Catalyst for preparing tetrafluoroethylene and hexafluoropropylene through catalytic cracking of trifluoromethane and preparation method thereof

Abstract

The invention provides a catalyst for preparing tetrafluoroethylene and hexafluoropropylene through catalytic cracking of trifluoromethane and a preparation method thereof. The catalyst is prepared through the steps of preparing a precursor from a carrier and an active component through an impregnation method and then carrying out roasting and trifluoromethane fluorination; the carrier is Al2O3 orAlF3; the active component is one or a combination of two of nitride and nitrate of Cs, La, Sm, Pd, Pt, K or Na. The preparation method provided by the invention is simple, is capable of catalytically cracking the trifluoromethane under lower temperature and mild conditions, and is low in equipment requirements, low in energy consumption and low in cost; the prepared catalyst is capable of effectively reducing the reaction temperature of the catalytic cracking of the trifluoromethane, the conversion rate of raw materials and selective increment of a target product can be realized under milderconditions, the problem of coking of the catalyst can be effectively solved, and the service life of the catalyst can be prolonged.

Description

technical field [0001] The invention relates to a catalyst for preparing tetrafluoroethylene and hexafluoropropylene by catalytic cracking of trifluoromethane and a preparation method thereof, belonging to the field of fluorine chemical catalyst preparation. 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 ti...

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Problems solved by technology

[0004] The process of preparing tetrafluoroethylene / hexafluoropropylene by pyrolysis of trifluoromethane is simple in process, high in added value of the product, and has great industrialization prospects. However, in the case of no catalyst, the cracking of empty tubes alone, the reaction temperature is 1000°C, and the conversion rate is 10%- About 20%; the conversion rate is low, and there are many by-products, and the separation is difficult

The catalyst of this invention can effectively reduce the reaction temperature of trifluoromethane catalytic cracking reaction, but the catalyst used is prone to coking and deactivation, the service life of the catalyst is short, the conversion rate of the catalyst is not high under low temperature conditions, and the low temperature reaction effect is not good

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