Steering the Reaction Pathway of Tandem Catalytic Oxidation of HCHO Under Ambient Condition via Methanol Intermediate

Abstract

ABSTRACT Tandem catalytic systems for HCHO oxidation are generally regarded as a relay process comprising intermediate (e.g., Methyl formate, MF) generation on zeolites and subsequent intermediates‐to‐CO 2 conversion on supported metal catalysts. Here, a new cascade pathway mediated by the secondary intermediate methanol (CH 3 OH) over ZSM‐5/Pt‐γ‐Al 2 O 3 tandem catalyst is proposed, which is composed of physically mixed ZSM‐5 and Pt‐γ‐Al 2 O 3 with an overall Pt content of only 0.3 wt%. In this system, the CH 3 OH is generated directly via MF decomposition on acidic ZSM‐5 and subsequently serves as the primary active intermediate on Pt‐γ‐Al 2 O 3 catalyst, enabling efficient HCHO‐to‐CO 2 complete conversion under ambient conditions. The deep studies with Pd‐ and Ag‐based tandem systems further reveal that the reaction pathway is steered by the intrinsic reactivity of intermediates on supported metal catalysts: CH 3 OH‐mediated cascade routes dominate in Pt‐ and Pd‐containing systems, whereas MF remains the sole reactive intermediate over Ag‐based tandem catalysts. Additionally, we demonstrate that the molecular diffusion of key intermediate within ZSM‐5 plays a decisive role in proximity‐dependent catalytic behavior. Specifically, the strong adsorption affinity and interfacial accumulation of CH 3 OH on ZSM‐5 necessitate close spatial proximity between the zeolite and Pt catalyst, in contrast to the weaker adsorption affinity of MF.