Tailoring the Olefin Selectivity in Catalytic Oxidative Dehydrogenation of Light Alkane by the Isolation Strategy

Olefins are important building blocks that have been extensively used to produce diverse consumer products in petrochemical industry. Owing to the requirement of low-carbon-footprint processes and the increasing use of light alkanes sourced from shale gas, an environmentally friendly and economic route alternative to the state-of-the-art steam cracking of crude oil has been investigated for olefin production. The oxidative dehydrogenation (ODH) of alkanes to olefins has attracted wide attention due to the absence of thermodynamic limitations and coke formation. However, excessive oxidation of olefin is prone to occur in this process. Developing a suitable ODH catalyst with high performance, particularly with enhanced selectivity, is more and more urgent but still remains a challenge. In this Review, we talk about the representative currently developed isolation strategies to optimize the selectivity of olefins via the ODH process, particularly for the conversion of ethane to ethylene, which include the dispersion regulation of metal oxide, the isolation of metal and nonmetal sites, the construction of dual functional sites to isolate dehydrogenation and oxidation steps, and the adoption of selective oxygen species with the promotion of soft oxidants as reactants. Furthermore, the mechanistic aspects about the activation of ethane and the participation of oxygen species for tailoring the selectivity are then classified and discussed in detail. Finally, the perspectives and the emerging technologies for the ODH process are listed and evaluated.