Chemical looping with oxygen uncoupling of biomass-derived hydrochar with Cu-based oxygen carriers modified by alkaline earth metals

In this paper, the effect of alkaline-earth metals (AEMs, Ca, Ba, and Sr) on the performance of CuO/ZrO2 oxygen carriers (OCs) and the hemical looping with oxygen uncoupling (CLOU) process of wheat-derived hydrochars with these Cu-based OCs were investigated. The results showed that after multiple cycles, the crystal phases of modified Cu-based OCs were the same as that of pure CuO/ZrO2 OC without any interaction between them. Due to the catalytic effects of AEMs, an increase in the decomposition of wheat and hydrochar-235 in modified Cu -based was observed at 500 degrees C. The combination of Ca and HTC promotes reoxidation, while Ba and Sr inhibit reoxidation. Notably, the Cu-based OCs exhibited moderate agglomeration after 20 redox cycles at 950 degrees C. The results of the kinetic analysis indicate that the chemical order models and diffusion models can suitably describe the first combustion stage for wheat and hydrochars with Cu-based OCs, respectively. The geometrical contraction model was also found to most suitably describe the second combustion stage of all samples. These results suggest that a combination of hydrothermal carbonization pretreatment with AEMs modification is an efficient approach for CLOU using CuO-based OCs.

Automated summary

This study investigates the effect of alkaline-earth metals (AEMs) on the performance of CuO/ZrO2 oxygen carriers (OCs) and the chemical looping with oxygen uncoupling (CLOU) process using wheat-derived hydrochars. The results show that modified Cu-based OCs have the same crystal phases as pure CuO/ZrO2 OCs, and no interaction is observed between them. AEMs catalytic effects increase the decomposition of wheat and hydrochar-235 in modified Cu-based OCs at 500°C. Additionally, Ca promotes reoxidation while Ba and Sr inhibit reoxidation. The study emphasizes the efficiency of using hydrothermal carbonization pretreatment with AEMs modification for CLOU using CuO-based OCs.