Effect of pore size in mesoporous MnO2 prepared by KIT-6 aged at different temperatures on ethanol catalytic oxidation

KIT-6 mesoporous silica aged at 40, 100, and 150 degrees C were used as hard templates to prepare different mesoporous MnO2 catalysts, marked as Mn-40, Mn-100, and Mn-150, respectively. The catalytic activities of these catalysts and the effect of pore sizes on ethanol catalytic oxidation were investigated. Mn-40, Mn-100, and Mn-150 have triple, double, and single pore systems, respectively. On decreasing the aging temperature of KIT-6, the pore sizes of KIT-6 decrease and that of mesoporous MnO2 catalysts increase. The pore sizes and catalytic activities increase in the order: Mn-40 > Mn-100 > Mn-150. Mn-40 catalyst has a higher TOF (0.11 s(-1) at 120 degrees C) and the best catalytic activity for ethanol oxidation because of a bigger pore size with three pore systems with maximum distribution at 1.9, 3.4, and 6.6 nm, decrease in symmetry and degree of order, more surface lattice oxygen species, oxygen vacancies resulting from more Mn3+ ions, and better low-temperature reducibility. (C) 2018, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.