Understanding the effects of manganese and zinc promoters on ferrite catalysts for CO2 hydrogenation to hydrocarbons through colloidal nanocrystals

CO2 hydrogenation is a crucial reaction in the pursuit of sustainable fuels and chemicals. Iron-based catalysts, known for their activity, have garnered attention due to their potential, but sintering and still limited performance have encouraged researchers to explore additives and promoters in ferrite phases. Nonetheless, a systematic approach is required to comprehensively understand the roles of the promoters. This study analyzed the catalytic performance of colloidal ferrite nanocrystals added with manganese and zinc additives for CO2 hydrogenation. The precise control afforded by colloidal synthesis enabled the fine-tuning of catalyst properties. The findings revealed that both manganese and zinc additives effectively counteracted sintering effects, leading to decreased particle sizes after the reaction. The contribution of manganese additives to promoting CO2 hydrogenation performance was however limited, resulting in lower CO2 conversion and reduced selectivity towards C2+ hydrocarbons compared to the bare ferrite catalyst. Notably, the introduction of zinc instead yielded a dual benefit of improved catalytic activity and selectivity. This enhancement was attributed to enhanced reducibility that facilitated the formation of carbide-like phases, considered the active species.