Abstract: The present disclosure provides a method for producing tetrahydrofuran (THF). The method includes: feeding 1,4-butanediol into a reactive distillation apparatus; performing the dehydration reaction in the presence of an acidic catalyst; and producing the top stream containing product THF and the bottom stream from the reactive distillation apparatus, wherein a weight ratio of a water content in the bottom stream to a water content in the top stream is 0.05 to 2.4, thereby providing a high conversion rate and more cost-effectiveness, and enhancing the value of the industrial application.

Abstract: An aspect of the present disclosure is a catalyst that includes a solid support, a first metal that includes at least one of ruthenium (Ru), platinum (Pt), palladium (Pd) deposited on the solid support, and a second metal comprising at least one of tin (Sn), rhenium (Re), cobalt (Co), molybdenum (Mo), or tungsten (W) deposited on the solid support, where the first metal and the second metal are present at a first metal to second metal mass ratio between about 1.0:2.0 and about 1.0:0.5.

Abstract: A process for the production of 1,4-butanediol and tetrahydrofuran by catalytic hydrogenation of dialkyl maleates includes the following steps: a) hydrogenating a stream of dialkyl maleate in a first stage of reaction over suitable catalysts to produce dialkyl succinate; b) further hydrogenating the dialkyl succinate in a second stage of reaction, by using a different suitable catalyst, for producing mainly 1,4-butanediol, together with gamma-butyrolactone and tetrahydrofuran as co-products. In both stages of reaction the conditions, as hydrogen/organic feed ratio, pressure and temperature, are such to maintain the reactors in mixed liquid/vapor phase.

Abstract: The present application relates to a process for manufacturing maleic anhydride that comprising the following steps: a) fermentation of renewable raw materials and optionally purification to produce a mixture comprising at least butanol; b) oxidation of the butanol to maleic anhydride at a temperature generally between 300° C. to 600° C., using a catalyst based on oxides of vanadium and/or molybdenum; c) isolation of the maleic anhydride obtained at the end of step b). It also relates to the maleic anhydride obtained from renewable raw materials, to the copolymers and compositions comprising said maleic anhydride and also uses of use of this maleic anhydride.

Abstract: This invention relates to a process for catalytically hydrogenating a hydrogenatable precursor in contact with a hydrogen-containing gas and a hydrogenation catalyst comprising one or more active hydrogenation catalyst components on a support comprising titanium dioxide in the rutile crystalline phase to produce 1,4-butanediol and, optionally, gamma-butyrolactone and/or tetrahydrofuran.

Abstract: The present invention relates to a hydrogenation catalyst represented by the following formula 1, a method for the preparation thereof, and a method for preparing gamma-butyrolactone using this catalyst. The method for preparing gamma-butyrolactone from maleic anhydride using the catalyst of the invention prepared by stabilizing the precursor particles of copper oxide, zinc oxide, and manganese oxide with a silica exhibits high selectivity, high yield, and high productivity under the operation conditions of a low molar ratio of hydrogen with regard to the reactants, and enables the preparation of gamma-butyrolactone from maleic anhydride with long-term stability without requiring frequent re-activation of the catalyst: Formula (I) CuO(a)ZnO(b)MnO2(c)SiO2(d) wherein a, b, c, and d are represented on the basis of weight, wherein a is 20 to 90, b is 0.01 to 10, c is 0.01 to 5, and d is 5 to 50.

Abstract: The present invention provides a process for hydrogenating carbonyl compounds, in particular C4-dicarboxylic acids to mixtures of tetrahydrofuran and gamma-butyrolactone, over supported rhenium catalysts, wherein rhenium and at least one further metal of groups VIII or Ib of the Periodic Table of the Elements, in particular ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), copper (Cu), silver (Ag) or cobalt (Co), is applied to the support in the form of at least one bimetallic precursor compound, and also to these catalysts.

Abstract: A process for coproducing alkyl-substituted or unsubstituted THF and pyrrolidones by catalytically hydrogenating C4-dicarboxylic acids and/or derivatives thereof in the gas phase in the presence of copper catalysts and reacting GBL with ammonia or primary amines to give pyrrolidones.

Abstract: C4-dicarboxylic acids or derivatives thereof are hydrogenated in the gas phase in a fluidized-bed reactor. It is possible to use catalyst compositions known per se.

Abstract: The present invention relates to a process for the gas-phase hydrogenation of C4-dicarboxylic acids and/or their derivatives over a catalyst based on copper oxide to give substituted or unsubstituted &ggr;-butyrolactone and/or tetrahydrofuran, which comprises, which a first reaction zone in which the C4-dicarboxylic acid and/or its derivatives is/are reacted to give a mixture comprising a substituted or unsubstituted &ggr;-butyrolactone as main product and a subsequent second reaction zone in which the substituted or unsubstituted &ggr;-butyrolactone present in the mixture from the first hydrogenation step is reacted at a temperature lower than the temperature in the first hydrogenation step to give substituted or unsubstituted tetrahydrofuran.

Abstract: C4-dicarboxylic acids or derivatives thereof are hydrogenated in the gas phase in a fluidized-bed reactor. It is possible to use catalyst compositions known per se.

Abstract: A textured catalyst having a hydrothermally-stable support, a metal oxide and a catalyst component is described. Methods of conducting aqueous phase reactions that are catalyzed by a textured catalyst are also described. The invention also provides methods of making textured catalysts and methods of making chemical products using a textured catalyst.

Abstract: A process is described for the co-production of maleic anhydride and at least one C4 compound selected from butane-1,4-diol, &ggr;-butyrolactone, and tetrahydrofuran in which maleic anhydride is produced by partial oxidation of a hydrocarbon feedstock selected from C4 hydrocarbons and benzene to yield a vaporous reaction effluent stream comprising maleic anhydride, water, unconverted hydrocarbon feedstock, and carbon oxides. A part of the maleic anhydride present in the vaporous reaction effluent stream is condensed to form a crude maleic anhydride stream and leave a residual vaporous stream containing residual amounts of maleic anhydride. Further maleic anhydride is absorbed from the residual vaporous stream by absorption in an organic solvent, water or an aqueous solution. Maleic anhydride is then recovered from the loaded liquid absorptions medium.

Abstract: A process for the production of gamma-butyrolactone. Starting from maleic and/or succinic anhydride the conversion takes place in the vapor phase of a Cu/Cr catalyst.

Abstract: The present invention relates to an improved for the hydrogenation of an immiscible mixture of an organic reactant in water. The immiscible mixture can result from the generation of water by the hydrogenation reaction itself or, by the addition of, water to the reactant prior to contact with the catalyst. The improvement resides in effecting the hydrogenation reaction in a monolith catalytic reactor from 100 to 800 cpi, at a superficial velocity of from 0.1 to 2 m/second in the absence of a cosolvent for the immiscible mixture. In a preferred embodiment, the hydrogenation is carried out using a monolith support which has a polymer network/carbon coating onto which a transition metal is deposited.

Abstract: A process for production of tetrahydrofuran and gamma butyrolactone by hydrogenation of maleic anhydride recovered from a process of conversion of a n-butane.

Abstract: Disclosed is a process for effecting liquid-phase hydrogenation of MAN to GBL in high conversion and high selectivity. The present invention provides an improved process of catalytic hydrogenation for converting MAN or SA to GBL in the liquid phase in the presence of a noble metal (palladium-molybdenum-nickel) catalyst supported on silica having a large surface area. The catalytic hydrogenation is conducted at a temperature of 150 to 250° C. and under a pressure of 50 to 150 kg/cm2.

Abstract: The invention relates to catalysts containing ruthenium and at least one other metal having an atomic number in the range of from 23 to 82 prepared by (a) mixing a suspension of a ruthenium compound having a specific surface area in the range of from 50 to 300 m2/g with a solution of at least one metal compound in which at least one such metal compound contains a metal different from ruthenium and has an atomic number in the range of from 23 to 82, and (b) treating the mixture of the suspension and the solution with a reducing agent.

Abstract: Disclosed is a process for effecting liquid-phase hydrogenation of MAN to GBL in high conversion and high selectivity. The present invention provides an improved process of catalytic hydrogenation for converting MAN or SA to GBL in the liquid phase in the presence of a noble metal (palladium-molybdenum-nickel) catalyst supported on silica having a large surface area. The catalytic hydrogenation is conducted at a temperature of 150 to 250° C. and under a pressure of 50 to 150 kg/cm2.

Abstract: Gamma-Butyrolactone (GBL) is recovered from a mixture containing GBL and other heavy organics by a process of azeotropic distillation in the presence of a C8-C 10 hydrocarbon as an azeotroping agent, wherein an azeotrope of GBL and the hydrocarbon is obtained as a distillate, which forms immiscible GBL-rich and hydrocarbon-rich phases, and the hydrocarbon-rich phase is decanted or isolated from the GBL-rich phase. By this process GBL can be efficiently separated from a large proportion of various compounds having boiling points close to that of GBL, e.g., the methyl-&ggr;-butyrolactones (MeGBL's).

Abstract: A catalyst for hydrogenating a dicarboxylic acid, a dicarboxylic acid anhydride, or an ester thereof, said catalyst comprising palladium and rhenium supported on a carrier, characterized in that not more than 20% of analyzed points have an intensity ratio of 2 or larger, wherein a catalyst particle is analyzed by electron probe microscope analysis (EPMA) for rhenium along a longest diameter in a largest cross-section of the catalyst particle, and a rhenium intensity at each analyzed point is divided by an average intensity of all of the analyzed points to give the intensity ration, and that the carrier at least one active carbon selected from the group consisting of coal-based active carbon, coconut-based active carbon and peat-based active carbon.

Abstract: Butane-1,4-diol, gamma-butyrolactone or tetrahydrofuran are prepared by vapor phase hydrogenation of a C4-dicarboxylic acid derivative. A maleic anhydride containing vapor stream is contacted in an absorption zone with a first high boiling solvent. A waste gas stream is passed to a scrubbing zone containing a second, higher boiling solvent. The waste gas is purged and the first and second solvents are recovered and recycled. Maleic anhydride is obtained from the absorption zone and converted to a maleic acid diester, which is stripped from the first solvent with hydrogen. The desired products are obtained by hydrogenation.

Abstract: This invention relates to a method of improving the catalytic performance of palladium or ruthenium, rhenium-on-carbon hydrogenation catalysts operating in aqueous media where loss of soluble rhenium may result in rapid catalytic failure. A rhenium-containing hydrogenation catalyst comprised of rhenium on a support material is regenerated by first treating the catalyst with aqueous perrhenic acid or potassium perrhenate followed by treating the catalyst under reducing conditions at elevated temperature and pressure. Treatment of the catalyst as described replenishes dispersed fresh finely divided rhenium which enhances the activity of the catalyst while at the same time allowing the operations to be carried out in situ in the hydrogenation reactor or in a side stream reactor with significant savings in reducing reactor down time and precious metal expenses.

Abstract: A process is described for the production of butane-1,4-diol, &ggr;-butyrolactone and/or tetrahydrofuran. A vaporous stream containing maleic anhydride, water, and carbon oxides is contact in an absorption zone with a high boiling ester as solvent to form a solution of maleic anhydride in the high boiling ester which has a boiling point at the atmospheric pressure at least about 30° C. higher than that of maleic anhydride and is selected from di-(C1 to C4 alkyl) esters of alkyl dicarboxylic acids containing up to 3 carbon atoms, mono- and di-(C10 to C18 alkyl) esters of maleic acid, fumaric acid, succinic acid, and mixtures thereof, (C1 to C4 alkyl) esters of naphthalene-monocarboxylic acids, tri-(C1 to C4 alkyl) esters of aromatic tricarboxylic acids, and di-(C1 to C4 alkyl) esters of isophthalic acid.

Abstract: The invention relates to chiral ferrocenyls of formula (I) ##STR1## wherein R.sub.a is --P(R.sub.10 R.sub.11) or --SR.sub.12 ;R.sub.b is --P(R'.sub.10 R'.sub.11), --SR'.sub.12, --CH.dbd.NR.sub.12, --CH.sub.2 --NH--R.sub.12 or --CH.sub.2 --O--P(R.sub.10 R.sub.11); and the other substituents are as defined in claim 1,which may be used as ligands for transition metal catalysts in enantioselective reactions.

Abstract: A process for the production of at least one C.sub.4 compound selected from butane-1,4-diol, .gamma.-butyrolactone and tetrahydrofuran comprises contacting a vaporous stream containing maleic anhydride vapour, water vapour, and carbon oxides in an absorption zone with a high boiling organic solvent thereby to form a solution of maleic anhydride in the high boiling organic solvent. Maleic anhydride in this solution is reacted under esterification conditions in an esterification zone with a C.sub.1 to C.sub.4 alkanol to form a solution of the corresponding di-(C.sub.1 to C.sub.4 alkyl) maleate in the high boiling solvent. This solution of the di-(C.sub.1 to C.sub.4 alkyl) maleate in the high boiling solvent is contacted with a gaseous stream containing hydrogen thereby to strip di-(C.sub.1 to C.sub.4 alkyl) maleate therefrom and to form a vaporous stream comprising hydrogen and di-(C.sub.1 to C.sub.4 alkyl) maleate.

Abstract: A process is described for the production of at least one C.sub.4 compound selected from butane-1,4-diol, .gamma.-butyrolactone and tetrahydrofuran, which includes the step of hydrogenation in the vapour phase of maleic anhydride in the presence of a heterogeneous hydrogenation catalyst, which process comprises:(a) contacting a vaporous stream containing maleic anhydride vapour, water vapour, and carbon oxides in an absorption zone with a high boiling organic solvent having a boiling point at atmospheric pressure which is at least about 30.degree. C.

Abstract: A process for manufacturing gamma-butyrolactone by the catalytic hydrogenation of maleic anhydride, succinic anhydride or their acids in the vapor phase in the presence of catalysts based on copper oxide and aluminum oxide in reduced form is described. The process is characterized in that a catalyst is employed to conduct the reaction which is formed on the basis of 50 to 95% by weight copper oxide, 3 to 30% by weight aluminum oxide and 0 to 25% by weight of a binder. Preferably the catalyst is formed on the basis of 83.5 to 85.5% by weight copper oxide, 9 to 11% by weight aluminum oxide, and 4.5 to 6.5% by weight graphite. The reaction mixture obtained can be used directly without separating off the water, e.g. for manufacturing N-methylpyrrolidone.

Abstract: There are described N-aminopyridone derivatives of the formula I: ##STR1## where the substituents R.sup.1 to R.sup.12 have the meanings given in claim 1, a process for their preparation, and their use for controlling undesirable vegetation.

Abstract: An improved two step (dual stage catalysis) aqueous hydrogenation process and a novel trimetallic hydrogenation catalysts consisting essentially of highly dispersed, reduced ruthenium and rhenium metals in the presence of a third metal tin on carbon support particular useful in the second stage of the process. Such process and catalyst exhibit high conversion rates in aqueous solution hydrogenation of hydrogenatable precursors (e.g., maleic acid, succinic acid, corresponding esters, .gamma.-butyrolactone, etc.) to tetrahydrofuran, .gamma.-butyrolactone, 1,4-butanediol and mixtures thereof wherein the relative molar ratio of 1,4-butanediol to tetrahydrofuran products being produced can be controlled.

Abstract: Improved hydrogenation catalysts consisting essentially of reduced or at least partially reduced ruthenium and tin on a refractory oxide support which is insoluble in aqueous acid. Such catalysts are very durable and exhibit high conversion rates in aqueous acidic solution hydrogenation of hydrogenatable precursors (e.g. maleic acid, succinic acid, gamma-butyrolactone etc.) and high selectivity for their conversion to 1,4-butanediol and gamma-butyrolactone and their mixtures.

Abstract: Disclosed is a process for the production of gamma-butyrolactone from maleic anhydride or succinic anhydride by hydrogenation in the presence of a catalyst composition comprising the mixed oxides of copper, zinc and zirconium.

Abstract: A process for vapor phase hydrogenation of maleic anhydride and/or succinic anhydride to .gamma.-butyrolactone, comprising contacting an alcoholic solution of a feedstock anhydride with reduced Cu-Zn-Cr-Zr catalyst under the conditions of hydrogenation.

Abstract: The disclosure describes a method for separating a ruthenium complex, which comprises removing an objective hydrogenation reaction product from a hydrogenation reaction solution of an organic carbonyl compound in the presence of a ruthenium complex having a tertiary organic phosphorus compound as ligand to obtain a catalyst solution, contacting said catalyst solution with a polar solvent, and carrying out a phase-separation into a liquid phase substantially composed of the polar solvent and an another liquid phase substantially containing the ruthenium complex.

Abstract: Gamma-butyrolactone is produced by catalytic hydrogenation of maleic anhydride in the vapor phase in the presence of copper chromite based catalysts in reduced form. The reaction is carried out using a substantially uniform catalyst derived substantially from the three components cupric oxide, chromic oxide, and silicon dioxide. The ratio of CuO to Cr.sub.2 O.sub.3 to SiO.sub.2 is preferably about 78:20:2. It can prove advantageous to use an inert gas such as nitrogen as a diluent.

Abstract: A lactone is prepared by catalytically hydrogenating a dicarboxylic acid having 3 to 10 carbon atoms or a functional derivative thereof in the presence of a catalyst comprising a metal selected from the elements of group VIII of the periodic table or a combination of said metal with an element selected from the elements of groups IVa, VIb and VIIb of the peridic table, and further in the co-presence of an alkali metal salt or an alkali metal hydroxide.

Abstract: Improved hydrogenation catalysts consisting essentially of highly dispersed, reduced ruthenium and rhenium on carbon support and methods of making and using the same. Such catalysts exhibit high conversion rates in aqueous solution hydrogenation of hydrogenatable precursors (e.g., maleic acid, succinic acid, .gamma.-butyrolactone, etc.) to tetrahydrofuran, 1,4-butanediol and mixtures thereof.

Abstract: Vapor phase catalytic hydrogenation of maleic anhydride to gamma-butyrolactone is achieved in a conversion of 95% or more and a selectivity of 80% or more during a prolonged period of production. The process uses an activated catalyst prepared by reducing a catalyst composition comprising 30-65% by weight of CuO, 18-50% by weight of ZnO and 8-22% by weight of Al.sub.2 O.sub.3, and activating the reduced catalyst composition in hydrogen at an activation temperature of at least 400.degree. C., preferably 400.degree. to 525.degree. C., and optimally about 425.degree. C. The process suitably is carried out under predetermined and advantageous process conditions, including a defined molar ratio of hydrogen to maleic anhydride in the vapor reactant stream, a selected pressure during hydrogenation, a defined feed rate space velocity, a predetermined contact time, and a suitable reaction temperature.

Abstract: A process for the preparation of tetrahydrofuran or tetrahydrofuran and .gamma.-butyrolactone from the product of the hydrogenation of maleic acid, succinic acid, maleic anhydride, succinic anhydride and/or fumaric acid, by treating the crude hydrogenation product, without prior work-up, at from 100.degree. to 300.degree. C. with a protic acid, and isolating pure tetrahydrofuran and .gamma.-butyrolactone from the resultant reaction mixture by distillation.

Abstract: Maleic anhydride is hydrogenated to produce 1,4-butanediol in a two-stage process. In the first stage maleic anhydride and/or maleic acid contacted with hydrogen at a temperature of about 100.degree. C. to about 350.degree. C. in the presence of a suitable hydrogenation catalyst to produce succinic anhydride and/or gamma-butyrolactone. In the second stage, the succinic anhydride and/or gamma-butyrolactone and hydrogen are contacted at a temperature of about 180.degree. C. to about 350.degree. C. in the presence of a ruthenium-containing hydrogenation catalyst to produce 1,4-butanediol.

Abstract: This invention provides a vapor phase process for the production of gamma-butyrolactone and tetrahydrofuran in a predetermined ratio by the steps of: hydrogenating a vapor mixture of maleic anhydride and excess hydrogen over a first bed of a Cu-Zn-Al catalyst, and directly contacting the crude reactor effluent therefrom with hydrogen over a second bed of Cu-Zn-Cr catalyst during a predetermined contact time and at a defined temperature, using selected amounts of catalyst in each bed.

Abstract: A process for producing gamma-butyrolactone by catalytic hydrogenation of maleic anyhydride in the liquid phase with hydrogen, at a high temperature and under pressure, in the presence of a catalyst comprising nickel and palladium deposited on a support, wherein said support is a silica based support having a very high specific surface area , the value of which may range from 50 m.sup.2 /g, preferably from about 100 m.sup.2 /g to about 800 m.sup.2 /g and more.Very high conversion rates of 90-98 mole % and excellent selectivities to gamma-butyrolactone of 95 to 97 mole % are achieved by the process.

Abstract: A method for producing a lactone by hydrogenating a dicarboxylic acid, a dicarboxylic acid anhydride and/or a dicarboxylic acid ester in the presence of a catalyst, wherein the hydrogenation reaction is conducted in the liquid phase in the presence of (1) ruthenium, (2) an organic phosphine and (3) a compound of a metal selected from the group consisting of Groups IVA, VA and IIIB in the Periodic Table.According to the present invention, for the production of a lactone by hydrogenating a dicarboxylic acid, a dicarboxylic acid anhydride and/or a dicarboxylic ester, the reaction is conducted in a homogeneous liquid phase reaction by using the ruthenium,organic phosphine and compound of a metal selected from the group consisting of Groups IVA, VA and IIIB, of the present invention as the catalyst, whereby the desired lactone product can be obtained at high selectivity under a mild condition as compared with the conventional methods.

Abstract: A process for preparing an optically active alcohol is disclosed, which comprises asymmetrically hydrogenating a carbonyl compound in the presence of a ruthenium-optically active phosphine complex as a catalyst. The resulting alcohol has high optical purity.

Abstract: Tetrahydrofuran and gamma-butyrolactone are prepared from at least one of maleic anhydride or succinic anhydride by catalytically hydrogenating vaporous maleic anhydride or vaporous succinic anhydride in the presence of hydrogen in contact with a catalyst comprising an essentially inert, at least partially porous support having an outer surface, and a catalytically active oxide material coating onto the outer surface of the support which strongly adheres to the support, wherein the catalytically active oxide material comprises the mixed oxides of copper, zinc and aluminum.

Abstract: A process for producing a lactone by reacting in a hydrogenation reaction zone a dicarboxylic acid, a dicarboxylic acid anhydride and/or a dicarboxylic acid ester with hydrogen in a liquid phase using a solvent in the presence of a catalyst comprising ruthenium and an organic phosphine, which process comprises the following steps (1) to (6):(1) a first step of recovering the liquid phase from the hydrogenation reaction zone,(2) a second step of distilling the liquid phase in a first distillation column to obtain a first distillate and a first residue,(3) a third step of recycling the first residue to the hydrogenation reaction zone,(4) a fourth step of distilling a part of the first residue in a second distillation column to obtain a second distillate and a second residue,(5) a fifth step of recycling the second distillate to the hydrogenation reaction zone or the first distillation column, and(6) a sixth step of recovering a lactone from the first distillate.

Abstract: What is provided herein is a vapor phase process for the production of butyrolactone in which the vapor mixture of the feed compound and hydrogen is provided at high flow rates from finely divided droplets of the feed compound which are vaporized rapidly with hot hydrogen gas.

Abstract: A method for producing a lactone by hydrogenating a dicarboxylic acid, a dicarboxylic acid anhydride and/or a dicarboxylic acid ester in the presence of a catalyst, wherein said catalyst is a ruthenium catalyst comprising (1) ruthenium, (2) an organic phosphine and (3) a conjugate base of an acid having a pKa of less than 2.

Abstract: A process for the production of esters or lactones, comprising reacting in the presence of a catalyst and under hydrogenation conditions hydrogen and an acyclic or cyclic carboxylic anhydride to produce the corresponding ester or lactone, wherein the catalyst is a supported catalyst comprising:(a) a group VIII metal, Re and Fe;(b) a group VIII metal on TiO.sub.2 ;(c) Ru and at least one of Re, Ag or Cu; or(d) Pd and Fe.Preferably, the anhydride has the formula ##STR1## and is reacted to form an ester of the formula ##STR2## or a lactone of the formula ##STR3## wherein R and R.sup.1 independently are lower alkyl or cycloalkyl; R.sup.2, R.sup.3, R.sup.4, R.sup.5 independently are hydrogen, lower alkyl, cycloalkyl or aryl; and wherein R.sup.3 and R.sup.4 taken together may form a saturated or unsaturated ring, or an aromatic ring. The more preferred starting material is phthalic anhydride.

Abstract: A process is described for the co-production of maleic anhydride and at least one C4 compound selected from butane-1,4-diol, ?-butyrolactone, and tetrahydrofuran in which maleic anhydride is produced by partial oxidation of a hydrocarbon feedstock selected from C4 hydrocarbons and benzene to yield a vaporous reaction effluent stream comprising maleic anhydride, water, unconverted hydrocarbon feedstock, and carbon oxides. A part of the maleic anhydride present in the vaporous reaction effluent stream is condensed to form a crude maleic anhydride stream and leave a residual vaporous stream containing residual amounts of maleic anhydride. Further maleic anhydride is absorbed from the residual vaporous stream by absorption in an organic solvent, water or an aqueous solution. Maleic anhydride is then recovered from the loaded liquid absorptions medium.