Engineering Co 3 O 4 @3DOM LaCoO 3 multistage-pore nanoreactor with superior SO 2 resistance for toluene catalytic combustion.

Sulfur dioxide poisoning is a significant factor in catalyst deactivation during the catalytic combustion of volatile organic compounds. In this study, we prepared the LaCoO 3 and Co 3 O 4 composite catalysts using both the Ship-in-Bottle and Building-Bottle-Around-Ship approaches. Three-dimensionally ordered macropores (3DOM LaCoO 3 ) were utilized as nanoreactors to protect the active sites during the catalytic combustion of toluene, preventing SO 2 poisoning. Additionally, we grew ZIF-67 confined in the nanoreactor to create a multistage-pore structure. The Co 3 O 4 @3DOM LaCoO 3 catalysts exhibited excellent activity in the complete catalytic oxidation of toluene. Various characterization studies confirmed the presence of a significant number of Co 3+ species and an abundance of surface weak acid sites in the Co 3 O 4 @3DOM LaCoO 3 catalysts, which synergistically enhanced the conversion of VOCs at low temperatures. Notably, the multistage pore structure provided a favorable reaction environment, accelerating the adsorption and diffusion of toluene and intermediates, resulting in excellent sulfur resistance of the catalysts. Moreover, XPS analysis confirmed a strong interaction between Co 3 O 4 and LaCoO 3 , promoting rapid electron transfer and increasing the activation of O 2- . In situ DRIFTS experiments verified that toluene mainly follows the MvK mechanism over Co 3 O 4 @3DOM LaCoO 3 catalysts, indicating the following reaction pathway: toluene adsorption → benzyl alcohol → benzaldehyde → benzoate → anhydride → CO 2 and H 2 O.