A surficial in situ growth strategy to fabricate monolithic catalysts of mesoporous Co-Cu bimetallic oxides supported on Ni foam for ethyl acetate efficiently oxidation

Abstract

A series of monolithic Cu-doped Co₃O₄ supported on Ni foam (NF) catalysts with mesoporous structure were successfully prepared by in situ hydrothermal synthesis, where the oxygen species and textural properties were regulated by varying the Cu/Co ratio of bimetallic mixed oxides supported on Ni foam. The role of oxygen species in catalytic oxidation of ethyl acetate (EA) was also elucidated. As a result, the monolithic catalyst with Co/Cu molar ratio of 1/2, labeled as CoCu₂O_x-NF, exhibited the highest conversion rate for EA oxidation (T₉₉ = 230 °C, GHSV = 3000 h⁻¹). The results of characterization show that its robust catalytic performance could be attributed to superior reducibility, sufficient Co³⁺ species and high mobility of active oxygen. In addition, the larger surface area and pore volume were also beneficial to catalytic performance due to increased gas diffusion. The characterization results of fresh and used catalysts and the study of reaction mechanism showed that lattice oxygen species played an important role in EA oxidation process which accelerated the EA activation and deep oxidation of carboxylate species over CoCu₂O_x-NF. As expected, the CoCu₂O_x-NF catalyst also presented good stability over EA oxidation in the presence of toluene as well as o-xylene. Hence, CoCu₂O_x-NF possessed satisfactory universality and long-term durability, which is a promising catalyst for industrial application.