The catalyst for ammoxidation of the present invention contains a catalyst particle containing molybdenum, bismuth and iron, and has a ratio of hollow particles of 23% or less. Furthermore, a method for producing the catalyst for ammoxidation includes a step of preparing a catalyst precursor slurry containing molybdenum, bismuth and iron and having a solid concentration of 30% by mass or less, a step of spray-drying the catalyst precursor slurry at a drier inlet temperature of 120 C. to 240 C. to thereby obtain a dried particle and a step of calcining the dried particle at 500 to 750 C.

A method for producing at least one oxidation product selected from the group consisting of acrolein and acrylic acid is provided. This method can alleviate concerns about deterioration of a gas-phase oxidation catalyst and reaction runaway in a restart period after a shutdown, and can allow the reaction to proceed in a stable state. Using a fixed-bed reactor filled with a gas-phase oxidation catalyst, at least one source gas selected from the group consisting of propylene and acrolein is subjected to a gas-phase contact oxidation reaction while a heating medium is caused to contact with or circulate through the fixed-bed reactor and thereby to heat the fixed-bed reactor. The temperature of the heating medium when the load is maximum in the restart period after the shutdown is controlled to be lower than the temperature of the heating medium when the load is maximum in an initial start-up period.

The present invention provides a catalyst including Mo, Bi, and Fe, wherein P/R is 0.10 or less, wherein P is a peak intensity at 2=22.90.2 and R is a peak intensity at 2=26.60.2, in X-ray diffraction analysis.

An object of the present invention is to provide a catalyst ensuring that when a gas-phase catalytic oxidation reaction of a material substance is conducted using a catalyst to produce a target substance, the pressure loss and coking are suppressed and the target substance can be produced in high yield. The present invention is related to a ring-shaped catalyst having a straight body part and a hollow body part, which is used when a gas-phase catalytic oxidation reaction of a material substance is conducted to produce a target substance, wherein a length of the straight body part is shorter than a length of the hollow body part and at least at one end part, a region from an end part of the straight body part to an end part of the hollow body part is concavely curved.

Oxidative dehydrogenation catalysts including mixed oxides of Mo, V, Nb, Te, and optionally a promoter may be dissolved in aqueous solutions of oxalic acid. This permits the removal of catalyst and catalyst residues from reactors for the oxidative dehydrogenation of paraffins and particularly ethane.

The present disclosure relates generally to catalyst materials and processes for making and using them. More particularly, the present disclosure relates to molybdenum, bismuth and iron-containing metal oxide catalyst materials useful, for example, in the partial oxidation or ammoxidation of propylene or isobutylene, processes for making them, and processes for making acrolein, methacrolein, acrylonitrile, and methacrylonitrile using such catalysts.

A method for producing an ammoxidation catalyst, comprising: a step of preparing a precursor slurry that is a precursor of the catalyst; a drying step of obtaining a dry particle from the precursor slurry; and a calcination step of calcining the dry particle, wherein the step of preparing the precursor slurry is a step of mixing a first solution or slurry having a first pH and a second solution or slurry to obtain a solution or slurry having a second pH after completion of mixing, a time during which a pH of a mixture passes through a particular range having an upper limit and a lower limit while the second solution or slurry is mixed is 1-70 seconds, the upper limit and the lower limit being designated as a third pH and a fourth pH respectively, and the third pH and the fourth pH are set between the first pH and the second pH.

The present invention relates to a method for producing unsaturated aldehydes and unsaturated carboxylic acids. According to the present invention, a method for producing unsaturated aldehydes and unsaturated carboxylic acids which can impart activity and control temperature independently in fixed catalyst layer zones in a shell-and-tube reactor, thereby exhibiting improved yield and operation stability, is provided.

The invention is concerned with a method for producing a conjugated diene including a reaction step of subjecting a raw material gas containing a monoolefin having a carbon atom number of 4 or more to an oxidative dehydrogenation reaction with a gas containing molecular oxygen in the presence of a catalyst, to obtain a reaction product gas containing a conjugated diene; and a cooling step of cooling the reaction product gas, wherein in the cooling step, a cooling agent is supplied into a cooling column and brought into contact with the reaction product gas; the cooling agent discharged from the cooling column is then cooled by a heat exchanger; a precipitate dissolved in the cooling agent is precipitated within the heat exchanger and recovered; and the cooling agent from which the precipitate has been recovered is circulated into the cooling column.

A process for producing unsaturated nitrile, using a fluidized bed reactor having an internal space having a catalyst capable of being fluidized therein, a feed opening to feed a starting material gas comprising hydrocarbon to the internal space, and a discharge port to discharge a reaction product gas from the internal space, the process comprising a reaction step of subjecting the hydrocarbon to a vapor phase catalytic ammoxidation reaction in the presence of the catalyst in the internal space to produce the corresponding unsaturated nitrile, wherein when in the internal space, a space where an existing amount of the catalyst per unit volume is 150 kg/m.sup.3 or more is defined as a dense zone and a space where an existing amount of the catalyst per unit volume is less than 150 kg/m.sup.3 is defined as a sparse zone in the reaction step, a gas residence time in the sparse zone is 5 to 50 sec.