Adsorption for Co2 Capture: Experimental Focus on the Thermodynamic and Kinetic Role of Water

Abstract

A global energy transition based on low-carbon energy is urgently needed to limit greenhouse gas emissions and the resulting global warming in the next decades. To tackle greenhouse gas effects, particularly CO2 contributing to 70% of the overall emissions, drastic changes must be made. TotalEnergies R&D is actively focusing efforts on different pieces of the CCUS (Carbon Capture Utilization and Storage) puzzle through different actions such as carbon capture using different technologies, geological sequestration, carbon conversion, etc. Among existing post-combustion capture technologies, the most mature, absorption from amine solvent, still presents many important challenges such as high energy consumption, corrosion and emissions which makes it important to investigate alternative technologies. Adsorption on a porous media appears as a promising alternative and has become a very active domain with over 30 specific reviews in the last decade. Many solid porous sorbents have been developed and characterized such as amine-based silicas, Metal Organic Frameworks (MOF’s), zeolites, Active Carbons (AC’s), Covalent Organic Polymers (COP’s), etc…Their characterization tends to focus specifically on CO2 and nitrogen adsorption performances and less attention is paid to the effect water. Two main reasons are that experimental techniques are more complicated as water in vapour phase is difficult to handle and its modelling is complex. However not including water strongly limits the value of the results obtained for adsorption-based CO2 capture as its impact on the sorbent and the process is vital to perform good technico-economical analysis in order to identify the most cost-effective combination of sorbent and process. The aim of this work is thus to present an experimental study that allows to evaluate the global impact of the presence of different moisture relative levels in the flue gas on the thermodynamic and kinetic properties on small amounts of some reference samples by coupling various experimental qualitative and quantitative as well as static and dynamic methods. More precisely, the adsorption isotherms of pure gases measured by manometric and gravimetric devices are coupled with qualitative coadsorption experiments performed by means of a thermogravimetric (TGA) apparatus coupled with an humidity generator and quantitative dynamic experiments carried out with a breakthrough curves apparatus.

Keywords: CO2 capture, adsorption, water, adsorbent