Deactivation Mechanism and Regeneration of the CuCl/Activated Carbon Catalyst for Gas-Solid Acetylene Dimerization.

Abstract

Acetylene dimerization is necessary to the coal chemical industry for producing monovinylacetylene, while the deactivation mechanism and regeneration of catalysts have not been studied in detail, which is crucial to the design of high-efficiency catalysts for acetylene dimerization. Herein, the deactivation mechanism and regeneration methods of CuCl/activated carbon catalysts in gas-solid acetylene dimerization were studied in detail. The catalysts with different reaction times were analyzed by temperature-programmed desorption of ammonia (NH3-TPD), Fourier transform infrared (FT-IR), thermogravimetry (TG), pyridine-FTIR, and X-ray photoelectron spectroscopy (XPS) analyses. NH3-TPD results demonstrated that as the time went on, the strong acid in the samples was enhanced, while the weak acid was weakened. Similarly, pyridine-FTIR results indicated that both Brönsted and Lewis acids in the samples were decreased. TG and XPS results showed that the reasons for deactivation for acetylene dimerization in the gas-solid reaction were significantly affected by coke deposition and the change of Cu valence. The more the content of Cu+, the higher the acetylene conversion rate, implying that Cu+ may be the active center of the acetylene dimerization reaction. Thus, removing carbon deposition through calcining and increasing the content of Cu+ was an effective way of regenerating the catalyst. This work strengthened the understanding of the deactivation behavior and provides a practicable regeneration method for the catalyst in gas-solid acetylene dimerization.