Ultra-deep oxidative desulfurization of high sulfur liquid fuels using W/W2C heterostructured nanoparticles embedded on N-doped graphene

Abstract

A novel composite, W/W2C@NC/NPrGO, was synthesized via an in situ pyrolysis method while employing polyethyleneimine (PEI)-modified graphene oxide (GO) loaded with Dawson-type K6[α-P2W18O62]·14 H2O (P2W18) (P2W18-PEI/GO). The synthesized composite demonstrated remarkable catalytic performance in the removal of thiophenic compounds from model oil while using the environmentally friendly H2O2 as an oxidant. Moreover, the composite achieved highly efficient desulfurization of liquid fuel under mild reaction conditions. At 60 °C and an initial concentration of 4000 ppm, practically complete removal of dibenzothiophene (DBT) was accomplished in 15 min using a molar ratio of H2O2 to S of 2 and a catalyst dosage of 0.02 g. The process showed a high kinetic constant of 0.33 min−1 and a low apparent activation energy of 37.5 kJ / mol. Similarly, the catalyst displayed excellent recyclability, maintaining its catalytic performance over six consecutive cycles without significant loss. The ODS reaction primarily proceeded via the •OH radical and electron transfer mechanism, as demonstrated by radical scavenger studies and electron paramagnetic resonance (EPR) analysis. The outstanding catalytic performance of W/W2C@NC/NPrGO in ODS can be attributed to various factors. Firstly, its unique porous nanostructure and abundant W/W2C heterogeneous interfaces contribute to an abundance of active sites. Secondly, the ligand effect between metal tungsten (W) and W2C, coupled with the electron transfer from the electron-rich nitrogen-doped reduced graphene (NPrGO) to W/W2C, synergistically promoted the generation of highly reactive oxygen species (•OH).