Solvent extraction of oxidized diesel fuel

Catalytic Photodegradation of Cyclic Sulfur Compounds in a Model Fuel Using a Bench-scale Falling-film Reactor Irradiated by a Visible Light

A homemade N doped-TiO2 nanoparticle were used to degrade dibenzothiophene (DBT) in a model fuel flowing on a bench-scale glass-made falling film reactor irradiated by a xenon lamp that emitted visible light. The photocatalyst was immobilized on the glass sheet. EDS, SEM, and FT-IR techniques were utilized to identify the morphology of the N doped-TiO2 nanoparticles. Different operating parameters (e.g., N loading (0, 4, 5, and 6 wt%), light intensity (20, 40, and 60 W/m2), and pH (4, 7, and 10)) were investigated for their effect on the DBT degradation.  The effect of the N loading on the wettability of the nano-TiO2 particles was also investigated. Experimental results revealed that the N loading did not affect the wettability characteristics of the nano TiO2 particles. Moreover, results showed that DBT conversion positively depends on N loading, light intensity (hv), and pH increase. The estimated optimal operating parameters were 5 wt% N loading, pH = 10, and hv = 40 W/m2 to ensure the best photo-oxidation efficiency of 91.4% after 120 min of operation. The outcomes of the present work confirmed the effective efficiency of the N-doped TiO2 nanoparticles irradiated by visible light for DBT degradation. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Synthesis and characterization of iron-alumina composites as novel efficient photocatalysts for removal of DBT

The content of sulfur compounds in diesel fuels is one of the main encountered drawbacks during the production process. Such compounds are generally of substantial, hazardous, and negative environmental impacts. Thus, the massive reduction of their content is recommended. Among these compounds, DBT is one of the most challenging compounds to be disposed of industrially via the HDS method. Therefore, this study presents the removal of such compounds using the oxidative-photocatalytic desulfurization technique. Three iron oxide doped alumina composites containing different weight percentages of iron (10-30%) were synthesized as novel photocatalysts. Structural characteristics of these composites were verified via X-ray diffraction (XRD) by detecting the indicative peaks for Fe₂O₃ and Al₂O₃. These composites' surface and optical properties could reveal their mesoporous nature and suitability as effective visible-light photocatalysts. These structures were next introduced to the process of DBT removal from a model diesel oil with a content of 1500 ppm at different operating conditions. The composite, which contains 20% iron oxide, was the most effective photocatalyst of DBT elimination. Specifically, 97% removal of sulfur content in the model diesel oil was successfully attained under visible-light irradiation source with a power of 500 W at a reaction time equals to 30 min, 1 g/L as photocatalyst dose and H₂O₂ to feed ratio of 1.5.

Oxidative desulfurization of model and real fuel samples with natural zeolite-based catalysts: experimental design and optimization by Box–Behnken method

In this study, oxidative desulfurization was performed on simulated oil fraction consist of 1000 ppm dibenzothiophene. Cobalt supported on natural zeolite of Kaolin has been used as heterogeneous catalysts. 10% Co/metaKaolin with hydrogen peroxide as oxidant and acetonitrile as extraction solvent have shown excellent performance on desulfurization. Response surface methodology in experimental design and its subset Box–Benken was used to evaluate the performance of the selected catalyst in different operating conditions such as temperature, oxidant to sulfur molar ratio, time and catalyst amount. Also, optimum conditions was obtained are equal to 60 °C, O/S molar ratio (10.8 mol/mol), time (46 min) and catalyst amount 0.04 g with 97.1% sulfur removal. Oxidative desulfurization of model oil containing 1000 ppm of each sulfur component benzothiophene and thiophene was also tested at the optimum conditions, Oxidative desulfurization yield was ordered as DBT > BT > Th. In addition, after four steps consecutive recycle under optimum conditions oxidative desulfurization capacity of 10% Co/metaKaolin catalyst decreased from 97% to 92%, which is still high desulfurization capability. Finally, the performance of 10% Co/metaKaolin catalyst in oxidative desulfurization was evaluated for real oil fractions, gasoline and gasoil that was provided from regional oil refinery with sulfur content of 286 ppm and 7900 ppm, respectively. At the optimum conditions of operating variables desulfurization yield was 58% and 79% of total sulfur removal for gasoline and gasoil respectively with no significant changes in fuels properties.

Nanoarchitectonics of Copper Tungsten-Mesoporous Silica with a New Template for Photo Oxidative-Desulfurization of Dibenzothiophene

A novel CuWO4/SiO2 heterojunction catalyst was successfully synthesized using a new sulfonamide derivative. The physical characteristics of the prepared samples were investigated by TGA, XRD, FTIR, SEM, UV, PL, and XPS. The prepared catalysts were applied as a nano photocatalyst for photooxidative desulfurization of dibenzothiophene under visible light using hydrogen peroxide as an oxidant. The photocatalytic oxidative desulfurization performances of the prepared samples were investigated. Various factors as the reaction time, dibenzothiophene concentration, catalyst dose, and the oxidizing agent dose were also studied. The prepared photocatalyst has high desulfurization activity in the removal of DBT under mild conditions. Results showed that the CuWO4/SiO2 exhibited considerably higher activity than neat support SiO2. Such improved photocatalytic activity is mainly attributed to the efficient separation of photogenerated electron–hole pairs on CuWO4/SiO2 heterojunction. Moreover, the synergistic effects of this photocatalytic oxidation and the green oxidant hydrogen peroxide played an essential role in desulfurization. The reaction is pseudo-first-order and can reach 98.6% removal of dibenzothiophene after 70 min and 97.2% after four cycles.

Graphical Abstract

Oxidative Desulfurization of Heavy Oils with High Sulfur Content: A Review

The demand for clean fuels is increasing throughout the world, with more stringent environmental regulations for transportation fuels including marine fuels, particularly regarding their sulfur content. Moreover, the quality of crude oil and derived petroleum cuts is getting lower while fossil fuels are still in high demand. Heavy oils are characterized by high sulfur content where most sulfur is found in bulky thiophenic structures difficult to remove using conventional high pressure hydrodesulfurization process. However they appeared more reactive in oxidative desulfurization (ODS) process, carried out at mild conditions without hydrogen pressure. This review focuses for the first time on the heavy fuels initially containing more than 0.5 wt.%S and upgraded by the ODS process. Different attractive approaches of the literature towards ODS are reported using homogeneous and heterogeneous catalysis. Recent developments in ODS assisted with ultrasound technology and the use of ionic liquid to enhance ODS efficiency will be fully detailed and discussed to better understand their viability when applied to high sulfur content, high viscosity, and high boiling point feeds.

Production of ultra-deep sulfur-free diesels using a sustainable catalytic system based on UiO-66(Zr)

The porous metal-organic framework UiO-66(Zr) obtained via non modulated synthesis, has revealed to be a notable heterogeneous catalyst, enabling extremely fast and very efficient desulfurization of a multicomponent model diesel and also a real diesel fuel.