Modified molecular sieve catalyst for ethanol dehydration to produce ethylene, and application thereof

Abstract

The invention discloses a modified molecular sieve catalyst for ethanol dehydration to produce ethylene. The catalyst is prepared through the following steps: preparing an unmodified bar-shaped molecular sieve catalyst from HZSM-5 molecular sieve powder and macro-porous pseudo-boehmite powder, sequentially carrying out alkali modification and acid modification by using an aqueous Na2CO3 solution and an aqueous citric acid solution, and baking and calcining the modified bar-shaped molecular sieve catalyst. The invention also discloses an application of the modified molecular sieve catalyst forethanol dehydration to produce ethylene. The preparation modification process of the catalyst does not require a stirring process, so the preparation process is simplified, the weak acid amount of thesurface of the catalyst is greatly increased, and the medium and strong acid amount is reduced, thereby the catalysis effect of the modified molecular sieve catalyst on an ethanol dehydration reaction for producing ethylene is improved, the conversion rate of the raw material ethanol and the selectivity of the product ethylene are increased, and the service life of the modified molecular sieve catalyst is prolonged; and the modified molecular sieve catalyst has a simple application in the dehydration of ethylene to produce ethylene, and is suitable for being promoted.

Description

technical field [0001] The invention belongs to the technical field of catalyst preparation, and in particular relates to a modified molecular sieve catalyst for ethanol dehydration to ethylene and an application thereof. Background technique [0002] Ethylene is one of the most basic raw materials in the organic chemical industry. It is mainly used in synthetic resins, rubber, fibers, coatings, adhesives, surfactants and other polymer materials. At the same time, the modern ethylene industry produces ethylene and by-products such as propylene, butadiene, benzene, xylene, etc., which are also important raw materials for the manufacture of related synthetic materials. At present, the main raw materials for industrial production of ethylene come from two ways: one is light hydrocarbons from natural gas processing plants: such as ethane, propane, butane, etc.; the other is processed products from refineries: such as refinery gas, gasoline, diesel oil, etc.; The raw materials o...

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Problems solved by technology

[0005] At present, there are various shortcomings in the process of acid-base modification of HZSM-5 molecular sieve: the main reason is that the modification process is relatively complicated. Generally, the acid-base modification of molecular sieve powder is carried out first, because the raw material exists in powder form, so in order to To ensure the uniformity of modification, it is necessary to use mechanical stirring, which leads to high energy consumption in the modification process. After modification, drying, roasting and other processes are required to form modified molecular sieve powder, and then use the modified molecular sieve powder Molecular sieve powder as raw material and macroporous pseudo-boehmite powder are bonded, extruded, dried, and roasted to prepare the acid-base modified molecular sieve catalyst

However, the molecular sieve catalyst uses relatively expensive organic bases such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, etc. in the modification, resulting in higher preparation costs for the modified catalyst

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