The Deposition of Isolated Fe(3+) Species in Mesoporous Silicon for Oxidation of Cyclohexane

Abstract The balance of activity and selectivity in liquid alkane oxidation is challenging for the design of supported Fe catalysts. When Fe species leach to the solvent, uncontrolled free radical chain reactions happen. Herein, isolated Fe(3+) species were constructed by forming a strong Fe−O−Si bond for the selective oxidation of cyclohexane to cyclohexanone by H 2 O 2 . Compared to the supported FeO x clusters, the strong Fe−O−Si bond between isolated Fe(3+) species and SiO 2 prevents the leaching of Fe in strong oxidation (H 2 O 2 ) reaction conditions and dominates the non‐free radical mechanism. The turnover frequency over 10FeO x /SBA‐15 reached 15.2 h −1 , higher than for reported Fe‐based catalysts. High selectivity of cyclohexanone is maintained at different conversions. Moreover, the (SiO) x Fe 3+ (OH) 3‐x −OOH active species were detected by Raman and FTIR and are generated from the oxidation of isolated Fe species. The strong Fe−O−Si bond and non‐free‐radical mechanism by (SiO) x Fe 3+ (OH) 3‐x −OOH active species induce high activity and selectivity for the oxidation of many other alkanes.