Photocatalytic oxidative DBT desulfurization using Ag@AgBr/Al-SBA-15 derived from natural halloysite

In recent decades, highly efficient deep desulfurization processes have become very necessary to decrease environmental pollution due to sulfur emissions from fuels. Herein, an enhanced photocatalytic desulfurization of a model fuel was investigated under sunlight irradiation using H2O2 as the oxidant and Ag@AgBr loaded mesoporous silica Al-SBA-15 as a catalyst. In this study, the photocatalyst (Ag@AgBr/Al-SBA-15) was synthesized via a chemical deposition using halloysite clay as the silica-aluminum source and characterized by X-ray diffraction (XRD), N2 adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The UV-Vis DRS results revealed that the light absorption expanded to the visible region (λ > 400 nm) for the various Ag@AgBr nanoparticles doped in the mesoporous Al-SBA-15 material. The 30% Ag@AgBr/Al-SBA-15 sample with a 30% Ag@AgBr doping exhibited enhanced photocatalytic activity and showed high stability even after four successive cycles. The results demonstrated that initial dibenzothiophene (DBT) concentrations (500 ppm) reached 98.66% removal with 50 mg of the catalyst dosage, 1.0 mL of H2O2, for 360 min of sunlight irradiation at 70 °C.

Fig 1. (A) Small-angle and (B) wide-angle of XRD patterns of 10%-60%Ag@AgBr/Al-SBA-15 samples

Fig 2. (A) N2 adsorption-desorption isotherms, and (B) pore size distribution of Al-SBA-15 and 10%-60%Ag@AgBr/Al-SBA-15 samples. (C) Room temperature photoluminescence (PL) spectra of 10-60%Ag@AgBr/Al-SBA-15 samples

Fig 3. Photodegradation of DBT with different photocatalyst contents under sunlight irradiation at reaction temperatures of (A) 70 °C and (B) 50 °C. (Reaction conditions: Vmodel oil = 50 mL, mcatalyst = 50 mg, VH2O2 = 1.0 mL)

Fig 4. (A) Photodegradation of DBT by 30%Ag@AgBr/Al-SBA-15 catalyst at different temperatures under sunlight irradiation. (Reaction conditions: Vmodel oil = 50 mL, mcatalyst = 50 mg, VH2O2 = 1.0 mL). (B) Photodegradation of DBT by 30%Ag@AgBr/Al-SBA-15 catalyst at different amount of catalyst under sunlight irradiation. (Reaction conditions: Vmodel oil=50 mL, VH2O2=1.0 mL, reaction temperature of 70 °C)

Fig 5. Plot of (A) pseudo first-order and (B) pseudo second-order kinetic models for the degradation of DBT by photocatalytic oxidative desulfurization at different temperatures

This work was published in the Journal of Industrial and Engineering Chemistry