Catalytic performance and stability of (V) MIL-47 and (Ti) MIL-125 in the oxidative desulfurization of heterocyclic aromatic sulfur compounds

Journal of Catalysis, Volume 305, September 2013, Pages 217–226
Catalytic performance and stability of (V) MIL-47 and (Ti) MIL-125 in the oxidative desulfurization of heterocyclic aromatic sulfur compounds
Nicholas D. McNamara, Gregory T. Neumann, Erin T. Masko, Jacqueline A. Urban, Jason C. Hicks
Department of Chemical and Biomolecular Engineering, University of Notre Dame, 182 Fitzpatrick Hall, Notre Dame, IN 46556, United States
Abstract
Reports synthesis and testing of a Ti-based metal organic framework (MOF), MIL-125 (MIL stands for Material from Institut Lavoisier), and a V-based MOF, MIL-47, for their catalytic activity in the oxidation of three heterocyclic sulfur compounds: dibenzothiophene, benzothiophene, and thiophene.
Researchers employed dibenzothiophene (DBT) oxidation studies to determine kinetic parameters. They observed activation energies for MIL-47 and MIL-125 to be 51 kJ/mol and 75 kJ/mol, respectively. They employed benzothiophene and thiophene oxidation studies to demonstrate that the greater catalytic activity of MIL-47 was not simply due to the limited accessibility to the active sites of MIL-125 in the pores. It was also a function of the type of metal center. MIL-125 exhibited faster reaction rates in the oxidation of thiophene than DBT, suggesting that catalysis occurs on the surface of the catalyst as well as in the pores. Without DBT, however, MIL-47 degraded first into MIL-47, and eventually 1,4-benzenedicarboxylic acid (BDC) and vanadium oxide in the presence of tert-butyl hydroperoxide (TBHP) alone.
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