Catalyst Deactivation Process in 1,1,2-TCE Catalytic Dehydrochlorination Reaction

Abstract

The heterogeneous catalytic splitting reaction of 1,1,2trichloroethane (1,1,2-TCE) was designed to study the process of catalyst deactivation. The results showed that the conversion of 1,1,2-TCE decreased from 51.34 to 44.01%, while the selectivity of vinylidene chloride decreased from 65.12 to 61.77% (260 °C, 8h), which indicated a decrease in catalyst activity. Solid-phase microextraction gas chromatography−mass spectrometry characterization was performed to confirm species on the surface of the spent catalyst. Density functional theory calculations revealed the essence of 1,1,2-TCE splitting to produce different products, and then a possible reaction network was proposed. Tandem side reactions occurred to generate chloroacetylene, which was an unstable species. Chloroacetylene selfpolymerized to form dichlorobutadiene and further polymerized to form aromatic compounds. The coke deposition precursors agglomerated on the surface of the active component, leading to catalyst deactivation. These conclusions explained the deactivation of the catalyst during 1,1,2-TCE dehydrochlorination, thus providing a theoretical basis for further research on methods to inhibit deactivation. Breaking through the key problem of catalyst deactivation would make it possible to replace the saponification reaction with catalytic dehydrochlorination in industry.