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CO2 Hydrogenation to Methanol over a Highly Active Cu–Ni/CeO2–Nanotube Catalyst

Tan, Qingqing, Shi, Zhisheng, Wu, Dongfang
Industrial & engineering chemistry process design and development 2018 v.57 no.31 pp. 10148-10158
adsorption, alloys, carbon dioxide, catalysts, catalytic activity, ceric oxide, cerium, copper, hydrogenation, methanol, nanotubes, nickel, oxygen, process design, space and time, synergism, yields
A series of Cu–Ni/CeO₂-nanotube catalysts is prepared by an impregnation method for CO₂ hydrogenation to CH₃OH. Regular CeO₂ nanotubes are perfectly formed with a tube diameter of about 30–50 nm and Cu–Ni alloy is well dispersed on CeO₂ nanotube without nanotube morphology change. There is a synergistic effect between Ni and Cu, promoting the bimetallic Cu–Ni dispersion, reducibility, CO adsorption and hydrogenation. Additionally, a strong interaction is observed between Cu–Ni alloy and CeO₂, and it contributes to partial reduction of Ce⁴⁺ to Ce³⁺ and formation of oxygen vacancies which adsorb and activate CO₂. It is shown that both CO₂ conversion and CH₃OH space-time yield increase at first, reach their maximum values at a Ni/(Cu+Ni) ratio of 2/3, and then decrease with increasing the Ni/(Cu+Ni) ratio. The CeO₂-nanotube supported CuNi₂ catalyst gives CO₂ conversion of 17.8% and CH₃OH space-time yield of 18.1 mmol/(gcₐₜ·h) after preliminary optimization. Furthermore, it exhibits an excellent catalytic performance within a wide range of space velocity.