Fluorating catalyst and preparation thereof

A fluorination catalyst and catalyst technology, applied in the direction of physical/chemical process catalysts, chemical instruments and methods, halogen substitution preparation, etc., can solve problems such as difficult control, complex catalyst fluorination treatment process, pipeline blockage, etc., to reduce fluorination Activation time, shorten the preparation cycle, easy to control the effect

Active Publication Date: 2009-08-05
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
Comparison scheme
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 evenly 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 pore v...

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 a nickel tube fixed-bed tubular reactor with an internal diameter of 38 mm, 30 ml of the above-mentioned fluorination catalyst prepared above are charged, and HF and trichloroethylene are introduced to react, and the molar ratio of HF / trichloroethylene 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 HF...

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 38mm, 30ml of the above-mentioned fluorination catalyst prepared above was charged, and HF and tetrachloroethylene were introduced to react, and the molar ratio of HF / tetrachloroethylene was 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, H...

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Abstract

The invention discloses a fluorination catalyst and a preparation method thereof. The purpose of the method is to solve the problems of complex fluorination activation treatment process of fluorination catalyst, long time, low specific surface area after roasting and fluorination, and the like. The precursor of the catalyst contains aluminum compound, trivalent chromium compound and ammonium fluoride, and its mass ratio is 40-80:10-30:10-30, wherein the aluminum compound is alumina, aluminum fluoride, aluminum oxyfluoride or Aluminum hydroxide, trivalent chromium compound is dichromium trioxide or chromium hydroxide, ammonium fluoride is ammonium fluoride or ammonium bifluoride. The preparation method of the fluorination catalyst of the present invention comprises the following steps: (1) uniformly mixing the aluminum compound, the trivalent chromium compound and the fluoride of ammonium according to the mass ratio, and pressing and molding to obtain a catalyst precursor; (2) making the step ( 1) The obtained catalyst precursor is calcined at 350° C. to 450° C., and then fluorinated with hydrogen fluoride gas at 300° C. to 400° C. to obtain a fluorination catalyst. The catalyst is suitable for synthesizing hydrofluorocarbons by fluorinating halogenated hydrocarbons in gas phase.

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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Patent Type & Authority Patents(China)
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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