CO2 chemisorption to characterize calcium catalysts in carbon gasification reactions

CO2 chemisorption, at different temperatures, has been studied in CaO and in the CaO-carbon system by means of simultaneous TG-DTA, MS, and XRD techniques. As a whole the different techniques used show that CO2 chemisorbs in an irreversible manner and is mainly restricted to the surface of the CaO particles, provided that the chemisorption temperature is lower than 573 K. CO2 chemisorption at 573 K can be used as a tool to measure the external surface area of CaO particles. Selective CO2 chemisorption at 573 K has been applied to the CaO-carbon system in the field of catalytic carbon gasification. Several examples are given to show the usefulness of the catalyst surface area determined by CO2 chemisorption in interpreting the catalytic activity of calcium in carbon gasification.