Mitsubishi Petrochemical Company Limited

Koju Kadowaki

Kohei Sarumaru

Takeshi Shibano

Yoshiaki Tanaka

Kenji Takagi

Propylene in admixture with molecular oxygen and steam is subjected to a two-step, vapor-phase, catalytic oxidation to convert into acrolein and then into acrylic acid. At least the first-step reaction is conducted in tubes of an apparatus of a shell-and-tube heat-exchanger type structure, and the reaction product of the first-step reaction is quenched before it is subjected to the second-step reaction. Reaction conditions in both the steps are specified.

Process for producing acrylic acid

Acrolein and acrylic acid are produced by vapor-phase catalytic oxidation of propylene in a multi-tubular, fixed-bed reaction vessel with the use of a composite oxide catalyst represented by the formula Mo.sub.a Bi.sub.b Fe.sub.c A.sub.d B.sub.e C.sub.f D.sub.g Si.sub.h O.sub.x, wherein A, B, C, and D represent components selectable from respective groups of elements, and the subscripts a through h and x are specific numbers of atoms of respective elements and groups of elements. This catalyst is adapted and packed in each reaction tube in a manner such that its activity is controlled to increase from the inlet toward the outlet of the tube.

Process for producing acrolein and acrylic acid

In the production of acrylic acid by a two-stage, vapor-phase catalytic oxidation of propylene, a composite oxide catalyst expressed by the formula Mo.sub.a Bi.sub.b Ni.sub.c Co.sub.d Fe.sub.e Na.sub.f Mn.sub.g B.sub.h K.sub.i Si.sub.j O.sub.x is used in the first-stage reaction, which is carried out under specific reaction and operational conditions, and the second-stage reaction is carried under specific reaction and operational conditions while oxygen is supplied by a specific mode.

Production of acrylic acid

In the production of a composite oxide catalyst containing at least Mo tegether with V and (or) Nb, the catalyst precursor is subjected to a thermal decomposition step in which: (1) the precursor is heated in a heat-exchanger type apparatus in which a first space accommodating the precursor and a second space through which a heating fluid flows are partitioned and separated from each other, the heating of the precursor being accomplished through the partitioning; (2) the thermal decomposition is carried out as an atmosphere gas of an oxygen concentration of 0.05 to 5 percent is caused to flow through the first space; and (3) the maximum temperature reached in the thermal decomposition is 300.degree. to 550.degree. C.

Process for producing composite oxide catalysts

An .alpha.,.beta.-unsaturated aliphatic carboxylic acid can be prepared in a high yield by catalytic vapor phase oxidation of the corresponding .alpha.,.beta.-unsaturated aldehyde in the presence of a catalyst represented by the following formula:

Catalyst for production of .alpha.,.beta.-unsaturated carboxylic acids

A process for the production of unsaturated acids by catalytic oxidation of the corresponding unsaturated aldehydes in the presence of molybdenum-vanadium-iron based catalysts at a temperature of from 200.degree. C to 400.degree. C.

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Ami, Japan

Koju Kadowaki