A Comprehensive Review of Chemical Looping Processes: From Fundamentals to Applications

Chemical looping (CL) technologies have emerged as transformative approaches for energy conversion, carbon capture, and sustainable chemical production. Based on cyclic redox reactions of solid oxygen or nitrogen carriers, CL processes enable inherent separation of CO2, high thermal efficiency, and reduced pollutant formation compared with conventional combustion and reforming methods. This review provides a comprehensive assessment of the current status and recent advances across multiple CL applications, including combustion of gaseous, liquid, and solid fuels, hydrogen generation via reforming, gasification, and water splitting, and novel extensions for ammonia synthesis, air separation, oxidative coupling of methane, and oxidative dehydrogenation of light hydrocarbons. Key developments in oxygen carrier (OC) materials, ranging from Ni-, Cu-, Fe-, Mn-, and Co-based oxides to natural ores, mixed oxides, perovskites, and composites, are critically evaluated in terms of redox activity, stability, cost, and environmental impact. Various reactor configurations and pilot-scale demonstrations worldwide are reviewed, highlighting progress in scaling CL from laboratories to MWth pilot units. Techno-economic and life cycle assessments consistently point to CL’s potential for achieving low-carbon power and chemical production, although challenges remain in oxygen carrier durability, reactor scale-up, and system integration under industrial conditions. Collectively, these advances position chemical looping as a versatile pathway for decarbonized energy generation, negative-emissions bioenergy systems, hydrogen production, and sustainable chemical manufacturing.