Catalyst used for preparing fluorinated alkene with chloro-fluoro alkane and preparation method thereof

Abstract

The invention belongs to the field of refrigerants, and provides a catalyst used for preparing fluorinated alkene with chloro-fluoro alkane and a preparation method thereof. The general formula of the catalyst is n wt.%M / X, wherein M stands for an active component, X stands for a carrier, and n stands for the dosage of the active component; the active component is composed of alkali metal oxide, rare-earth oxide, and high valent metal oxide; the carrier adopts coal-based activated carbon or plant-based activated carbon; the dosage of the active component is less than or equals to 40% of the total mass of the catalyst. The method comprises the following steps: dipping the carrier in water solution corresponding to the active component, drying the dipped carrier at the temperature of 80-120 DEG C for more than 12 h, and finally, roasting at the temperature of 400 DEG C-550 DEG C for 6 h to obtain the catalyst. The catalyst manufactured by the method has higher preferential adsorption for chloro-fluoro alkane molecules, so as to have low purity requirement for raw materials, high selectivity for dehydrochlorination, and high yield for a target product.

Description

technical field [0001] The invention belongs to the field of refrigerants and relates to a catalyst, in particular to a catalyst and a preparation method for preparing fluorine-containing olefins from chlorofluoroalkanes. Background technique [0002] Fluorine-containing olefins, especially hydrofluoroolefins (hydrofluoroolefins, HFO), such as 2,3,3,3-tetrafluoropropene (HFO-1234yf) are new organic fluorines with zero ozone depletion potential (ODP) and low GWP value. Compounds have been considered to be the best substitutes for HFCs widely used at present, as refrigerants, fluorine-containing plastic monomers, etc. [0003] Gas-phase catalytic dehydrochlorination of chlorofluoroalkanes is a major method for the preparation of hydrofluoroalkenes. Such as 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb) dehydrochlorination to generate HFO-1234yf. [0004] Chinese patent (publication number: CN102046569) discloses an alkali metal-doped magnesium oxyfluoride catalyst for the ...

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Problems solved by technology

[0004] Chinese patent (publication number: CN102046569) discloses an alkali metal-doped magnesium oxyfluoride catalyst for the reaction of HFO-1234yf from HCFC-244bb under high temperature gas phase conditions; Chinese patent (publication number: CN101772480) discloses A method using activated carbon as a catalyst to prepare HFO-1234yf by removing HCl from HCFC-244bb at a certain temperature. The conversion rate can reach up to 80%, but there is no report on the selectivity of HFO-1234yf

[0005] The gas-phase dehydrochlorination catalysts reported above have high requirements on the purity of raw materials during their use (generally, the purity of 244bb should be above 95%), otherwise the selectivity of the target fluoroolefins and the service life of the catalyst will be greatly reduced. Therefore, large-scale preparations containing There are many separation operations in the process of fluoroolefins, and the energy consumption and cost are high