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Recycling method of byproduct-trifluoromethane in HCFC-22 production

A technology of trifluoromethane and resource utilization, applied in organic chemistry, halogen substitution preparation, etc., can solve the problems of failure to convert trifluoromethane, high reaction temperature, many by-products, etc., and achieve high catalyst selectivity and low reaction temperature. , The effect of small investment in equipment

Active Publication Date: 2019-05-14
ZHEJIANG LANTIAN ENVIRONMENTAL PROTECTION HI TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] In the prior art, when treating trifluoromethane with gas-phase cracking reaction, a very high reaction temperature is required to achieve a certain conversion rate, and there are many by-products and serious carbon deposition; by adding halogenated hydrocarbons, trifluoromethane is converted into HCFC- At 22 o'clock, it only converts trifluoromethane into HCFC-22, but fails to convert trifluoromethane into higher value compounds

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0062] Catalyst pretreatment: adding γ-alumina to N 2 Treat at 250°C for 5 hours, fluoride at 250°C for 2 hours in a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen, and finally treat at 300°C for 5 hours with hydrogen fluoride.

[0063] Reaction: Pass trifluoromethane and dichloromethane at a ratio of 1:1 (molar ratio) into a reactor equipped with 20ml of pretreated γ-alumina catalyst, at a temperature of 350°C, a pressure of 1bar, and a space velocity of 1000h -1 The reaction was carried out under the conditions to obtain the reaction product. During the reaction, all pipelines were kept warm to 60°C with heating tape. In the reaction product, main product comprises difluoromethane, monofluorochloromethane and difluorochloromethane, and its selectivity is respectively 32.3%, 26.2% and 41.1%, and wherein the transformation rate of trifluoromethane and dichloromethane is respectively 18.4% and 17.7%. The catalyst activity remained stable after 150 hours of reacti...

Embodiment 2

[0066] Catalyst pretreatment: magnesium fluoride in N 2 at 200 ℃ Treat for 5 hours, fluoride treatment at 350°C for 2 hours in a mixed atmosphere of 10% hydrogen fluoride and 90% nitrogen, and finally treat with hydrogen fluoride at 350°C for 5 hours.

[0067] Reaction: Pass trifluoromethane and dichloromethane at a ratio of 1:1 (molar ratio) into a reactor containing 20ml of pretreated magnesium fluoride catalyst, at a temperature of 450°C, a pressure of 2bar, and a space velocity of 2000h -1 The reaction was carried out under the conditions to obtain the reaction product. During the reaction, all pipelines were kept warm to 60°C with heating tape. In the reaction product, the main product includes difluoromethane, chlorofluoromethane and chlorodifluoromethane, and its selectivity is 21.5%, 26.2% and 40.4% respectively, wherein the conversion rates of trifluoromethane and dichloromethane are respectively 13.6% and 12.1%. The catalyst activity remained stable after 200 hou...

Embodiment 3

[0070] Catalyst preparation: take by weighing 260.4g of Al(NO 3 ) 3 9H 2 O was dissolved in 500ml of water, and 25% ammonia solution was added dropwise to the above solution to control the pH value to 7, and at the same time turn on the magnetic stirring, centrifugally dry, remove the lower layer of precipitate, dry at 100°C and place in N 2 Calcined at 500°C for 3h in atmosphere 2 o 3 catalyst.

[0071] Reaction: The catalyst is loaded into the reactor, and trifluoromethane and dichloromethane are passed into the reactor containing 20ml of pretreated γ-alumina catalyst at a temperature of 350°C and 1:1 (molar ratio). Pressure 1bar, space velocity 1000h -1 The reaction was carried out under the conditions to obtain the reaction product. During the reaction, all pipelines were kept warm to 60°C with heating tape. In the reaction product, the main product includes difluoromethane, chlorofluoromethane and chlorodifluoromethane, and its selectivity is 24.8%, 21.7% and 43.4%...

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PUM

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Abstract

The invention discloses a method of recycling trifluoromethane. The method includes: under action of at least one catalyst of MgF2, Al2O3, partially fluorinated alumina and AlF3, allowing trifluoromethane and dichloromethane to react to obtain a reaction product containing difluoromethane and monochlorodifluoromethane, and rectifying to obtain difluoromethane. The method can realize recycling of trifluoromethane, can convert the same into difluoromethane with high value and has great economic benefit.

Description

technical field [0001] The invention relates to a resource utilization method of by-product trifluoromethane in the production of HCFC-22, in particular to a resource utilization method of converting by-product trifluoromethane into difluoromethane. Background technique [0002] Chlorodifluoromethane (HCFC-22, R22 or CHClF 2 ) used to be the most widely used refrigerant and blowing agent, because it is an ozone-depleting substance, it will be gradually banned. However, HCFC-22 is also the main raw material for preparing plastic monomers such as tetrafluoroethylene (TFE) and hexafluoropropylene (HFP). Its mass production is inevitable, and my country's HCFC-22 production capacity has exceeded half of the global total (about 700,000 tons). CHF 3 It is an inevitable by-product produced in the process of producing R22. According to different technological processes, CHF 3 The production amount of Fluorine is about 2-5% of R22 [Journal of Fluorine Chemistry, 2012, 140:7-16]. ...

Claims

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Application Information

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IPC IPC(8): C07C17/20C07C19/08
Inventor 韩文锋习苗王术成
Owner ZHEJIANG LANTIAN ENVIRONMENTAL PROTECTION HI TECH
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