Method for prolonging running period of acrylic acid device

Abstract

The invention provides a method for prolonging the running period of an acrylic acid device. The method comprises the following steps: loading a catalyst without diluting by use of an inert filler, arranging coated catalyst bed layers having different heat resistances in a tube fixed-bed reactor according to the heat resistance in the axial direction of the reactor; and loading a coated catalyst relatively low in heat resistance in a position near the outlet of a reaction tube, and then orderly loading coated catalysts relatively high in heat resistance in such a manner that the coated catalyst close to the inlet of the reaction tube has the highest heat resistance, wherein the coated catalysts having different heat resistances are catalysts the inner cores of which are high-activity composite oxides with heat-resistant ceramic balls, and are obtained by controlling the sizes of the heat-resistant ceramic balls and the coating ratio of an active ingredient. Due to the adopted method, not only is the running period of the acrylic acid device prolonged, but also the production device has relatively high reaction efficiency.

Description

Technical field: [0001] The invention relates to the gas-phase catalytic oxidation of propylene to produce acrolein and acrylic acid, and provides a method for prolonging the operation period of an acrylic acid device. Background of the invention: [0002] The technology of producing acrolein and acrylic acid by the gas phase contact method has been developed into a relatively complete two-step process through continuous innovation by the majority of engineers, that is, propylene and gas containing molecular oxygen generate acrolein and propylene in the first oxidation reactor The aldehyde is further oxidized to acrylic acid in the second reactor in series. The two reactors are filled with different catalysts, the first reactor is mainly Mo-Bi-Fe-O composite oxide catalyst, and the second reactor is filled with Mo-V-W-O catalyst. [0003] However, there are various problems in the process of using this catalyst to produce acrolein and acrylic acid in industry, one of which ...

AI Technical Summary

Problems solved by technology

This method reduces the difficulty of catalyst loading because it does not use diluted packing, but because it also reduces the catalyst bed hot spot temperature by reducing the catalyst activity, the use efficiency of the catalyst is reduced

In addition, the coated catalyst is affected by the preparation process, and the specific surface loss of the catalyst is large. After the propylene concentration at the reactor inlet is increased or the space velocity is increased in the industrial device, the catalyst activity decreases and the acrolein yield decreases. economic benefits

Patent CN1255366C reports a method for preparing acrolein and acrylic acid. First, catalysts with different activities are prepared by different occupied volumes, calcination temperatures, or alkali metals, and then the catalyst activity is gradually increased from the inlet to the outlet of the raw material gas. Catalysts are filled into the reaction zone in sequence. Although this method reduces the hot spot temperature of the catalyst bed, the catalyst activity gradually weakens from the raw material inlet to the outlet, which reduces the reaction efficiency of the catalyst.

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