Chapter 10: Gas-phase CO₂ Recycling via the Reverse Water–Gas Shift Reaction: A Comprehensive Overview

Since the Industrial Revolution in the 1860s, the level of atmospheric CO₂ has been rising continuously, and this inevitably has taken our planet to an environmental limit situation. In this scenario, significant efforts have been made not only to reduce CO₂ emissions at the source but also to remove CO₂ via CO₂ capture and reutilisation. Among the developed strategies, the utilisation of CO₂ in a thermal-catalytic process to produce value-added chemicals and fuels has been attracting enormous attention over other strategies. Recently, the reverse water–gas shift reaction (RGWS) has been placed as a reviving pathway to convert CO₂ into CO since this process is the key intermediate stage in CO₂ hydrogenation. CO is an essential reactant in different reactions, which allows the further conversion of CO to high-value chemicals, such as methanol, methane, formic acid, olefins and liquid fuels. Thus, the RWGS is able to unlock opportunities to boost the CO₂ conversion efficiency and provide a unique opportunity in large-scale industrial applications. However, the design and development of highly active and robust heterogeneous catalysts is still a fundamental requirement for this process to overcome CO₂ activation and the catalytic deactivation and yield high level of CO. In this chapter, an overview of the main advances in the RWGS process and the different novel catalysts reported in the last decades are presented. The authors' aim is that this chapter will constitute a useful starting point for researchers working in this field.