Issue 4, 2024

Interaction of SO2 with a Cu–Mn oxide oxygen carrier during chemical looping with oxygen uncoupling

Abstract

Chemical looping with oxygen uncoupling (CLOU) is a variant of the chemical looping combustion (CLC) process, where fuel combustion occurs via metal oxides, known as oxygen carriers. The purpose of this study is to investigate how SO2 interacts with a Cu–Mn oxide oxygen carrier during CH4 combustion in the CLOU process. The oxygen carrier was reduced via CH4–N2 gas mixture with and without SO2 in a batch fluidized-bed reactor. The results indicate that SO2 does not affect the oxygen release capacity of a Cu–Mn oxide. However, it negatively affects the CH4 conversion by increasing CO formation as well as the unreacted CH4 amount. This adverse effect becomes more pronounced as the SO2 concentration increases. Increasing the temperature from 850 to 950 °C improves the conversion of CH4. During a reduction cycle, SO2 oxidizes to SO3, creating a competing demand for oxygen between fuel and SO2, and lowers CH4 conversion if there is not enough oxygen for both reactions. Hence, decreasing the feed CH4 concentration with a fixed oxygen carrier amount improves CH4 conversion in the presence of SO2. Additionally, characterization of SO2-exposed oxygen carriers shows that sulfate species form on the surface, possibly causing a further reduction in CH4 conversion. However, the presence of SO2 does not cause a permanent deactivation of the particles and they can be fully regenerated during the oxidation cycle.

Graphical abstract: Interaction of SO2 with a Cu–Mn oxide oxygen carrier during chemical looping with oxygen uncoupling

Supplementary files

Article information

Article type
Paper
Submitted
22 Sept. 2023
Accepted
21 Dec. 2023
First published
10 Janv. 2024

React. Chem. Eng., 2024,9, 888-900

Interaction of SO2 with a Cu–Mn oxide oxygen carrier during chemical looping with oxygen uncoupling

T. Barua and B. Padak, React. Chem. Eng., 2024, 9, 888 DOI: 10.1039/D3RE00498H

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