Aerobic Oxidation of Hydrocarbons Catalyzed by Mn-Doped Nanoporous Aluminophosphates (II): Hydroperoxide Decomposition

Abstract

Electronic structure methods based on hybrid-exchange functionals in Density Functional Theory (DFT) and periodic boundary conditions have been applied to study the reaction mechanism of the aerobic oxidation of hydrocarbons catalyzed by Mn-doped nanoporous aluminophosphates. In this paper we examine the decomposition of hydroperoxide intermediates (ROOH). The reaction takes place on MnII acid sites, charge-balanced by a proton on a nearest neighbor framework oxygen, resulting from the preactivation step. In this stage, the MnII sites catalyze the homolytic decomposition of the hydroperoxide molecules to produce MnIII and oxo-containing radical species, stabilized by complexation to MnIII, yielding in addition alcohol and water molecules. Two parallel reaction pathways have been identified for this process, through alkoxy (RO·) or hydroxy (HO·) radical-like intermediates. The occurrence of the two mechanisms depends on the stereochemistry of the initial adsorption of ROOH onto the active site, which takes...