction zone 114, where the effluent and hydrogen gas are mixed in a second catalyst bed 126 containing a noble-metal catalyst to substantially convert any remaining AMS to cumene. Cumene is collected, separated from the hydrogen, and can be resupplied to the hydrogenation reactor 110, or supplied as feed to a phenol synthesis loop.

Abstract: A process for removing acetylenic compounds using unsulfided metallic nickel or unsulfided metallic nickel modified with metallic Mo, Re, Bi or mixtures in which the catalyst is used alone or is used in combination with other acetylenic selective catalysts. The unsulfided metallic nickel catalyst or modified catalyst must be the first catalyst to contact the hydrocarbon stream.

Abstract: A process for total hydrogenation of polyunsaturated compounds that have n nonsaturations that are contained in a hydrocarbon feedstock in the presence of a catalytic reactor with a hydrogen-selective membrane is described. This process comprises the introduction of said feedstock that is co-mixed with hydrogen into a reaction zone of said reactor, the contact of hydrogen with the face that is upstream from said membrane, which is inorganic and porous, then the catalytic reaction of said feedstock with hydrogen that has selectively traversed the membrane.

Abstract: The present invention is a process for removing alkynes and/or dienes from an olefin product stream withdrawn from an oxygenate-to-olefins reactor. The process comprises hydrogenating a first olefin stream that has alkynes and/or dienes in the presence of excess hydrogen and a first hydrogenation catalyst. The hydrogenation of the first olefin stream produces a second olefin stream that has unreacted hydrogen. The second olefin stream is contacted with a second hydrogenation catalyst producing a third olefin stream. The third olefin stream has low levels of hydrogen and alkynes and/or dienes.

Abstract: The invention relates to a process for conversion of hydrocarbons in the presence of at least one catalyst with controlled acidity, characterized in that the level of activity of said catalyst in isomerization of the cyclohexane is less than 0.10 and/or in that the ratio of toluene hydrogenation activity to the cyclohexane isomerization activity is greater than 10.

Abstract: The charge gas from the thermal cracking of a hydrocarbon feedstock is processed in a front-end catalytic distillation hydrogenation system of an olefins plant to more effectively recover ethylene and propylene product and to process the by-products. The rate of fouling in the system is reduced by employing two columns in the system with the first column operating at a higher pressure and the second column operating at a lower pressure. The hydrogenation as well as fractionation takes place in the first column while the second column is only a fractionator. The temperature of the bottoms from each column is maintained at a temperature less than 200° C. to avoid fouling.

Abstract: An improved selective hydrogenation process for removing acetylenic impurities such as vinyl acetylene, ethyl acetylene, propyl acetylene and acetylene in a steam cracked crude butadiene stream by selective hydrogenation is carried out in two steps. In the first step, the partial selective hydrogenation is carried out in a fixed bed with a copper based catalyst to have the ratio of vinyl acetylene to ethyl acetylene in a range of from 0 to about 1, preferably from about 0.01 to 0.6, in the product stream. In the second step, the selective hydrogenation of the remaining C4 acetylenic impurities is carried out to completion in the catalytic distillation mode using a palladium promoted copper catalyst, an improved palladium catalyst or a combination of these two.

Abstract: It has been discovered that a dual bed process using two different catalysts for the selective hydrogenation of acetylene and/or methyl acetylene (MA) and/or propadiene (PD) in a light olefin-rich feedstream can be accomplished with less selectivity to making oligomers (green oil) as compared with existing commercial technologies, if a low oligomers selectivity catalyst is used first in the process. A palladium catalyst may be used as a second, sequential catalyst to further hydrogenate acetylene and/or MAPD while consuming at least a portion of the balance of the hydrogen present. The first catalyst should be different from the second catalyst.

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 invention is directed to a process for the hydrogenation of a sulfur containing feedstock, having a sulfur content of less than 50 ppm, wherein the feedstock is hydrogenated in the presence of a precious metal catalyst and a nickel-catalyst, said process being carried out in such a manner, that the feedstock is contacted with a mixture of precious metal catalyst, metal oxide and nickel catalyst, the feedstock is contacted initially with the precious metal catalyst followed by contact with the metal oxide and nickel catalyst, either in combination or sequentially, or the feedstock is contacted first with a mixture of precious metal catalyst and metal oxide, followed by contact with the nickel catalyst.

Abstract: The invention relates to a process for converting cycle oils produced in catalytic cracking reactions into olefin and naphtha. More particularly, the invention relates to a process for hydroprocessing a catalytically cracked light cycle oil, and then re-cracking it in an upstream zone of the primary FCC riser reactor.

Abstract: A method is disclosed for maintaining a volumetric gas to liquid ratio in a segmented gas/liquid flow along a reactor of monolithic catalyst beds in series. The present invention includes the steps of: initiating the segmented gas/liquid flow at a first end of the reactor by introducing feed liquid and feed gas both at a predetermined volume and a predetermined flow rate; injecting an additional amount of gas at least once into any of the spaces between catalyst beds; and combining the segments of the segmented gas/liquid flow at a second end of the reactor. The injection of gas is controlled such that the segmented gas/liquid flow can be maintained near or at the Taylor regime.

Abstract: It has been discovered that a dual bed process using two different catalysts for the selective hydrogenation of acetylene and/or methyl acetylene (MA) and/or propadiene (PD) in a light olefin-rich feedstream can be accomplished with less selectivity to making oligomers (green oil) as compared with existing commercial technologies, if a low oligomers selectivity catalyst is used first in the process. A palladium catalyst may be used as a second, sequential catalyst to further hydrogenate acetylene and/or MAPD while consuming at least a portion of the balance of the hydrogen present. The first catalyst should be different from the second catalyst.

Abstract: Presented is an improvement to a previous invention involving the catalytic hydrogenation of the C2 to C5 and heavier acetylenes and dienes in a thermally cracked feed stream without significantly hydrogenating the C2 and C3 olefins. The improvement involves the use of a fixed bed hydrogenation reactor system in combination with a modified version of the catalytic distillation unit used in the prior art. The modification to the catalytic distillation unit involves improvement of the liquid recycle scheme. The fixed bed reactors combined with the modified catalytic distillation allows for 100% conversion of acetylene and helps to maintain high conversion of the other dienes and acetylenes with no ethylene or propylene conversion under a variety of conditions. These condition variations include but are not limited to the feed diene and acetylene composition, the mol % carbon monoxide in the feed, and catalyst deactivation.

Abstract: An improved selective hydrogenation process for removing acetylenic impurities such as vinyl acetylene, ethyl acetylene, propyl acetylene and acetylene in a steam cracked crude butadiene stream by selective hydrogenation is carried out in two steps. In the first step, the partial selective hydrogenation is carried out in a fixed bed with a copper based catalyst to have the ratio of vinyl acetylene to ethyl acetylene in a range of from 0 to about 1, preferably from about 0.01 to 0.6, in the product stream. In the second step, the selective hydrogenation of the remaining C4 acetylenic impurities is carried out to completion in the catalytic distillation mode using a palladium promoted copper catalyst, an improved palladium catalyst or a combination of these two.