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Chromium base fluorating catalyst and preparation thereof

A technology based on fluorination catalysts and catalysts, applied in the direction of physical/chemical process catalysts, chemical instruments and methods, halogen substitution preparation, etc., can solve complex fluorination treatment process of catalysts, low specific surface area of ​​fluorination catalysts, long activation time, etc. problems, to achieve easy control, reduced time, and good repeatability

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

[0007] The above-mentioned chromium-based fluorination catalyst has the following deficiencies: (1) the catalyst precursor is treated with a mixed gas of hydrogen fluoride and an inert gas to suppress 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; (2) After the catalyst precursor is roasted and activated by hydrogen fluoride, the specific surface area of ​​the fluorination catalyst is relatively low

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] 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 .

[0032] The obtained Cr(OH) 3 It is uniformly mixed with ammonium fluoride at a mass ratio of 60:40, 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 After fluorination for 8 hours, a chromium-based fluorination catalyst was prepared.

[0033] The specific surface area of ​​the catalyst was measured by BET low temperature nitrogen adsorption method to be 66.8m 2 g -1 , the por...

Embodiment 2

[0036] The catalyst preparation process is substantially the same as in Example 1, except that Cr(OH) 3 The mass ratio to ammonium fluoride is 50:50.

[0037] The specific surface area of ​​the catalyst was measured by BET low temperature nitrogen adsorption method to be 65.2m 2 g -1 , the pore volume is 0.18ml·g -1 , and the proportion of pores with a diameter smaller than 2nm was 34%.

[0038]In a nickel tube fixed-bed tubular reactor with an internal diameter of 38mm, 30ml of the chromium-based fluorination catalyst prepared above is loaded into it, and HF and HCFC-123 are introduced to react, and the molar ratio of HF / HCFC-123 is controlled to be 10: 1. The contact time is 10 seconds, the reaction temperature is 330°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 HCFC-123 is 85% according to gas chromatography analysis. HCFC-124 and HFC -125 has an overall selectivity of 99%.

Embodiment 3

[0040] The catalyst preparation process is substantially the same as in Example 1, except that Cr(OH) 3 The mass ratio to ammonium fluoride is 70:30.

[0041] The specific surface area of ​​the catalyst was measured by BET low-temperature nitrogen adsorption method to be 60.9m 2 g -1 , the pore volume is 0.19ml·g -1 , and the proportion of pores with a diameter smaller than 2nm is 35%.

[0042] In a nickel tube fixed bed tubular reactor with an inner diameter of 38 mm, 30 ml of the chromium-based fluorination catalyst prepared above 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 84% ​​according to gas chromatography analysis. HCFC-123, HCFC The overall selecti...

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Abstract

The invention discloses a chromium-based 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 chromium-based fluorinated catalyst contains trivalent chromium compound and fluoride of ammonium, the mass ratio of which is 40 to 70 : 20 to 50, wherein, 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 chromium-based fluorinated catalyst of the invention includes the following steps: (1) 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 chromium-based fluoride catalyst. The chromium-based fluoride catalyst of the invention is applicable to reaction for preparation of hydroflurocarbon with gas-phase fluorinated halohydrocarbon.

Description

technical field [0001] The invention relates to a chromium-based fluorination catalyst and a preparation method thereof, in particular to a chromium-based fluorination catalyst for gas-phase fluorination of halogenated hydrocarbons to synthesize hydrofluorocarbons (HFCs for short) and a preparation method thereof. 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. Chromium-based fluorination catalysts and chromium-based fluorination catalysts are commonly used fluorination catalysts in the prior art. [0003] Chinese patent 01141970.9 discloses a fluorination catalyst composed of Cr, Mn, Mg metal, oxygen and fluorine. The catalyst uses a ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J27/132B01J27/12C07C17/20
Inventor 吕剑张伟寇联岗石磊王博李凤仙
Owner XIAN MODERN CHEM RES INST
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