Selective oxidation of sulfurs and oxidation desulfurization of model oil by 12-tungstophosphoric acid on cobalt-ferrite nanoparticles as magnetically recoverable catalyst

Exploring the impact of competitive compounds and catalyst synthesis method in DBT oxidative desulfurization using MoO3-V2O5/Al2O3 catalyst

This research endeavors to address the pressing challenge of reducing sulfur content in fuels, an environmental imperative. It does so by employing bimetallic catalysts to enhance the efficiency of oxidative desulfurization (ODS) processes. This involves utilizing successive impregnation and co-impregnation methods to prepare a MoO3-V2O5/Al2O3. The catalysts underwent characterization using various techniques including X-ray diffraction (XRD), N2 adsorption-desorption, UV-vis (DRS), temperature-programmed desorption (NH3-TPD), Raman, Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), and energy dispersive spectrum (EDS). The catalyst was utilized for the evaluation of the ODS process of dibenzothiophene (DBT). The effects of oxidants, namely H2O2 and t-butyl hydroperoxide (TBHP), were studied in the ODS. The catalyst prepared using the co-impregnation method (5M-15V-co) demonstrated significant acidic sites and exhibited remarkable efficiency in oxidative desulfurization. Remarkably, this catalyst achieved 100% oxidation of sulfur components within 30 min (min). To assess the catalyst's performance further, competitive compounds including nitrogen-containing compounds (NCCs) and saturated and unsaturated hydrocarbon compounds (HCs) were employed in the ODS. Initially, the introduction of NCCs led to a decrease in the sulfur removal rate; however, the catalyst successfully oxidized DBT completely within 60 min. When cyclohexene was present as an olefinic hydrocarbon compound, the catalyst oxidized DBT by approximately 75%, whereas DBT oxidation reached 100% within 20 min when p-xylene was introduced to the catalytic reactor. Additionally, as the O/S ratio increased from 2/5 to 10, the sulfur removal rate improved from 30 to 90%, indicating that HCs and NCCs compete with sulfur in terms of oxidant consumption.

Insights to the oxidative desulfurization process of fossil fuels over organic and inorganic heterogeneous catalysts: advantages and issues

Strict environmental laws have been put in place around the world to reduce the amount of sulfur in the fuel to reduce the emissions of harmful gases from fuel combustion and improve air quality. Therefore, extensive researches have been undertaken to devise effective processes or to improve the desulfurization processes. Among the desulfurization processes, the oxidative desulfurization (ODS) process is a promising method to achieve very low and near-zero sulfur content of the fuel. In this process, sulfur compounds are converted to the corresponding sulfone by a catalyst and in the presence of an oxidant. The obtained compounds by polar solvents or adsorbents are removed from the fuel. In recent decades, extensive studies have been carried out on the catalysts used in the oxidative desulfurization process. In this review, a comprehensive survey has been performed on heterogeneous catalysts used in the oxidative desulfurization process. According to the reported researches, the heterogeneous catalysts used can be divided into five groups: ionic liquids, carbon materials, polyoxometalates, transition metal oxides stabilized on porous solid substrates, and metal-organic frameworks. The proposed mechanisms with different catalysts have also been studied in this work.

Polyoxometalate as an effective catalyst for the oxidative desulfurization of liquid fuels: a critical review

In order to meet the stringent environmental and industrial legislation on fuel specifications, sulfur compounds have to be removed efficiently from fuels. The requirement to produce ultralow-sulfur fuels (S < 10 ppm) has stimulated many works in the area of conventional hydro-desulfurization (HDS) method. Oxidative desulfurization (ODS), as an alternative or complementary technology to HDS for deep desulfurization, is conducted with high selectivity and reactivity to sterically hindered S compounds under mild reaction conditions. In the ODS process, using an appropriate oxidant in the presence of a catalyst, organic sulfur compounds can be oxidized selectively to their corresponding sulfoxides and sulfones, which can be easily removed by different separation methods. Having great catalytic characteristics, polyoxometalate materials have been utilized as a vital class of catalysts for deep desulfurization of fuels. In the past few decades, ODS of fuels using polyoxometalate as catalyst has drawn much attention, and various studies have been carried out in this area. Here, we give a critical review for the removal of sulfur compounds from liquid fuels (mostly from diesel and model fuels) by ODS via homogeneous and heterogeneous polyoxometalate catalysts.

Heterogenization of heteropoly compounds: a review of their structure and synthesis

The heterogenization of different types of heteropoly compoundsviasix popular methods from those published over the past recent 15 years is reviewed.

Performances, kinetics and mechanisms of catalytic oxidative desulfurization from oils

Ultra-deep desulfurization technologies are critical for cleaner oils and consequent better air quality.