Cu(II)Cu(I)/AC Catalysts for Gas–Solid Acetylene Dimerization

Influence of Brönsted Acid Sites on Activated Carbon-Based Catalyst for Acetylene Dimerization

Activated carbon (AC) has been widely used as a support material with both tunable acidity and abundant functional groups for solid acid catalysts in various chemical processes such as acetylene dimerization. A facile, mild acid modification method that directly activates AC to generate rich defects and oxygen functional group surface structures with Brönsted acid sites and an enhanced conductivity is presented here. Impressively, the catalyst with optimized Brönsted acid sites and an enhanced dispersion of active components exhibited a superior acetylene dimerization catalytic activity. Moreover, theoretical calculations indicated that an increase in hydrogen concentration could inhibit the formation of coke. This research offered a feasible potential way to devise and construct a carbon-based solid acid catalyst with an excellent catalytic performance.

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

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.