Controlled template removal from nanocast La0.8Sr0.2FeO3 for enhanced CO2 conversion by reverse water gas shift chemical looping

This study addresses an enhanced CO2 conversion of mesoporous La0.8Sr0.2FeO3 (LSF) perovskite synthesized using a nanocasting method in reverse water gas shift chemical looping (RWGS-CL) process. The effects of controlled template removal from the nanocast LSF on its textural property and resulting redox reactivity were thoroughly investigated. LSF was first impregnated on SBA-15 (a mesoporous silica template), which was removed by NaOH etching to monitor the residual Si content. Specific surface area, total pore volume, and metal dispersion of the nanocast LSF were dramatically enhanced as the residual Si content decreased, but Si contents of < 5 wt% caused the mesoporous structure to collapse. Temperature-programmed experiments revealed that both the reactivity and capacity of reducible oxygen were maximized by optimizing residual Si content at 10 wt %. XPS analyses showed that the atomic ratio of surface oxygen to lattice oxygen, a key indicator of CO productivity, was also maximized at a Si content of 10 wt%. The mesoporous LSF with this Si content achieved the highest average CO yield of 2.80 mmol/g for RWGS-CL at 600 degrees C, which was 5.9 fold-higher than that achieved by bulk LSF.

Automated summary

This study focuses on the enhanced CO2 conversion of mesoporous La0.8Sr0.2FeO3 perovskite synthesized using a nanocasting method in the reverse water gas shift chemical looping process. The study investigates the effects of controlled template removal on the textural property and redox reactivity, and finds that optimizing the residual Si content at 10wt% maximizes the reactivity and capacity of reducible oxygen. The mesoporous LSF with this Si content achieves a significantly higher average CO yield compared to bulk LSF.