Abstract: A catalyst containing, as an essential component, molybdenum; bismuth; and cobalt, in which a sum (S) of ratios of peak intensities expressed by the following formula in an X-ray diffraction pattern obtained by using CuK? rays as an X-ray source is 42 or more and 113 or less. S={(peak intensity at 2?=14.1°±0.1°+(peak intensity at 2?=25.4°±0.1°)+(peak intensity at 2?=28.5°±0.1°)}/(peak intensity at 2?=26.5°±0.

Abstract: A catalyst containing, as an essential component, molybdenum; bismuth; and cobalt, in which, with respect to a peak intensity at 2?=25.3°±0.2° in an X-ray diffraction pattern obtained by using CuK? rays as an X-ray source, a changing rate (Q1) per 1000 hours of reaction time represented by the following formulae (1) to (4) is 16 or less. Q1={(U1/F1?1)×100}/T×1000??(1) F1=(peak intensity of catalyst before oxidation reaction at 2?=25.3°±)0.2°/(peak intensity of catalyst before oxidation reaction at 2?=26.5°±0.2°)×100??(2) U1=(peak intensity of catalyst after oxidation reaction at 2?=25.3°±0.2°)/(peak intensity of catalyst after oxidation reaction at 2?=26.5°±0.

Abstract: Provided is a method for producing an unsaturated aldehyde including subjecting an alkene to partial oxidation using a fixed bed multi-tube reactor to produce the corresponding unsaturated aldehyde, in which n catalyst layers (n is 2 or more) in a gas flow direction in a reaction tube are provided, when a filling length of the catalyst layers from a first catalyst layer to an (n-1)th catalyst layer from a gas inlet side of the reaction tube is L, and a filling length of an nth catalyst layer from the gas inlet side of the reaction tube is Ln, a relationship between L and Ln satisfies the following equation (1): 1 < L ? / ? Ln ? 3 , ( 1 ) and a composition of a catalytically active component contained in the catalyst layers from the first catalyst layer to the (n-1)th layer from the gas inlet side of the reaction tube is different from a composition of a catalytically active component contained in the nth catalyst layer from the gas inlet side of the reaction tube.

Abstract: Provided is a method for producing at least one of an unsaturated aldehyde and an unsaturated carboxylic acid from an alkene by an oxidation reaction, in which a n-layered catalyst layer (n?2) is provided in a gas flow direction in a reaction tube, two or more kinds of catalysts having different activities are used; and the catalysts are packed in such a manner that dT?20° C. is satisfied, when a difference between a temperature PTn of an exothermic peak in a n-th layer as counted from a gas inlet and a minimum value mTn?1 of a temperature of a catalyst layer which appears between an exothermic peak in a (n-1)th layer and an exothermic peak in a n-th layer from the gas inlet is represented as dT (=PTn?mTn?1), and the change rate of dT is 2.5 or less at a reaction bath temperature within a range of ±6° C. of a reaction bath temperature at which the highest yield is obtained.

Abstract: Provided is a method for producing at least one of an unsaturated aldehyde and an unsaturated carboxylic acid from an alkene by an oxidation reaction, in which a n-layered catalyst layer (n?2) is provided in a gas flow direction in a reaction tube, two or more kinds of catalysts having different activities are used; and the catalysts are packed in such a manner that dT?20° C. is satisfied, when a difference between a temperature PTn of an exothermic peak in a n-th layer as counted from a gas inlet and a minimum value mTn-1 of a temperature of a catalyst layer which appears between an exothermic peak in a (n?1)th layer and an exothermic peak in a n-th layer from the gas inlet is represented as dT (=PTn?mTn-1), and the change rate of dT is 2.5 or less at a reaction bath temperature within a range of ±6° C. of a reaction bath temperature at which the highest yield is obtained.

Abstract: Provided is a method for producing an unsaturated aldehyde and/or an unsaturated carboxylic acid, which enables one to achieve an operation stably over a long period of time while improving an effective yield, even in a high-load reaction, and in the method for producing an unsaturated aldehyde and/or an unsaturated carboxylic acid, multilayer filling of stacking two or more catalyst layers each containing a complex metal oxide catalyst in the axial direction of the tube under specified conditions is performed, and the catalyst layer on the most gas outlet side in the tube axis contains a catalyst containing a compound represented by a specified formulation formula.