Catalyst used in preparation of (methyl) acrylic aldehyde and (methyl) acrylic acid

Abstract

The invention relates to a catalyst used in preparation of (methyl) acrylic aldehyde and (methyl) acrylic acid. The catalyst is a composite oxide catalyst containing molybdenum, bismuth and iron, which is mainly used for selective oxidation of propylene or isobutene (tert-butyl alcohol) for producing the (methyl) acrylic aldehyde and (methyl) acrylic acid. Oxide nanocrystals are added during the preparation of the catalyst to not only play a part in adjusting the alkalinity or acidity of the catalyst so as to improve the selectivity of the (methyl) acrylic aldehyde and (methyl) acrylic acid and reduce the yield of carbon oxide serving as the byproduct but also enhance the mechanical strength of the catalyst; thus the invention is suitable for the preparation of an industrial catalyst and industrial application for a long period.

Description

technical field [0001] The invention relates to a composite oxide catalyst for the selective oxidation of propylene or isobutene (tert-butanol) in the presence of molecular oxygen to produce (meth)acrolein and (meth)acrylic acid. Oxide nanocrystals in the form of wires, tubes, or rods. Background technique [0002] Catalysts for the selective oxidation of propylene or isobutylene or tert-butanol to prepare (meth)acrolein and (meth)acrylic acid, mainly molybdenum-bismuth-iron composite oxides. There are many patents on its preparation and oxidation reactions 报道,如JP5-293389、JP56-52013B1、US4250339、US4258217、CN93103817.0、CN95115847、CN200480004485、US4217309、US4267385、CN100354042C、CN1255366C、US5981804、CN00804787.1、CN01116867、CN1168696C、US5808142等。 The preparation of its composite oxide mainly adopts the precipitation method. In addition to the main molybdenum, bismuth and iron components, alkali metals, alkaline earth metals, W, Co, Ni, Ti, P, B, As, Cd, Zn, Si, Al are also added ...

AI Technical Summary

Problems solved by technology

[0003] However, in the previous catalyst preparation technology, it was found that in addition to molybdate as the precursor compound of the main component molybdenum, many precursors of other components used nitrate, resulting in an excessively large ratio of nitrate and molybdenum in the oxide. , which has more negative effects on the subsequent calcination of the catalyst, which not only has a bad effect on the catalytic performance, but also affects the molding performance of the catalyst.

To solve this problem, researchers have also made many attempts. For example, Japanese Patent Publication No. 62-234548A1 proposes a method for preparing a composite oxide catalyst, in which bismuth oxide or bismuth oxycarbonate is used As the precursor of bismuth; Chinese patent CN93103817.0 proposes to use ammonium molybdate roasted molybdenum oxide to partially replace part of molybdenum in the catalyst, but because this part of molybdenum oxide is obtained by roasting ammonium molybdate, the particle size is large , low utilization rate, poor repeatability; Chinese patents CN02107805.X, CN1386579A, proposed to improve the mechanical properties of the catalyst by adding glass fiber, alumina fiber, silica fiber or carbon fiber

[0004] Although the above methods have improved the reaction performance and mechanical properties of the finished catalyst to a certain extent, from the perspective of long-term industrial application, the yield of the target product and the mechanical properties of the catalyst are still not very satisfactory.