Effect of Fuel Gas Composition in Chemical-Looping Combustion with Ni-Based Oxygen Carriers. 1. Fate of Sulfur

Fe2O3/Al2O3/ZnO oxygen carriers with small content ZnO (5 wt% to 10 wt%) were prepared by physical mixing method and were evaluated its capability as an oxygen carrier in a chemical looping combustion. The combustion was conducted by using CH4 as a fuel gas. The reduction process of Fe2O3/Al2O3/ZnO oxygen carrier was carried out in a fixed bed reactor. The solid reduction products were characterized by X-ray diffraction (XRD) and Scanning Electron Microscope with EDS Attachment (SEM-EDS). The results show that the reactivity of Fe2O3/Al2O3/ZnO oxygen carriers is greater than that of Fe2O3/Al2O3 which is implied the synergetic effect between ZnO and Fe2O3. XRD results show that the iron oxide in the oxygen carriers is reduced to metallic iron. SEM-EDS also shows that the iron agglomeration is prevented. Consequently, the suitable content of ZnO in oxygen carriers is ranged from 5 wt% to 10 wt%.

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

Research Society and Development ◽

10.33448/rsd-v10i4.12831 ◽

2021 ◽

Vol 10 (4) ◽

pp. e15110412831

Author(s):

Romário Cezar Pereira da Costa ◽

Rebecca Araújo Barros do Nascimento ◽

Dulce Maria de Araújo Melo ◽

Dener Silva Albuquerque ◽

Rodolfo Luiz Bezerra de Araújo Medeiros ◽

...

Keyword(s):

Reaction Rate ◽

Direct Reduction ◽

Oxygen Carrier ◽

Chemical Looping Combustion ◽

Chemical Looping ◽

Impregnation Method ◽

Oxygen Carriers ◽

Fuel Gas ◽

Promising Alternative ◽

X Ray

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.

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