Performance Study of Catalysts for Dehydrochlorination Reaction of 1,1,2-TCE Using In Situ FTIR-MS

Dichloroethylene is mainly used to prepare high polymer compounds such as vinyl chloride fibers and polyvinylidene chloride. It is also an important raw material for producing lithium-ion battery adhesives. The industrial method for producing dichloroethylene involves a saponification reaction between trichloroethane and sodium hydroxide, which can lead to high environmental pollution. The 1,1,2-TCE (1,1,2-trichloroethane) catalytic cracking method has been widely studied due to its environmentally friendly potential to replace the saponification method. However, the low performance and stability of the catalysts have hindered the further development. The main reason is the lack of research on the intermediate processes of catalytic cracking. In this paper, in situ FTIR (Fourier transform infrared spectroscopy) and mass spectrometry combined technology was innovatively adopted to study the intermediate process of catalytic cracking of 1,1,2-TCE. In situ FTIR was used to analyze the generation of intermediate products, and online mass spectrometry was used to analyze the composition of exhaust gas. The formation of saturated steam from inert gas bubbling reactants in an in situ reaction pool could be used to investigate the microscopic reaction behavior of reactants on the catalyst surface in a macroscopic time system. The results indicated that 1,1,2-TCE produced residual products such as chloroacetylene and vinyl chloride during the dehydrochloride process. When 0.6 Cs/Al₂O₃ (activated alumina loaded with cesium chloride) was used as the catalyst, the dehydrochlorination of 1,1,2-TCE produced more chloroacetylene, reaching 4.62% at 533 K. When 0.6 Ba/Al₂O₃ (activated alumina loaded with barium chloride) was used as the catalyst, the dehydrochlorination of 1,1,2-TCE produced more vinyl chloride, reaching 6.54% at 533 K. Under the catalysis of 0.6 Cs/Al₂O₃, the initial cracking temperature of 1,1,2-TCE was 405 K, while under the catalysis of 0.6 Ba/Al₂O₃, the initial cracking temperature of 1,1,2-TCE was 450 K. The results revealed real-time changes in reactants and products during the reaction process, which was of great significance for catalyst screening, process condition selection, and research on the reaction mechanism.