Abstract: The invention provides a process for industrially and advantageous production of methacrolein and methacrylic acid which comprises subjecting isobutylene or tert-butanol to gas phase catalytic oxidation with a molecular oxygen-containing gas in the presence of a catalyst having the composition represented by the following formula:Mo.sub.a W.sub.b Bi.sub.c Fe.sub.d Sb.sub.e Cr.sub.f Si.sub.g A.sub.h X.sub.i Y.sub.j Z.sub.k O.sub.

Abstract: A method for preparing a multicomponent catalyst including molybdenum, bismuth, iron and cesium or thallium for producing methacrolein and methacrylic acid by the gas-phase catalytic oxidation of isobutylene or tert-butanol with molecular oxygen, wherein an aqueous nitric acid solution containing 0.01 to 0.36 mole of nitric acid per mole of ammonium molybdate, which is a material for the molybdenum component of the catalyst, and at least one material for the bismuth, iron, cesium and thallium components of the catalyst is added to an aqueous solution containing ammonium molybdate and materials for the remaining catalyst components, if any, to obtain a slurry which is then dried and calcined, provided that the nitric acid excludes nitric acid radicals contained in the materials containing the catalyst components. The amount of nitric acid used is controlled in a particular range, so that a highly active catalyst for gas-phase catalytic oxidation is obtained.

Abstract: A process for preparing a multi-component catalyst for producing methacrylic acid, containing phosphorus, molybdenum and vanadium, comprising mixing oxides of molybdenum and vanadium, water and materials for the other catalyst-constituting elements except potassium, rubidium, cesium and thallium to prepare a mixed solution, heating and reacting the mixed solution at 85.degree. C. or more for 1 to 10 hours, then cooling the mixed solution to 80.degree. C. or less, adding thereto a material for at least one element component selected from the group consisting of potassium, rubidium, cesium and thallium, adding further thereto at least one compound selected from the group consisting of ammonium nitrate, ammonium carbonate, ammonium hydrogencarbonate, ammonium sulfate and ammonium hydrogensulfate with the temperature of the mixed solution kept at 80.degree. C. or less, then removing water therefrom and heat-treating the residual product.

Abstract: A process for preparing a multi-component catalyst for producing methacrylic acid containing phosphorus, molybdenum and vanadium comprising using in preparing the catalyst, at least one number selected from the group consisting of the oxide, carbonates, acetates and hydroxides of each catalyst-constituting element as a source of the element; dissolving or dispersing the selected sources of the catalyst-constituting elements in water; adding at least one member selected from the group consisting of ammonium carbonate, ammonium hydrogen-carbonate, ammonium sulfate and ammonium hydrogen-sulfate to the resulting aqueous solution or dispersion; removing water therefrom and then heat-treating the residual product.

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: In a process for producing a catalyst having a composition represented by the following formula usable to produce methacrylic acid by the gas-phase catalytic oxidation of methacrolein with molecular oxygen,P.sub.a Mo.sub.b Cu.sub.c V.sub.d X.sub.e Y.sub.f Z.sub.g O.sub.hwherein P, Mo, Cu, V and O are phosphorus, molybdenum, copper, vanadium and oxygen, respectively, X is at least one element selected from the group consisting of arsenic, antimony, bismuth, germanium, zirconium, tellurium and silver, Y is at least one element selected from the group consisting of iron, zinc, chromium, magnesium, tantalum, manganese, barium, boron, gallium, cerium and lanthanum, Z is at least one element selected from the group consisting of potassium, rubidium, cesium and thallium, a, b, c, d, e, f, g and h are an atomic ratio of each element, and when b is 12, a is 0.5 to 3, c is 0.01 to 2, d is 0.01 to 3, e is 0.01 to 3, f is 0 to 3, g is 0.

Abstract: A process for producing methacrylic acid which includes subjecting methacrolein to gaseous phase catalytic oxidation using molecular oxygen and a catalyst represented by the general formula:P.sub.a Mo.sub.b V.sub.c Fe.sub.d Ce.sub.e (NH.sub.4).sub.f X.sub.g Y.sub.h Z.sub.i O.sub.jwherein P, Mo, V, Fe, Ce, NH.sub.4 and O represent phosphorus, molybdenum, vanadium, iron, cerium, ammonium group and oxygen, respectively; X represents at least one element selected from the group consisting of copper, zinc, bismuth, chromium, magnesium, silver, tantalum and lanthanum; Y represents at least one element selected from the group consisting of arsenic, antimony, zirconium, barium, manganese, germanium and tellurium; Z represents at least one element selected from the group consisting of potassium, rubidum, cesium and thallium; a, b, c, d, e, g, h, i and j each represents an atomic ratio of each element, and b is 12, a is in a range of 0.5-3, c is in a range of 0.01-3, d is in a range of 0.01-2, e is in a range of 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 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 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: The present invention provides a process for the production of methacrolein and methacrylic acid by the gas phase catalytic oxidation of isobutylene or t-butanol at high temperature using molecular oxygen in the presence of catalyst consisting of molybdenum, tungsten, bismuth, iron, nickel, antimony, and an alkali metal, to which zinc or lead is added, and further phosphorus sulfur, silicon, selenium, germanium or boron, and magnesium, cobalt, manganese or tin are added.

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: A catalyst represented by the general formulaP.sub.a Mo.sub.b V.sub.c Fe.sub.d Cu.sub.e Z.sub.f X.sub.g Y.sub.h O.sub.iwherein X represents at least one or more of the elements selected form the group consisting of potassium, rubidium, cesium and thallium, Y represents at least one or more of the elements selected from the group consisting of tellurium, lanthanum, boron, silver, chromium, magnesium and barium, Z represents any one of the elements of zirconium or antimony, a to i denote atomic ratios of respective elements, and when b=12, a=0.3-4, c=0.01-3, d=0.01-4, e=0.01-3, f=0.01-3, g=0.01-3, h=0.001-5 and i denotes the number of oxygen atoms required for satisfying the valence number of the said ingredients, and a process for the production of methacrylic acid comprising contacting methacrolein in vapor phase in the presence of said catalyst.