Thiophene Conversion Research Articles

Recent Advancements in Polythiophene-Based Materials and their Biomedical, Geno Sensor and DNA Detection.

In this review, the unique properties of intrinsically conducting polymer (ICP) in biomedical engineering fields are summarized. Polythiophene and its valuable derivatives are known as potent materials that can broadly be applied in biosensors, DNA, and gene delivery applications. Moreover, this material plays a basic role in curing and promoting anti-HIV drugs. Some of the thiophene’s derivatives were chosen for different experiments and investigations to study their behavior and effects while binding with different materials and establishing new compounds. Many methods were considered for electrode coating and the conversion of thiophene to different monomers to improve their functions and to use them for a new generation of novel medical usages. It is believed that polythiophenes and their derivatives can be used in the future as a substitute for many old-fashioned ways of creating chemical biosensors polymeric materials and also drugs with lower side effects yet having a more effective response. It can be noted that syncing biochemistry with biomedical engineering will lead to a new generation of science, especially one that involves high-efficiency polymers. Therefore, since polythiophene can be customized with many derivatives, some of the novel combinations are covered in this review.

One-step synthesis of mesoporous alumina-supported molybdenum carbide with enhanced activity for thiophene hydrodesulfurization

A new mesoporous alumina-supported molybdenum carbide (Mo2C/γ-MA) has been successfully prepared by one-step hydrolysis method without template, followed by carbonization with a mixed gas of CH4 and H2. The Mo2C particles (2.5 ± 0.3 nm) are homogeneously dispersed in the γ-alumina (γ-MA) framework and exhibit high catalytic activity and stability for thiophene hydrodesulfurization (HDS). Taking 1 wt% thiophene (3810 ppm S) as an example, the Mo2C/γ-MA exhibits 92% thiophene conversion, higher than the MoS2/γ-MA (85%), and other molybdenum carbides supported over commercial alumina and γ-MA prepared by the impregnation method. The stability test demonstrated that the Mo2C/γ-MA almost showed no deactivation during 150 h reaction, and no obvious carbon deposition and sulfurization of Mo2C species were observed over the spent Mo2C/γ-MA. The high HDS activity and stability of the Mo2C/γ-MA for HDS could be attributed to the formation of small Mo2C nanoparticles, appropriate surface acidity and the strong interaction between Mo2C species and alumina inhibiting the sulfurization of Mo2C species.

Density functional theory study of thiophene desulfurization and conversion of desulfurization products on the Ni(111) surface and Ni55 cluster: implication for the mechanism of reactive adsorption desulfurization over Ni/ZnO catalysts

Density functional theory calculations were performed to study thiophene desulfurization and conversion of desulfurization products on the Ni(111) surface and Ni55 cluster.

Acid-Catalytic Oxidation of Thiophene by Hydrogen Peroxide in n-Octane–Water System

The effect of the reaction time and temperature, composition and concentration of the oxidizing mixture on the degree of thiophene conversion in the n-octane–water two-phase system was studied. The oxidative activity of peroxyacids generated from hydrogen peroxide and acids (trifluoroacetic, formic, nitrous) changes in the series СF3COOOH > HCOOOH > HOONO. The addition of cetyl(trimethyl)ammonium bromide inhibit the oxidation of thiophene.

Gasification and oxidation of thiophene in supercritical water fluids

The paper deals with the gasification of thiophene in supercritical water (SCW) at a molar ratio of H2O:C4H4S = 1:0.107, a temperature of 873–1023 K, a pressure of 30 MPa, and a holding time of 150–600 s in a batch reactor. The gases of CO2, CO, H2, CH4, and H2S were detected in the composition of SCW gasification products. The maximum degree of thiophene gasification (>99.9%) was achieved at 1023 K and 600 s. The conversion of thiophene in SCW is described by a pseudo-first-order macro kinetic equation. It was revealed that the oxidation of thiophene in H2O/O2 mixture at uniform heating of the reactor (1 K·min−1) begins at T ≈ 400 K. The lack of O2 results in the formation of soot. It is shown that the formation of sulfuric acid during the oxidation of thiophene in the H2O/O2 mixture causes corrosion of stainless steel.

The Improvement on One‐pot Preparation of CoMo/Al2O3‐TiO2 Catalysts with Citric Acid Post‐treatment for Hydrodesulfurization of Thiophene

AbstractThe preparation of the supported catalysts with the treatment of various chelating agents would significantly influence their physicochemical properties and corresponding catalytic performance. In the present work, three different methods such as the incipient wetness impregnation method, wet mixing method, and the one‐pot method were employed to prepare the CoMo/Al2O3‐TiO2 hydrodesulfurization (HDS) catalysts. After the comprehensive consideration of the characterization and catalytic performance results, the catalyst prepared by the one‐pot method (OP) was further post‐treated by citric acid (CA) with different concentrations. The thiophene conversion over the CA post‐treated catalysts was significantly improved in comparison with that of the parent catalyst, especially for the OP‐C1.5 catalyst (molar ratio of CA/Mo=1.5) with the thiophene conversion higher than 97.2 %. The CA with the appropriate addition amount in the post‐treatment solution can weaken the MoO3‐Al2O3 interaction for promoting the re‐dispersion of Mo species, which is responsible for the enhanced HDS performance over the CA post‐treated catalysts.

NiMo Catalysts Supported on Al-Based Mixed Oxide Prepared By Hydrothermal Method: Effect of Zn/Al Ratio and Addition of Silica on HDS Activity

The effect of Zn/Al ratio and addition of silica to Al–Znx oxides on the structure and catalytic properties of supported NiMo catalysts in hydrodesulfurization reaction of thiophene was studied. NiMo catalysts were synthesized by simultaneous impregnation of Ni acetate and 12-molybdophosphoric acid on Al–Znx and Al–Zn0.16–Si mixed oxide (with x = Zn/Al ratio of 0.05–0.57) prepared by hydrothermal synthesis at 180 °C. Colloidal SiO2 was added to the Al–Znx oxides (Si/Al = 0.3 ratio) to modify textural and structural properties of NiMo catalysts. These materials were characterized by N2 physisorption, SEM, XRD, FTIR, UV–Vis DRS, TPR–H2, TPD–NH3, XPS, HRTEM and tested in thiophene conversion at 280–400 °C and 1.0 MPa. It was found out that the surface area of the supports calcined at 500 °C, decreases with the increasing Zn/Al ratio, which could be due to the interaction of the Zn with the alumina, leading to formation of Zn-spinel. After impregnation of the supports with NiMo active components, the presence of Zn increases the amount of surface Mo in octahedral sites at Zn/Al = 0.21 ratio. At this ratio maximum in HDS activity of NiMo/Al–Znx samples was observed. Addition of silica to Al-Zn mixed oxide (Zn/Al = 0.16) leads to more active NiMo catalyst due to formation of more Ni(Zn)–Mo–S active species as revealed by XRD and HRTEM.

Three-dimensionally ordered macroporous bulk catalysts with enhanced catalytic performance for thiophene hydrodesulfurization

The microstructure tuning of bulk catalysts would significantly influence their physical/chemical properties for the subsequent applications. In this work, the three-dimensionally ordered macroporous (3DOM) bulk catalysts (CoMo, CoMoW and CoW) were successfully fabricated by employing the poly-(methyl methacrylate) (PMMA) as hard template. The prepared bulk catalysts were characterized by means of techniques, such as TG/DTG, XRD, low-temperature N2 adsorption-desorption, SEM, etc. The characterization and catalytic performance evaluation results indicated that the unique hierarchical pore system of the 3DOM bulk catalysts could not only supply more available surface area, thus more active sites, but also facilitate the diffusion of the reactants/products to/from the active sites of the bulk catalyst. Moreover, the 3DOM structure of the bulk catalysts was retained after the pre-sulfurization process and hydrodesulfurization reaction, illustrating the relatively high stability of prepared bulk catalysts in the experimental investigation. The 3DOM CoMo bulk catalyst exhibited superior catalytic performance with thiophene conversion of 99.2% at 360 °C in comparison with the CoW and CoMoW bulk catalysts.

In situ hydrothermal preparation and photocatalytic desulfurization performance of graphene wrapped TiO2 composites

Organosulfur impurities in fuels cause severe environmental pollution and poison the catalysts used in vehicle exhausts’ gas converters. Here we developed a facile “In suithydrothermal” method to prepare reduced graphene oxide (RGO) supported TiO2 catalyst and applied it for oxidative desulfurization of thiophene(T) in model fuel. The RGO/TiO2 catalysts were characterized by FT-IR, XPS, SEM, XRD and UV–Vis spectroscopy. The photocatalytic properties were evaluated by the degradation of thiophene in model fuel. The catalytic activity of RGO/TiO2 composites for the oxidation of thiophene in n-octane is relatively higher than those of pure GO or TiO2 power. Moreover, the thiophene conversion rate reached 94.3% with RGO/TiO2 composite catalyst after treatment for 100 min at atmospheric pressure. The graphene oxide is partially reduced during the “in situ hydrothermal” process. The photocatalysis mechanism indicated that RGO/TiO2 photocatalysts are facilitating to electron transfer fromTiO2 to RGO and enhance the adsorption of the target pollutants to improve the oxidative desulfurization (ODS) performance.

THIOPHENE CRACKING USING MAGNESIUM MODIFIED BETA ZEOLITE

The development of additives for FCC catalysts aiming at a greater sulfur removal in the gasoline fraction has been a priority with tougher environmental legislation demands. In this context, this study has evaluated the effect of magnesium modified beta zeolite on n-hexane cracking, and the catalytic conversion of thiophene added as contaminant. Catalytic tests’ results, performed at low conversion at 400 ºC with a WHSV of 0.83 s-1 indicate that magnesium addition increased n-hexane cracking from 37.7 to 53.6% in mols, but favored the formation of alkylated sulfur compounds over H2S production.

CATALYTIC REMOVAL OF SULFUR COMPOUNDS FROM PETROLEUM STREAMS

Sulfur removal aiming at attending environmental legislation standards has been the focus of many studies. The use of Fluid Catalytic Cracking, FCC, in the removal of gasoline-fraction sulfur contaminants is regarded as advantageous when compared to desulfurization processes downstream of the FCC process. This paper evaluates the effect of Mg addition to the Beta zeolite over n-hexane and thiophene cracking. The catalysts were characterized by X-ray diffraction (XRD), X-ray with dispersive energy fluorescence analysis (EDXRF), Fourier transform infrared spectroscopy (FTIR), ammonia temperature programmed desorption (NH3-TPD), and Brunauer-Emmett-Teller method (BET). The magnesium incorporation into the zeolite increased the number of Bronsted active sites and total acidity in the catalyst, favoring an increase in selectivity for catalytic cracking reactions and a decrease of isomerization reactions in the n-hexane conversion step. In thiophene conversion, the greater selectivity for hydrogen transfer promoted the formation of H2S, and adsorptive capacity is a key factor in alkylated product formation due to the presence of Lewis active sites, which are more predominant in magnesium incorporated catalysts.

Role of Mn/Al2O3 catalyst in deep oxidative desulfurization of diesel

In this work, a series of supported manganese catalyst has been synthesized and utilized in oxidative desulfurization to remove 4,6-dimethyldibenzothiophene (4,6-DMDBT), dibenzothiophene (DBT) and thiophene. The influences of catalyst parameters were investigated including manganese precursors, manganese loading and calcination temperature in details. The synthesized catalyst was characterized by scanning electron microscopy (SEM), N2 adsorption/desorption and X-ray diffraction (XRD) techniques. 90.2% of 4,6-DMDBT, 98.5% of DBT and 95.5% of thiophene conversion were achieved under mild operational conditions using 3Mn(NO3)2/Al2O3 at 500 °C calcination temperature. A slight decrease in desulfurization activity was observed after Mn/Al2O3 catalyst being used in five cycles ODS.

Pollutant reduction and catalytic upgrading of a Venezuelan extra-heavy crude oil with Al2O3-supported NiW catalysts: Effect of carburization, nitridation and sulfurization

Alumina-supported Ni-promoted W oxides, carbides and nitrides were presulfided and employed for reducing pollutants and increasing the quality of an extra-heavy crude oil during catalytic upgrading reactions. These materials were prepared by temperature programmed reaction using reactive gases and varying the (Ni/(Ni + W)) atomic ratio from 0.00 to 1.00. Catalysts were characterized by XRD, SEM, HRTEM and N2 physisorption. In order to study the effect of the atomic ratio in the conversion of the model molecule thiophene, room pressure HDS tests were used. The catalysts with best performances during thiophene HDS were tested in the upgrading of a Venezuelan extra-heavy crude oil characterized by having high asphaltenes, S and N contents, affecting competitiveness in the global market. These results were compared with a commercial NiMo catalyst. API gravity of crude oil, CHNS elemental analysis, 13C- and 1H NMR of crude oil and asphaltenic fraction, in addition to flocculation threshold of asphaltenes, were studied in order to verify variations in physicochemical properties of oil due to catalytic upgrading and to seek evidence of pollutants reduction and improvement of quality during this process. NiW catalysts with atomic ratio (Ni/(Ni + W) = 0.50 showed remarkable performance during thiophene HDS and heavy oil hydrotreatment, improving API gravity and reducing S content, modifying chemical nature of crude oil and asphaltenes, as it was revealed by results of elemental analysis, H/C ratio, flocculation threshold, Caro/Cali and Haro/Hali ratios. However, no significant variations were found in N contents of crudes and asphaltenes revealing poor HDN performance, apparently due to Na traces from the W precursor remaining in the final NiW catalysts.

Mechanism and site requirements for thiophene hydrodesulfurization on supported Re domains in metal or sulfide form

The elementary steps and active structures involved in thiophene hydrodesulfurization (HDS) are examined here through structural and functional assessments of Re and ReSx catalysts prepared from ReOx precursors by treatment in H2 or H2S. These samples retain their respective bulk phases at sulfur chemical potentials prevalent during HDS, because nucleation barriers inhibit the interconversion of isotropic Re metal and lamellar ReSx layers. HDS turnover rates were much higher on ReSx than Re, but both phases showed similar kinetic effects of thiophene, H2, and H2S and binding constants for adsorbed thiophene and S-atoms, consistent with a common mechanism involving active sites that differ in number but not in binding properties. In such elementary steps, the surface consists of a template of refractory S-atoms that are bound irreversibly, known to form even at H2S/H2 ratios much lower than in HDS practice. Interstices within such templates can reversibly bind reactive intermediates, thus allowing catalytic turnovers, and act as HDS active sites. The number of such interstices depends on MS bond strength, which is lower for particles with ReSx than with Re bulk phases; their binding properties, however, are not dictated by the bulk phase, because they consist of those surface spaces that become capable of binding S-species weakly enough to allow their formation and removal as part of each catalytic turnover. On both Re and ReSx, thiophene conversion rates are limited by the addition of one H-atom to bound thiophene to form intermediate species that give tetrahydrothiophene (THT) and C4 hydrocarbons at a kinetic branch after this kinetically-relevant step. Thiophene pressures and H2S/H2 ratios do not influence THT/C4 product ratios, which decrease as residence time increases because of secondary CS cleavage in THT to form C4 products. Both products form in a single surface sojourn at similar site coverages by intermediates, as is also the case for secondary THT reactions. The effects of H2 on these primary and secondary events indicate that the kinetic branching occurs at a bound intermediate with the H-content of dihydrothiophene, from which the CS bond cleavage transition state is also formed. As in CC and CO cleavage, CS bond scission requires H-removal from saturated reactants (THT) by (i) increasing the bond order of its surface attachment; (ii) weakening the CX bond being cleaved (X = C, O, S); and (iii) evolving H2 to minimize entropy losses upon formation of the transition state.

Nickel Cobalt Thiospinel Nanoparticles as Hydrodesulfurization Catalysts: Importance of Cation Position, Structural Stability, and Sulfur Vacancy.

First-row transition metal-based thiospinels are prepared via a one-pot versatile strategy and for the first time investigated as hydrodesulfurization (HDS) catalysts. X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy analysis confirm that these thiospinels consist of agglomerated nanoparticles (NPs) and contain multivalent metal cations. Among the sulfides synthesized at 230 °C, NiCo2S4 presents the highest thiophene conversion. This high intrinsic activity is found to be correlated with the normal spinel structure with Ni cations located on the tetrahedral sites and Co cations on the octahedral sites. However, the spent NiCo2S4 NPs experience phase transformation because of the relatively low synthetic temperature. Accordingly, six NiCo2S4 samples are prepared in the temperature range of 180-350 °C, and their HDS activity increases monotonically with the synthetic temperature, which is attributed to the higher structural stability and more surface sulfur vacancy of the NiCo2S4 NPs prepared at higher temperatures. Notably, the NiCo2S4 NPs synthesized at 350 °C exhibit a much higher thiophene conversation of 62.9% than the classic MoS2 catalyst (39.3%) as well as excellent reusability. Our study suggests that the NiCo2S4 thiospinels with high activity and stability can represent a new promising class of industrial HDS catalysts.

Synthesis of nano-Hap prepared through green route and its application in oxidative desulfurisation

Nano hydroxyapatite (Hap) was synthesized by green route using carrot peal extract and used as catalyst in thiophene oxidation reaction. The catalyst was characterized with TEM, XRD, XRF, SEM, BET and DLS size analysis. The particle size was found to be in the nano range. The highest conversion for thiophene oxidation was observed as 65%. Titanium and molybdenum were impregnated in nano Hap to investigate any further improvement of its efficiency towards the oxidation and a substantial increase in conversion of thiophene, 82%, was observed after impregnation. The influence of different process parameters on oxidation of thiophene using Ti-Mo impregnated nano Hap as catalyst was investigated. The metal-impregnated catalyst was characterized with FTIR, SEM, XRD, EDS analysis before and after the reaction. Langmuir-Hinshelwood (LH) model was proposed to explain the kinetics of the reaction.

Hydrodesulphurization of Thiophene over Co, Mo and CoMo /g-Al2O3 Catalysts

The hydrodesulphurization (HDS) of thiophene was performed on monometallic catalysts Co/g -Al2O3, Mo/g -Al2O3 and bimetallic CoMo/g -Al2O3. Experiments were carried out on a fixed bed catalytic reactor at 175-300�C, 30-60 atm, thiophene volume hourly space velocities of 1h-1- 4h-1 and molar ratio hydrogen/thiophene of 60/1. The thiophene conversion on the bimetallic CoMo/g -Al2O3 catalyst was higher than on Co/g -Al2O3 or Mo/g -Al2O3.

The Effects of Chelating Agents on CoMo/TiO2–Al2O3 Hydrodesulfurization Catalysts

A series of CoMo/TiO2–Al2O3 catalysts with different chelating agents were prepared by co-impregnation method. The influence of chelating agents on dispersions of active phase, textural properties, and hydrodesulfurization (HDS) activity for CoMo/TiO2–Al2O3 catalysts was studied. XRD characterization demonstrates that the addition of chelating agents can promote the dispersion degree of active components. TPR experiments exhibit an important effect of chelating agents on the catalysts. CoMo/TiO2–Al2O3 catalysts prepared with different chelating agents shows different HDS activity, and the addition of EDTA results in a remarkable improvement in both thiophene and DBT HDS conversions compared with others.

Comparative catalytic evaluation of nickel and cobalt substituted phosphomolybdic acid catalyst supported on silica for hydrodesulfurization of thiophene

Phosphomolybdic acid supported on silica (PMoA), and phosphomolybdic acid supported on silica substituted with nickel (Ni-PMoA), cobalt (Co-PMoA), are prepared with different loadings. All catalysts have been characterized using thermogravimetric analysis (TGA), BET surface area, Solid-state 31P NMR spectra, FT-IR, Diffuse Reflectance Infrared Fourier Transform (DRIFT) and Powder X-ray diffraction analysis (XRD). The surface areas of the catalysts are slightly lower than the surface area of the silica used in making these catalysts, while the XRD studies indicated the amorphous nature of the prepared catalysts. All catalysts are tested for their activity in the hydrodesulfurization of thiophene in the temperature range of 300–500°C. Under similar conditions the silica supported catalyst i.e. PMoA, showed lower hydrodesulfurization activity, compared to the nickel and cobalt substituted heteropoly acids, i.e. Ni-PMoA and Co-PMoA, indicating enhancement of catalytic activity with substitution of nickel and cobalt. Moreover, the nickel-substituted catalyst, Ni-PMoA, showed slightly higher activity than the cobalt-substituted ones, Co-PMoA. At 500°C, Ni-PMoA gave a 99.6% HDS conversion of thiophene whereas the Co-PMoA yielded a 98.3%. HDS conversion of thiophene. Brønsted/Lewis acidity of the catalyst precursor appear to be essential for the catalytic hydrodesulfurization.

Improvement of HDS catalysts through the modification of the oxidic precursor with 1,5-pentanediol: Gas phase sulfidation and thiophene conversion

Abstract The performance, in thiophene HDS, of a CoMo/Al 2 O 3 catalyst was successfully improved through chemical modification of its oxidic precursor by impregnation with 1,5-pentanediol solution. The gas phase activation with a H 2 /H 2 S mixture was followed by thermogravimetric analysis coupled with a rapid chromatograph; the catalysts were characterized at different steps of the activation using X-ray photoelectron spectroscopy (XPS). It appeared that the addition of the organic agent retards the sulfidation of the supported metals, leading to a simultaneous sulfidation of Co and Mo atoms. This induces the formation of smaller MoS 2 slabs and thus an increase in the number of active CoMoS sites, directly correlated with the better HDS performance of the modified solid. The role of 1,5-pentanediol is likely to inhibit, at low temperature, the adsorption of H 2 S on the solid and thus the sulfidation of the supported metals.