Molybdenum nitride@porous carbon, derived from phosphomolybdic acid loaded metal-azolate framework-6: A highly effective catalyst for oxidative desulfurization

Abstract

A new composite of the metal-azolate framework (MAF-6) and phosphomolybdic acid (PMA), named PMA(x)@MAF-6, was prepared. Well-dispersed (size: ∼4 nm) Mo2N, on porous carbon, was prepared without external nitrogen sources firstly via carbonization of the PMA(x)@MAF-6. The prepared catalyst was applied in oxidative desulfurization (ODS) with H2O2 as a greenoxidant and showed remarkable performance. A selected catalyst Mo2N@C-3 had the highest turnover frequency (30 h-1, around 2–3 times of the best catalyst so far) with the lowest activation energy (27.8 kJ·mol−1) in ODS (with H2O2) among any molybdenum-based catalysts. The ODS over Mo2N@C was explained by a non-radical mechanism via active Mo-peroxo species. Moreover, the high activity of the catalyst is partly because of the contribution of nitrogen in Mo2N. The studied catalyst could be easily recycled by solvent washing. Therefore, Mo2N, especially supported on carbon (like Mo2N@C), could be firstly suggested as a promising catalyst in ODS.