Study of the effect of ceria on the activity and selectivity of Co and Ce co-doped birnessite manganese oxide for formaldehyde oxidation

Catalytic oxidation is a promising approach to eliminating formaldehyde (HCHO) to improve indoor air quality. Herein, CeO2 was explored due to its remarkable properties for oxygen storage and oxygen transfer capability for co-doping 8-MnO2 alongside cobalt for enhanced low-temperature oxidation of HCHO. Various characterization techniques were deployed to understand the morphology and physicochemical properties of the synthesized catalysts. The Co-Ce co-doped catalysts with low CeO2 loading (0.05 and 0.1) showed higher catalytic activity for HCHO oxidation due to their higher concentration of surface-active oxygen species. Catalytic oxidation results showed that the presence of CeO2 leads to the generation of methanol as a secondary hazardous pollutant. Methanol selectivity increases with increasing CeO2 loading in the catalysts. The results from in-situ DRIFTS confirmed the formation of methoxy species in the presence of CeO2, which are intermediates for methanol generation. Considering the recent interest in CeO2 as a potential catalyst for practical abatement of HCHO from the indoor environment, this work has thus raised questions on the safety of using CeO2 as a catalytic material for HCHO oxidation. It also provides insights into the surface reaction mechanism leading to the generation of methanol in the presence of CeO2.

Automated summary

CeO2 is explored as a catalyst for oxidation of formaldehyde to improve indoor air quality, but it leads to the generation of methanol as a secondary hazardous pollutant. The study provides insights into the surface reaction mechanism leading to methanol generation during formaldehyde oxidation in the presence of CeO2.