Catalyst for production of unsaturated aldehyde (acid) and preparation method thereof

Abstract

The invention relates to a catalyst for the production of unsaturated aldehyde (acid) and a preparation method thereof. The catalyst comprises active components and a heat-transfer medium. The active components are oxides of metals such as molybdenum, bismuth, iron, and the like or composite oxides. The heat transfer medium is silicon dioxide coated metal powder or alloy powder, and the heat conductive performance is excellent. During the catalyst preparation process, a freeze drying mode is adopted, and the burning atmosphere is a mixed gas composed of oxygen and an inert gas according to a certain ratio. The catalyst is applied to the strongly exothermic catalytic oxidation of unsaturated alkene to generate unsaturated aldehyde (acid), especially catalytic reactions of preparing methylacrolein (methacrylic acid) from isobutene; the problem of excess temperature of local hot spots is solved; and at a low hot spot temperature, the catalyst has an excellent unsaturated alkene conversion rate and unsaturated aldehyde (acid) selectivity.

Description

technical field [0001] The invention belongs to the field of catalysts, and relates to a catalyst with high thermal conductivity and a preparation method thereof, and also relates to the application of the catalyst in the production of unsaturated aldehydes (acids). Background technique [0002] The oxidation of unsaturated olefins to unsaturated aldehydes (acids) is a strong exothermic reaction, and a large amount of heat will be released in a short period of time during the start-up process. The accumulation of heat in the reactor will cause local hot spots to be too high, reduce the selectivity of the target product, and even burn Wear reactor, cause molten salt leakage, cause parking or explosion and other accidents. Therefore, in order to achieve safe production and increase the yield of the target product, the catalyst needs to have good heat transfer ability and excellent selectivity. [0003] Chinese patent CN1089081C proposes that catalysts with different reactivit...

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Problems solved by technology

[0003] Chinese patent CN1089081C proposes that catalysts with different reactivity should be loaded sequentially from the reactor feed gas inlet to the outlet in order from low to high to suppress the accumulation of heat, but this method greatly increases the production cost of the catalyst and gives the catalyst Filling in large-scale reactors can be inconvenient

Chinese patent CN101385978B proposes to add some materials with good thermal conductivity (such as silicon powder, germanium powder, graphite, etc.) Both the efficiency and the selectivity of methacrolein have been improved, but the heat transfer capacity of the heat transfer medium reported in the patent is limited, and the catalyst activity still has a large gap with the industrial production demand. It is necessary to further improve the heat transfer capacity of the catalyst and reduce the hot spot temperature. Maintain high isobutylene conversion and methacrolein selectivity

Among them, the olefin intermediates are prone to deep oxidation reaction on the acidic site, and generate small molecule aldehydes, acids, and COx, which greatly increases the heat release of the reaction system and decreases the selectivity.

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