Transportadores sólidos de oxigênio a base de Cu e Mn suportados em minerais para utilização em tecnologia de recirculação química com captura de CO2

Abstract

Energy systems with carbon dioxide capture and storage have been shown to be an alternative to minimize greenhouse gas emissions. The capture of CO2 by combustion by chemical recirculation, from Chemical Looping Combustion (CLC), stands out for not having energy penalty, but the cost and efficiency of the process depend on the materials used as oxygen carriers. In view of this, this work aims to synthesize and evaluate solid copper and manganese oxygen carriers supported on diatomite and kaolin in order to produce energy through indirect burning of fossil fuels through the CLC process. The carriers were synthesized by the incipient wet impregnation technique and characterized by X-ray diffraction, scanning electron microscopy equipped with an X-ray dispersive energy analyzer, mechanical resistance, air jet index, reduction at programmed temperature and reactivity tests by thermogravimetry. The oxygen transport capacity of each sample (Roc) was also obtained by thermogravimetry. X-ray diffraction analysis detected the presence of characteristic peaks of the active phases (CuO, Mn3O4 and Mn7SiO12), which were also confirmed by programmed temperature reduction tests. The mechanical resistance of conveyor particles below 1N is unviable in CLC beds. The samples Mn-C, Cu-C e Cu-D obtained mechanical resistance between 1.76 and 2.96N. The reactivity of the samples was evaluated by thermogravimetry, where three reduction and oxidation cycles were performed. In this analysis it was observed that CuO supported in diatomite (Cu-D) stood out in relation to the others, due to its high reactivity and oxygen transport capacity. This material obtained a conversion percentage of H2 above 95%, followed by kaolin supported CuO (~ 90%). Manganese-based materials presented conversion results of H2 and CH4 above 90%, but were not efficient in oxidation, losing reactivity at each cycle. The copper-based samples are promising, as they obtained mechanical resistance above 2N, high oxygen transport capacity and fuel conversion efficiency, with values above 95%.