Preparation of carbon-containing copper-based catalysts and its performance in selective hydrogenation of acetylene

The solid precursor was synthesized by adding NaOH dropwise to the Cu(NO3)2 solution while passing acetylene gas, and the precursor was reduced under H2 atmosphere to produce the copper-based catalyst, containing CuxC.. The prepared precursors and catalysts were characterized by XRD, XPS, TEM, GC-MS and N2 physisorption-desorption. The catalysts were evaluated in the selective hydrogenation of acetylene. The results showed that in the strongly alkaline environment provided by NaOH, Cu²⁺ is reduced by the introduced acetylene gas to form Cu⁺, which then reacts with acetylene to generate Cu₂C₂. Under the coexistence of Cu²⁺ and alkaline conditions, Cu₂C₂ undergoes the Glaser coupling reaction to form polyynic copper. The precursor containing copper acetylide and polyynic copper is then reduced by H₂ to obtain a copper-based catalyst containing CuₓC-Cu. The optimal preparation conditions of the catalyst were acetylene gas flux time of 1 h, molar ratio of NaOH to Cu2+ OH-:Cu2+=4:1, precursor synthesis temperature of 50 ℃, and hydrogen reduction temperature of 150 ℃. The copper-based catalysts prepared under the optimum conditions showed 100 % acetylene conversion and 18 % ethane selectivity at 95 ℃ and 0.1 MPa, which remained stable for 100 h.