Selective hydrogen combustion as an effective approach for intensified chemical production via the chemical looping strategy

Abstract

Demand continues to grow rapidly for commodity chemicals, such as light olefins, at a time when the chemicals sector must strive to reduce its energy consumption and greenhouse gas emissions. Process intensification provides a framework for producing the same chemical products with higher efficiency and lower emissions. In recent years, chemical looping has received increasing attention as a strategy for intensified chemical production. For example, the chemical looping oxidative dehydrogenation (CL-ODH) of ethane to ethylene offers the potential for near order-of-magnitude reductions in process energy usage and CO2 emissions in comparison to conventional ethane steam cracking, while chemical looping dehydroaromatization (CL-DHA) of methane offers a pathway for aromatics production at higher yields. In these examples, the CL processes rely on selective hydrogen combustion (SHC) to remove the co-produced H2 gas as water, providing several benefits, including yield increase, autothermal operation, and simplified downstream separation. As a yield-enhancing strategy, SHC is not new. However, the design of redox catalysts for SHC in a chemical looping context has only recently begun to be explored. In this perspective, we summarize previous research on SHC in chemical production schemes, and we attempt to outline priority areas of research in the years to come.