The present invention relates to a method of preparing butadiene. More particularly, the present invention relates to a method of preparing butadiene by feeding butene and oxygen into a reactor containing a composite metal oxide catalyst and performing oxidative dehydrogenation, wherein a mole ratio of the oxygen to the butene is 1.8 to 2.2. In accordance with the present invention, a method of preparing butadiene to secure long-term operation stability by maintaining the intensity of a catalyst despite oxidative dehydrogenation and not to decrease selectivity due to less side reaction is provided.

Provided is a method for preparing a diol. In the method, a saccharide and hydrogen as raw materials are contacted with a catalyst in water to prepare the diol. The employed catalyst is a composite catalyst comprised of a main catalyst and a cocatalyst, wherein the main catalyst is a water-insoluble acid-resistant alloy; and the cocatalyst is a soluble tungstate and/or soluble tungsten compound. The method uses an acid-resistant, inexpensive and stable alloy needless of a support as a main catalyst, and can guarantee a high yield of the diol in the case where the production cost is relatively low.

Provided is a method for preparing a diol. In the method, a saccharide and hydrogen as raw materials are contacted with a catalyst in water to prepare the diol. The employed catalyst is a composite catalyst comprised of a main catalyst and a cocatalyst, wherein the main catalyst is a water-insoluble acid-resistant alloy; and the cocatalyst is a soluble tungstate and/or soluble tungsten compound. The method uses an acid-resistant, inexpensive and stable alloy needless of a support as a main catalyst, and can guarantee a high yield of the diol in the case where the production cost is relatively low.

An exhaust gas-purifying catalyst includes a support and a catalytic metal as one or more precious metals supported by the support. The support includes a composite oxide having a composition represented by a general formula AB.sub.C.sub.O.sub.3, wherein A represents one or more elements selected from the group consisting of lanthanum, neodymium, and yttrium, B represents iron or a combination of iron and aluminum, C represents one or more elements selected from the group consisting of iridium, ruthenium, tantalum, niobium, molybdenum, and tungsten, and each represents a numerical value within a range of more than 0 and less than 1, and and satisfy relational formulae of > and +1.

An exhaust gas-purifying catalyst includes a support and a catalytic metal as one or more precious metals supported by the support. The support includes a composite oxide having a composition represented by a general formula AB.sub.C.sub.O.sub.3, wherein A represents one or more elements selected from the group consisting of lanthanum, neodymium, and yttrium, B represents iron or a combination of iron and aluminum, C represents one or more elements selected from the group consisting of iridium, ruthenium, tantalum, niobium, molybdenum, and tungsten, and each represents a numerical value within a range of more than 0 and less than 1, and and satisfy relational formulae of > and +1.

The subject matter of the present invention is a process for direct synthesis of (meth)acrolein from a reactive mixture comprising at least one compound chosen from ethers, acetals or hemiacetals derived from linear alcohols comprising from 1 to 3 carbon atoms. Examples of compounds are dimethyl ether, diethyl ether, methyl ethyl ether, dimethoxymethane, diethoxymethane, dipropoxymethane, 1,1-dimethoxyethane or 1,1-diethoxyethane. The process of the invention comprises two successive phases: oxidation then aldol condensation, which can be carried out in the presence of a solid oxidation catalyst chosen from molybdenum-based catalysts and optionally of an aldol condensation catalyst. These two phases are carried out in a reaction system comprising a single reactor or optionally two reactors in cascade.

The subject matter of the present invention is a process for direct synthesis of (meth)acrolein from a reactive mixture comprising at least one compound chosen from ethers, acetals or hemiacetals derived from linear alcohols comprising from 1 to 3 carbon atoms. Examples of compounds are dimethyl ether, diethyl ether, methyl ethyl ether, dimethoxymethane, diethoxymethane, dipropoxymethane, 1,1-dimethoxyethane or 1,1-diethoxyethane. The process of the invention comprises two successive phases: oxidation then aldol condensation, which can be carried out in the presence of a solid oxidation catalyst chosen from molybdenum-based catalysts and optionally of an aldol condensation catalyst. These two phases are carried out in a reaction system comprising a single reactor or optionally two reactors in cascade.

A hollow cylindrical shaped catalyst body for gas phase oxidation of an alkene to an ,-unsaturated aldehyde and/or an ,-unsaturated carboxylic acid comprises a compacted multimetal oxide having an external diameter ED, an internal diameter ID and a height H, wherein ED is in the range from 3.5 to 4.5 mm; the ratio q=ID/ED is in the range from 0.4 to 0.55; and the ratio p=H/ED is in the range from 0.5 to 1. The shaped catalyst body is mechanically stable and catalyzes the partial oxidation of an alkene to the products of value with high selectivity. It provides a sufficiently high catalyst mass density of the catalyst bed and good long-term stability with acceptable pressure drop.

A hollow cylindrical shaped catalyst body for gas phase oxidation of an alkene to an ,-unsaturated aldehyde and/or an ,-unsaturated carboxylic acid comprises a compacted multimetal oxide having an external diameter ED, an internal diameter ID and a height H, wherein ED is in the range from 3.5 to 4.5 mm; the ratio q=ID/ED is in the range from 0.4 to 0.55; and the ratio p=H/ED is in the range from 0.5 to 1. The shaped catalyst body is mechanically stable and catalyzes the partial oxidation of an alkene to the products of value with high selectivity. It provides a sufficiently high catalyst mass density of the catalyst bed and good long-term stability with acceptable pressure drop.

A catalyst structure for exhaust gas cleaning obtained by superimposing flat plate-like catalyst elements composed of a flat part, which is a main structural part, and a linear spacer part composed of raised strips and recessed strips so that a gas flow channel is ensured along the lengthwise direction of the spacer part, wherein the flat part has at least one baffle part composed of a leg plate erectly provided on the flat part with a height that is less than that of the spacer part with reference to the flat part, and a top plate disposed substantially parallel to the flat part from the upper end of the leg plate. Turbulence can be imparted by the baffle part to gas that flows to the gas flow channel.