Photocatalytic Oxidative Desulfurization Research Articles

Efficient oxidative desulfurization of model fuel by visible-light-driven MoS2-CeO2/SiO2-Al2O3 nano photocatalyst coating

The MoS2-CeO2 nano photocatalyst on silica-alumina support was synthesized and dip- coated on glass plates with the aid of three polymeric surfactants, including polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA) and polyethylene glycol (PEG). The activity of resultant coatings was evaluated in photocatalytic oxidative desulfurization (ODS) of dibenzothiophene (DBT) and the results were compared with the activity of photocatalyst as powder. The MoS2-CeO2/SiO2-Al2O3 photocatalyst as powder degrades 96 % of DBT while immobilized photocatalyst coating (without surfactant) degraded 88 % of DBT. Using PVP, PVA, and PEG in MoS2-CeO2/SiO2-Al2O3 coating resulted in 86, 89, and 93 % of DBT conversion, respectively. Higher DBT removal by PEG containing coating compares to surfactant-free coating, was due to uniform morphology, more absorption of light, more shift of adsorption edge toward visible light, more surface OH groups, more porosity, more surface area, and bigger pore size, confirmed by FESEM, UV–vis DRS, BET-BJH, and FTIR. Beside PEG, silica sol was applied as a binder for MoS2-CeO2/SiO2-Al2O3 nano photocatalyst coating. The weight loss for this sample was insignificant after 30min of sonication, and none of the composing elements of coating was found in the fuel after five successive runs. With considering operating parameters like the number of photocatalyst coatings, the concentration of DBT, and pH, the DBT removal reached 98 %. Based on the obtained results, a mechanism was proposed for photocatalytic oxidative desulfurization of DBT using PEG containing MoS2-CeO2/SiO2-Al2O3 nano photocatalyst coating.

Accurate Regulating of Visible-Light Absorption in Polyoxotitanate-Calix[8]arene Systems by Ligand Modification.

With use of a macrocyclic polyphenol, tert-butylcalix[8]arene (TBC[8]), as ligands, a series of TBC[8]-stabilized {Ti4O2}clusters, containing penta- and hexacoordinated Ti centers, were synthesized. Such complexes are "core-shell" shaped containing a {Ti4O2} core arranged in a zigzag fashion. While outer walls of the clusters are decorated by deprotonated TBC[8], their upper and lower surfaces can be modified by various O- or N-donor ligands, and the ratio of the penta- and hexacoordinated Ti(IV) centers in the {Ti4O2} core can be precisely regulated from 4:0, to 3:1, to 2:2, to 1:3, and finally to 0:4. The combined coordination of different ligands in the axial direction shows significant influence on the adsorption of the TBC[8]-Ti4 system in the visible-light region, and their absorption edge can be precisely regulated from 600 to 700 nm. The above structural functionalization in the TBC[8]-Ti4 system also tunes their photocatalytic H2 production activities and oxidative desulfurization ability. Thus, for the first time, by confining the polyoxotitanium cluster in macrocyclic molecules, we provide an example of understanding the structure-property relationship of titanium-oxygen materials by ligand modification.

Preparation of a AgCl/PbMoO4 Composite and Investigation of Its Photocatalytic Oxidative Desulfurization Performance.

PbMoO4 materials were synthesized by the glycerol and hydrothermal methods, and AgCl nanoparticles were loaded onto the surface of PbMoO4 by using the precipitation–deposition method. Finally, a AgCl/PbMoO4 photocatalyst was successfully prepared. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and UV–vis diffuse reflectance spectroscopy (UV–vis-DRS) were used to characterize the phase composition, morphology, and light absorption characteristics of the catalyst. An n-octane solution of dibenzothiophene (DBT) was used to simulate fluid catalytic cracking to make gasoline. The photocatalytic oxidation performance of DBT under visible light was studied in terms of the type of light source as well as of the catalyst, substrate, and AgCl content. The mechanism of photocatalytic oxidation was also studied. The results show that AgCl loading causes a red shift of the absorption edge of PbMoO4, which improves the photocatalytic activity of the material. When the AgCl loading was 25.0%, the amount of catalyst was 1.5 g/L, and the visible light irradiation time was 2.0 h, the highest desulfurization rate of DBT reached 97.0%.

Photocatalytic oxidative desulfurization and denitrogenation for fuels in ambient air over Ti3C2/g-C3N4 composites under visible light irradiation

MXene Ti3C2 modified g-C3N4 composites were prepared and used in photocatalytic oxidative denitrogenation and desulfurization under visible light. The photocatalysis system adapted to oxidation of small molecular pyridine and thiophene for fuels in the ambient air without adding extra H2O2 or pure O2 oxidants. Structural and photoelectric properties of the photocatalysts were characterized and compared. In an optimal composite, g-C3N4 nanosheets were successfully intercalated by Ti3C2 layers to form an interfacial effect and heterojunction. Intercalation effect accelerated the photogenerated electrons transferring from g-C3N4 to Ti3C2, and inhibited the recombination of electron-hole pairs. Ti3C2/g-C3N4 composite exhibited enhanced photocatalytic performance, high mineralization efficiency, and good recyclability in the removal of pyridine and thiophene. Mechanism and DFT studies proposed that the holes acted as the major active species for the photocatalysis procedures to form the reactant intermediates, while the electrons and O2 generated superoxide radicals provided a promotion effect on the final conversions.

Cube-like Cu/Cu2O/BiVO4/Bi7VO13 composite nanoparticles: Facile sol-gel synthesis for photocatalytic desulfurization of thiophene under visible light

In this paper, for the photocatalytic oxidative desulfurization of the oil derivatives under visible light, composite nanostructures of copper oxides and bismuth vanadate were prepared using Pechini sol gel method. Parameters affecting the size and morphology of nanostructures such as type of chelating and gelling agents, and molar ratio of copper salts to other metals were also investigated. The results of the analyzes showed that using ethylenediamine as a gelling agent, tannic acid as a chelating agent, and a 1:1:1 ratio for Cu:Bi:V, Cu/Cu2O/BiVO4/Bi7VO13 resulted in production of composite nanoparticles with rectangular cube morphology, which exhibit the highest efficiency (92% after 150 min) in the photocatalytic oxidation of thiophene. Experiments on the trapping of active radical species as well as the recyclability of the catalyst were also conducted and the O2− and h+ were found to be active species and the catalyst showed remarkable stability.

Single-step sonochemical synthesis of Cu2O-CeO2 nanocomposites with enhanced photocatalytic oxidative desulfurization.

In this paper, for the first time, composite nanostructures of Cu2O-CeO2 were prepared by a facile and single-step sonochemical method for thiophene photocatalytic oxidative desulfurization. Sonication was performed utilizing a high-intensity ultrasonic probe with a maximum output power of 80 Wcm-3 and operating frequency at 20kHz. The direct effect of ultrasonic waves on the composition and morphology of the obtained products was also evaluated and it was found that under ultrasonic irradiation, Cu2O-CeO2 can be produced while the main product in the absence of ultrasonic waves is CuO-CeO2. Cu2O-CeO2 exhibits much higher photocatalytic efficiency (84%) than CuO-CeO2 (39%) due to its higher light absorption and electron synergistic effect. The effect of Ce:Cu on photocatalytic efficiency was examined by considering the ratios of 1:0.25, 1:1, 0.5:1, and 0.25:1 and yields of 64, 81, 84, and 76% were obtained, respectively. This indicates that there is an optimal value for the Ce:Cu ratio in the Cu2O-CeO2 nanocomposite.

Dye-sensitized TiO2@SBA-15 composites: Preparation and their application in photocatalytic desulfurization

Photocatalytic oxidation desulfurization has become a research hotspot in recent years because of mild reaction conditions, less energy consumption and high selectivity. In this paper, TiO2 was loaded onto SBA-15 molecular sieves and sensitized with organic dyes (2, 9-dichloroquinacridone, DCQ) to extend its spectral response range from ultraviolet light to visible light. The catalyst DCQ-X%TiO2@SBA-15 was characterized by BET measurements, X-ray diffraction, Fourier transform infrared spectroscopy and Ultraviolet–visible diffuse reflection spectra, and then it was applied for photocatalytic oxidation desulfurization of gasoline. The effects of different catalytic systems, TiO2 concentration, catalyst dosage, and different model sulfur compounds on catalytic desulfurization performance were investigated. Experimental results show that DCQ-TiO2@SBA-15 has a better performance than the unsensitized TiO2@SBA-15, and the desulfurization rate can reach up to 96.1% in a reaction time of 90 min.

Biotemplating synthesis of N-doped two-dimensional CeO2–TiO2 nanosheets with enhanced visible light photocatalytic desulfurization performance

The novel nitrogen doped two-dimensional CeO2–TiO2 nanosheets with a thickness of less than 5 nm were synthesized by a facile impregnation method using Chinese rose petals as biological templates. The detailed characterization by field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) exhibited that the CeO2–TiO2 composites exactly duplicated the microstructure of Chinese rose petal and the self-owned nitrogen was successfully doped into the CeO2–TiO2 composites, which could enhance the visible light absorption efficiency. UV–Vis diffuse reflection spectroscopy (DRS), photocurrent measurement (PM), electrochemical impedance spectroscopy(EIS) and photoluminescence spectroscopy (PL) were used to analyze the electrons and holes separation efficiency, which revealed that CeO2 and TiO2 formed well-defined hetero junctions promoting the effective separation of photogenerated electrons and holes. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of dibenzothiophene (DBT) in model oil. The amount of hydrogenperoxide (H2O2) and photocatalysts, the molar ratios of Ce and Ti in CeO2–TiO2 composites as photocatalytic reaction conditions were investigated. Results showed that the removal rate of DBT could reach 93.7% under visible light irritation for 3 h, when the molar ratio of Ce/Ti was 1/1, the mass ratio of photocatalyst/DBT was 1/2 and the molar ratio of H2O2/DBT was 2/1. The trapping experiments confirmed that the photoinduced active species (•OH radical) was responsible for the degradation of DBT. Further studies demonstrated that DBT was converted to the corresponding sulfone, which could be extracted by the polar solvent. Moreover, a plausible mechanism for the photocatalytic oxidative desulfurization of this nanocomposite was proposed.

The Novel Z-Scheme Ternary-Component Ag/AgI/α-MoO3 Catalyst with Excellent Visible-Light Photocatalytic Oxidative Desulfurization Performance for Model Fuel.

The novel ternary-component Ag/AgI/α-MoO3 (AAM) photocatalyst was successfully fabricated by a facile hydrothermal method combined with a charge-induced physical adsorption and photo-reduced deposition technique. X-ray diffraction, scanning/transmission electron microscope, X-ray photoelectron, UV-vis diffuse reflectance, photoluminescence and electrochemical impedance spectroscopy were employed to characterize the composition, morphology, light-harvesting properties and charge transfer character of the as-synthesized catalysts. The ternary-component AAM heterojunctions exhibited an excellent visible-light photocatalytic oxidative desulfurization activity, in which the AAM-35 (35 represents weight percent of AgI in AAM sample) possessed the highest photocatalytic activity of the conversion of 97.5% in 2 h. On the basis of band structure analysis, radical trapping experiments and electron spin resonance (ESR) spectra results, two different catalytic mechanisms were suggested to elucidate how the photogenerated electron-hole pairs can be effectively separated for the enhancement of photocatalytic performance for dual composites AM-35 and ternary composites AAM-35 during the photocatalytic oxidative desulfurization (PODS) of thiophene. This investigation demonstrates that Z-scheme Ag/AgI/α-MoO3 will be a promising candidate material for refractory sulfur aromatic pollutant’s removal in fossil fuel.

Magnetically recyclable Fe3O4@SiO2/Bi2WO6/Bi2S3 with visible-light-driven photocatalytic oxidative desulfurization

Novel core-shell structural magnetic Fe3O4@SiO2/Bi2WO6 (F-BWO) was obtained by a multistep process. Bi2S3 Quantum Dots (QDs) with the size of about 5 nm were deposited on the surface of Bi2WO6 “shell” to obtain Fe3O4@SiO2/Bi2WO6/Bi2S3 (F-BWO-BS) heterostructures. The experimental results indicated that F-BWO-BS exhibits the enhanced fuel oil photocatalytic-oxidative-desulfurization (Photo-Cat-ODS) and RhB photocatalytic degradation activity than that of F-BWO. The as-prepared F-BWO-BS-2 exhibited the best activity, the rate constant (kapp/min−1) for RhB photocatalytic degradation is approximately 1.5 times higher than that of F-BWO. Furthermore, the F-BWO-BS-2 exhibited the best Photo-Cat-ODS activity, the desulfurization rate could reach 100% after illumination for 1.5 h. The enhanced photocatalytic activity of F-BWO-BS can be attributed to the synergistic effect of magnetic Fe3O4@SiO2 support − “core”, Bi2WO6 − “shell” and Bi2S3 QDs. The experimental result also revealed that magnetic F-BWO-BS photocatalyst is easily magnetically separated with good stability and recyclability.

Construction of novel amphiphilic [Bmin]3PMo12O40/g-C3N4 heterojunction catalyst with outstanding photocatalytic oxidative desulfurization performance under visible light

Abstract Oxidative desulfurization technology has attracted the attention of many catalytic scholars because of its high desulfurization efficiency and mild conditions. However, during the catalytic reaction, the oxidant and the sulfur-containing compounds are separated into two phases, and the mass transfer problem becomes the biggest obstacle to suppress the desulfurization effect. In this work, a novel amphiphilic material [Bmin]3PMo12O40 (BPMO) was prepared and loaded onto porous g-C3N4 with a 2D structure using an in situ precipitation method. Using hydrogen peroxide as the oxidant and dibenzothiophene (DBT) n-heptane solution as the simulated oil, the photocatalytic oxidative desulfurization properties of the catalyst under visible light were investigated. The results show that the BPMO can simultaneously adsorb DBT in the oil phase and H2O2 in the water phase during the reaction and promote the mass transfer at the oil–water interface. g-C3N4 not only increases the dispersion of BPMO as a carrier, but forms a heterojunction with BPMO and effectively increases the utilization rate of electrons. Thus, BPMO/g-C3N4 can efficiently oxidize simulated oil with a sulfur content of 1000 ppm while showing excellent catalytic stability. The possible mechanism of the photocatalytic oxidative desulfurization process is discussed.

Upconversion nanocomposite CeO2:Tm3+/attapulgite intermediated by carbon quantum dots for photocatalytic desulfurization

Upconversion CeO2:Tm3+/attapulgite (ATP) nanocomposites intermediated by carbon quantum dots (CQDs) were synthesized by a facile deposition method using hexamethylenetetramine as precipitator. The products were characterized by various techniques. The photocatalytic degradation of dibenzothiophene (DBT) in simulated gasoline was conducted under visible light irradiation by taking advantage of CeO2:Tm3+/CQDs/ATP nanocomposites as catalyst. The influence of Tm3+ doping amount and the mass fraction of CeO2 to ATP on the desulfurization performance were investigated. Results indicated that the CeO2:Tm3+ nanoparticles were coupled uniformly on the CQDs/ATP surface. The desulfurization rate of DBT reached the highest 96% when the molar fraction of Tm3+ in CeO2 was 2% and the mass fraction of CeO2 to ATP was 20 wt%. The enhanced photocatalytic oxidative desulfurization was attributed to the upconversion property of CeO2:Tm3+ which transformed visible light into ultraviolet light increasing the utilization of solar energy, while CeO2:Tm3+ built indirect Z-scheme heterojunction with modified ATP mediated by CQDs, both favored the separation of the charges carriers and benefits the redox potentials.

Structure and photocatalytic oxidation desulfurization performance of CeO2/HTi2NbO7-NS nanocomposite

CeO2/HTi2NbO7-NS nanocomposite based on HTi2NbO7 nanosheet (HTi2NbO7-NS) and Cerium dioxide nanoparticles (CeO2-NPs) was fabricated through an exfoliation-restructuring method. The as-prepared samples were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), laser Raman Spectroscopy (LRS), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflection spectroscopy (UV–Vis DRS) and N2 adsorption-desorption measurements. The adsorption and photocatalytic properties of the as-prepared samples were evaluated using ethyl mercaptan (EM) in methane gas as the model pollutant. The results indicated that CeO2-NPs were uniformly distributed on the surface of HTi2NbO7-NS and the band gap energy of CeO2/HTi2NbO7-NS nanocomposite was reduced compared with its precursor. The type-II heterojunction was formed due to suitable band structures of host and guest materials. The CeO2/HTi2NbO7-NS nanocomposite owns the best adsorption capacity and photocatalytic oxidation activity, which was mainly attributed to the lower band gap and efficient separation of electron-hole pairs of CeO2/HTi2NbO7-NS nanocomposite.

Photocatalytic oxidative desulfurization and denitrogenation of fuels over sodium doped graphitic carbon nitride nanosheets under visible light irradiation

Abstract A cost-efficient photocatalytic oxidative denitrogenation and desulfurization system for fuels under visible light was developed on the basis of Na doped g-C3N4 nanosheets catalyst. The process adopted molecular O2 as oxidant to substitute for the expensive H2O2, and it adapted to the removal of small molecules of pyridine and thiophene. Na doped g-C3N4 nanosheets were obtained via a simple mixed-calcination pathway using NaCl as Na source. The structural, photophysical and chemical properties of the photocatalysts were characterized and compared to those of the original g-C3N4. It was verified that Na was successfully doped in the g-C3N4 lattice in a uniform chemical state. Moderate amount of Na doped in g-C3N4 generated the highly dispersed and porous nanosheets, which further improved the surface energy and reduce the recombination rate of electron-hole pairs. Na doped g-C3N4 exhibited enhanced performance simultaneously in the photocatalytic oxidative denitrogenation and desulfurization. The optimal catalyst obtained considerable removal efficiency for pyridine and thiophene, depending on its improved structural and photochemical properties by Na doping. A proposed mechanism revealed that the holes acted as the major active species for the denitrogenation and desulfurization, while the superoxide radicals originating from the combination of electron and O2 gave a promotion effect.

Boosting the photocatalytic oxidative desulfurization of dibenzothiophene by decoration of MWO4 (M=Cu, Zn, Ni) on WO3

The surface of WO3 was partially decorated with transition metal tungstate MWO4 (M = Cu, Zn, Ni) using impregnation method followed by solid-state reaction. It is found that MWO4/WO3 photocatalysts showed a higher activity for photocatalytic oxidative desulfurization (PODS) of dibenzothiophene (DBT) than pure WO3 or MWO4 under visible light irradiation. Moreover, the activity for PODS of DBT on MWO4/WO3 depends on the content of MWO4 decoration on WO3 surfaces. 0.2% CuWO4/WO3, 1% ZnWO4/WO3, and 0.5% NiWO4/WO3 exhibited the highest activity among CuWO4/WO3, ZnWO4/WO3 and NiWO4/WO3 samples. However, as compared with 1% ZnWO4/WO3 and 0.5% NiWO4/WO3, the 0.2% CuWO4/WO3 sample exhibited superior visible light photocatalytic activity for DBT conversion. Brunauer-Emmett-Teller method (BET), SEM, and ultraviolet-visible diffuse reflectance spectra (UV–vis DRS), high resolution transmission electron microscope (HRTEM), photoluminescence spectroscopy (PL), and a series of titration experiments were used to seek the reason for the positive impact of MWO4 on the photocatalytic activity of WO3. As compared with pure WO3, no notable changes of specific surface areas, morphologies, and light absorption are observed after MWO4 (M = Cu, Zn, Ni) decoration. The formation of heterojunction structure between MWO4 and WO3, which promotes charge separation efficiency, was the main reason for the high photocatalytic activity of MWO4/WO3 photocatalyst. Moreover, difference in PODS activity between MWO4/WO3 heterojunctions is proved to be affected by their charge separation and transfer efficiency and amount of active species.

Photocatalytic oxidative desulfurization of liquid petroleum fuels using magnetic CuO–Fe3O4 nanocomposites

In the present study, dual-functional CuO–Fe3O4 magnetic nanocomposites (MNCs) have been prepared through a simple impregnation method and used as catalyst for photocatalytic oxidative desulfurization of model-fuel (dibenzothiophene, DBT in n-hexane) and real naphtha at moderate conditions. The CuO–Fe3O4 MNCs were characterized by X-ray diffraction, BET surface area and pore volume using nitrogen adsorption–desorption and VSM methods The effects of different reaction parameters such as initial DBT concentration in model-fuel, CuO–Fe3O4 MNCs dose, reaction time, H2O2/DBT molar ratio and CuO:Fe3O4 weight ratio of the MNCs were studied in detail. Results for model-fuel treatment showed that the prepared nanocomposite can eliminate 95.2% of DBT after 120 min under the following conditions: CuO:Fe3O4 weight ratio of 1:1, catalyst dose of 10 g/l, H2O2/DBT mole ratio of 7.5:1 and initial DBT concentration of 250 mg/l. Furthermore, 93% of sulfur conversion was obtained for naphtha fuel (initial sulfur concentration of 533 mg/l) after 240 min reaction time. The synthesized CuO–Fe3O4 magnetic nanocomposites combines the photocatalytic activity of CuO and the adsorption capacity of both Fe3O4 and CuO species, which make it have important applications in the deep desulfurization of liquid fuels.

Electron-hole interactions in choline-phosphotungstic acid boosting molecular oxygen activation for fuel desulfurization

Many studies have been conducted regarding the separation behavior of carriers (electrons and holes) because of involving the generation of superoxide radicals (O2−), hydroxyl radicals (HO), and hydrogen peroxide (H2O2) in the photocatalytic process of heteropolyacids. Instead, relatively little attention has been focused on the potential Coulomb interactions between photogenerated electrons (e−) and holes (h+). Herein, choline-phosphotungstic acid (Ch3-HPW) was synthesized via one-step acid-base neutralization reaction method, and characterized. The electronic excited state analysis of Ch3-HPW showed that the formation of singlet oxygen (1O2) was related to the electron-hole interactions in the photocatalytic process of ground state molecular oxygen (3O2) activation. Subsequently, a facile fuel photocatalytic oxidative desulfurization and extraction system was established on the basis of Ch3-HPW, air, and acetonitrile (MeCN), to better understand the 3O2 activation in specific applications. The main photocatalytic reaction conditions affecting the desulfurization process, including the amount of Ch3-HPW, the volume ratio of MeCN to model oil, the initial S-concentration, air/N2 bubbling, sulfur compounds, and fuel composition, were systematically investigated under UV radiation. The sulfur removal for model oil and straight-run gasoline in the system were 99.6% and 89.9%, respectively. The results of radical scavenger experiments, electron spin-resonance (ESR) spectroscopy, and density functional theory (DFT) calculations further demonstrated that 1O2, H2O2, and h+ played important roles in the oxidation of sulfur-containing compounds. A new method was developed for the desulfurization of liquid fuels using green and inexpensive O2 in this work to promote the development of photocatalytic process of exciton-involved HPA-based photocatalysts.

Synthesis of Zinc Oxide Supported on Titanium Dioxide for Photocatalytic Oxidative Desulfurization of Dibenzothiophene

Photocatalytic oxidative desulfurization (PODS) has received much attention due to low energy consumption and high efficiency, as well as simple and pollution-free operation. In this study, zinc oxide supported on titanium dioxide (ZnO/TiO2) catalysts were prepared via a simple electrochemical method. The presence of anatase phase TiO2 and wurtzite ZnO was confirmed by X-ray diffraction (XRD) analysis while band gap energies were determined by UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The photocatalytic activity was tested for desulfurization of 100 mg/L dibenzothiophene (DBT). The highest desulfurization rate (2.20 × 10-3 mM/min) was achieved using 1 g/L of 10 wt% ZnO/TiO2 after 2 hr under UV irradiation.

Synthesis of Ag-AgBr/Al-MCM-41 nanocomposite and its application in photocatalytic oxidative desulfurization of dibenzothiophene

A series of Ag-AgBr/Al-MCM-41 nanocomposites were synthesized by dispersion of Ag-AgBr on mesoporous silica Al-MCM-41 obtained from natural bentonite. The synthesized Ag-AgBr/Al-MCM-41 composites with Ag nanoparticles growing on the surface of Al-MCM-41 were used for photocatalytic oxidative desulfurization of dibenzothiophene. The physical properties of Ag-AgBr/Al-MCM-41 were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Ultraviolet–visible diffuse reflection spectroscopy (UV–Vis DRS), photoluminescence (PL) emission spectra, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity results showed that in the presence of 40% Ag-AgBr/Al-MCM-41 photocatalyst the oxidative desulfurization of dibenzothiophene reached the maximum efficiency at 99.22% and the photocatalytic activity still keeps high level after four cycles.

Visible light photocatalytic oxidative desulfurization using Ti-MCM-41-loaded iron phthalocyanine combined with ionic liquid extraction

Iron phthalocyanine (PcFe) was loaded on Ti-MCM-41 as visible light photocatalyst (R-PcFe/Ti-MCM-41). Dibenzothiophene (DBT) was photooxidized using R-PcFe/Ti-MCM-41 as a photocatalyst, air as an oxidant, and ionic liquid as the extraction agent during visible light irradiation at room temperature and ambient conditions. The results indicated that photocatalytic efficiency of the amino iron phthalocyanine (NH2-PcFe)/Ti-MCM-41 was superior to the other substituent groups. The DBT content in the model oil decreased from 1000 to 44 μg/mL with 95.6% removal rate under the optimal reaction conditions (model oil 10 mL, photocatalyst NH2-PcFe/Ti-MCM-41 0.02 g, loading amount of NH2-PcFe 0.3 g/g, air flow rate 100 mL/min, reaction time 2 h, room temperature). The kinetics of photocatalytic oxidation of DBT follows first-order kinetics with a rate constant of 1.319 h−1 and halftime of 0.525 h. The photocatalyst NH2-PcFe/Ti-MCM-41 was reused for five times, and the catalytic activity decreased slightly. The photocatalytic oxidation system demonstrated significant desulfurization effects on different sulfur compounds and real gasoline, and the sulfur content of the actual gasoline could be reduced from 1000 to 78 ppm.