Catalyst for preparing dimethyl ether by methanol and preparation method thereof

Abstract

The invention discloses a preparation method of a catalyst for preparing dimethyl ether by methanol. The method comprises the following steps: firstly, dissolving a template agent in strong alkaline solution, and adding microporous molecular sieves to be dipped so as to obtain mixed liquor, secondly, performing primary crystallization and cooling on the mixed liquor, adjusting the pH of the mixed liquor to be 6 to 11, performing secondary crystallization on the mixed liquor, and then filtering, washing and drying the mixed liquor so as to obtain dried solid powder, and thirdly, performing ammonium ion exchange, washing and drying on the solid powder in ammonium salt solution, and calcining to remove the template agent and NH3 so as to obtain the catalyst. The catalyst for preparing dimethyl ether by methanol disclosed by the invention is based on cellular material, adopts strong base to dissolve material to partly destroy microcellular structures, then performs hydrothermal reconstruction in the condition that quaternary ammonium salt template agent exists, so as to form mesoporous structure and obtain the hierarchical pore structure catalyst containing millipore and mesopore. According to the catalyst, the microcellular structures are kept, the activity decline of the catalyst is prevented, hollow structures are formed, products can be separated from the surface layer of the catalyst conveniently, and carbon distribution is prevented. According to the preparation method, the stability, the activity and the selectivity of the catalyst are improved.

Description

technical field [0001] The invention relates to a catalyst for producing dimethyl ether from methanol and a preparation method of the catalyst. Background technique [0002] With the rapid development of the world economy, the increasing shortage of oil resources, and the continuous deterioration of the natural environment, people are trying to find clean alternative energy. Dimethyl ether is an important chemical product with properties similar to that of liquefied petroleum gas. It is characterized by good combustion performance and low NO X High emission, no smoke, low noise, non-toxic, non-corrosive, inert ultra-clean energy and environmentally friendly fuel. DME can be used as an alternative aerosol, refrigerant and foaming agent for Freon; it can replace liquefied petroleum gas for civil fuel; it can replace diesel for clean fuel for diesel engines. [0003] At present, the main methods for preparing DME include one-step method and two-step method. The so-called one-...

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Problems solved by technology

The single oxide-based solid acid catalyst has the advantages of good selectivity and good stability, but the existing problems are low activity and high reaction temperature, most of which can only achieve 80% conversion of methanol at 290°C

In order to improve the activity of the catalyst, the researchers loaded other components on the surface of the solid acid or introduced acid ions to reduce the reaction temperature, but the degree of reduction was limited, and carbon deposition was easy to occur, which reduced the selectivity of dimethyl ether and the stability of the catalyst. sex

The advantage of molecular sieve catalysts is high activity, but the reaction rate is too fast, and the catalyst pores are too narrow, which is easy to deposit carbon, so that the catalyst deactivates quickly. For example: through experiments, ZSM-5 molecular sieve can achieve 86% conversion of methanol at 210°C rate, but after 15 days of use, the catalyst has a very obvious decline, and after 40 days, the catalyst will be completely deactivated

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