Energy and cost-saving potential of combined carbon capture and conversion: a pioneering design of a process intensification concept harnessing CeO2 as a dual-functional material

Abstract

Materials that can catalyse the conversion of carbon dioxide (CO₂) into chemicals are gaining increasing attention. However, the high energy consumption for CO₂ capture hinders the commercial application of such materials. To overcome this gap, here, we propose an intensified process concept termed combined carbon capture and conversion (quad-C). In this concept, the captured CO₂ is seamlessly provided to the subsequent reaction, without having to prepare purified CO₂. This concept can be realised, for example, by harnessing a material capable of adsorbing CO₂ from a gas mixture, such as flue gas and air, while catalysing the CO₂ conversion when the reactant is supplied under appropriate conditions. Cerium oxide (CeO₂) is one of the most promising materials that exhibit such dual functions for carbon capture and conversion. We present the quad-C concept instantiated as a packed column that functions as a carbon capture devise and carbon conversion reactor in turn, for the production of organic urea derivatives. The energy-saving potential of the quad-C process is explored by incorporating the data from state-of-the-art quad-C experimental studies using ethylenediamine (EDA) to produce 2-imidazolidinone (ethyleneurea, EU). Process intensification via quad-C can reduce energy consumption and enhance economic viability for CO₂ capture, while the energy-saving potential for EU production depends on the recycle ratio of the EU-rich liquid. The energy-saving potential of the quad-C process can be further enhanced by incorporating various strategies, such as air-drying and EDA liquid reduction.