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Chromium base catalyst, and preparation method and use thereof

A chromium-based catalyst and catalyst technology, applied in the direction of dehydrohalogenation preparation, chemical instruments and methods, physical/chemical process catalysts, etc., can solve the problems of shortened catalyst service life, high reaction temperature, pollution, etc., and achieve the suppression of catalyst carbon deposition , good repeatability and simple process

Inactive Publication Date: 2015-09-16
BEIJING YUJI SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, chromium-based catalysts are generally used for gas-phase catalyzed fluorine-chlorine exchange reactions or dehydrofluorination reactions. The reaction temperature is relatively high, often reaching about 400°C. The reaction of halogenated olefins in the reaction materials is prone to polymerization or cracking, resulting in "coking". As a result, the surface of the chromium-based catalyst is polluted, the pores are blocked, the catalyst is rapidly deactivated, and the service life of the catalyst is greatly shortened.
Therefore, traditional chromium-based catalysts have the disadvantages of small specific surface area, severe carbon deposition, and short service life.

Method used

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  • Chromium base catalyst, and preparation method and use thereof
  • Chromium base catalyst, and preparation method and use thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Dissolve chromium nitrate in water, add precipitant ammonia water at 60°C, control the pH range of the solution to 7.5-8.5, make it fully precipitate under stirring conditions, filter the formed slurry, wash with deionized water until neutral , and then dried at 150°C for 12 hours to obtain chromium hydroxide.

[0038] The obtained chromium hydroxide and zinc silicate are divided into 95% and 5% by mass percentage and uniformly mixed, and pressed into tablets to obtain a catalyst precursor, and 60 mL of the catalyst precursor is packed into a SUS316 system with an inner diameter of 1 inch and a length of 23.6 inches. Tubular reactor, fed with nitrogen and roasted at 450°C for 8 hours, nitrogen space velocity is 200h -1 , to obtain the catalyst precursor. Then the catalyst precursor is at 300°C, and at the same time, a mixed gas composed of hydrogen fluoride and nitrogen with a mass ratio of 10:1 is passed through, and the total space velocity of the gas is 220h -1 , a...

Embodiment 2

[0043] The preparation process of the catalyst is basically the same as in Example 1, except that the mass percentages of chromium hydroxide and zinc silicate are 99.9% and 0.1%.

[0044] The results of BET detection processing are as follows:

[0045] Catalyst precursor: specific surface area = 365.8m 2 / g, pore volume=0.57cc / g, average pore diameter

[0046] Chromium-based catalyst: specific surface area = 176.4m 2 / g, pore volume=0.46cc / g, average pore diameter

Embodiment 3

[0048] The preparation process of the catalyst is basically the same as in Example 1, except that the mass percentages of chromium hydroxide and zinc silicate are 90% and 10%.

[0049] The results of BET detection processing are as follows:

[0050] Catalyst precursor: specific surface area = 406.7m 2 / g, pore volume=0.68mL / g, average pore diameter

[0051] Chromium-based catalyst: specific surface area = 186.8m 2 / g, pore volume=0.58mL / g, average pore diameter

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Abstract

The invention discloses a chromium base catalyst, and a preparation method and a use thereof, and belongs to the field of chemical synthesis. The precursor of the catalyst is composed of 90-99.9mass% of a trivalent chromium compound and 0.1-10mass% of a silicon-containing compound, wherein the trivalent chromium compound is chromic oxide or chromium hydroxide, and the silicon-containing compound can be zinc silicate, nickel silicate, magnesium silicate, aluminum silicate, zirconium silicate, barium silicate, bismuth silicate, ammonium fluorosilicate, nickel hexafluorosilicate, zinc fluorosilicate, magnesium fluorosilicate, aluminum fluorosilicate or calcium fluorosilicate The chromium base catalyst has the advantages of large specific surface area, effective inhibition of carbon formation, and long service life, is mainly used for gas phase catalysis of reactions for preparing hydrofluorocarbons or fluorinated alkenes from halogenated hydrocarbons or halogenated alkenes at a high temperature, and can also be used for gas phase catalysis of reactions for preparing hydrofluoroalkenes through hydrogen fluoride removal of hydrofluorocarbons at a high temperature.

Description

technical field [0001] The invention relates to a chromium-based catalyst, in particular to gas-phase catalytic fluorine-chlorine exchange reaction at high temperature to prepare hydrofluorocarbons or fluorine-containing olefins, and to gas-phase catalytic hydrofluorocarbon dehydrofluorination reaction to prepare hydrofluoroolefins at high temperature. Background technique [0002] Generally, the industrial production of hydrofluorocarbons or fluorine-containing olefins mostly adopts the method of gas-phase fluorinated halogenated hydrocarbons or halogenated olefins. This method has the advantages of simple process, easy continuous large-scale production, and safe operation. Chromium-based catalysts play a central role in the gas-phase fluorination of halogenated hydrocarbons or halogenated olefins. [0003] Chromium-based catalyst is a kind of high-activity chromium-based catalyst studied earlier at home and abroad. The catalyst matrix often exists in the form of oxides. Th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J23/26B01J23/86B01J27/132B01J27/138B01J35/10C07C17/20C07C19/08C07C19/12C07C23/08C07C21/18C07C17/25
Inventor 权恒道周晓猛陈朝晖贾晓卿
Owner BEIJING YUJI SCI & TECH
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