A highly effective Ni-modified MnOx catalyst for total oxidation of propane: the promotional role of nickel oxide

Abstract

Nickel promoted manganese oxide (MnNiO_x) was prepared by the co-precipitation method and used as a catalyst for propane deep oxidation. The results show that the doping of Ni can effectively improve the catalytic performance of MnO_x for propane total oxidation, and when Ni/Mn is 0.2, the MnNi_0.2O_x catalyst exhibits the highest catalytic activity, for instance, the reaction temperature of 90% propane conversion (T₉₀) was only ∼240 °C, and it demonstrates good thermal stability in the operation at temperatures alternating between 220 °C and 350 °C. It was found that an Mn–Ni–O solid solution can be formed by adding a moderate Ni amount into MnO_x, resulting in changes in catalytically active sites by the synergetic interaction of Mn–Ni, such as a higher surface concentration of Mn⁴⁺ and oxygen vacancies, higher oxygen mobility and better reducibility. And the outstanding catalytic property of MnNi_0.2O_x can be also related to its high surface area. Furthermore, the in situ DRIFT technique was used to investigate the reaction process of propane oxidation over the MnO_x and MnNi_0.2O_x catalysts, and the results suggest that the reaction mechanism is hardly changed after Ni doping in MnO_x.