In Situ Synthesis of Olefin Hydration Molecular Sieve Catalysts with MFI Structure

Abstract

The invention discloses an in-situ synthesizing method for an olefin-hydration molecular sieve based catalyst. The catalyst is a mixed element modified molecular sieve based catalyst with an MFI structure. A mixed element modifier, namely a water solution containing at least one element of Cu, P, La, Ge, Pd and Nb, is utilized as a modifying source to be introduced into a hydrothermal synthesis system prepared from a silicon source, an aluminum source, a template, alkali and distilled water to react to prepare an in-situ modified molecular sieve. According to a preparation method disclosed bythe invention, a disposable in-situ synthesizing technology is utilized, a synthesizing process is simplified, preparation cost is reduced, and industrial popularization is facilitated. The prepared molecular sieve based catalyst has the advantages of higher strength and stability; furthermore, the catalyst has the advantages of better low temperature activity and catalyst activity and high selectivity to lower alcohol; in addition, the service life of the catalyst is prolonged.

Description

technical field [0001] The invention belongs to the technical field of catalyst synthesis, and more specifically relates to an in-situ synthesis method of an olefin hydration molecular sieve catalyst with an MFI structure. Background technique [0002] Low carbon mixed alcohol refers to C 1 ~C 6 Alcohol mixtures, neither aromatic nor sulfur, have broad application prospects. (1) Low-carbon mixed alcohols are important chemicals and organic chemical raw materials. In recent years, the chemical application prospects of low-carbon mixed alcohols are gradually promising. Low-carbon mixed alcohols can be further separated to obtain ethyl, propylene, butanol and pentanols with higher prices. (2) Low-carbon mixed alcohols can also be directly used as clean fuels. Due to the presence of oxygen in alcohols, their combustion is more complete than that of gasoline and diesel, and CO, NO x It has less emissions and is an environmentally friendly fuel; (3) low-carbon mixed alcohol is ...

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Problems solved by technology

[0004] The traditional process of olefin hydration adopts sulfuric acid indirect hydration method, which was gradually eliminated due to equipment corrosion and waste acid treatment problems. After that, Texaco Company of the United States developed a medium-pressure, low-temperature direct hydration method using strong acidic cation exchange resin as a catalyst. Preparation of isopropanol by hydration method can obtain higher conversion rate of propylene and selectivity of isopropanol, but the catalyst has poor thermal stability, the use temperature must be lower than 175°C, and the catalyst has the problem of loss of sulfonic acid groups; China Patent CN1245738A developed a zeolite molecular sieve olefin hydration catalyst. Zeolite molecular sieve is a solid acid that does not cause acid loss. Therefore, this molecular sieve catalyst overcomes the shortcomings of resin catalysts and successfully solves the problem of catalyst thermal stability. However, the zeolite molecular sieve The catalyst must undergo ion exchange and metal element solution impregnation, the preparation process is complicated, and this will destroy the molecular sieve lattice, thereby forming a skeleton defect, which will eventually lead to a decrease in the activity and stability of the catalyst. If it is frequently regenerated, its skeleton structure will also be destroyed. service life

[0005] In recent years, with the continuous breakthrough of in-situ synthesis technology, the use of in-situ synthesis technology to improve the performance of catalysts has been valued by various research units, but there are few reports on the preparation methods of in-situ synthesis of olefin hydration catalysts.

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