Oxidative Dehydrogenation of Isobutane to Isobutene over Metal-modified Mesoporous Silica Catalysts

Future petrochemical production will require more efficient use of fossil resources and reduction of CO2 emissions to achieve carbon neutrality. This review focuses on the production of isobutene, a key raw material for methyl methacrylate. Isobutene is present in the C4 fraction of naphtha and is as an important feedstock for plastics and solvents. The use of plant-derived feedstocks is being explored, but must be realistically combined with the better use of fossil resources, improved process efficiency, and CO2 capture and utilization technologies (carbon capture and storage and carbon capture, utilization, and storage). Both dehydrogenation and oxidative dehydrogenation have been investigated for isobutene production. Oxidative dehydrogenation occurs at low temperatures and results in minimal catalyst degradation, but reducing CO2 emissions remains challenging. This review focuses on the use of metal-modified mesoporous silica catalysts as a strategy to address this issue. In particular, Cr-modified SBA-15 has a high specific surface area which enhances isobutene yields. Addition of Mo inhibits catalyst degradation and produces high yields over extended reaction times. This review primarily summarizes experimental studies by our research groups and discusses the mechanism of enhancing isobutene yields over Cr-modified SBA-15 and the potential of Cr,Mo-modified SBA-15.