Abstract: The present invention provides a gene involved in the growth-promoting function of acetic acid bacteria and a microorganism containing the gene. In particular, the present invention provides a method for enhancing the growth-promoting function of acetic acid bacteria and a method for efficiently producing vinegar containing acetic acid at a high concentration in a short time using such acetic acid bacteria having an enhanced growth-promoting function.

Abstract: Non-natural amino acids such as 2-alkylated amino acids allow for the synthesis of a wider variety of peptidal and non-peptidal pharmaceutically active agents. In one embodiment, the present invention relates to a method of preparing a 2-alkylcysteine comprising condensing cysteine with an aryl nitrile to form a 2-arylthiazoline-4-carboxylic acid, esterifying the 2-arylthiazoline-4-carboxylic acid using a substituted or unsubstituted alcohol group comprising one or more chiral carbons, and alkylating at the 4-position of the thiazoline ring to form a 2-aryl-4-alkyl-thiazoline-4-carboxylic acid ester. The chiral templates present in the thiazoline carboxylic acid ester can provide face selectivity, and consequently desired stereochemistry, during the delivery of an alkyl group to the 4-position of the thiazoline ring. The present invention also discloses a method of preparing a class of iron chelating agents related to desferrithiocin, all of which contain a thiazoline ring.

Abstract: A process is provided which can effectively inhibit occurrence of hot spots in reaction zones or heat accumulation at the hot spots, in the occasion of producing acrolein and acrylic acid through vapor phase oxidation of propylene in the presence of a catalyst using a fixed bed shell-and-tube reactor, said catalyst having a composition represented by a general formula (1): MoaWbBicFedAeBfCgDhEiOx (wherein A is at least an element selected from Co and Ni; B is at least an element selected from P, Te, As, B, Sb, Sn, Ce, Nb, Pb, Cr, Mn and Zn; C is alkali metal element; D is alkaline earth metal element; E is at least an element selected from Si, Al, Ti and Zr; and O is oxygen; a, b, c, d, e, f, g, h, i and x denote the atomic numbers of Mo, W, Bi, Fe, A, B, C, D, E and O, respectively, and where a is 12, b is 0-5, c is 0.1-10, d is 0.1-10, e is 1-20, fis 0-5, g is 0.001-3, h is 0-3, i is 0-30, and x is a numerical value which is determined depending on the extent of oxidation of each of the elements).

Abstract: A process for preparing an antimonate-based mixed metal oxide catalyst in a catalytically active oxidized state, wherein the catalyst is represented by the empirical formula MeaSbbXcQdReOf, wherein Me, X, Q, R, a, b, c, d, e, and f are as defined herein, comprising (a) contacting an aqueous Sb2O3 slurry with HNO3 and one or more Me compounds, and, optionally, one or more compounds selected from X, Q, or R compounds to form a first mixture; (b) heating and drying the first mixture to form a solid product; and (c) calcining the solid product to form the catalyst, the catalysts prepared by the process, and the use of the catalysts in ammoxidation and oxidation processes. The catalysts of the invention are particularly useful for the production of acrylonitrile from propylene, ammonia, and an oxygen-containing gas.

Abstract: In a process for the production of acetic acid by carbonylation of methanol and/or a reactive derivative in the presence of a Group VIII noble metal carbonylation catalyst, methyl iodide co-catalyst at a concentration of at least 2 wt %, optionally at least one promoter at least a finite concentration of water, methyl acetate at a concentration of at least 8% w/w and acetic acid product, the separability of an upper (aqueous) layer and a lower (organic) layer in the decanter of the light ends column is achieved by maintaining the concentration of acetic acid in the condensed overhead vapor fraction passed to the decanter at or below 8 wt %.

Abstract: The invention relates to a method for selectively producing acetic acid from a gaseous feedstock of ethane, ethylene or mixtures thereof and oxygen at a high temperature. Said gaseous feedstock is brought together with a catalyst containing the elements Mo, Pd, X and Y in the gram-atomic ratios a:b:c:d in combination with oxygen: MoaPdbXcYd (I). Symbols X and Y have the following meaning: X represents one or several of the elements chosen from the group Cr, Mn, Nb, Ta, Ti, V, Te and W; Y represents one or several of the elements chosen from the group B, Al, Ga, In, Pt, Zn, Cd, Bi, Ce, Co, Rh, Ir, Cu, Ag, Au, Fe, Ru, Os, K, Rb, Cs, Mg, Ca, Sr, Ba, Nb, Zr, Hf, Ni, P, Pb, Sb, Si, Sn, Tl and U, the indices a, b, c, d and x represent the gram-atomic ratios of the corresponding elements: a=1, b=0.0001 to 0.01, c=0.4 to 1 and d=0.005 to 1. The space-time yield in the oxidation to acetic acid using the inventive method is >150 kg/hm3.

Abstract: A shell and tube heat exchanger reactor with forced circulation is used to improve heat and mass transfer for exothermic liquid--liquid, gas-liquid and gas-liquid-solid reactions. Enhanced productivity and selectivity are obtained.

Abstract: A process for the catalytic gas-phase oxidation of acrolein to acrylic acid in a fixed-bed reactor with contacting tubes, at elevated temperature on catalytically active oxides with a conversion of acrolein for a single pass of .gtoreq.95%, wherein the reaction temperature in the flow direction along the contacting tubes in a first reaction zone before the starting reaction gases containing the reactants enter the contacting tubes is from 260.degree. to 300.degree. C. until an acrolein conversion of from 20 to 40% is reached, and the reaction temperature is subsequently reduced by a total of from 5.degree. to 40.degree. C., abruptly or successively in steps or continuously along the contacting tubes until a methacrolein conversion of .gtoreq.95% has been reached, with the proviso that the reaction temperature in this secondary reaction zone is not lower than 240.degree. C.

Abstract: A method to oxidize an oxidizable component in a liquid phase with an oxygen-containing gas is disclosed. The method comprises mixing the liquid phase and gas phase in a reactor with a rotating agitator element operated at constant power.

Abstract: The gas phase catalytic oxidation of an unsaturated aldehyde with molecular oxygen at 200.degree. to 500.degree. C. to give the corresponding unsaturated carboxylic acid is conducted in the presence of a catalyst represented by the following formula:Mo.sub.12 P.sub.a X.sub.b Y.sub.c Z.sub.d O.sub.ewherein the subscripts represent the atomic ratios of each component and a is 0.5 to 6, b is 0.001 to 6, c is 0.2 to 6, d is 0 to 6, and e is a value determined by the valencies of the elements present in the catalyst; and Mo is molybdenum, P is phosphorus, O is oxygen, X is at least one metal selected from the group consisting of rhodium, cerium and zirconium, Y is at least one alkali metal selected from the group consisting of potassium, rubidium and cesium, and Z is at least one metal selected from the group consisting of iron, cobalt, nickel, zinc, antimony, silicon, bismuth, cadmium, uranium, manganese, copper, vanadium, niobium and tantalum.

Abstract: A process for producing acetic acid directly from ethylene under mild conditions is provided, wherein ethylene and oxygen are respectively coordinated with the respective transition metals contained in a specified composite catalyst system, and ethylene activated thereby is successively oxidized by two kinds of oxygen complexes contained in the system and having their electric charge states adjusted, the composite catalyst system comprising a complex represented by a formula (MmXn.Ll) and a complex represented by a formula (M'm'Xn'.L'l') wherein is a transition metal of the groups I, IV.about.VII and iron group; X, an anion; L, an organic phosphorus compound as a ligand; M', a transition metal of Pt group; L', a nitrile, organic fluorine compound or organic phosphorus compound as a ligand; m, m', n and n', each a number determined by the valences of the transition metals and anion; and l and l' each the number of ligands.

Abstract: A novel process for producing oxygen-containing organic compounds with high selectivity and good yield by oxidizing organic compounds under mild conditions is provided, which process comprises using as a catalyst for the oxidation, a complex (M.sub.m X.sub.n.L.sub.l) consisting of a transition metal compound (M.sub.m X.sub.n) and an organic phosphorous compound (L) as a ligand, wherein M represents a transition metal belonging to group I, group IV.about.VII or iron group in group VIII of the periodic table; X represents an anion such as a halogen; ligand L represents an organic phosphorous compound; and m and n mean a number of the atomic valence of said transition metal (ion) M and said anion X, respectively, and l means a number of said ligand.

Abstract: Production of acrylic acid by oxidation of acrolein with gas containing oxygen in the gas phase at elevated temperature in the presence of a catalyst which, in addition to oxygen, consists essentially of (a) molybdenum, (b) tungsten, (c) vanadium and (d) iron and/or copper. The atomic ratio of molybdenum:tungsten:iron and/or copper is 1 to 20:0.01 to 10:1 and the atomic ratio of vanadium:molybdenum is 0.2 to 6:6. Acrylic acid is an important starting material for the production of high polymers.

Abstract: A process for separation of methacrylic acid from a methacrylic acid-containing, gaseous reaction mixture obtained by subjecting methacrolein or a compound which can afford methacrolein under reaction conditions and molecular oxygen to gas phase reaction in the presence of a catalyst for oxidation under the coexistence of an inert gas for dilution which comprises (a) cooling the gaseous reaction mixture from a reactor wherein the gas phase reaction has been effected to separate into condensable components including methacrylic acid, acetic acid and water vapor as a condensed liquor and non-condensable components including methacrolein as a non-condensed gaseous mixture, (b) eliminating contaminating methacrolein from the condensed liquor and (c) contacting the resulting condensed liquor with an organic solvent to extract methacrylic acid, followed by separation into an organic solvent solution including methacrylic acid and an aqueous solution as waste water, characterized in that (1) the inert gas for diluti

Abstract: A vapor phase catalytic process for making an unsaturated carboxylic acid from an olefinically unsaturated aldehyde, particularly acrylic acid from acrolein, by oxidation thereof with molecular oxygen, optionally in the presence of steam and a new catalyst comprising a complex oxide catalyst of Mo, V and Zr.

Abstract: Carboxylic acids having the general formula:R--COOHwherein R is selected from the group consisting of aryl, aralkyl, aralkenyl, aralkynyl, heteroaryl, heteroarylalkyl, heteroarylalkenyl, heteroarylalkynyl, alkyl, alkenyl and alkynyl, optionally substituted by inert or non-reactive substituents under the reaction conditions, are obtained by oxidation of the corresponding aldehydes with an alkali metal or alkaline-earth metal chlorite in the presence of hydrogen peroxide and in an aqueous-organic solvent. The resulting carboxylic acids are utilizable as intermediates for preparing fine chemicals in known ways.

Abstract: A process for producing methacrylic acid by the vapor phase catalytic oxidation of methacrolein with molecular oxygen or a molecular oxygen-containing gas comprises using a catalyst of multi-elemental complex oxide having the formulaMo.sub.a P.sub.b As.sub.c Cu.sub.d Cr.sub.e X.sub.f O.sub.gwherein X represents at least one of element of Ce, Nd, W and Fe; a, b, c, d, e, f and g respectively represent atomic ratios and a=12, b=0.5 to 3.0, c=0.01 to 1.2, d=0.01 to 2.0, e=0.05 to 2.0 and f=0 to 1.0; and g is decided on the valences of the other components such as usually 37 to 58 which is prepared with or without a reduction using a dibasic carboxylic acid, an oxycarboxylic acid, mannitol or pyrogallol.

Abstract: An oxidation catalyst wherein the catalytically active component has the general formulaMo.sub.12 P.sub.a Rh.sub.b Cu.sub.c V.sub.d Cs.sub.e X.sub.f Y.sub.g Z.sub.h O.sub.x,where X is Cr and/or Fe, Y is Nb, Z is Na, Li, K and/or Rb, a is 0.1-4, b is 0.001-1, c is 0.05-2, d is 0.05-4, e is 0.1-5, f is 0-2, g is 0-3 and h is 0-2, and x is the number of oxygen atoms required to saturate the valencies of the other constituents, is very suitable for the preparation of methacrylic acid by gas phase oxidation of methacrolein with an oxygen-containing and steam-containing gas mixture.

Abstract: Methacrylic acid is prepared by reacting methacrolein with molecular oxygen in the vapor phase at a temperature of from 230.degree. C. to 450.degree. C. in the presence of a catalyst having the formula Mo.sub.12 P.sub..alpha.' X.sub..beta.' Y.sub..gamma.' O.sub..delta.' wherein X is at least one member of the group consisting of Cs and Tl:Y is at least one member of the group consisting of Cs and Tl; Y is at least one member of the group consisting of V, Zr, Nb, Ni, Ta and Fe; .alpha.'=0.1-3; .beta.'=0.2-9; .gamma.'=0.1-7; .delta.'=36-100.

Abstract: A catalyst comprising (1) palladium, (2) phosphorus, (3) antimony, (4) X and (5) oxygen wherein X denotes at least one element selected from the group consisting of potassium, sodium, rubidium, lithium, cerium, beryllium, magnesium, calcium, vanadium, strontium, zinc, thorium and rhenium.There is also provided a process for the manufacture of methacrylic or acrylic acid by oxidizing methacrolein or acrolein with molecular oxygen in the vapor phase in the presence of the catalyst defined above.

Abstract: Aldehydes, such as acetaldehyde, are oxidized to carboxylic acids, such as acetic acid, by contacting the aldehyde with oxygen at oxidative conditions in the presence of a catalyst of the empirical formulaMo.sub.12 P.sub.0.1-3 Cu.sub.0.01-2 V.sub.0.1-3 M.sub.0.1-3 M'.sub.0.01-3 O.sub.x (I)whereM is at least one of K, Rb, Cs and Tl;M' is at least one of Be, Mg, Ca, Sr, Ba, Nb, Ti, Zr, Ta, Mn, Fe, Co, Ni, Zn, Ag, Al, Ge, Sn, Pb, As, Bi, Te, Ce, Th, U and Sb; andx is a number that satisfies the valence requirements of the other elements present.

Abstract: A stabilized heteropoly molybdate catalyst precursor in calcined form and containing anionic molybdenum in defect state is surface impregnated with certain metal cations. The stabilized precursor is one obtained by incorporating into the reaction product of a molybdate and a soluble phosphate, silicate or arsenate, an aqueous chloride ion and a compound of phosphotungstate, silicotungstate, vanadium arsenate, silico-arsenate, phosphovanadate, or silicovanadate, followed by drying and calcining. During the chloride ion stabilization step other metals may be optionally incorporated in forming the stabilized precursor.The obtained precursor is catalytically active in the conversion of the unsaturated aldehydes to the corresponding unsaturated carboxylic acids with or without incorporation of the metal cation during the chloride ion stabilization step.

Abstract: The solid oxalate of a catalytic metal such as cobalt, typically formed as an undesired and useless by-product during the liquid-phase oxidation of an organic compound, typically a hydrocarbon, in the presence of a homogeneous catalyst comprising said metal, is treated to convert the metal moiety to a reusable form by a process comprising leaching the metal oxalate with an aqueous solution of a soluble salt of ethylenediaminetetraacetic acid (EDTA). The resulting solution of EDTA-metal complex or chelate is then mixed with a soluble calcium salt to precipitate the oxalate moiety as insoluble calcium oxalate leaving the metal-EDTA complex in solution. After removing the resulting solid calcium oxalate, the remaining filtrate is acidified to convert the metal moiety to a simple salt which can be recycled to the liquid-phase oxidation, while the EDTA is precipitated as a solid which can also be recovered and re-used in the complexation step of the process.

Abstract: A process is provided for the preparation of practically formic acid-free acetic acid by oxidation of acetaldehyde in the liquid phase with oxygen or oxygen-containing gases in the presence of mixtures of cobalt, nickel and manganese salts as catalysts.

Abstract: In the production of acrylic acid by a two-stage, vapor-phase catalytic oxidation of propylene, a composite oxide catalyst expressed by the formula Mo.sub.a Bi.sub.b Ni.sub.c Co.sub.d Fe.sub.e Na.sub.f Mn.sub.g B.sub.h K.sub.i Si.sub.j O.sub.x is used in the first-stage reaction, which is carried out under specific reaction and operational conditions, and the second-stage reaction is carried under specific reaction and operational conditions while oxygen is supplied by a specific mode.

Abstract: The present invention relates to a process for the production of unsaturated aliphatic acids and the catalyst therefor, by the vapor phase oxidation of the corresponding unsaturated aliphatic aldehydes with molecular oxygen, optionally in the presence of steam, in the presence of an oxidation catalyst consisting of the oxides of the elements molybdenum, vanadium, and tungsten, plus at least one of the oxides selected from the group consisting of rhenium, and titanium and optionally one or more of the oxides of the elements manganese, iron, copper, tin, aluminum, cobalt, nickel, phosphorus, zinc, bismuth, silver, cadmium, niobium,arsenic, chromium, the alkali and the alkaline earth elements.

Abstract: The gas phase catalytic oxidation of an unsaturated aldehyde with molecular oxygen at 240.degree. to 450.degree. C. to give the corresponding unsaturated carboxylic acid is conducted in the presence of a catalyst of the following formula:Mo.sub.12 P.sub.a Q.sub.b R.sub.c X.sub.d Y.sub.e Z.sub.f O.sub.gwherein Mo is molybdenum, P is phosphorus, O is oxygen, Q is calcium and/or magnesium, R is at least one metal element selected from the group consisting of potassium, rubidium, cesium and thallium, X is at least one element selected from the group consisting of boron, silicon, manganese, iron, cobalt, zinc, germanium, uranium, tin, lead, chromium, titanium, tantalum, antimony, niobium and bismuth, Y is at least one metal element selected from the group consisting of vanadium, copper and nickel, Z is strontium and/or barium, and wherein the subscripts represent the atomic ratio of each component and a is 0.5 to 6, b is 0.2 to 6, c is 0.2 to 6, d is 0.

Abstract: The present invention provides a supported catalyst for use in a vapor phase reaction for the high yield conversion of lower aliphatic hydrocarbons such as butane to corresponding monocarboxylic acids such as acetic acid. The catalyst is prepared by the carbon monoxide reduction of a vanadium pentoxide-impregnated, inert porous carrier.

Abstract: In a process for producing acrylic acid which comprises contacting with water an acrylic acid-containing reaction product gas which has been obtained by the catalytic vapor phase oxidation of an olefinic compound of a general formula, CH.sub.2 .dbd.CHX, wherein X represents at least one group selected from the group consisting of CH.sub.

Abstract: A process for preparing carboxylic acids by the oxidative conversion of the corresponding aldehydes comprises oxidizing the aldehydes in the presence of a catalyst comprising the anion [Fe(CN).sub.5 H.sub.2 O].sup.-3. The catalyst may be selected from [Fe(CN).sub.5 H.sub.2 O].sup.-3, compounds that form [Fe(CN).sub.5 H.sub.2 O].sup.-3 under the reaction conditions, and their salts. The catalyst is useful for the oxidation of aldehydes with oxygen or oxygen-containing gases. The present process permits the use of lower reaction times and temperatures, and reduces the formation of undesirable reaction by-products.

Abstract: An oxidizable hydrocarbon is oxidized in a reaction zone at elevated temperature in the presence of a liquid reaction medium by introducing the hydrocarbon and a feed stream containing molecular oxygen to the reaction zone under conditions sufficient to oxidize at least a portion of the hydrocarbon; withdrawing at least a portion of the liquid reaction medium from the reaction zone; passing at least a portion of the withdrawn liquid reaction medium to an oxygen injection zone located external to the reaction zone; contacting the liquid in said oxygen-injection zone with a gas stream containing molecular oxygen under conditions sufficient to form a two-phase gas/liquid mixture; and passing said two-phase gas/liquid mixture to the reaction zone as the feed of molecular oxygen thereto.

Abstract: Acetic acid and acetic anhydride are produced continuously from acetaldehyde which is reacted by oxidizing it with gaseous oxygen in liquid phase in the presence of copper acylate and cobalt acylate as a catalyst and in the presence of an aliphatic carboxylic acid ester as a diluent. More specifically, the reaction is effected at temperatures of 62.degree. to 90.degree. C. over a period of less than 20 minutes with the use of the diluent and acetaldehyde in a quantitative ratio of 60:40 to 40:60; the resulting reaction products are delivered to a distilling zone in which the carboxylic acid ester and water are distilled off overhead and separated into two phases. Next, the organic phase is recycled with a reflux ratio of at least 1:1 to the distilling zone; base product accumulating in the distilling zone is delivered to an evaporating zone in which 2 to 12 parts by weight of an acetic acid/acetic anhydride-mixture as distillate are produced per part by weight of catalyst solution as base product.

Abstract: Methacrylic acid is produced from methacrolein by gaseous phase oxidation in a very high selectivity, when methacrolein, molecular oxygen-containing gas and steam in a molar ratio of methacrolein:molecular oxygen:steam of 1:1-3:0-50 are subjected to reaction at a temperature in the range of 250.degree. to 400.degree. C., at a space velocity of 250 to 3,000 hr.sup.-1 (at 0.degree. C. and 1 atm.) with a novel catalyst having the following composition formula in atomic ratio:Mo.sub.a P.sub.b Zr.sub.c V.sub.d Mn.sub.e X.sub.f O.sub.gwherein X represents at least one member selected from the group consisting of potassium, rubidium, cesium and thallium, and a, b, c, d, e, f or g represents the number of atoms of Mo, P, Zr, V, Mn, X or O, respectively, and when a is 12, b is 0.5 to 5, c is 0.1 to 5, d is 0.05 to 3, e is 0.05 to 1.5, f is 0.1 to 3 and g is 40 to 60; and g is a number sufficient enough to satisfy the valencies of the respective catalyst component elements.

Abstract: C.sub.2 -C.sub.6 monocarboxylic and dicarboxylic acids are scrubbed from gas phase mixtures of such acids and water by gas absorption techniques utilizing a liquid solvent comprising a polyoxyalkylene glycol or a monoalkyl or dialkyl ether thereof. The solvent enriched with the acid is subjected to distillation to recover a substantially anhydrous acid product.

Abstract: The present invention relates to a process for the production of unsaturated aliphatic acids and the catalyst therefor, by the vapor phase oxidation of the corresponding unsaturated aliphatic aldehydes with molecular oxygen, optionally in the presence of steam, in the presence of an oxidation catalyst consisting of the oxides of the elements molybdenum, vanadium, tungsten and lanthanum, and optionally one or more of the oxides of the elements manganese, iron, copper, aluminum, cobalt, nickel, phosphorus, zinc, bismuth, silver, cadmium, niobium, arsenic, chromium, the alkali and the alkaline earth elements.

Abstract: The present invention provides an unsupported catalyst with superior crush strength for use in a vapor phase reaction for the high yield conversion of lower aliphatic hydrocarbons such as n-butane to corresponding monocarboxylic acids used as acetic acid. The catalyst is prepared by the reduction of a vanadium oxide containing chromium catalyst.

Abstract: The present invention provides a highly efficient process for use in the high pressure catalytic vapor phase reaction for the high yield conversion of lower aliphatic hydrocarbons such as n-butane to corresponding monocarboxylic acids such as acetic acid. The oxidation reaction takes place under hydrocarbon rich conditions. The increased efficiency in this process is realized by the judicious use of steam and the catalyst systems set forth in the instant invention.

Abstract: Methacrylic acid is produced by the vapor phase oxidation of methacrolein in the presence of a complex oxide catalyst having the formula:Mo.sub.a V.sub.b P.sub.c Ce.sub.d Cu.sub.e X.sub.f O.sub.gwherein X represents at least one of the elements selected from the group of Mn, Fe, Co, Sn and Te and a, b, c, d, e, f and g represent atomic ratios wherein a=12; b=0.01 to 2; c=0.1 to 3; d=0.01 to 2; e=0.01 to 2; f=0 to 2 and g is determined by the valences of the non-oxygen components of the catalyst and is usually in a range of 38 to 50. The catalyst can be optionally reduced by subjecting the metal oxide mixture to at least one reducing organic material selected from the group consisting of dibasic carboxylic acids, oxycarboxylic acids, and polyols.

Abstract: The present invention relates to a catalyst composition consisting of oxide complexes of vanadium, molybdenum and copper plus an additional metal oxide selected from the group consisting of antimony and germanium or mixtures thereof. These catalysts are especially useful for producing acrylic acid from acrolein and for producing methacrylic acid from methacrolein.

Abstract: Methacrolein or acrolein is oxidized with molecular oxygen in the presence of water vapor, a catalyst containing palladium, phosphorus, antimony(optionally) and oxygen and a phosphoric acid or a compound capable of forming phosphoric acid during the reaction.

Abstract: In an oxidation process for converting methacrolein to methacrylic acid, methacrylic acid is recovered by cooling and condensing the effluent from the oxidation, followed by azeotropic distillation of the condensate with a suitable solvent, such as methyl n-propyl ketone. The condensed effluent contains methacrylic acid and water as the major components along with by-product acetic acid, a minor amount of unreacted methacrolein and impurities. Substantially dry crude methacrylic acid is separated as a bottom product from the azeotropic distillation and an azeotrope of water and the solvent is taken overhead and condensed. After condensation, solvent-rich and water-rich phases form and are separated. The solvent-rich phase is returned to the distillation column as a reflux, while the water-rich phase is sent to a stripping column for recovery of residual solvent. Water is withdrawn from the bottom of the stripping column and recycled or discarded, as desired.

Abstract: Methacrylic acid or acrylic acid are produced by the oxidation of methacrolein or acrolein, respectively, with molecular oxygen in the vapor phase in the presence of a catalytic oxide of molybdenum, phosphorus, arsenic, at least one element selected from the group consisting of Ag, Rh, Ru, and Au, oxygen, and optionally, at least one of Cd, Pt, Tl, Pd, Al, Ge, Cu, Ni, alkaline earth metal, NH.sub.4 and Cl.