ZSM-5 molecular sieve modified catalyst as well as preparation method and application thereof

Abstract

The invention relates to a ZSM-5 molecular sieve modified catalyst. The ZSM-5 molecular sieve modified catalyst comprises the following porous crystal materials in molar ratio: Al2O3 to nSiO2. The invention also relates to a preparation method of the ZSM-5 molecular sieve modified catalyst, a load modified catalyst which is used for low-concentration ethanol dehydration reaction and is specifically prepared performing radical grafting and surface modification by taking a ZSM-5 molecular sieve as a carrier and, and a preparation method for preparing ethylene through dehydration of low-concentration ethanol on a fixed bed reactor. In the preparation method, the low-concentration ethanol dehydration catalyst prepared by loading a modified ZSM-5 molecular sieve has the characteristics of high catalytic activity, high selectivity, easiness in regeneration and the like. Through long-term continuous running on the fixed bed reactor, the ZSM-5 molecular sieve modified catalyst shows the low reaction temperature and low energy consumption performances when used in a low-concentration ethanol dehydration process, the ethanol conversion ratio is high, the ethylene selectivity and yield are high, and the catalyst has the advantages of being stable in activity, convenient to regenerate, stable to operate and the like.

Description

technical field [0001] The invention relates to a catalyst, especially a ZSM-5 molecular sieve modified catalyst; the invention also relates to a preparation method of the catalyst and its application in low-concentration ethanol dehydration reaction. Background technique [0002] Ethanol dehydration reaction is one of the common reactions. It can convert ethanol into ethylene which is more widely used. Usually, industrial ethanol is used as raw material, and ethylene is dehydrated at 350~400℃ under the action of a catalyst. However, using industrial ethanol as a raw material not only has high reaction temperature and high energy consumption, but also is uneconomical. Therefore, someone proposed a new process of dehydration preparation using low-concentration ethanol as a raw material, so that the fermented ethanol after simple treatment can be used as a raw material instead of It needs to be concentrated and dehydrated to generate ethylene at a relatively low temperature. ...

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Problems solved by technology

Chinese patent document CN1340485 is the method for synthesizing ZSM-5 molecular sieve under the condition that replaces organic template with inorganic ammonium, promptly in Na 2 O-A1 2 o 3 -SiO 2 -NH 3 -H 2 O-H 2 Synthesize ZSM-5 in the O system, but the synthesized molecular sieve particles are small and have the disadvantage of uneven molecular sieve crystal form, so it is difficult to obtain a highly selective catalyst

[0007] The ZSM-5 molecular sieve used in the prior art has a silicon-aluminum ratio difference of less than 10% between the body and the surface. The low-concentration ethanol dehydration catalyst prepared after ammonium salt ion exchange has high temperature and poor selectivity in the catalytic reaction process. High concentration of dilute ethanol solution and many by-products

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