Effect of interconnected mesoporous structure on HCHO catalytic oxidation over transition metal doped Ag/MCM-41

Abstract

HCHO, as a major indoor air pollution, has been a threat to human health for many years. In this work, we successfully synthesized Ag/MCM-41 with parallel hexagonal mesopore array and Ag/TM-MCM-41 (TM = Fe, Mn or Ce) with highly interconnected mesopore array to discover the effect of interconnect mesoporous structure on HCHO catalytic oxidation activity. All three different Ag/TM-MCM-41 exhibited better HCHO catalytic oxidation activity than Ag/MCM-41 during activity test. We believe that the interconnected short-range mesopores are caused by the transition metal ions attached to the outer surface of silicate-CTA+ micellar rods during synthesis process of TM-MCM-41, which speeds up the polymerization and restricts the mobility of micellar rods. As a result, those micellar rods which are later mesopores stay crossed with each other rather than rearrange to long-range parallel hexagonal array. These specific mesopores not only can improve the loading and dispersion of Ag, but also lead to a more effective mass transfer than typical mesopores of Ag/MCM-41. Besides, by interacting with Ag species, transition metal oxides significantly enhance the electron transfer on Ag/TM-MCM-41, which is responsible for the generation of abundant active O species for HCHO oxidation reaction.