One-step oxidative-adsorptive desulfurization of DBT on simulated solar light-driven nano photocatalyst of MoS2-C3N4-BiOBr @MCM-41

Abstract

Using a catalyst-adsorbent for simultaneous oxidation and adsorption of sulphuric compounds in liquid fuels is an effective and economical way. Thus in this paper, the core–shell MoS2-C3N4-BiOBr@MCM-41 photocatalyst-adsorbents with different percentages of MoS2 (1, 3, and 5 wt%) were prepared and used in a one-step photo oxidative-adsorptive desulfurization under simulated solar light. Thesamples were characterized by XRD, FESEM, FTIR, EDX, BET-BJH, TEM, UV–Vis DRS, and PL analyses. Theresults indicated that the final C/C0decreased from 0.42 to 0.016 with increasing the MoS2percentage (98.4% conversion). Despite the lowest surface area (845 m2/g) and the broad bandgap energy (2.8 eV), the sample with 5 wt% of MoS2illustrated the most degree of desulfurization due to strong interaction between components, the highest coverage of MCM-41 with active phases, high population of structural defects, high capability of light absorption and low recombination rate of charge carriers. GC-MS analysis indicated no DBT, DBTO or DBTO2 in the treated fuel. However, the presence of DBTO2 on the surface of the photocatalyst was confirmed that reveals the successful one-step oxidative-adsorptive desulfurization on the MoS2-C3N4-BiOBr@MCM-41. The adsorption mechanism was consistent with the pseudo-second-order kinetics, indicating that the rate-limiting step was chemical adsorption. Moreover, selectivity evaluations showed that while MoS2-C3N4-BiOBr@MCM-41 photocatalyst had high activity in the desulfurization of DBT, its affinity for adsorption and photocatalytic oxidation of non-sulfur aromatic compounds such as benzene, xylene and toluene was very low.