Abstract: A process for producing methacrylic acid, which comprisesfilling a plurality of catalysts of different activities into a plurality of reaction zones which have been formed in each of the reaction tubes of a fixed bed multi-tubular reactor by dividing said reaction tube into two or more portions in the direction of tubular axis, so that the activity of catalyst is higher as the reaction zone is closer to the outlet of the reaction tube, andintroducing into the reaction zones containing the catalysts at least one compound selected from methacrolein, isobutyl aldehyde and isobutyric acid to oxidize the at least one compound with molecular oxygen or a molecular oxygen-containing gas.

Abstract: A composite oxide catalyst represented by the general formula: Mo-V-P-X-Y (wherein X represents at least one element selected from the group consisting of Sb, Cu, Co, Bi and As; Y represents at least one element selected from the group consisting of K, Rb, Cs and Tl) and a method for preparing methacrylic acid through gas phase catalytic oxidation of methacrolein with molecular oxygen in the presence of the foregoing catalyst are herein disclosed. The catalyst exhibits excellent catalytic activity, selectivity to methacrylic acid, catalytic stability and lifetime.

Abstract: The processes for oxidation of propylene to acrolein and the oxidation of propylene to acrylic acid in two stages with acrolein as an intermediate are improved by use of essentially inert essentially anhydrous diluent gases to replace steam in the reaction streams. In particular, the use of essentially inert essentially anhydrous diluents which raise the composite heat capacity of the diluent gaas mixture to at least about 6.5 calories/(gram-mole) (.degree.C.) will improve selectivity to desired products and will reduce both the waste water load on the system and by-product formation.

Abstract: A method for the production of acrylic acid by the vapor-phase oxidation of acrolein with a molecular oxygen-containing gas in the presence of a catalyst formed of an oxide or a composite oxide of a metal element composition represented by the following formula I:Mo.sub.a V.sub.b W.sub.c Cu.sub.d X.sub.e Y.sub.f (I)wherein X is at least one element selected from the group consisting of Zr, Ti and Ce, Y is at least one element selected from the group consisting of Mg, Ca, Sr and Ba, and the subscripts a, b, c, d, e, and f are such that b=1 to 14, 0<c.ltoreq.12, 0<d.ltoreq.6, 0<e.ltoreq.10, and f=0 to 3 where a is fixed at 12, 2.0<Cu+X.ltoreq.10.0 and 0.25.ltoreq.Cu/X.ltoreq.6.0.

Abstract: In a process for preparing a catalyst for producing methacrylic acid represented by the formula,P.sub.a Mo.sub.b V.sub.c Cu.sub.d Bi.sub.e X.sub.f Y.sub.g O.sub.hwherein P, Mo, V, Cu, Bi and O are phosphorus, molybdenum, vanadium, copper, bismuth and oxygen, respectively, X is at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, Y is at least one element selected from the group consisting of antimony, zinc, iron, cerium, magnesium, chromium, indium, tellurium, manganese, tin, germanium, arsenic, boron, silicon, selenium, zirconium, silver, tantalum and tungsten, a, b, c, d, e, f, g and h are an atomic ratio of each element, and when b is 12, a is 0.1 to 3, c is 0.01 to 2, d is 0.01 to 2, e is 0.05 to 1, f is 0.01 to 2 and g is 0.

Abstract: Methacrylic acid can be prepared with advantage by gas phase oxidation of methacrolein or isobutyraldehyde over Mo- and P-containing catalysts at from 250.degree. to 400.degree. C. with cooling of the hot reaction gas to below 100.degree. C., absorption of the methacrylic acid in a water-operated absorption column, at below 100.degree. C. and partial recycling into the oxidation reactor after admixture of methacrolein or isobutyraldehyde and oxygen by feeding a quantity of methacrolein or isobutyraldehyde equal to the quantity of methacrolein or isobutyraldehyde consumed in the reaction in liquid form together with a polymerization inhibitor into the reactor gas in the lower two-thirds of the absorber column and upstream of the feed point for the fresh methacrolein or isobutyraldehyde or down-stream of the absorption column splitting off the reactor off-gas a side stream which is washed in a wash column operated with water at <10.degree. C.

Abstract: Vapor phase catalytic oxidation of propylene into acrolein in the first step and then into acrylic acid in the second step has been improved (1) by utilizing as a diluent for the oxidation in the first step the effluent gas from the second step after the acrylic acid produced has been recovered therefrom and after it has been catalytically combusted and (2) by specifying operation conditions set in view of the recycle of the combusted "waste" gas.The improved process, embodying the present invention, has made it possible to produce a high concentration of acrylic acid as both gas and condensation and also to prolong the catalytic activity of a Mo-Bi composite oxide catalyst used for the first oxidation reaction.

Abstract: The present invention provides a process for the preparation of a catalyst used in the production of unsaturated carboxylic acids such as methacrylic acid by the gas phase catalytic oxidation of the corresponding unsaturated aldehydes such as methacrolein. Said catalyst is composed of a multi-component composition containing at least phosphorus, molybdenum and antimony. The present invention has attained an improvement in its catalytic performance such as conversion rate, selectivity, single-pass yield, etc. by using antimony trioxide with average particle size of no more than 0.2 micron as a starting material upon preparing said catalyst.

Abstract: The process for the preparation of the E isomers of the compounds of formula A: ##STR1## in which R.sub.1 is selected from H or C.sub.1 -C.sub.4 alkyl, comprises according to the invention the reaction of propionaldehyde with a phosphorus derivative of formula: ##STR2## in which R.sub.1 designates C.sub.1 -C.sub.4 alkyl and R.sub.2 is selected from C.sub.1 -C.sub.4 alkyl or phenyl, and, optionally, the hydrolysis of the compound of formula A in which R.sub.1 is alkyl in order to form the compounds of formula A in which R.sub.1 is H.Pharmaceutical industry.

Abstract: The present invention relates to a process for producing methacrylic acid by oxidizing methacrolein in vapor phase with molecular oxygen or a gas containing molecular oxygen, characterized in that the oxidation is carried out in the presence of a catalyst having a composition shown by the following formula:Mo.sub.a V.sub.b P.sub.c X.sub.d Y.sub.e O.sub.fwherein Mo, V, P and O respectively represent molybdenum, vanadium, phosphorus and oxygen; X represents at least one element selected from the group consisting of potassium, rubidium, cesium, and thallium; Y represents at least one element selected from the group consisting of copper, silver, tin, thorium, germanium, nickel, iron, cobalt, titanium, rhenium, chromium, cerium, antimony and magnesium; and a, b, c, d, e and f denote the atomic ratio of respective elements where, a is 10, b is a number of 6 or less than 6 excluding 0, preferably 0.5 to 3, c is a number of 0.5 to 6, preferably 0.5 to 3, d is a number of 0.5 or less than 0.

Abstract: The present invention provides a process for the preparation of a catalyst used in the production of unsaturated carboxylic acids such as methacrylic acid by the gas phase catalytic oxidation of the corresponding unsaturated aldehydes such as methacrolein. Said catalyst is composed of a multi-component composition containing at least phosphorus, molybdenum and antimony. The present invention has attained an improved in its catalytic performance such as conversion rate, selectivity, single-pass yield etc. by using antimony trioxide with average particle size of no more than 0.2 micron as a starting material upon preparing said catalyst.

Abstract: Disclosed herein is a process for bringing methacrylic acid, which has been obtained by the catalytic oxidation of compound having 4 carbon atoms, into contact with a basic anion-exchange resin so as to remove byproduced dibasic acids and the like from the methacrylic acid and to purify the same.

Abstract: A method for regenerating a phosphorus-, molybdenum- and alkali metal-containing oxidation catalyst spent in the production of an unsaturated carboxylic acid by vapor-phase oxidation of an unsaturated aldehyde, which comprises treating the deactivated catalyst with aqueous ammonia and an aqueous solution containing at least one of a nitrogen-containing heterocyclic compound, an amine, and ammonium carbonate, followed by drying and calcining the treated catalyst.

Abstract: Disclosed is a process for producing methacrylic acid from methacrolein in high yields and at high selectivity which comprises vapor phase catalytic oxidation of methacrolein with molecular oxygen, characterized by using a catalyst represented by the formula: P.sub.a Mo.sub.b V.sub.c Cu.sub.d Zn.sub.e A.sub.f B.sub.g C.sub.h D.sub.i O.sub.

Abstract: Method for regenerating catalysts containing molybdenum, phosphorus, and vanadium in oxidic association and useful for the oxydehydrogenation of isobutyric acid or its lower esters to form methacrylic acid or its lower esters, by oxidizing the spent catalyst with an oxygen containing gas at temperatures from 200.degree. C. to 400.degree. C., suitably intermittently and in alternation with oxydehydrogenation.

Abstract: A catalyst having a heteropoly-acid structure and the general formula:Mo.sub.a V.sub.b P.sub.c Cu.sub.d X.sub.e O.sub.fwherein Mo, V, P, Cu and O represent respectively molybdenum, vanadium, phosphorus, copper and oxygen, X represents one or more elements selected from the group consisting of tin, thorium, germanium, nickel, iron, cobalt, magnesium, zinc, titanium, lead, rhenium, zirconium, and chromium, and a, b, c, d, e and f represent the atomic ratio of the elements where,a is 10b is a number of 3 or less than 3 excluding 0,c is a number of 0.5 to 3,d is a number of 3 or less than 3 excluding 0,e is a number of 3 or less than 3 excluding 0,f is a number determined depending on the valency and atomic ratio of other elements.There is also provided a process for producing methacrylic acid by oxidizing methacrolein with molecular oxygen or molecular oxygen-containing gas in the presence of the catalyst defined above.

Abstract: The molybdovanadophosphoric acid H.sub.8 PMo.sub.10 VO.sub.39, its PMo.sub.10 VO.sub.35 anhydride, methods for their preparation, and methods for making methacrylic acid and its esters by oxidation/dehydrogenation wherein the above acid and/or its anhydride is employed as a catalyst.

Abstract: A method for regenerating a spent oxidation catalyst useful in the production of unsaturated carboxylic acids by vapor-phase oxidation of unsaturated aldehydes, the catalyst containing, at least, phosphorus, molybdenum, and an alkali metal(s), which method comprises dissolving and/or suspending the spent catalyst in a liquid composition, wherein the contents of ammonium ion and nitrate ion are controlled to be from 7 to 15 moles and from 0.1 to 4.0 moles, respectively, per 12 gram atoms of molybdenum, and immediately thereafter mixing the spent catalyst and the liquid composition.

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: A process for producing methacrylic acid by vapor phase oxidation of methacrolein with molecular oxygen or molecular oxygen-containing gas in the presence of isobutylene and/or tertiary butanol and in the presence of a catalyst having a heteropolyacid structure represented by the following general formula:Mo.sub.a V.sub.b P.sub.c X.sub.d O.sub.ewherein Mo, V, P, and O represent molybdenum, vanadium, phosphorus, and oxygen respectively, X represents the coexistence of copper and aresenic and the a, b, c, d and e represent the atomic ratio of the elements where:a is 10,b is a number of 6 or less excluding 0,c is a number of 0.5 to 6,d is a number of 3 or less excluding 0, ande is a number determined depending on the valance and atomic ratio of the other elements.

Abstract: A 1,2-unsaturated carboxylic acid or its ester such as acrylic or methacrylic acid or its alkyl ester is purified to remove aldehyde impurities contained therein by treating the acid or its ester with a mercapto containing compound in the presence of an acid catalyst.

Abstract: A catalyst for the vapor-phase oxidation of an unsaturated hydrocarbon, alcohol, saturated aliphatic aldehyde or unsaturated aliphatic aldehyde having 4 carbon atoms, said catalyst comprising a molybdovanadophosphoric acid having X-ray diffraction lines (Cu-K.sub..alpha. radiation) at 2.theta.=about 26.2.degree., about 10.5.degree., about 21.3.degree. and about 30.3.degree. and a crystal structure approximating that of its salt, and said catalyst having the composition represented by the general formulaP.sub.a Mo.sub.b V.sub.c X.sub.d Y.sub.e O.sub.

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: Oxidation catalysts of the general formulaW.sub.6 Mo.sub.a V.sub.b P.sub.c Cu.sub.d As.sub.e Sb.sub.f X.sub.g Y.sub.h O.sub.xwhere X is K, Rb and/or Cs, Y is Nb, Fe, Mn, Sn, Li, Na, Sr, Rh, Ce, Ti and/or Cr, a is from 2.0 to 6, b is from 0 to 3, c is from 0.1 to 3, d is from 0.01 to 1, e is from 0 to 1, f is from 0 to 2, g is from 0.01 to 3, h is from 0 to 1 and x is the number of oxygen atoms formally required to saturate the valencies of the catalyst components, give high conversions and particularly high selectivity in the oxidation of methacrolein in the gas phase to methacrylic acid.

Abstract: A heteropoly-acid of the formula:H.sub.3+x (PMo.sub.12-x V.sub.x O.sub.40).nH.sub.2 Owherein x and n are numbers satisfying respectively the equations: 0.ltoreq.x.ltoreq.3 and n.ltoreq.6, and comprising phosphorus as the central atom and molybdenum or molybdenum and vanadium as the coordinating atoms, or its reduction-form product, which is in a cubic crystal structure having diffraction lines at lattice spacings (d) of at least 8.4, 6.8, 5.9, 4.8, 4.2 and 3.4 in the X-ray powder diffraction. The heteropoly-acid is useful as a catalyst, especially as a catalyst in the production of methacrylic acid by the gas-phase catalytic oxidation of methacrolein.

Abstract: In a process for preparing methacrylic acid by the vapor-phase catalytic oxidation of methacrolein or a methacrolein-containing mixture with molecular oxygen in the presence of an oxidation catalyst; the improvement wherein said process comprisesa first-stage oxidation step of oxidizing methacrolein or a methacrolein-containing mixture as a starting material,a first-stage separating step of separating the resulting methacrylic acid from the reaction product obtained in the first-stage oxidation step,a second-stage oxidation step of oxidizing the mixture containing the unreacted methacrolein and obtained in the first-stage separating step, anda second-stage separating step of separating the resulting methacrylic acid from the reaction product obtained in the second-stage oxidation step, andwith or without at least one additional oxidation step and separating step subsequent to the second-stage separating step,and wherein the conversion of methacrolein in the first-stage oxidation step is adjusted to 30-85 mole

Abstract: Compositions of the empirical formula:Mo.sub.12 P.sub.0.1-3 M.sub.0.1-3 Cu.sub.0.1-2 V.sub.0.1-2 Sb.sub.0.01-2 X.sub.0.01-2 Y.sub.a O.sub.x (I)whereM is at least one of K, Rb and Cs;X is at least one of Ba, La, Ga, Al, Ag, Cd, Ti, Tl, Hg, Pb and Zn;Y is at least one of Fe, Co, Ni, Sr, Mn, In, Ta, Ge, S and Be when a>0;a is a number of 0 to about 2; andx is a number that satisfies the valance requirements of the other elements present,are excellent catalysts for the oxidation of oxygenated C.sub.4 hydrocarbons, such as methacrolein, to methacrylic acid.

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: A catalyst composition useful for the oxidation of unsaturated aldehydes, particularly the oxidation of methacrolein to produce methacrylic acid, comprises the combination of oxides of molybdenum, copper, phosphorus, antimony, and cesium and/or calcium and optionally may include one or more of the elements Ni, Zn, Ru, Rh, Pd, Pt, As, K, Rb, Sr, Ba, Cr, V, Nb, W, Mn, Re, and rare earth metals including La.

Abstract: A process for isolating methacrylic acid by solvent extraction from an aqueous methacrylic acid solution obtained from a gas phase catalytic oxidation reaction, characterized in that the aqueous methacrylic acid solution is previously first contacted with an extraction solvent, polymers precipitated out from the aqueous methacrylic acid solution are removed and the remainder is fed into an extraction column.

Abstract: The present invention relates to a method for the preparation of phosphomolybdic acid based catalysts utilized in the oxidation of aldehydes to unsaturated carboxylic acids by forming a solution of hydrated phosphomolybdic acid in a substantially anhydrous alkanol, adding a base to the solution, evaporating the solution to yield a catalyst powder and thereafter drying and calcining the powder to form the active catalyst. A second method for preparation is also provided and includes the steps of forming a solution of hydrated phosphomolybdic acid in a substantially anhydrous alkanol, evaporating the solution to form a concentrate, impregnating a catalyst support material with the concentrate, contacting the impregnated support with ammonia gas in an amount sufficient to form an insoluble precipitate of ammonium alkyl phosphomolybdic acid within the pore structure of said support material and thereafter drying and calcining said impregnated support material so as to form a coated catalyst.

Abstract: A process is disclosed for preparing coated catalysts, inter alia, for gas phase oxidations in organic chemistry, comprised of an inert support and a coating of catalyst material enclosing this support, wherein a suspension of the starting material for the coating is sprayed onto an agitated bed of the support, while the suspending medium is being partially removed by a gas stream, and the raw material is then dried and heat-treated. For this purpose, the support bed is mechanically agitated and loosened by a gas stream blown in from below. The catalyst precursor containing a binder and, if appropriate, a pore-former is sprayed in an increasing amount from above onto the bed, the ratio between suspending medium sprayed on and drawn off remaining about constant. The thermal expansion coefficient of the precursor as a dry powder must not deviate by more than 15% from that of the support.

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: A catalyst composition useful for the oxidation of unsaturated aldehydes, particularly the oxidation of methacrolein to produce methacrylic acid, comprises the combination of oxides of molybdenum, copper, phosphorus, antimony, cesium and rhenium in predetermined relative atomic ratios.

Abstract: Oxidation catalysts which in addition to oxygen ions, with or without NH.sub.4.sup.+ ions, contain molybdenum, tungsten, phosphorus and antimony as basic components, in the atomic ratio Mo:W:P:Sb=12:0.1-3:0.1-4:0.1-3, and which are prepared in a conventional manner by combining molybdenum, phosphorus, antimony and tungsten compounds in aqueous solutions or suspensions, removing the water and calcining the residues, the combination being carried out at chloride ion concentrations of less than 0.3 mole per mole of molybdenum and in the presence of ions of monocarboxylic acids of 1 or 2 carbon atoms, dicarboxylic acids or hydroxycarboxylic acids, are particularly suitable for the gas phase oxidation of methacrolein to methacrylic acid.

Abstract: The present invention relates to a method for maintaining the activity of PMA based catalysts during reactor shutdown by flushing the reactor with an oxide of nitrogen gas at a temperature of from about 150.degree. C. to about 370.degree. C. The method can be employed in the reactor by terminating the feed of hydrocarbon to the reactor and then flushing the reactor. The method can be employed to treat PMA based catalysts having the general formula Mo.sub.x P.sub.y A.sub.a B.sub.b C.sub.c D.sub.d E.sub.e O.sub.z wherein A is selected from the group consisting of ammonium, cesium, potassium, rubidium and thallium; B is selected from the group consisting of copper and vanadium; C is selected from the group consisting of antimony, arsenic, bismuth and tellurium; D is palladium; E is aluminum, barium, calcium, cerium, chromium, cobalt, iron, magnesium, manganese, nickel tantalum, titanium, tungsten, zinc, zirconium, chlorine and/or bromine; x can be 3 to 15, y can be 1 to 1.5; a can be 0.1 to 3; b can be 0.

Abstract: The present invention relates to a method for the reactivation of phosphomolybdic acid based catalysts used for the conversion of saturated and unsaturated aldehydes to acids. The method comprises the step of feeding an oxide of nitrogen over the deactivated catalyst at a temperature of from about 100.degree. C. to about 400.degree. C. The method can be employed in the reactor by terminating the feed of reactant to the reactor, adjusting the reactor temperature as may be necessary to one suitable for reactivation and sweeping the reactor with a gas. Alternatively, the catalyst can be removed from the reactor for reactivation. Reactivated phosphomolybdic acid based catalysts are also disclosed. These catalysts have a ratio of molybdenum to phosphorus of 3:1 to 15:1 and are prepared by the process of feeding an oxide of nitrogen over the catalyst at a temperature of from about 100.degree. C. to about 400.degree. C.

Abstract: A catalyst having heteropoly-acid structure and the general formula:Mo.sub.a V.sub.b P.sub.c Cu.sub.d As.sub.e X.sub.f O.sub.gwherein,X represents one or more elements selected from the group consisting of tin, lead, cerium, cobalt, iron, zirconium, thorium, tungsten, germanium, nickel, rhenium, bismuth, antimony, chromium, boron, magnesium, silver, aluminum, zinc and titanium and a, b, c, d, e, f and g represent the atomic ratio of the elements where,a is 10,b is a number of 3 or less than 3 excluding 0,c is a number of 0.5 to 6,d is a number of 3 or less than 3 excluding 0,e is a number of 3 or less than 3 excluding 0,f is a number of 0 to 3,g is a number determined depending on the valency and atomic ratio of other elements.There is also provided a process for producing methacrylic acid by oxidizing methacrolein with molecular oxygen or molecular oxygen-containing gas in the vapor phase in the presence of the catalyst defined above.

Abstract: A catalyst composition useful for the oxidation of unsaturated aldehydes, particularly the oxidation of methacrolein to produce methacrylic acid, comprises the combination of oxides of molybdenum, copper, phosphorus, antimony, and cesium in predetermined relative atomic ratios.

Abstract: A method for preparing attrition resistant, high percentage active component catalysts comprises using two types of silica, one of which is fumed silica, in a two stage catalyst preparation.

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 novel catalyst comprising the elements Mo, V and Nb, and an oxidation process, is provided for oxidizing alpha-beta unsaturated aliphatic aldehydes in the vapor phase with molecular oxygen to produce the corresponding alpha-beta unsaturated carboxylic acid.

Abstract: A process is disclosed for the preparation of acrylic acid or methacrylic acid by reacting in vapor phase acrolein or methacrolein with molecular oxygen or with an oxygen-containing gas, at a temperature between 200.degree. and 350.degree. C., in the presence of a solid catalyst and with a contact time between 0.5 and 5 seconds, characterized in that said catalyst consists of molybdenum, vanadium, tungsten, one or more of the elements selected from the class consisting of silver, titanium, chromium, cerium, lanthanum and tantalum, and oyxgen chemically combined with the above-indicated elements, and wherein the atomic ratios between the various elements present in the catalyst are represented by the empirical formula:Mo.sub.12 V.sub.a W.sub.b X.sub.c O.sub.dwhereinX represents one or more of the elements Ag, Ti, Cr, Ce, La, Ta;a varies between 0.5 and 10;b varies between 0.5 and 8;c varies between 0.1 and 3 for X=Ag and from 0.

Abstract: A novel catalyst comprising the elements Mo, V and Ti, and an oxidation process, is provided for oxidizing alpha beta unsaturated aliphatic aldehydes in the vapor phase with molecular oxygen to produce the corresponding alpha-beta unsaturated carboxylic acid.

Abstract: A novel catalyst comprising the elements Mo, V and Ta, and an oxidation process, is provided for oxidizing alpha-beta unsaturated aliphatic aldehydes in the vapor phase with molecular oxygen to produce the corresponding alpha-beta unsaturated carboxylic acid.

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: A catalyst composition useful for the oxidation of unsaturated aldehydes, particularly the oxidation of methacrolein to produce methacrylic acid, comprises the combination of oxides of molybdenum, copper, phosphorus, antimony, and cesium in predetermined relative atomic ratios.

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: An improved catalyst suitable for use in the production of an unsaturated carboxylic acid by the catalytic vapor phase oxidation of an unsaturated aldehyde is provided. In this catalyst, a heat-resistant inorganic substance, such as alumina, silica-alumina and silicon carbide, having a particle diameter of 3 through 10 mm, an apparent porosity of 35 through 60%, a water absorption of 20 through 50%, an average pore diameter of not less than 40 microns, a specific surface area of not more than 2 m.sup.2 /g and a bulk specific gravity of 1.5 through 2.0 is used for supporting a composition containing molybdenum, phosphorus, vanadium and the alkali metals. The use of the above-mentioned carrier results in the advantages that the unsaturated carboxylic acid, such as methacrylic acid, can be selectively produced from the unsaturated aldehyde at a high yield and that the mechanical strength of the catalyst is remarkably improved.

Abstract: A process for the catalytic oxidation of olefins to unsaturated aldehydes and acids and the ammoxidation of olefins to unsaturated nitriles in which the catalyst comprises a promoted, reduced, antimony oxidemolybdenum oxide-containing catalyst.