Thermocatalytic analysis of CO2-CO selective chemisorption mechanism on lithium cuprate (Li2CuO2) and oxygen addition effect

Abstract

In the present work, thermogravimetric and catalytic analyses were performed in order to evidence the chemisorption selective mechanism followed during the CO and CO2 chemisorption processes on Li2CuO2 under different atmosphere conditions. Results were contrasted with some thermodynamic data. According to TG results, when the gas flow was composed by one gas (CO or CO2), chemisorption occurred through a superficial reaction followed by a volumetric capture. In the CO case, a double process was produced; CO oxidation and subsequent CO2 chemisorption. Here, Li2CuO2, initially, catalyzed the CO oxidation and then it sorbed CO2. However, as Li2CuO2 structure and composition evolves, it could not be strictly considered as a catalyst. On the other hand, when both gases were present (CO-CO2), a chemisorption competition was observed as a function of temperature, where CO was always selectively chemisorbed. Furthermore, O2 presence modified positively the chemisorption abilities in binary (CO-O2 and CO2-O2) and ternary (CO-CO2-O2) gas systems, in comparison with analogous tests performed in absence of O2.