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Method for preparing tetrafluoroethylene and producing hexafluoropropylene by catalytic cracking of trifluoromethane

A trifluoromethane, catalytic cracking technology, applied in the field of fine chemicals, can solve the problems of further improvement of trifluoromethane conversion rate and total selectivity, increase of production cost, high reaction temperature, etc., to reduce post-processing cost and low cost , The effect of simple preparation method

Active Publication Date: 2019-01-11
SHANDONG DONGYUE CHEM
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The invention realizes low energy consumption and low-cost trifluoromethane resource utilization, but the reaction temperature is high, the required cost is high, and there are many by-products, resulting in a certain degree of waste of raw materials, and the conversion rate of trifluoromethane and the total selection Sex needs to be further improved
[0006] In the prior art of trifluoromethane cracking to prepare tetrafluoroethylene and hexafluoropropylene, there are some common problems, that is, under the gas-phase cracking reaction conditions of trifluoromethane, if a certain ideal conversion rate is to be achieved, the reaction temperature is high, and side reactions Many, serious carbon deposition on the catalyst, serious waste of raw materials, and many by-products, subsequent separation requires high equipment requirements and is difficult, which increases production costs

Method used

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  • Method for preparing tetrafluoroethylene and producing hexafluoropropylene by catalytic cracking of trifluoromethane

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] A method for preparing tetrafluoroethylene and co-producing hexafluoropropylene by catalytic cracking of trifluoromethane, the involved reaction equation is:

[0045]

[0046] Include steps:

[0047] (1) 5%wtCsF / Al 2 o 3 The supported catalyst was prepared as follows: 5 g of CsNO 3 Dissolved in water, prepared as 5wt% CsNO 3 Aqueous solution, ie impregnation solution; 100g of dried Al 2 o 3 Put the carrier into the impregnating solution, take it out after immersing for 20min, and dry it at 100°C for 3h to obtain the precursor; then bake it in nitrogen atmosphere at 400°C for 6h; In the reaction tube, N 2 , N 2 The flow rate is 300ml / min, and it is dried at a temperature of 300°C for 24h. Then pass trifluoromethane gas at 300°C for fluorination, with a flow rate of 6L / min, and turn off nitrogen after 2h; pass trifluoromethane alone, with a flow rate of 6L / min, and fluorinate at 350°C for 60h to finally obtain a catalyst, which is recorded as 5%wtCsF / Al 2 o...

Embodiment 2

[0055] A method for preparing tetrafluoroethylene co-production of hexafluoropropylene by catalytic cracking of trifluoromethane, different from Example 1:

[0056] The supported catalyst used was 3.6% wtLaF 3 / Al 2 o 3 , its preparation method is consistent with the preparation method of the supported catalyst in Example 1, the difference is: 3.6gLa(NO 3 ) 3 Dissolved in water, prepared as 3.6wt% La(NO 3 ) 3 Aqueous solution, i.e. dipping solution; All the other steps are identical with embodiment 1;

[0057] In step (2), the space velocity of trifluoromethane is 20h -1 ;

[0058] Other steps and conditions are consistent with Example 1.

[0059] After the cyclic reaction in this example, the conversion rate of trifluoromethane was 86%, and the total selectivity between tetrafluoroethylene and hexafluoropropylene was 97%.

Embodiment 3

[0061] A method for preparing tetrafluoroethylene co-production of hexafluoropropylene by catalytic cracking of trifluoromethane, different from Example 1:

[0062] The supported catalyst used was 1% wtPtF 4 / Al 2 o 3 , its preparation method is consistent with the preparation method of the supported catalyst in Example 1, the difference is: 1gPtCl 4 Soluble in water, prepared as 1wt% PtCl 4 Aqueous solution, i.e. dipping solution; All the other steps are identical with embodiment 1;

[0063] In step (2), the space velocity of trifluoromethane is 1000h -1 ;

[0064] Other steps and conditions are consistent with Example 1.

[0065] After the cyclic reaction in this example, the conversion rate of trifluoromethane was 87%, and the total selectivity between tetrafluoroethylene and hexafluoropropylene was 98%.

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Abstract

The invention relates to a method for preparing tetrafluoroethylene and producing hexafluoropropylene by catalytic cracking of trifluoromethane. The method comprises the steps of: under the catalysisof a supported catalyst, catalytic cracking of trifluoromethane is carried out to obtain a reactant; the reactant is washed with cooling alkali to remove acid, dried, rectified and extracted, and separated into tetrafluoroethylene, hexafluoropropylene and incompletely reacted trifluoromethane; the obtained trifluoromethane is introduced into a reaction system to carry out a cracking reaction; thesupported catalyst comprises a carrier and an active component, and the carrier is AlF3 or Al2O3, the active component is one or a combination of two or more of CsF, LaF3, SmF3, PdF2 or PtF4, and themass of the active component is 0.2 to 12% of that of the supported catalyst. The method of the invention is simple and the reaction conditions are mild; the catalyst used overcomes the problem of easy carbon deposition, and the high conversion of trifluoromethane and the high selectivity of tetrafluoroethylene and hexafluoropropylene can be achieved at lower temperature.

Description

technical field [0001] The invention relates to a method for preparing tetrafluoroethylene and co-producing hexafluoropropylene by catalytic cracking of trifluoromethane, belonging to the technical field of fine chemicals. Background technique [0002] Trifluoromethane (CHF 3 , HFC-23) is a by-product produced during the catalytic reaction of chloroform and HF to prepare difluorochloromethane (HCFC-22), and its generation amount is about 1.5-3.5wt% of the content of HCFC-22; but due to HCFC -22 itself is used as the main raw material for the manufacture of perfluoroolefins such as tetrafluoroethylene (TFE), so difluorochloromethane is excluded from the emission reduction items stipulated in the "Kyoto Protocol"; therefore trifluoromethane (CHF 3 ) emissions will continue for a long time, and the annual CHF 3 As many as tens of thousands of tons. Trifluoromethane is a greenhouse gas (GWP value is about 14800, equivalent to CO 2 14800 times of that), and have a long lifeti...

Claims

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Application Information

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IPC IPC(8): C07C17/269C07C21/185C07C21/18B01J27/125B01J37/02B01J37/08B01J37/26
CPCB01J27/125B01J37/0201B01J37/082B01J37/26C07C17/269C07C21/185C07C21/18
Inventor 王鑫都荣礼丁晨王伟徐强
Owner SHANDONG DONGYUE CHEM
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