Heteropolyacid ammonium salt catalyst and its preparation method

Abstract

The invention discloses a heteropolyacid ammonium salt catalyst and a preparation method thereof. The catalyst comprises an active component, an auxiliary agent and a carrier. The active component is heteropolyacid ammonium salt, the auxiliary agent is Fe, and the carrier is a composite carrier of alumina and silicon dioxide. The catalyst of the invention has high low-temperature activity and selectivity, and is especially suitable for the reaction of dehydrating methanol raw materials with high water content to produce dimethyl ether.

Description

technical field [0001] The invention relates to a heteropolyacid ammonium salt catalyst and a preparation method thereof, in particular to a loaded heteropolyacid ammonium salt catalyst used for methanol dehydration to produce dimethyl ether and a preparation method thereof. Background technique [0002] Dimethyl ether (Dimethy Ether, abbreviated as DME) is a colorless, non-toxic gas at normal temperature and pressure, which can be compressed into a liquid. Dimethyl ether is an important organic chemical raw material and chemical intermediate, which can be used in aerosols, refrigerants, alkylating agents, pharmaceuticals, cosmetics, fuels and other industries. [0003] Dimethyl ether was first produced by rectification of by-products in high-pressure methanol production, and soon developed into two processes of methanol dehydration and direct synthesis of synthesis gas. The liquid-phase method of methanol dehydration to produce dimethyl ether, the reaction is carried out i...

AI Technical Summary

Problems solved by technology

[0004] At present, the catalyst used for methanol dehydration is generally Al 2 o 3 Or molecular sieves, among which the commonly used molecular sieves include aluminum phosphate, HZSM-5, HY, SAPO, etc., and they all have their own shortcomings: for example, although alumina has high stability, the reaction temperature is high, and the requirements for reaction equipment are very high, resulting in cost High; molecular sieve catalysts have strong acidity and low initial temperature, but they also have the disadvantages of many by-products, easy carbon deposition, and easy deactivation

The above-mentioned catalysts have high catalytic activity and selectivity in the reaction, and the optimal load of silicotungstic acid is 10wt%~16wt%. Under normal pressure, when used to treat pure methanol raw materials, its selectivity is high, but Its low-temperature activity is not good, and when it is used as a methanol raw material containing water, its stability is not good, and the selectivity and activity also decrease.