Metal-free oxidative desulfurization over a microporous triazine polymer catalyst under ambient conditions

Abstract

A metal-free microporous triazine polymer (MCTP) was applied as a heterogeneous catalyst for the oxidative desulfurization (ODS) of thiophenic sulfur compounds in decane as a model fuel. Using a molecular oxygen (O2)/aldehyde system as the oxidant, complete removal of dibenzothiophene (DBT) from a 400 ppm DBT solution (10 mL) was achieved at room temperature in 15 min with 2 mmol of isobutyraldehyde (IBA). The highly efficient conversion of the DBT was explained by the formation of an acyl radical from IBA aided by the MCTP catalyst, which was converted to a peroxyacid that oxidized the DBT to DBT sulfone. The conversion efficiency of thiophenic compounds followed the sequence of electron densities in the individual S atoms: DBT > benzothiophene > thiophene. The MCTP catalyst could be reused for ODS for at least five consecutive runs without any reduction in the catalytic performance after a simple acetone wash.