Effect of A, B-site cation on the catalytic activity of La1−xAxMn1-yByO3 (A = Ce, B = Ni) perovskite-type oxides for toluene oxidation

Roles of the A-Site Ca Dopant in Modifying Surface Properties of a Co-Based Perovskite Catalyst for Selective Oxidation of Cyclohexane

“…are regarded as inert in catalysis and act as a rigid structural element in the crystal of perovskite oxides, while the B-site transition metal elements (e.g., Co, Mn, Fe, etc.) are mainly responsible for catalytic activity. , However, it should be noticed that the valence states of B-site redox elements and the crystal structure in perovskite oxides can be effectively altered by doping with both of A/B-site elements, which will also trigger the formation of abundant oxygen vacancies and lead to enhancement of oxygen mobility. − In previous studies, the low-valence elements (such as K, Sr, Ca, Co, Ni, and Cu) were usually applied to dope into the A/B-sites of various perovskite oxides to further improve their catalytic activity. − For example, Zhao et al reported the effect of different doping contents of Co 2+ in the B-site of LaFeO 3 on chemical looping steam methane reforming. They found that the substitution of Fe with an appropriate content of Co could promote the generation of oxygen vacancies, improve the reducibility of LaFe 1– x Co x O 3 , and change the types of oxygen species, which eventually facilitated the partial oxidation of methane, inhibited the direct decomposition of methane, and produced more hydrogen in chemical looping methane reforming.…”

“…Similarly, Cui et al reported that the doping of Ca 2+ into the A-site of LaCoO 3 could further enhance its reducibility and promote the generation of oxygen vacancies on the surface of the catalyst, leading to a better performance in catalytic combustion of toluene. To our knowledge, the perovskite-type oxides provide a large space for screening optimal catalysts with considerable cost reduction compared with noble-metal and complex catalysts, which have been widely used in gas-phase combustion of alkanes to produce CO 2 and H 2 O with good performance. ,− However, the application of perovskite-based oxide catalysts in liquid-phase selective catalytic oxidation of alkanes to high value-added chemicals is rarely reported in the past studies. This may be restricted by the harsh conditions for the synthesis of perovskite oxides, which result in a very low specific surface area (e.g., < 10 m 2 /g) of most perovskite oxides synthesized from combustion or solid-state synthesis methods.…”