Oxidative desulfurization using graphene and its composites for fuel containing thiophene and its derivatives: An update review

Oxidative desulfurization, in which the aromatic sulfur containing compounds are oxidized to their analogical sulfones and subsequently extracted, has assured to be one of the exceedingly effective desulfurization processes for resulting ultra-low sulfur import fuels. The oxidative desulfurization process using graphene oxide has attracted significant interest for sulfur removal from fuels. In this survey, we discussed systematically the techniques of desulfurizations in catalytic oxidation, including the role of graphene as a supported catalyst, the research results of oxidative desulfurization using graphene oxide and provided the factors affecting the desulfurization process. We also debate the challenges counterattack the use of graphene oxide in this view, including their preparation methods and their efficiency and stability as a supported catalyst. Also, there are some of the desulfurization processes currently under investigation such as oxidation, biodesulfurization, and adsorption was outlined in brief. The combustion of fossil fuels containing sulfur compounds emits some of the sulfur oxides which considered a harmful influence on human health and the surrounding environment as well as the economy. It can be concluded that GO remains a kind of ideal supported catalysts to recognize a pure fuel in the near futurity due to their eligible physicochemical characteristics.     

Novel 3,4-disubstituted thiophenes for weak passivation of Au nanoparticles

Novel self-assembled monolayers of 3,4-disubstituted thiophenes (3,4-dioctylthiophene and 3,4-diheptyloxythiophene) were prepared and characterized by contact angle measurements, ellipsometry and X-ray photoelectron spectroscopy. In addition, Au nanoparticles passivated with the 3,4-disubstituted thiophenes (3,4-dioctylthiophene and 3,4-diheptyloxythiophene) and monosubstituted thiophene (3-octylthiophene) were synthesized and characterized by UV/visible spectroscopy, transmission electron microscopy and dynamic light scattering. The Au nanoparticles had diameters in the range 5–7?nm. The Au nanoparticles stabilized with the thiophene derivatives were, as expected, less stable than the Au nanoparticles passivated with decanethiol and didecylsulfide. Surprisingly, the particles passivated with the monosubstituted 3-octylthiophene were more stable than the 3,4-dioctyl and 3,4-diheptyloxythiophene passivated particles. Such lower stability Au nanoparticles may find uses as negative tone resists in the formation of nanowires by e-beam lithography, via the more readily cleavable Au–S bond     

A comparative study on the effect of promoter content of hydrodesulfurization catalysts at different evaluation scales

CoMo and NiMo supported Al₂O₃ catalysts have been investigated for hydrotreating of model molecule as well as industrial feedstock. Activity studies were carried out for thiophene and SRGO hydrodesulfurization (HDS) in an atmospheric pressure and batch reactor respectively. These activities on sulfided catalysts were evaluated as a function of promoter content [M/(M + Mo) = 0.30, 0.34, 0.39; M = Co or Ni] using fixed (ca. 8 wt.%) molybdenum content. The promoted catalysts were characterized by textural properties, XRD, and temperature programmed reduction (TPR). TPR spectra of the Co and Ni promoter catalysts showed that Ni promotes the easy reduction of Mo species compared with Co. With the variation of promoter content NiMo catalyst was found to be superior to CoMo catalyst for gas oil HDS, while at low-promoter content the opposite trend was observed for HDS of thiophene. The behavior was attributed to the several reaction mechanisms involved for gas oil HDS. A nice relationship was obtained for hydrodesulfurized gas oil refractive index (RI) and aromatic content, which corresponds to the Ni hydrogenation property.     

NiY/Beta复合分子筛吸附脱硫性能研究

采用液相离子交换法制备了NiY及NiY/Beta分子筛,利用智能重量分析仪测定了噻吩、苯在NiY、NiY/Beta分子筛上的吸附-脱附等温线,计算比较了噻吩、苯在分子筛上的扩散系数,同时使用固定床技术考查了改性后的分子筛对催化裂化汽油的吸附脱硫性能。结果表明,复合分子筛NiY/Beta仍然保持着较好的微孔结构,对噻吩的饱和吸附量大于苯的。而且噻吩在NiY/Beta分子筛上的相对扩散系数明显增大,而苯的扩散系数有所减少,这有利于噻吩在分子筛上的扩散过程,抑制了苯在分子筛上的吸附,从而提高了NiY/Beta复合分子筛对噻吩的选择性脱除能力。对于FCC汽油NiY/Beta复合分子筛也表现出更好的深度脱硫能力。     

The Mechanism of HDS Catalysis

The mechanism of heterogeneous catalytic reactions is much more difficult to elucidate than that of homogeneous systems. Despite the facilities provided by physical methods for investigating the surface of solids, obtaining detailed information on the structure of the active component in real heterogeneous catalysts presents difficulties due to the nonuniform chemical composition of the surface species. Some of these surface species are totally inactive in catalysis, and others can catalyze the given chemical reaction by different pathways and according to different mechanisms. This results in a change of selectivity to the desired product and the appearance of intermediates and reaction by-products. Furthermore, the effect of the reaction medium on the catalyst gains importance during a catalytic process when, at high temperature and pressure, one type of surface species is transformed into another, thus changing the mechanism and direction of the catalyzed reaction.

     

β-Selective C−H Arylation of Electron-Deficient Thiophenes,Pyrroles, and Furans

A general β-C−H arylation of electron-deficient thiophenes, pyrroles, and furans has been developed using ligand-modulated palladium catalyst. The use of a modified norbornene is crucial for reversing the conventional α-selectivity of these substrates. This method features good yields, high β-selectivity, and good tolerance of functional groups.     

烷基化脱除FCC汽油中噻吩硫研究进展

综述了烷基化脱硫技术脱除FCC汽油中噻吩硫的研究进展。介绍了噻吩烷基化反应机理以及在FCC汽油精制中的工艺,详细阐述了噻吩烷基化催化剂要求及发展现状。建议为推动烷基化深度脱硫工业化进程,应大力发展对新型烷基化催化剂的研究。     

Conjugated polythiophene/Ni doped ZnO hetero bilayer nanocomposite thin films: Its structural,optical and photoluminescence properties

In this study, synthesis and characterization of plasma polymerized Thiophene/ Nickel doped Zinc Oxide (PTNZO) bilayer nanocomposite films were carried out. Nickel doped zinc oxide (NZO) thin films were obtained by magnetron sputtering technique on glass substrates at 40 W Radio Frequency (RF) power. Plasma polymerized Thiophene (PT) thin films were deposited on the NZO thin films obtained on the glass substrate by Radio Frequency (RF) plasma polymerisation technique. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), FTIR and Photoluminescence (PL) analyzes were performed for the characterization of PTNZO hetero bilayer nanocomposite films. In the XRD spectra of PTNZO bilayer nanocomposite thin films, (002) planes were determined as the most basic peak, and it was determined that the intensity of this peak, changed depending on the RF power of polymer thin films. Optical properties of nanocomposite thin films such as transmittance, absorbance and optical band gap were determined by UV–Vis spectroscopy. Optical band gap for PTNZO nanocomposites were 2.72?eV, 2.34?eV, and 2.45?eV, respectively, with increasing RF power. For NZO thin films, this value is 3.12?eV. The optical band gaps calculated from the absorption and transmittance spectra obtained using UV–visible spectroscopy had a good compatibility with those of the optical band spectra calculated from the PL spectra. The tetragonal wurtzite structure of the NZO thin films was examined by SEM analysis. The grain size of NZO nanostructure was found to be approximately 59?nm.     

Preparation of π-conjugated polymers consisting of 2-decylbenzimidazole and thiophene units and chemical properties of the polymers

Polycondensation by Stille coupling of 2-decyl-4,7-dibromobenzimidazoles and N-methyl-2-decyl-4,7-dibromobenzimidazole with 2,5-bis(trimethylstannyl)thiophene and 5,5′-bis(trimethylstannyl)-2,2′-bithiophene gave the corresponding π-conjugated polymers, poly(2-decylbenzimidazole-4,7-diyl-thiophene-2,5-diyl) 1b, poly(2-decylbenzimidazole-4,7-diyl-bithiophene-2,5-diyl) 1c and poly(N-methyl-2-decylbenzimidazole-4,7-diyl-thiophene-2,5-diyl) 2b, in 98-99% yields. The polymers 1b and 2b were fully soluble in CF₃COOH, and partially soluble in DMF (about 60 and 40% for 1b and 2b, respectively) and NMP (about 70 and 40%, respectively). The NMP soluble part of 1b and DMF soluble part of 2b gave values of 0.36 and 0.24 dl g⁻¹ in NMP and DMF, respectively. The DMF soluble part of 1b, 1c and 2b showed absorption peaks at about 458, 465 and 388 nm, respectively, in DMF. In an alkaline medium the absorption peaks of 1b and 1c are shifted to a longer wavelength by 92-101 nm; the observed shifts in the acidic medium and alkaline medium were much larger than those observed with usual benzimidazoles with low molecular weights. Packing structures of 1b, 1c and 2b are discussed based on their XRD patterns.     

Synthesis and characterization of all-conjugated diblock copolymers consisting of thiophenes with a hydrophobic alkyl and a hydrophilic alkoxy side chain

Novel thiophene-based all-conjugated block copolymers consisting of 3-hexylthiophene and 3-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}thiophene were synthesized using the Grignard metathesis (GRIM) polymerization method in the presence of Ni(dppp)Cl₂. Favorable transfer of the catalytic site from an electron-poor precursor to an electron-rich monomer was found to produce the block copolymer. The molecular weights of the copolymers increased slightly with increasing polymerization temperature (10.1 × 10³M_n (35 °C) → 11.1 × 10³M_n (55 °C)), suggesting that transit of the catalytic site was accelerated at high temperatures. Size exclusion chromatography, UV-vis and photoluminescence spectroscopies, and cyclic voltammetry measurements confirmed that the polymers were block copolymers. The blocks were associated and organized relative to one another in adjacent chains.