Status and Outlook of Solid Electrolyte Membrane Reactors for Energy, Chemical, and Environmental Applications

Abstract

Solid electrolyte membrane-based reactors (SEMRs) can be operated at super high temperatures with distinct reaction kinetics, or at reduced temperatures (300-500 oC) for industrial-relevant energy applications (such as solid oxide fuel/electrolysis cells, direct carbon fuel cells, and metal–air batteries), chemical (such as alkanes dehydrogenation, C-C coupling, and NH3 synthesis), environmental (De-NOx, CO2 utilization, and separation), as well as their combined (one-step coupled CO2/H2O co-electrolysis and methanation reaction fields, power and chemical cogeneration) applications. SEMRs can efficiently integrate electrical, chemical, and thermal energy sectors, thereby circumventing thermodynamic constraints and production separation issues. They offer a promising way to achieve carbon neutrality and improve chemical manufacturing processes. This review thoroughly examines SEMRs utilizing various ionic conductors, namely O2-, H+, and hybrid types, with operations in different reactor/cell architectures (such as panel, tubular, single chamber, and porous electrolyte). The reactors operate in various modes including pumping, extraction, reversible, or electrical promoting modes, providing multi-functionalities. The discussion extends to the examination of critical materials for solid-state cells and catalysts essential for specific technologically important reactions, focusing on electrochemical performance, conversion efficiency, and selectivity. The review also serves as a first attempt at work that delves into the potential of process-intensified SEMRs through the integration of photo/solar, thermoelectric, and plasma energy and explores the unique phenomenon of electrochemical promotion of catalysis (EPOC) in membrane reactors. The ultimate goal is to offer insight into ongoing critical scientific and technical challenges like durability and operational cost hindering the widespread industrial implementation of SEMRs while exploring the opportunities in this rapidly growing research domain. Although still in its early stages and with limited large-scale demonstration and application, advances in materials, catalysis science, solid-state ionics, and reactor design, as well as process intensification and/or system integration will reduce the gaps in the current high temperature operation of SEMRs and industrial-relevant applications like sustainable clean chemical production, efficient energy conversion/storage, as well as environmental enhancement.