Redox-driven restructuring of lithium molybdenum oxide nanoclusters boosts the selective oxidation of methane

Abstract

Selective methane oxidation is one of the key challenges in modern chemistry. To increase the value-added chemical production, the oxidation state of active metals should be easily converted to oxidized or reduced states in order to adsorb or provide an oxygen atom efficiently into methane. Here, we firstly report that lithium incorporating molybdenum oxide with silica supports significantly enhances HCHO production in virtue of redox-driven restructuring of active molybdenum sites. In reduction conditions under CH4 flow, lithium ions are inserted into the molybdenum-oxide phase by forming lithium molybdenum oxide (LiyMoO3) nanoclusters and conversely extracted by O2 oxidation. Due to the redox migration of lithium ions and reconstruction of LiyMoO3 nanoclusters under the reaction process, the oxidation state of active molybdenum centers is effectively controlled to both oxidized and reduced states. These findings provide insight into the distinct role of lithium ions in various catalytic systems and suggest new strategies for developing active sites for selective oxidation area. © 2020