Deep catalytic oxidative desulfurization process catalyzed by TBA-PWFe@NiO@BNT composite material as an efficient and recyclable phase-transfer nanocatalyst

Abstract

The production of high-quality fuel with substantially lowered sulfur level has attracted a great deal of attention in recent years. Developing high-performance and recyclable catalysts for the desulfurization process remains largely a challenge. In this study, an efficient catalytic oxidative desulfurization (CODS) strategy has been developed using a new phase-transfer nanocatalyst. The TBA-PWFe@NiO@BNT nanocatalyst was fabricated from the mono Fe-substituted phosphotungstate with tetra (n-butyl) ammonium chains (TBA-PWFe), nickel oxide (NiO), and sodium activated bentonite (BNT) for the first time. The TBA-PWFe@NiO@BNT composite was utilized as a recyclable nanocatalyst for the desulfurization of simulated fuels and real gasoline using acetic acid/hydrogen peroxide (VCH3COOH/VH2O2 = 1/2). The best desulfurization results were attained with the TBA-PWFe@NiO@BNT phase-transfer nanocatalyst at 35 °C after just 60 min, showing identical CODS performance under mild reaction conditions. The total sulfur removal efficiency of real gasoline achieved a remarkable 98% and the concentration of mercaptans (RSH; R = alkyl group) was reduced from 98 to 3 ppm. On the other hand, thiophenes (Ts), benzothiophenes (BTs), and dibenzothiophenes (DBTs) were near completely removed from the simulated fuels phase with efficiencies of 96, 97, and 99%, respectively. Finally, the recycling capacity of TBA-PWFe@NiO@BNT nanocatalyst was confirmed for five consecutive desulfurization runs without remarkably decreases in its catalytic performance. The overall results obtained have been discussed in detail.