Desarrollo y modificación superficial de adsorbentes para la captura de CO2 postcombustión

Resumen

[EN] Climate Change is a global phenomenon, caused by the increase in greenhouse gas emissions, the main cause being CO2 emissions arising from fossil fuel combustion. Moreover, due to the increase in global energy demand, fossil fuels are expected to remain the dominant source of energy in the near future. Therefore, CO2 capture and storage technologies will be essential if the global energy demand is to be met without contributing to global warming. The research carried out in this work falls within the framework of postcombustion CO2 capture by adsorption. More precisely, it focuses on the production of adsorbents specific for CO2 capture, by means of the development and surface modification of low-cost porous solids. During the course of the research, two different types of commercial adsorbents were evaluated as CO2 adsorbents: activated alumina and activated carbons. Activated carbons were also developed from biomass residues, olive stones and almond shells through a carbonisation step followed by physical activation with CO2. In addition, the surface chemistry of the adsorbents was modified in order to study its influence on CO2 adsorption. Surface modification was conducted by two techniques: wet impregnation with amines, and heat treatment in the presence of ammonia gas. The adsorbents were chemically and texturally characterised, and their CO2 capture capacity was evaluated by means of a thermogravimetric analyser, in pure CO2, between 25 and 100 ºC. Finally, the CO2 capture performance of selected adsorbents was evaluated using a binary mixture of CO2 and N2, representative of postcombustion conditions, in a purpose-built experimental device. With this equipment, the breakthrough curves of the materials were obtained, and three different regeneration strategies studied: Vacuum Swing Adsorption (VSA), Temperature Swing Adsorption (TSA) and VTSA.