Modified silicon-boron molecular sieve, and preparation method and application thereof

Abstract

The invention discloses a preparation method for a modified silicon-boron molecular sieve. The preparation method is characterized by comprising the following steps of: (1) mixing an agglomerated B-ZSM-5 molecular sieve of which the silicon-boron mole ratio is 3 to 100 and the particle size is 70 to 100 nm and an acidic substance aqueous solution of which the concentration is 1 to 5 mol / L; and (2) treating the mixture for 1 to 5 hours at 20 to 100 DEG C. The stability of a catalyst of the modified silicon-boron molecular sieve is greatly improved compared with that of the B-ZSM-5 molecular sieve, and the catalyst still has high catalytic performance after being used for 200 hours. Moreover, the modified silicon-boron molecular sieve has the advantages of high selectivity, high stability and high activity.

Description

technical field [0001] The invention relates to a boron molecular sieve catalyst and belongs to the technical field of catalysts. Background technique [0002] Low-carbon olefins such as ethylene and propylene are important chemical raw materials. my country is in the stage of rapid economic and social development, and will still maintain high-speed growth in a certain period of time in the future. The demand for propylene and its derivatives will continue to expand. . At present, the traditional production processes of ethylene and propylene are mainly steam cracking of hydrocarbons and catalytic cracking of oil refining. However, the reaction conditions of this process are harsh and oil resources are increasingly scarce, and the price of oil is under great upward pressure, which restricts its large-scale industrial development. The technology of producing methanol from coal and natural gas has been perfected. By 2015, my country's total methanol production capacity will r...

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Problems solved by technology

[0006] CN200810207259.8 obtains W-HZSM-5 by modifying HZSM-5 with metal element W, which improves the P / E ratio, but the stability of the catalyst needs to be further investigated and improved, and the ratio of silicon to aluminum of the catalyst parent used in this patent is partial High, the synthesis conditions are relatively harsh, which increases the production cost; CN200710202215.1 obtains Ce-HZSM-5 by using metal element Ce to modify HZSM-5, and uses it as a catalyst for preparing propylene from methanol, and the addition of Ce to a certain extent The selectivity of molecular sieves to propylene is improved, but the by-product methane is generated in a large amount; CN200710039073.1 firstly treats the catalyst with water vapor at 500°C-650°C, and then uses one of oxalic acid, citric acid or hydrochloric acid to acidify Treatment improves the P / E ratio and the hydrothermal stability of the catalyst, but the modification steps are relatively cumbersome; CN200410017715.4 uses Zn-SAPO-34 as a catalyst to improve the selectivity of low-carbon olefins; CN200910090842 The synthetic grain size is controllable , adjustable silicon-aluminum ratio and high-dispersion HZSM-5, which improves the P / E mass ratio

[0007] At present, MTP technology has great research significance and development space in my country, but to a certain extent, there is a problem of low P / E value, that is, high ethylene selectivity and unsatisfactory propylene selectivity.

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