Controlled Growth of Silver Nanoparticles by Metal–Support Interaction for Enhanced Tandem Catalytic Oxidation of HCHO at Low Temperature
Yue Ding, Hui Wang, Bin Huang, Yuchun Chang, Yang Hua, Zhenping Qu
Abstract
Bifunctional zeolite-Ag catalysts with a tandem process offer a versatile pathway for efficient HCHO removal at low temperature. The overall performance of tandem systems is highly sensitive to the tunable nature of the Ag component. Herein, we report a tandem ZSM-5||Ag/γ-Al 2 O 3 catalyst that exhibits superior low-temperature activity compared to the ZSM-5||Ag/SiO 2 catalyst, achieving 100% conversion at 55 °C versus 32% for the latter. This dramatic improvement is attributed to the morphological variations induced by differences in the mobility and dispersion of supported Ag nanoparticles. This process involves a complex interplay between the properties of metal nanoparticles (NPs) and the supports. Combining experiments and advanced ab initio molecular dynamics simulations (AIMD), the control of Ag NPs growth behaviors by regulating metal–support interaction (MSI) strength and surface diffusion on different supports is revealed. Strong MSI and high diffusion barrier on γ-Al 2 O 3 triggers the slow Ostwald ripening (OR), whereas weak MSI and low diffusion barrier on SiO 2 stimulates the facile particle migration and coalescence (PMC), leading to rapid activity decay. The observed activity difference is strongly related to the surface activation of MF intermediates and the O 2 molecule, which was controlled by Ag NPs size. These findings demonstrate the feasibility and efficacy of controlling MSI strength for the design of stable and high-performance supported metal catalysts.