Metal-free aerobic oxidative desulfurization over a diethyltriamine-functionalized aromatic porous polymer

Abstract

A new cross-linked aromatic porous polymer (CAPP) from bifonazole and 4,4′-bis(bromomethyl)biphenyl was prepared and functionalized with diethyltriamine (DETA). The product CAPP-DETA was applied as a catalyst for the removal of thiophenic sulfur compounds via oxidative desulfurization: 100% conversion of dibenzothiophene (DBT) was achieved with 50 mg of CAPP-DETA for 400 ppm DBT in decane at 120 °C after 4 h using O2 as the oxidant. The reaction was carried out under different reaction conditions of temperature (80 to 140 °C), catalyst amount (10 to 50 mg), and concentration (200 to 1000 ppm). Radical scavenger experiments indicated the reaction involving the triamine functionality in the catalyst generating the superoxide (O2•-) radicals. The conversion efficiency among the thiophenic compounds followed a sequence of dibenzothiophene > benzothiophene > thiophene. The catalyst was reusable for four repetitive cycles without deterioration in catalytic activity.