Photocatalytic Desulfurization Research Articles

The effective separation of photogenerated carriers in MIL101 nanocomposites promoting the efficient photocatalytic desulfurization in air.

The extensive industrial applications of fuel oil, a critical strategic resource, are accompanied by significant environmental and health concerns due to the presence of sulfur-containing compounds in its composition, which result in hazardous combustion waste. Extensive research has been conducted to develop technologies for low-vulcanization fuel production to address this issue. Consequently, the investigation of catalysts for environmentally friendly and safe photocatalytic desulfurization becomes imperative. To that end, we have designed efficient MIL-101(Fe)/CQDs@g-C3N4 (MIL101/CDs-C3N4) Z-scheme heterojunction photocatalysts with high carrier separation and mobility through a thermal polymerization-hydrothermal strategy. The high concentration of photogenerated carriers facilitates the activation of oxygen and H2O2, leading to increased production of ROS (·O2-, ·OH, h+), thereby enhancing the photocatalytic desulfurization (PODS). Additionally, DFT calculations were utilized to determine the electron migration pathways of the catalysts and adsorption energies of DBT (dibenzothiophene). Moreover, Gibbs free energy calculations indicated that MIL101/CDs-C3N4 exhibited the lowest activation energy for oxygen and H2O2. The mechanism of photocatalytic desulfurization was proposed through a combination of theoretical calculations and experimental studies. This study provides guidance for the development of MOF-based Z-scheme systems and their practical application in desulfurization processes.

Constructing interface chemical coupling S-scheme heterojunction MoO3-x@PPy for enhancing photocatalytic oxidative desulfurization performance: Adjusting LSPR effect via oxygen vacancy engineering

Construction of photocatalyst that combines excellent electron transfer and photoresponse capabilities to enhance photocatalytic performance remains a challenging task. In this work, interfacial Mo-N bonds and vacancy engineering collaborative modified MoO3-x@polypyrrole (MP) S-scheme heterojunction is rational designed for efficient photocatalytic oxidative desulfurization. The addition of polypyrrole introduces rich defects which inducing the localized surface plasmon resonance (LSPR) effect and enhancing light absorption. Furthermore, the combination facilitates the formation of Mo-N bonds. The modifications amplify the built-in electric field and conduct the efficacious separation of photogenerated carriers. With the synergism of LSPR effect and interfacial chemical Mo-N bonds, the optimal MP photocatalyst displays attractive desulfurization rate of 100% for dibenzothiophene (DBT) in 60 min under illumination, touching the objective of ultra-deep desulfurization. The study extends a novel understanding of the impact of LSPR effect and heterojunction interface charge transfer on the photocatalytic desulfurization ability.

Solar-powered commercial diesel fuel desulfurization: Exploring the factors affecting and recyclability of mesoporous Tl-doped TiO2 nanofiber photocatalysts

The study aims to fabricate mesoporous TiO2 nanofibers (NFs) with different thallium (Tl) doping ratios (1–2 wt%) using the solution electrospinning method and examine their photocatalytic oxidation activity in the desulfurization of commercial diesel fuel. The results show that the Tl doping restricted the transition of the anatase to rutile fraction, shifting it from an initial composition of 58.3% rutile and 41.7% anatase to a significantly altered state with only 2.4% rutile and 97.6% anatase. Additionally, Tl-doping resulted in a decrease in crystalline size (from 55.4 to 9.5 nm), a reduction in the band gap from 3.2 to 2.93 eV, and a decrease in the diameter of the nanofibers from 200 nm to 100 nm, compared to pristine TiO2 NFs. The most efficient photocatalyst, 1 wt% Tl-doped TiO2 NFs, demonstrated remarkable performance with 98.74% sulphur removal under Xenon lamp irradiation (450 nm, 500 Watts) for 90 min. Under sunlight, the photocatalytic oxidation activity in the desulfurization process resulted in a remarkable reduction of 99.2% in sulphur content, decreasing from 11500 ppm to 98 ppm. Notably, this photocatalyst demonstrated efficient oxidative photocatalytic desulfurization and maintained the recyclability of the solvent over eight cycles without any loss.

Phosphotungstic acid ionic liquid for efficient photocatalytic desulfurization: Synthesis, application and mechanism

Efficient mass transfer process is a critical factor for regulating catalytic activity in a photocatalytic desulfurization system. Herein, phosphotungstic acid (HPW) active center is successfully composited with a quaternary ammonium phosphotungstate based hexadecyltrimethylammonium chloride ionic liquid (CTAC-HPW) by the ion exchange method for the photocatalytic oxidative desulfurization of dibenzothiophene sulfide. The keggin structure of HPW and highly mass transfer performance organic cations synergistically enhanced the photocatalytic activity towards the effectively convertion of dibenzothiophene (DBT) with the excitation of visible light. The deep desulfurization (<10 mg·kg−1) is attained within 30 min and well stability is demonstrated within 25 cycles. Moreover, the CTAC-HPW photocatalyst projects well selectivity to interference from coexisting compounds such as olefins and aromatic hydrocarbons and universality of dibenzothiophenes, for example, 4-methyldibenzothiophene (4-MDBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). Ultimately, a possible photocatalytic desulfurization mechanism is proposed according to the GC-MS, proving that the final product is the corresponding sulfone. The trapping experiment and ESR analysis confirmed that h+ and •COOH played critical roles in oxidation process. The work offers a practicable strategy for efficiently converting DBT to DBTO2 with added value.

Graphene-decorated novel Z-scheme Bi@MOF composites promote high performance photocatalytic desulfurization

The Z-scheme photocatalyst constructed based on bismuth-based metal oxides (BMO) and metal–organic frameworks (MOF) holds significant potential for effectively degrading odorous Reduced Sulfur Compounds (RSC) due to its robust redox capabilities. However, challenges such as lattice mismatch, interface defects, and rapid recombination of photogenerated charges substantially impede the Z- scheme charge transfer in BMO@MOF photocatalysts. In this research, graphene was introduced into the BiVO4@NH2-UiO-66 system as an electron bridge and co-catalyst to reduce the interfacial transfer resistance and increase the absorption of near-infrared light, resulting in superior degradability of RSCs compared to both the individual components and BiVO4@NH2-UiO-66. The incorporated graphene not only serves as the growth substrate for BiVO4 and NH2-UiO-66 but also plays a crucial role as an electron mediator in enhancing the vectorial charge transfer from BiVO4 to NH2-UiO-66. This strengthens the Z-scheme charge transfer pathway, suppressing bulk charge recombination, increasing overall carrier density, and maintaining robust redox capabilities. Additionally, the investigation of active species and key intermediate products was conducted to explore potential degradation pathways of RSCs. This work demonstrates a novel approach in promoting photocatalytic degradation of RSCs by harnessing the synergistic effects between doping and heterogeneous structures within the photocatalyst.

Photocatalytic desulfurization of gas condensate using zinc diacetate and cadmium diacetate liquid catalysts

This inquiry studied the application of photocatalytic desulfurization as an effective method for removing sulfur-containing organic compounds from gas condensate extracted from oil wells. To this end, cadmium diacetate and zinc diacetate compounds were prepared as the liquid catalysts. Then their structures were confirmed and their properties were determined by common methods, including FTIR, NMR, and UV. Subsequently, their performances as catalysts were investigated by an optical technique for the desulfurization process. Accordingly, the study used a photoreactor equipped with a 250 W mercury ultraviolet lamp with a maximum wavelength of 365 nm, and investigated and optimized the effect of the ratios of the influencing parameters on the total sulfur removal efficiency. These included the ratios of fuel to photocatalyst, H2O2, and acetonitrile. Ratios of 1:2:3:2 and 1:3:2:1 (fuel: catalyst: oxidant: solvent) of zinc and cadmium diacetate led to 93.5 % and 87.1 % reduction of the total sulfur content, respectively, after 60 min since the exposure process. Also, under sunlight, the total sulfur removal was 67.0 % for the Zn diacetate and 42.0 % for Cd diacetate. Liquid diacetate photocatalysts were successfully recycled over five cycles with only a maximum of 10 % reduction in efficiency. The kinetics of the systems studied were evaluated under optimal conditions and it was found that both systems fit the pseudo-first order model with rate constants of 0.148 min−1 and 0.098 min−1, respectively. In the final step, some physicochemical properties of the desulfurized sample crucial in evaluation of fuel quality were determined under optimal conditions and compared with the properties of the original sample. The results indicated that the liquid photocatalysts used in the experiment increased the quality of the fuel by changing its important indicators by reducing its freezing point in addition to increasing its cetane number.

Removal of Dibenzothiophene from Liquid Fuels by Photocatalytic Desulfurization over Zn‐Terephthalate Complex: A Process Modelling and Optimization by Response Surface Methodology

AbstractThe Zn‐terephthalate complex was synthesized by hydrothermal method at 180 °C and applied as a novel macroporous photocatalyst in the desulfurization of dibenzothiophene (DBT) from a fuel model to produce DBT sulfone. The physical‐chemical properties of the photocatalyst were characterized by Fourier Transform Infrared (TIR), Raman spectroscopy, powder X‐ray diffraction (XRD), field‐emission scanning electron microscopy (FESEM), photoluminescence spectroscopy and UV‐Vis diffuse reflectance spectroscopy (UV‐Vis DRS). The characterization results indicated the formation of mono‐nuclear paddlewheel metal‐organic framework (MOF) as Zn [COO]2 frameworks. The photocatalytic experiments were designed by the Box‐Behnken method of response surface methodology (RSM) and the photocatalytic process was modelled and optimized. Three independent process variables i. e. concentration of dibenzothiophene, the amount of photocatalyst and light irradiation time were considered in the experimental design. The determination coefficient (R2) of the model is 0.97. The optimum removal of DBT (50.4 %) resulted in a fuel model containing 50 ppm DBT, desulfurized by 0.060 g of Zn‐MOF photocatalyst under visible light for 180 min. The predicted response (DBT removal%) by the RSM model was 50.68 %. According to the Pareto analysis, the order of importance of independent factors on the response was as follows: Irradiation time&gt;m(photocatalyst)&gt;C(DBT).

The powerful combination of 2D/2D Ni-MOF/carbon nitride for deep desulfurization of thiophene in fuel: Conversion route, DFT calculation, mechanism

2D/2D Ni-MOF/g-C3N4 nanocomposite was utilized for desulfurization. The multilayer pore structure and high specific surface area of Ni-MOF/g-C3N4 promote the adsorption and conversion of thiophene. In addition, the two-dimensional structure exposes more active centers and shortens photogenerated carrier migration to the material surface distance, it enhances photogenerated charge transfer. The Ni-MOF and g-C3N4 construct a Z-scheme heterojunction structure with tight contact, it effectively enhances the material's photocatalytic redox ability. In the light, the material generates more photocarriers for the production of free radicals including hydroxyl radicals, holes, and superoxide radicals. The higher carrier concentration of Ni-MOF/g-C3N4 promotes the activation and oxidation of thiophene, consequently enhancing the photocatalytic desulfurization capability. The results showed that the conversion of thiophene was 98.82 % in 3 h under visible light irradiation. Radical capture experiments and analysis using electron paramagnetic resonance spectroscopy demonstrated that superoxide radicals, holes, and hydroxyl radicals played crucial roles in PODS (photocatalytic oxidative desulfurization). In addition, DFT (density functional theory) calculations were conducted to determine the paths of electron migration and TH (thiophene) adsorption energy. Finally, a mechanism for photocatalytic desulfurization was proposed based on the comprehensive analysis of theoretical calculations and experimental studies.

Construction of 3D mesoporous silica supported MoO3 nanoparticles for the efficient photocatalytic oxidative desulfurization under visible light

A series of Mo-KIT-6 catalysts were developed to photocatalytic oxidize sulfur compounds and promote effective product separation in a photocatalytic extraction oxidative desulfurization (PEODS) system with visible light, extractant [Omim]PF6 and oxidant H2O2. Morphological and pore structure characterization showed that Mo-KIT-6 possessed significant three-dimensional mesoporous structure and large specific surface area which enhanced mass transfer effect and be provided good dispersion of active sites. Doping of Mo enhanced the light absorption and promoted the photogenerated electron hole pair separation, resulting the improvement of the ability of photocatalytic oxidation desulfurization. Among the catalysts, the 15 wt% Mo doping KIT-6 revealed the best desulfurization performance and reached 100 % sulfur removal in 25 min. The circulation experiment proved that the good circulation performance and stability of the photocatalyst within 5 cycles. Radical scavenger experiments and ESR analysis confirmed that OH and h+ played a major role in the reaction. Furthermore, a possible photocatalytic desulfurization mechanism was proposed.

Phosphomolybdic acid clusters and carbon nitride coloading on NH2-N-rGO for photocatalytic oxidation desulfurization

The uncontrolled burning of fossil fuels results in a tremendous increase in atmospheric pollution, which requires immediate mitigation. Herein, an HPMo-g-C3N4/NH2-N-rGO photo-catalytic desulfurization composite was fabricated by wet impregnation and characterized by SEM, XPS, XRD, EIS, PL, FTIR, and UV-Vis. Characterization results showed that g-C3N4 and N-rGO in composites promoted the separation of electron-hole pairs under visible light. The photocatalytic performance of the catalyst was evaluated by the removal of 4, 6-dimethlydibenzothiophene under visible light irradiation. The desulfurization performance of HPMo-g-C3N4/NH2-N-rGO with good stability reached 99.8% in 60 min and 60 ℃, which was much higher than that of g-C3N4, HPMo-g-C3N4, and HPMo-g-C3N4/N-rGO. A possible photocatalytic desulfurization mechanism of HPMo-g-C3N4/ NH2-N-rGO was presumed by density functional theory combined with the experimental results. The developed application of the photocatalytic desulfurization strategy provides a new route for the large-scale processing of transportation fuels.

Sonochemical synthesis of heterostructured ZnO/Bi2O3 for photocatalytic desulfurization

In this study, metal oxides nanoparticles heterogeneous photocatalysts prepared by coprecipitation and ultrasonic techniques were used for diesel desulfurization. They were characterized by scanning electron microscope, powder X-ray diffraction, energy dispersive analysis, diffused reflectance spectra, photoluminescence analysis and BET surface area. The surface area of catalyst B is larger than catalyst A confirming its higher reactivity. X-ray reflectance spectroscopy was used to analyze the sulfur contents in feed. Thiophene was used as a model fuel to evaluate the photocatalytic activity of catalysts A and B. Using the Scherrer equation, sharp and intense signals suggesting their higher degrees of crystallinity, with average crystal sizes for ZnO, Bi2O3, catalysts A and B, respectively; of 18, 14.3, 29.7, and 23.8 nm. The operational parameters of the desulfurization process were optimized and have been studied and the maximum sulfur removal was achieved via a further solvent extraction step. A diesel fuel with a 24 and 19 ppm sulfur content and hence a total sulfur removal of 94.6% and 95.7% was acquired for catalysts A and B, respectively (sulfur compounds concentration in diesel fuel feedstock was 450 ppm). These findings demonstrated that photocatalysts A and B are good and effective catalysts for desulfurization of diesel fuel.

Designing flower-like La-Bi2WO6/Ni@N-rGO composite for the photocatalytic oxidation coupled in-suit hydrogenation desulfurization of diesel oil

The ultra-deep removal of 4,6-DMDB and decrease in loss of C/ H atoms is one of the bottlenecks in achieving ultra-low sulfur fuel oil, which is resolved with photocatalytic oxidation coupled with in-situ hydrodesulfurization. Herein, a flower cluster microsphere composite La-Bi2WO6/Ni@N-rGO as photocatalytic oxidation coupling with in-situ hydrodesulfurization catalysts was prepared by a one-step hydrothermal method. The characterization results of STEM, SEM, Raman, and XPS showed that La-Bi2WO6 combined with Ni@N-rGO formed flower-like microspheres with large specific surface areas. The experimental results showed that the catalysts had excellent photocatalytic oxidation coupling with in-situ hydrodesulfurization performance and good stability. A desulfurization ratio of 4,6-DMDBT reached 99.9% under mild conditions. A plausible mechanism for the photocatalytic desulfurization of 4,6-DMDBT was presumed by combining experiments with density functional theory. The designed La-Bi2WO6/Ni@N-rGO could be utilized for a large-scale process of diesel and other transpiration fuel oil.

Magnetic Z-scheme bismuth molybdate(1-x)/Fe3O4@MIL-125(Ti)(x) nanocomposite as a high-performance visible-light-active photocatalyst for ultra-deep oxidative desulfurization of liquid fuel

Photocatalytic oxidative desulfurization (PODS) under visible light was accomplished by employing bismuth molybdate-modified magnetic MIL-125(Ti) composites, which effectively prevented electron-hole pair recombination and enhanced photoresponse through the formation of Z-scheme photocatalysts. In addition, the inclusion of Fe3O4 facilitated the band gap reduction and enabled the easy separation of the composite for catalyst recycling using a strong permanent magnet. By varying the weight ratios of bismuth molybdate (BMO) to Fe3O4@MIL-125(Ti) (Fe@MIL), the resulting composite was denoted as x%-BFM. Notably, the composite with a weight percentage of 75% (75%-BFM) exhibited remarkable performance in the PODS. This can be attributed to its high specific surface area (235.35 m2/g), ability to combine electron-hole pairs, low energy gap (1.99 eV), improved visible light collection, and superparamagnetic property with a value of 20 emu/g. Within 60 min, this composite achieved a sulfur removal of 99.7% under visible light irradiation, signifying its performance in the oxidation reaction. Furthermore, the 75%-BFM demonstrated exceptional recyclability, as the apparent activity of the catalyst remained unaffected after undergoing at least five recycling cycles. These findings underscore the potential of the 75%-BFM composite as a highly efficient catalyst for photocatalytic desulfurization.

Preparation of a novel BiVO4-Ni(Ⅱ)/g-C3N4 bifunctional photo electrocatalyst for oxidative and absorptive desulfurization of model fuel

This investigation aims to remove sulfur-based compounds (SBCs) by a combination of absorptive and oxidative desulfurization processes. Accordingly, a series of novel Bi-based bifunctional photo electrocatalysts is prepared by thermal method and used to remove dibenzothiophene (DBT) as a source of SBC from n-heptane as model fuel. The catalysts are used in photo electrocatalytic, photocatalytic, and electrocatalytic desulfurization systems and their effect on oxidative and absorptive processes is compared. The catalysts showed higher efficiency in absorptive desulfurization (ADS) by electrocatalytic desulfurization (EDS) and better results in oxidative desulfurization (ODS) by photocatalytic desulfurization (PDS). Among the results, photoelectrocatalytic desulfurization (POEDS) performed best in DBT removal (94%). The catalyst characterization was carried out with various analyses such as XPS, Raman, FTIR, DRS, TGA, FESEM, TEM, and chronoamperometry. The effect of adding radical scavengers on desulfurization was studied to determine the reaction mechanism. The stability of the selected catalyst is examined by repeating the reaction under optimum reaction conditions.

Synthesis and characterization of Ce0.5Bi0.5VO4/rGO nanocomposite by sonochemical method for photocatalytic desulfurization of petroleum derivatives

In order to improve the desulfurization efficiency of petroleum derivatives, Ce0.5Bi0.5VO4/rGO nanocomposite was synthesized by sonochemical method. The prepared nanocomposites were characterized by XRD, FESEM, EDS, FT-IR, BET, and DRS analyses. XRD analysis shows that the synthesized nanocomposite is amorphous. FESEM images showed that nanostructures with a smaller particle size distribution were synthesized under optimal conditions, i.e. controlling the synthesis temperature between 0 and 5 °C. The results of desulfurization showed that nanocomposites containing reduced graphene oxide (rGO) have higher photocatalytic efficiency than pure samples, the main reason of which can be better charge separation in the samples through the π electron in the rGO structure. The highest amount of desulfurization of CeVO4/rGO, BiVO4/rGO, and Ce0.5Bi0.5VO4/rGO nanocomposites was 95.62, 91.25, and 96.38%, respectively, after exposure to UV light for 40 min. The enhancement of photocatalytic activity of Ce0.5Bi0.5VO4/rGO composite could be attributed to the efficient separation of electron–hole pairs and the inhibition of recombination. Desulfurization in the presence of hydrochloric acid and hydrogen peroxide increased the efficiency by 12%, which is a significant amount.

Efficient photocatalytic oxidative desulfurization of liquid petroleum fuels under visible-light irradiation using a novel ternary heterogeneous BiVO4-CuO/modified natural clinoptilolite zeolite

With the enhancement of the public’s awareness of environmental protection and the progressively severe formulation of the regulation on the sulfur contents in fuel, it is crucial for researchers to develop the new ultra-deep desulfurization technology of fuel. In this study, a novel ternary heterogeneous BiVO4-CuO-natural clinoptilolite zeolite (CLT) was synthesized successfully by a hydrothermal method and carried out to degrade dibenzothiophene (DBT) sulfur compound under visible light irradiation. The parent natural clinoptilolite zeolite was modified by dealumination-desilication process. The morphology and structure of the photocatalyst were determined by many analyses including XRD, FT-IR, FE-SEM, EDX-MAP, BET, UV–vis DRS, and PL. The results demonstrated that the band gap energy (Eg) of the adsorbents was reduced by adding the clinoptilolite zeolite to the heterojunction as a carrier and subsequently the recombination rate of electron-hole pairs was decreased. Furthermore, the photocatalytic performance of BiVO4-CuO/clinoptilolite zeolite was evaluated under several variables such as DBT concentrations, catalyst dosage, CuO loading amount, and H2O2 amount as an oxidant. The UV–visible spectrophotometry results showed that BiVO4-Meso CLT-CuO with proper band gap (1.96 eV) had the best photocatalytic desulfurization activity (94.7%) after 30 min of visible light irradiation and it was almost maintained even after five cycles. In addition, a suitable mechanism of improved photocatalytic activity was suggested. Trapping examinations illustrated that the active OH– and O2– species were the prominent and superior reactive species for degrading dibenzothiophene.

Designing oxygen vacancy rich mesoporous CeO2 nanorods with co-doped Cd and Ni for synergistic oxidative‑hydrogenation desulfurization of transportation fuel oils

Photocatalytic oxidative coupled in situ hydrogenation is an emerging and alternative route to the traditional costly hydrodesulfurization strategy for the eradication of organosulfur compounds from transportation fuels under mild operating conditions. In this study, Cd/Ni-doped CeO2 catalysts were prepared by improved hydrothermal method, and were in turn applied for the ultra-deep desulfurization of highly resilient 4,6-dimethyldibenzothiophene (4,6-DMDBT) from diesel oil under visible light irradiation. The prepared photocatalyst were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, Fourier transform infra-red (FTIR) spectroscopy, ultra-violet visible (UV–vis) spectroscopy and Brauner-Emmette-Teller (BET) analyses. Characterization results revealed that bimetallic doped CeO2 mesoporous nanorods were of uniform size (length: 100–200 nm and width: 30–40 nm) having different oxygen vacancies. Catalytic activity evaluation results revealed that under visible light irradiation, 20%Cd/Ni@CeO2 achieved 100% desulfurization performance of 4,6-DMDBT within 50 min at 60 °C, thus surpassing many state of the art catalysts reported in literature. Cd/Ni@CeO2 remained highly active after 10 successive reuses with rapid recovery by simple washing and filtration. Based on the experimental and characterization results, a suitable reaction mechanism was speculated for the photocatalytic desulfurization of 4,6-DMDBT using Cd/Ni@CeO2.

Direct synthesis of unnatural amino acids and modifications of peptides via LADA strategy

Unnatural amino acids (UAAs) have broad applications in pharmaceutical sciences and biological studies. Current synthetic methods for UAAs mainly rely on asymmetric catalysis and often require several steps. There is a lack of direct and simple methods. To address this challenge, we designed the LADA (labeling-activation-desulfurization-addition) strategy: selective labeling and activation of cysteine residues, the photocatalytic desulfurization and the subsequent radical addition to alkenes. Although composed of two steps, it is one-pot synthesis and has advantages such as high functional group tolerance, biocompatible reaction condition, and retained stereochemistry. This highly efficient strategy was successfully applied in the direct synthesis of unnatural amino acids and modifications of peptides with more than 50 examples.

Preparation of Two-Dimensional Layered CeO2/Bi2O3 Composites for Efficient Photocatalytic Desulfurization

A two-dimensional layered CeO2/Bi2O3 composite was synthesized by microwave solvothermal method. X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), UV-Vis diffuse reflection spectroscopy (DRS), and X-ray photoelectron spectroscopy (XPS) were used to studied crystal structure, morphology, optical performance, elemental composition and the surface electronic state of the samples. The photocatalytic properties of the prepared samples were evaluated by photocatalytic desulfurization under visible light. When the molar ratio of Ce and Bi was 1:2, CeO2/Bi2O3 composite presented the highest photocatalytic desulfurization rate. Transient Photocurrent measurement, electrochemical impedance spectroscopy (EIS) and photoluminescence spectroscopy (PL) showed that CeO2 and Bi2O3 formed a heterojunction, which could promote the separation of photogenerated electrons and holes, improving the photocatalytic activity. Furthermore, it was found that the active species of hydroxyl radical (·OH) played an important role in the photocatalytic degradation of dibenzothiophene (DBT) based on the active species capture experiment. Finally, a plausible mechanism for the photocatalytic oxidative desulfurization of this nanocomposite was proposed.

Synergetic Effect of Fe2O3 Doped-CeO2 Nanocomposites Prepared via Different Techniques on Photocatalytic Desulfurization of Heavy Gas Oil

The photocatalytic performances of three Fe2O3–CeO2 nanocomposites were investigated toward the sulfur removal from a petroleum heavy gas oil (HGO) sample. The three composites were prepared by three different routes namely; auto-combustion, post-precipitation and precipitation. The physio-chemical features and optical properties of the presented composites were determined via proper analytical techniques. Formation of Fe2O3–CeO2 solid solution in all the prepared composites was verified via XRD analysis. These composites were then employed in photo-desulfurization of HGO and their activities were investigated at several operating conditions. The highest photocatalytic desulfurization exploit (91.5%) could be detected for the composite which was prepared via auto-combustion technique, denoted as (Fe20Ce80)ac. This maximum percentage of sulfur removal could be obtained under visible light irradiation at the following optimum operating conditions: 15 g/L (as photocatalyst dose), time of 6 h and 2:1 of H2O2 to oil ratio. The subsequent implementation of a solvent extraction step using N-methyl pyrrolidone was needed to attain the deepest desulfurization of HGO. The efficiencies of the presented composites against the process of sulfur removal were discussed in spot of their textural and optical characteristics as well as the available oxygen vacancies through their lattices structures.