An object is to provide a catalyst which has high heat resistance and which can allow for production of methacrylic acid at a high yield, and to provide methods for producing methacrylic acid and methacrylic acid ester with the catalyst, and the object is achieved by use of a catalyst having a specified .sup.31P-NMR spectrum.

Homogeneous water oxidation catalysts (WOCs) for the oxidation of water to produce hydrogen ions and oxygen, and methods of making and using thereof are described herein. In a preferred embodiment, the WOC is a polyoxometalate WOC which is hydrolytically stable, oxidatively stable, and thermally stable. The WOC oxidized waters in the presence of an oxidant. The oxidant can be generated photochemically, using light, such as sunlight, or electrochemically using a positively biased electrode. The hydrogen ions are subsequently reduced to form hydrogen gas, for example, using a hydrogen evolution catalyst (HEC). The hydrogen gas can be used as a fuel in combustion reactions and/or in hydrogen fuel cells. The catalysts described herein exhibit higher turn over numbers, faster turn over frequencies, and/or higher oxygen yields than prior art catalysts.

The present invention relates to a method for producing an unsaturated carboxylic acid using a catalyst having both a high catalytic performance and a high mechanical strength, and in the method, a supported catalyst obtained by feeding a liquid binder component and a catalytic active component containing molybdenum and vanadium and/or a precursor thereof into a rolling granulator and conducting granulation at a relative centrifugal acceleration of 0.5 G or more and 30 G or less is used.

The present invention relates to a method for producing an unsaturated carboxylic acid using a catalyst having both a high catalytic performance and a high mechanical strength, and in the method, a supported catalyst obtained by feeding a liquid binder component and a catalytic active component containing molybdenum and vanadium and/or a precursor thereof into a rolling granulator and conducting granulation at a relative centrifugal acceleration of 0.5 G or more and 30 G or less is used.

The present invention relates to a process for preparing acrylic acid from acetic acid and formaldehyde, which comprises (a) provision of a stream S1 comprising acetic acid and formaldehyde, where the molar ratio of acetic acid to formaldehyde in the stream S1 is in the range from 0.5:1 to 2:1; (b) contacting of the stream S1 with an aldol condensation catalyst comprising vanadium, phosphorus and oxygen to give a stream S2 comprising acrylic acid, where, in (b), the space velocity WHSV is in the range from 0.35 to 7.0 kg/kg/h.

The present invention relates to a process for preparing acrylic acid from acetic acid and formaldehyde, which comprises (a) provision of a stream S1 comprising acetic acid and formaldehyde, where the molar ratio of acetic acid to formaldehyde in the stream S1 is in the range from 0.5:1 to 2:1; (b) contacting of the stream S1 with an aldol condensation catalyst comprising vanadium, phosphorus and oxygen to give a stream S2 comprising acrylic acid, where, in (b), the space velocity WHSV is in the range from 0.35 to 7.0 kg/kg/h.

A promoted VPO catalyst for the oxidation of n-butane to maleic anhydride wherein the catalyst comprises the mixed oxides of vanadium and phosphorus, niobium and at least one of antimony and bismuth, wherein the catalyst may be produced in a process comprising impregnating a VPO catalyst with a metal source compound of niobium and a metal source compound of at least one of antimony and bismuth, to form a metal impregnated VPO catalyst, and then drying the metal impregnated VPO catalyst to form the promoted VPO catalyst.

A promoted VPO catalyst for the oxidation of n-butane to maleic anhydride wherein the catalyst comprises the mixed oxides of vanadium and phosphorus, niobium and at least one of antimony and bismuth, wherein the catalyst may be produced in a process comprising impregnating a VPO catalyst with a metal source compound of niobium and a metal source compound of at least one of antimony and bismuth, to form a metal impregnated VPO catalyst, and then drying the metal impregnated VPO catalyst to form the promoted VPO catalyst.

An oxidic composition comprising vanadium, tungsten, phosphorus, oxygen and optionally tin, where the molar ratio of phosphorus to the sum total of vanadium, tungsten and any tin in the oxidic composition is in the range from 1.4:1 to 2.4:1.

An oxidic composition comprising vanadium, tungsten, phosphorus, oxygen and optionally tin, where the molar ratio of phosphorus to the sum total of vanadium, tungsten and any tin in the oxidic composition is in the range from 1.4:1 to 2.4:1.