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Fluorating catalyst and preparation thereof

A fluorination catalyst and catalyst technology, applied in the direction of physical/chemical process catalysts, chemical instruments and methods, metal/metal oxide/metal hydroxide catalysts, etc., can solve difficult control, complex catalyst fluorination treatment process, activation Long time and other problems, to achieve the effect of reducing the time of fluorination activation, shortening the preparation cycle, and simple process

Active Publication Date: 2008-07-09
XIAN MODERN CHEM RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] There are following deficiencies in the above-mentioned fluorination catalyst: (1) in Al 2 o 3 SiO 2 , using hydrogen fluoride and SiO 2 The reaction generates volatile fluorosilicon compounds to increase AlF 3 The specific surface area of ​​the carrier, but the volatile fluorosilicon compound is easy to cool and condense, resulting in pipeline blockage, so that the preparation process of the catalyst cannot be carried out continuously; (2) The catalyst precursor is treated with a mixed gas of hydrogen fluoride and inert gas to inhibit the sintering of the catalyst , although there is a certain degree of effect, the fluorination treatment process of the catalyst is complicated, difficult to control, and the activation time is long; (3) the preparation process of the catalyst is complicated, and the fluorination temperature of the catalyst precursor needs to be strictly controlled

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0029] Dissolve chromium nitrate in water, react with precipitant ammonia water at 60°C, adjust the pH value of the reaction solution in the range of 7.5 to 8.5, make it fully precipitate under stirring conditions, filter the formed slurry, and use deionized Wash with water until neutral, then dry at 120°C for 12 hours to obtain Cr(OH) 3 .

[0030] β-AlF 3 ·3H 2 O and the resulting Cr(OH) 3 and ammonium fluoride are uniformly mixed at a mass ratio of 60:20:20, and pressed into tablets to obtain a catalyst precursor. The catalyst precursor was calcined in a muffle furnace at 380°C for 8 hours, then loaded into a tubular reactor, heated to 300°C, fed with hydrogen fluoride gas for fluorination for 1 hour, then raised to 350°C at a heating rate of 1°C / min, and continued Fluorination for 8 hours to obtain a fluorination catalyst.

[0031] The specific surface area of ​​the catalyst was determined by BET low temperature nitrogen adsorption method to be 49.4m 2 g -1 , the por...

Embodiment 2

[0034] The preparation process of the catalyst is basically the same as in Example 1, except that β-AlF 3 ·3H 2 O, Cr(OH) 3 The mass ratio to ammonium fluoride is 80:10:10.

[0035] The specific surface area of ​​the catalyst was measured by BET low-temperature nitrogen adsorption method to be 43.1m 2 g -1 , the pore volume is 0.16ml·g -1 , and the proportion of pores with a diameter smaller than 2nm was 29%.

[0036] In the nickel tube fixed-bed tubular reactor with inner diameter of 38mm, 30ml of the above-mentioned prepared fluorination catalysts are loaded into, and HF and trichlorethylene are introduced to react, and the mol ratio of HF / trichlorethylene is controlled to be 8: 1. The contact time is 3 seconds, the reaction temperature is 250°C, and after 40 hours of reaction, the reaction product is washed with water and alkali to remove HCl and HF, and the conversion rate of trichlorethylene is 100% according to gas chromatography analysis. HCFC-133a and HFC-134a Th...

Embodiment 3

[0038] The preparation process of the catalyst is basically the same as in Example 1, except that β-AlF 3 ·3H 2 O, Cr(OH) 3 The mass ratio to ammonium fluoride is 40:30:30.

[0039] The specific surface area of ​​the catalyst was measured by BET low temperature nitrogen adsorption method to be 45.8m 2 g -1 , the pore volume is 0.20ml·g -1 , and the proportion of pores with a diameter smaller than 2nm is 30%.

[0040] In a nickel tube fixed bed tubular reactor with an internal diameter of 38 mm, 30 ml of the above-mentioned fluorination catalyst prepared are loaded into, and HF and tetrachloroethylene are introduced to react, and the mol ratio of HF / tetrachloroethylene is controlled to be 8: 1. The contact time is 10 seconds, the reaction temperature is 280°C, and after 40 hours of reaction, the reaction product is washed with water and alkali to remove HCl and HF, and the conversion rate of tetrachlorethylene is 78% according to gas chromatography analysis. HCFC-123, HCFC...

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Abstract

The invention discloses a fluorinated catalyst and a preparation method thereof. The invention is to solve the problems of complicacy and long time of fluorination activation treatment to the fluorinated catalyst as well as quite small specific surface area after calcination and fluoride. The precursor of the catalyst contains aluminium compound, trivalent chromium compound and fluoride of ammonium, the mass ratio of which is 40 to 80:10 to 30:10 to 30, wherein, the aluminium compound is aluminum oxide, aluminum fluoride, fluoride oxidize aluminum or aluminum hydroxide, the trivalent chromium compound is chromic oxide or chromium hydroxide, and the fluoride of ammonium is ammonium fluoride or ammonium bifluoride. The preparation method of the fluorinated catalyst of the invention includes the following steps: (1) the aluminium compound, the trivalent chromium compound and the fluoride of ammonium are evenly mixed by the mass ratio, pressed and shaped, and the precursor of the catalyst is obtained; (2) the catalyst precursor obtained in step (1) receives calcination under 350 DEG C to 450 DEG C, and then receives fluorination by hydrogen fluoride gas under 300 DEG C to 400 DEG C to obtain the fluoride catalyst. The catalyst is applicable to synthesis of gas-phase fluorinated halohydrocarbon into hydroflurocarbon.

Description

technical field [0001] The invention relates to a fluorination catalyst and a preparation method thereof, in particular to a fluorination catalyst and a preparation method thereof for gas phase fluorination of halogenated hydrocarbons to prepare hydrofluorocarbons (HFCs for short). Background technique [0002] Generally, the large-scale production of HFCs in industry adopts the method of gas-phase fluorinated halogenated hydrocarbons. This method has the advantages of simple equipment, easy continuous large-scale production, safety, and environmental protection. The fluorination catalyst plays a central role in the gas-phase fluorination of halogenated hydrocarbons. It has been proved that the specific surface area of ​​the carrier and catalyst is closely related to the catalytic activity. The higher the proportion of micropores, the larger the specific surface area, the higher the catalytic activity and the better the stability. [0003] Chinese patent 95115476.1 has repo...

Claims

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Application Information

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IPC IPC(8): B01J27/132B01J27/12B01J23/26C07C17/20
Inventor 吕剑张伟寇联岗石磊何飞李凤仙
Owner XIAN MODERN CHEM RES INST
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