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

Updated: Aug 21

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