Zinc isomorphism-substituted nano molecular sieve catalyst and preparation method and application thereof

Abstract

The invention provides a zinc isomorphism-substituted nano ZSM-5 molecular sieve catalyst and a preparation method thereof. In the method, solution of zinc amine or solution of zinc ammonia is taken as a zinc source, a one-pot method is adopted to directly make zinc atoms enter a framework of a molecular sieve, the prepared molecular sieve is a nano plate crystal with the dimension of 250nm*50nm*25nm, and the molecular sieve has the advantages of high yield, easy product separation, short preparation time and simple preparation method. When the molecular sieve serving as a catalyst is applied to methanol and ethanol aromatization reaction, the molecular sieve has the characteristics of high aromatic selectivity, high BTX proportion, long service life of the catalyst, stable catalytic performance, flexible technical operation, and the like.

Description

technical field [0001] The invention belongs to the field of catalytic materials, and relates to a molecular sieve type alcohol aromatization catalyst, in particular to a catalyst for catalyzing the aromatization reaction of methanol and ethanol. Background technique [0002] The output and scale of aromatics, especially benzene, toluene, and xylene (BTX for short) are important organic chemical raw materials next to ethylene and propylene. Its derivatives are widely used in chemical products and fine chemicals such as fuel, petrochemical, chemical fiber, plastic and rubber. With the continuous development of society, the world's demand for aromatics continues to grow. In recent years, the shortage of petroleum resources has caused the prices of aromatics, mainly benzene, toluene and xylene, to remain high. The preparation of aromatics (MTA or ETA) from methanol or bioethanol is a beneficial process route, which can use coal or biomass resources to make up for the shortage...

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Problems solved by technology

After Al was introduced into Zn-MFI molecular sieve by ion exchange method, it was used for the decomposition reaction of 2-propanol, and the catalytic activity was improved, but it was still not ideal, and the conversion rate of 2-propanol was still not more than 10%; S .Valange et al. prepared and characterized Zn-MFI molecular sieves using short-chain alkylamines as mineralization reagents [see: S.Valange, B.Onida, F.Geobaldo, E.Garrone, Z.Gabelica.Preparation and characterization of Zn- MFI zeolites using short chain alkylamines as mineralizing agents, Studies in Surface Science and Catalysis, 2002, 142A: 215-222], the molecular sieve grains are large and thick, and the crystallization time is long: to obtain pure Zn-MFI crystals, the crystallization time It takes more than 6 days; Liu Zhongmin et al. [Zn(NH 3 ) 4 ] 2+ As a zinc source, n-butylamine was used as a template to directly prepare snowflake-like Zn-ZSM-5 molecular sieves [see: Ligang Wang, Shiyun Sang, Shuanghe Meng, Ying Zhang, Yue Qi, Zhongmin Liu.Direct synthesis of Zn- ZSM-5 with novel morphology, Materials Letters, 2007, 61(8-9): 1675-1678], the length of the molecular sieve is 6-8 microns, and the crystallization time takes 5 days

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