One-Pot Cascade Catalysis of Dehydrochlorination of Greenhouse Gas HCFC-142b and Hydrochlorination of Acetylene for the Spontaneous Production of VDF and VCM

Abstract

Hydrochlorofluorocarbon (HCFC) has been widely applied as the third-generation refrigerant globally, however, the global warming potential of such gases is often 100 and 1000 times higher than that of CO2. Dehydrochlorination reaction offers an encouraging strategy to transform the high-global-warming-potential gases of hydrochlorofluorocarbons (HCFCs) to low-global-warming-potential gases of hydrofluoroolefins (HFOs). However, the handling of a large amount of byproduct HCl remains one of the major challenges blocking the industrialization of dehydrochlorination of HCFC-142a for the production of vinylidene fluoride (VDF). A one-pot cascade reaction combining dehydrochlorination of HCFC-142b and hydrochlorination of acetylene was first proposed to spontaneously produce valuable monomers of VDF and vinyl chloride monomer (VCM) while eliminating the tedious HCl treatment step. Both thermodynamic calculations and experimental results validate the feasibility of the cascade reaction. Five different heterogeneous catalysts were screened for the proposed cascade reaction, including monocomponent catalyst BaF2, NAC, bifunctional BaF2/NAC catalyst, and bicomponent BaF2-NAC-S and BaF2-NAC-M catalysts. Among them, the mixed BaF2-NAC-M catalyst demonstrated the best catalytic performance, with BaF2 mainly acting as the dehydrochlorination site and NAC mainly acting as the hydrochlorination site. The corresponding reaction mechanism was also proposed.