Development of CuO-based oxygen carriers supported on diatomite and kaolin for chemical looping combustion

Abstract

Chemical Looping Combustion (CLC) technology has emerged as a promising alternative capable of restricting the effects of global warming due to anthropogenic gas emissions, especially CO2, through its inherent capture. This study aims to synthesize and evaluate Cu-based oxygen carriers supported on natural materials such as diatomite and kaolin, through the incipient wet impregnation method for CLC process applications. Oxygen carriers were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), and scanning electron microscopy with surface energy dispersive x-ray spectroscopy (SEM-EDS). The mechanical strength of the two oxygen carrier particles was determined after the sintering procedure resulting in high crushing force. Reactivity of oxygen carriers was evaluated in a thermobalance with CH4 and H2 gases. Different reaction pathways were attempted when undergoing the redox cycles: total direct reduction of CuO to Cu0 for Cu-K and partial reduction of CuO to Cu2O and CuO to Cu-D. However, the highest reactivity and reaction rate was achieved in Cu-D due to the pore structure of diatomite, the chemical composition and the resulting interaction between CuO and the support. H2 gas reactivity tests showed a higher conversion rate and greater stability between cycles for both oxygen carriers. Thus, the reducible CuO content present in Cu-Diatomite during the reactivity test with H2 as the fuel gas was ideal for achieving high solids conversion, tendency for greater stability and a higher reaction rate.

A influência de Ni e Co suportados em diatomita brasileira para produção de H2 via reforma a seco do metano

“…Wang et al, 2016) . Studies point to this material being used as a filtration aid for the removal of heavy metals and organic pollutants (Tanniratt et al, 2016;Xia et al, 2017) as a source of silica in the synthesis of zeolites (Garcia et al, 2016;Nascimento et al, 2014) in the preparation of photocatalysts (B. Li et al, 2015), besides of support from oxygen carriers in Chemical Looping Combustion (Romário, 2021) and in the production of ceramic bricks (Costa et al, 2021). Recently, diatomite has been highlighted as catalytic support due to some properties such as thermal and mechanical resistance (Liu et al, 2018).…”