Metal-Organic Frameworks as a Potential Platform for Selective Treatment of Gaseous Sulfur Compounds

The release of various anthropogenic pollutants such as gaseous sulfur compounds into the environment has been accelerated as globalization has promoted the production of high-quality products at lower prices. Because of strict enforcement of mitigation technologies, advanced materials have been developed to efficiently remove gaseous sulfur compounds released from various source processes. Metal-organic frameworks (MOFs) are promising materials to treat sulfur compounds via adsorption, catalysis, or separation. Nonetheless, the practical applicability of MOFs is limited by a number of factors including loss of structural integrity after use, limited reusability of spent MOFs, and low stability toward omnipresent molecules (e.g., H₂O). Here, we provide a comprehensive assessment of MOF technology for the effective control of gaseous sulfur compounds. This review will thus help expand the fields of real-world application for MOFs with a roadmap for this highly challenging area of research.

Simultaneously saccharification and fermentation approach as a tool for enhanced fossil fuels biodesulfurization

Biodesulfurization can be a complementary technology to the hydrodesulfurization, the commonly physical-chemical process used for sulfur removal from crude oil. The desulfurizing bacterium Gordonia alkanivorans strain 1B as a fructophilic microorganism requires fructose as C-source. In this context, the main goal of this work was the optimization of a simultaneous saccharification and fermentation (SSF) approach using the Zygosaccharomyces bailii strain Talf1 crude enzymes with invertase activity and sucrose as a cheaper fructose-rich commercial C-source (50% fructose) towards dibenzothiophene (DBT) desulfurization by strain 1B. The determination of optimal conditions, for both sucrose hydrolysis and DBT desulfurization was carried out through two sequential experimental uniform designs according to the Doehlert distribution for two factors: pH (5.5-7.5) and temperature (28-38 °C), with the enzyme load of 1.16 U/g/L; and enzyme load (0-4 U/g/L) and temperature (28-38 °C), with pH at 7.5. Based on 2-hydroxybiphenyl production, the analysis of the response surfaces obtained pointed out for pH 7.5, 32 °C and 1.8 U/g/L as optimal conditions. Further optimized SSF of sucrose during the DBT desulfurization process permitted to attain a 4-fold enhanced biodesulfurization. This study opens a new focus of research through the exploitation of sustainable low cost sucrose-rich feedstocks towards a more economical viable bioprocess scale-up.

A Non-catalytic Deep Desulphurization Process using Hydrodynamic Cavitation

A novel approach is developed for desulphurization of fuels or organics without use of catalyst. In this process, organic and aqueous phases are mixed in a predefined manner under ambient conditions and passed through a cavitating device. Vapor cavities formed in the cavitating device are then collapsed which generate (in-situ) oxidizing species which react with the sulphur moiety resulting in the removal of sulphur from the organic phase. In this work, vortex diode was used as a cavitating device. Three organic solvents (n-octane, toluene and n-octanol) containing known amount of a model sulphur compound (thiophene) up to initial concentrations of 500 ppm were used to verify the proposed method. A very high removal of sulphur content to the extent of 100% was demonstrated. The nature of organic phase and the ratio of aqueous to organic phase were found to be the most important process parameters. The results were also verified and substantiated using commercial diesel as a solvent. The developed process has great potential for deep of various organics, in general, and for transportation fuels, in particular.

Remarkable adsorptive removal of nitrogen-containing compounds from a model fuel by a graphene oxide/MIL-101 composite through a combined effect of improved porosity and hydrogen bonding

A composite was prepared by combining a highly porous metal-organic framework (MOF), MIL-101 (Cr-benzenedicarboxylate), and graphene oxide (GnO). The porosity of the composite increased appreciably by the addition of GnO up to a specific amount in the MOF, though further increases in the quantity of GnO was detrimental to porosity. The improved porosity of the GnO/MIL-101 composite was utilized for adsorptive denitrogenation (ADN) of a model fuel where indole (IND) and quinoline (QUI) were used as nitrogen-containing compounds (NCCs). It was found that both IND and QUI showed improved adsorption on the composite compared with pristine MIL-101 or GnO due to the improved porosity of the composite. Interestingly, the improvement in adsorption of IND was much higher than the quantity estimated for the porosity. Importantly, GnO/MIL-101 showed the highest adsorption capacities for NCCs. Irrespective of the studied solvents and co-presence of IND and QUI, the composite adsorbent performed ADN most effectively. This remarkable improvement is explained by the additional mechanism of hydrogen bonding between the surface functional groups of GnO and the hydrogen attached to the nitrogen atom of IND. This hydrogen bonding mechanism is also supported by the results of the adsorption of pyrrole and methylpyrrole. On the other hand, QUI does not show hydrogen-bonding capability, and therefore, its enhanced adsorption originates from only the increased porosity of the adsorbents.

Hybrid Polymer/UiO-66(Zr) and Polymer/NaY Fiber Sorbents for Mercaptan Removal from Natural Gas

Zeolite NaY and metal organic frameworks MIL-53(Al) and UiO-66(Zr) are spun with cellulose acetate (CA) polymer to create hybrid porous composite fibers for the selective adsorption of sulfur odorant compounds from pipeline natural gas. Odorant removal is desirable to limit corrosion associated with sulfur oxide production, thereby increasing lifetime in gas turbines used for electricity generation. In line with these goals, the performance of the hybrid fibers is evaluated on the basis of sulfur sorption capacity and selectivity, as well as fiber stability and regenerability, compared to their polymer-free sorbent counterparts. The capacities of the powder sorbents are also measured using various desorption temperatures to evaluate the potential for lower temperature, energy, and cost-efficient system operation. Both NaY/CA and UiO-66(Zr)/CA hybrid fibers are prepared with high sorbent loadings, and both have high capacities and selectivities for t-butyl mercaptan (TBM) odorant sorption from a model natural gas (NG), while being stable to multiple regeneration cycles. The different advantages and disadvantages of both types of fibers relative are discussed, with both offering the potential advantages of low pressure drop, rapid heat and mass transfer, and low energy requirements over traditional sulfur removal technologies such as hydrodesulfurization (HDS) or adsorption in a pellet packed beds.

A metal-organic framework with immobilized Ag(i) for highly efficient desulfurization of liquid fuels

A metal-organic framework immobilized with Ag(i) sites, namely, (Cr)-MIL-101-SO3Ag, was successfully developed as a highly efficient desulfurization adsorbent because of the strong binding of these Ag(i) sites for thiophene derivatives.

Inorganic–organic hybrid sorbent for aromatic desulfurization of hydrocarbons: regenerative adsorption based on a charge-transfer complex

Inorganic–organic hybrid materials for aromatic desulfurization based on the charge-transfer complex (CTC) of 4,6-dimethyldibenzothiophene:1,5-dichloro-4,8-dinitro-anthraquinone.

Theoretical study on the mechanism of oxidative–extractive desulfurization in imidazolium-based ionic liquid

The oxidation of TH to SP by H₂O₂ with the assistance of IL experiences two steps via two transition states.

Advances in the Reduction of the Costs Inherent to Fossil Fuels' Biodesulfurization towards Its Potential Industrial Application

Biodesulfurization (BDS) process consists on the use of microorganisms for the removal of sulfur from fossil fuels. Through BDS it is possible to treat most of the organosulfur compounds recalcitrant to the conventional hydrodesulfurization (HDS), the petroleum industry's solution, at mild operating conditions, without the need for molecular hydrogen or metal catalysts. This technique results in lower emissions, smaller residue production and less energy consumption, which makes BDS an eco-friendly process that can complement HDS making it more efficient. BDS has been extensively studied and much is already known about the process. Clearly, BDS presents advantages as a complementary technique to HDS; however its commercial use has been delayed by several limitations both upstream and downstream the process. This study will comprehensively review and discuss key issues, like reduction of the BDS costs, advances and/or challenges for a competitive BDS towards its potential industrial application aiming ultra low sulfur fuels.

Enhancement of dibenzothiophene biodesulfurization by weakening the feedback inhibition effects based on a systematic understanding of the biodesulfurization mechanism by Gordonia sp. through the potential “4S” pathway

Gordonia sp. JDZX13 (source: industrial petroleum soil) shows good potential for dibenzothiophene (DBT) biodesulfurization.

A Mn(iii) polyoxotungstate in the oxidation of organosulfur compounds by H2O2 at room temperature: an environmentally safe catalytic approach

A manganese monosubstituted Keggin-type polyoxometalate was used as a catalyst in the oxidation of recalcitrant organosulfur compounds by hydrogen peroxide at room temperature.

Ionic liquid@MIL-101 prepared via the ship-in-bottle technique: remarkable adsorbents for the removal of benzothiophene from liquid fuel

Ionic liquids were firstly synthesized in a pore of metal–organic framework via a ship-in-bottle technique; and the obtained IL@MOF showed a remarkable reusability/stability in the adsorptive desulfurization of model fuel.

A multicomponent assembly approach for the design of deep desulfurization heterogeneous catalysts

An assembly approach has been employed for the preparation of a multi-component heterogeneous catalyst showing high efficiency in deep desulfurization processes.

Ability of Gordonia alkanivorans strain 1B for high added value carotenoids production

Currently, carotenoids are valuable bioactive molecules for several industries, such as chemical, pharmaceutical, food and cosmetics, due to their multiple benefits as natural colorants, antioxidants and vitamin precursors.

Influence of a porous MOF support on the catalytic performance of Eu-polyoxometalate based materials: desulfurization of a model diesel

An aluminum 2-aminoterephthalate based metal–organic framework material was used to prepare highly efficient heterogeneous catalysts in desulfurization processes.

Co-promoted MoO3 nanoclusters for hydrodesulfurization

In this paper, we report the synthesis of ultrasmall Co-promoted MoO₃ nanoclusters (∼2 nm) supported over γ-Al₂O₃ possessing an increased number of Mo edge atoms, using colloidal synthesis for hydrodesulfurization reaction.

Synergistic interactions of Cu and N on surface altered amorphous TiO2 nanoparticles for enhanced photocatalytic oxidative desulfurization of dibenzothiophene

Amorphous TiO₂ (AT) nanoparticles were prepared by a simple sol–gel method and subsequent incorporation with 5–20 wt% copper via an electrochemical method in the presence of tetraethylammonium perchlorate gave an active CuO/TiO₂ (CAT) photocatalyst.

A recyclable ionic liquid-oxomolybdenum(vi) catalytic system for the oxidative desulfurization of model and real diesel fuel

The extractive and catalytic oxidative desulfurization (ECODS) of model and real diesel has been studied using the complex [MoO₂Cl₂(di-tBu-bipy)](1) (di-tBu-bipy = 4,4′-di-tert-butyl-2,2′-bipyridine) as a (pre)catalyst, aq. H₂O₂ as an oxidant, and either acetonitrile or an ionic liquid (IL) as a solvent and extractant.

Plasmon-mediated photothermal conversion by TiN nanocubes toward CO oxidation under solar light illumination

Titanium-nitride (TiN) nanocubes were decorated with platinum nanoparticles via a wet-chemistry route to yield TiN-supported Pt catalysts (Pt/TiN).

Direct preparation of [(CH3)3NC16H33]4Mo8O26 and its catalytic performance in oxidative desulfurization

The catalyst [(CH₃)₃NC₁₆H₃₃]₄Mo₈O₂₆ has been synthesized by a direct precipitation method and shows efficient oxidative desulfurization performance.

Nanotechnology Applied to the Biodesulfurization of Fossil Fuels and Spent Caustic Streams

The use of nanostructured materials in combination with desulfurizing microorganisms is a promising technique that would improve the desulfurization processes of gaseous fuels, oil, and some wastewater. Nanoparticles are highly versatile and tunable depending on the necessities of each particular contaminated media. The chapter shows the current technological options for the biodesulfurization of natural gas, oil and wastewater produced from the petroleum refining, where the application of nano-sized materials combined with desulfurizing microorganisms would improve the desulfurization capacities. In addition, advantages, disadvantages and opportunities of this hybrid technology are presented.

Solvent desulfurization regeneration process and analysis of activated carbon for low-sulfur real diesel

The adsorption desulfurization process of diesel fuel is suffering from adsorbent regeneration limitation.

Adsorption of indole and quinoline from a model fuel on functionalized MIL-101: effects of H-bonding and coordination

Adsorptive denitrogenation was carried out with functionalized metal–organic frameworks in order to understand plausible adsorption mechanisms.

Effect of gas oil composition on performance parameters of the extractive desulfurization process

Extraction of sulfur compounds reveal that sulfur removal from gas oil strongly depends on the molecular structure of the sulfur compound and composition of the carrier phase.

Lanthanide complexes as luminogenic probes to measure sulfide levels in industrial samples

A series of lanthanide-based, azide-appended complexes were investigated as hydrogen sulfide-sensitive probes. Europium complex 1 and Tb complex 3 both displayed a sulfide-dependent increase in luminescence, while Tb complex 2 displayed a decrease in luminescence upon exposure to NaHS. The utility of the complexes for monitoring sulfide levels in industrial oil and water samples was investigated. Complex 3 provided a sensitive measure of sulfide levels in petrochemical water samples (detection limit ∼ 250 nM), while complex 1 was capable of monitoring μM levels of sulfide in partially refined crude oil.

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.