China 
Africa 
Explore chapters and articles related to this topic
Biocatalytic Upgrading of Opportunity Crudes
Published in Wael Ahmed Ismail, Jonathan Van Hamme, Hydrocarbon Biotechnology, 2023
Early BDS studies, mostly on DBT, relied on gas chromatography for measuring conversion based on the disappearance of the peak corresponding to the reactant. In these studies, the area reduction of the S-compound peak was taken as S-removal, when in reality it was only its partial oxidation. The 4S pathway for microbial DBT desulfurization was first reported in 1993, by Kayser et al. (Kayser et al., 1993) and involves three enzymes: two mono-oxygenases to generate a sulfoxide and then a sulfone, and a desulfinase for C-S cleavage (Olson et al., 1993; Monticello, 1998). The BDS of DBT to 2-hydroxybiphenyl (HBP) and sulfite via the 4S pathway (shown in Figure 9.10 (Ramirez-Corredores and Borole, 2007)) consists of four reaction steps: DBT is oxidized by DszC (DBT monooxygenase, DBT-MO) to DBT sulfoxide (dibenzothiophene-5-oxide, DBTO);DBTO is converted to the corresponding sulfone (dibenzothiophene-5,5-dioxide, DBTO2) by DszC;DBTO2 forms hydroxyphenyl benzene sulfonate (phenol-phenyl sulfinate, HBPS) on DszA; andSulfite is eliminated from HBPS to produce 2HBP (2-hydroxybi-phenyl) by HPBS desulfinase (DszB).
Feedstock Composition
Published in James G. Speight, Refinery Feedstocks, 2020
Heterocyclic constituents are significant contributors to the VGO fraction. In terms of sulfur compounds, thiophene and thiacyclane sulfur predominate over sulfide sulfur. Some molecules even contain more than one sulfur atom. The benzothiophene derivatives and dibenzothiophene derivatives are the prevalent thiophene forms of sulfur. In the VGO range, the nitrogen-containing compounds include higher-molecular-weight pyridine derivatives, quinoline derivatives, benzoquinoline derivatives, amide derivatives, indole derivatives, carbazole derivative, and molecules with two nitrogen atoms (diaza compounds) with three and four aromatic rings are especially prevalent (Green et al., 1989). Typically, approximately one-third of the compounds are basic, i.e., pyridine and its benzo- derivatives while the remainder is present as neutral species (amide derivatives and carbazole derivatives). Although benzo- and dibenzo-quinoline derivatives found in crude oil are rich in sterically hindered structures, hindered and unhindered structures have been found to be present at equivalent concentrations in source rocks. This has been rationalized as geo-chromatography in which the less polar (hindered) structures moved more readily to the reservoir and are not adsorbed on any intervening rocks structures.
Green Synthesis of Carbonaceous Adsorbents and Their Application for Removal of Polyaromatic Hydrocarbons (PAHs) from Water
Published in Sanjay K. Sharma, Bioremediation, 2019
S. R. Barman, A. Mukhopadhyay, P. Das
Silver (Ghaedi et al., 2012a), palladium (Ghaedi et al., 2012b), gold (Roosta et al., 2014a), zinc sulfide (Ghaedi et al., 2015), cobalt ferrite (Mehrabi et al., 2017), iron oxide magnetite (Bagheri et al., 2017), as well as bimetallic nanoparticles (Saleh, 2018) have been loaded on AC for the removal of various dyes, petroleum and other pollutants from water. Aromatic compounds such as benzothiophene, thiophene and dibenzothiophene have been reportedly removed utilizing iron and cerium nanoparticles loaded AC (Danmaliki and Saleh, 2017). It has also been established that several nanoparticles have antimicrobial properties which makes them even more potent for water treatment (Satapathy et al., 2015). Thus, it is clear that the use of porous carbon-based nano composites is a promising avenue for the treatment of aqueous organic as well as inorganic pollutants. The modifications of porous carbon using nano scale materials, with high surface area, enhance the removal percentage and adsorption capacity of adsorbent.
Efficient, selective and mild oxidation of sulfides and oxidative coupling of thiols catalyzed by Pd(II)-isatin Schiff base complex immobilized into three-dimensional mesoporous silica KIT-6
Published in Journal of Sulfur Chemistry, 2020
Saeedeh Pakvojoud, Mehdi Hatefi Ardakani, Samira Saeednia, Esmaeil Heydari-Bafrooei
The environmentally friendly catalytic oxidation of sulfides to sulfoxides with high performance has been the subject of numerous studies over the last two decades [1–4]. Sulfoxides have been applied in the synthesis of chemically useful materials such as drugs, flavors, germicides, and biologically active molecules like catabolism regulators [5]. On the other hand, the oxidation of organic sulfides such as dibenzothiophene (DBT) as an impurity in crude oil, is a major challenge in the petroleum industry and its removal is a necessary action in the petrochemical processes. Recently, Doustkhah and co-workers have prepared a green and recyclable catalyst by supporting copper(II) ions onto the internal pore surface of the thiourea-bridged periodic mesoporous organo-aluminosilica material. This catalyst (Cu@Al/Si-PMO-TU) was successfully applied for deep oxidation of dibenzothiophene to dibenzothiophen dioxide with hydrogen peroxide under aqueous conditions at room temperature [6]. Likewise, the conversion of thiols to the corresponding disulfides is a main transformation in both chemical and biological processes [7,8]. Disulfides are used in the sulfonylation of anions such as enolates, preparation of the sulfinyl and sulfenyl compounds as well as the vulcanizing agents for rubber and elastomers [9,10]. In addition, the thiol group can be protected as a disulfide, because disulfides are relatively more stable than the corresponding free thiols in the oxidation, alkylation and acylation reactions [11].
Biodesulfurization of model oil using growing cells of Gordonia sp. SC-10
Published in Petroleum Science and Technology, 2019
Shuiquan Chen, Shuo Sun, Chaocheng Zhao, Qiyou Liu, Meng Zang
Sulfur-containing components in petroleum are one of the factors that reduce the quality of oils. The combustion of sulfur containing oils will release a large amount of sulfur oxides into environment and cause serious environmental pollution. Accordingly, to control the adverse effect, legislative provisions on sulfur content in oils are becoming increasingly stringent; the regulations of sulfur contents in oils set by many countries should be less than 10 ppm (Chen et al. 2018). Hydrodesulfurization (HDS) is a traditional oil desulfurization method. Although HDS is effective in removing sulfur from oils, it is costly, requires high operational conditions and does not work well on recalcitrant organic sulfur compounds in oils, such as dibenzothiophene (DBT) and its alkylated derivatives (Mohebali and Ball 2016). The other desulfurization technologies, such as oxidative desulfurization and extraction desulfurization technologies, will result in loss of oil calorific value. Although these traditional desulfurization processes can reduce sulfur levels in oils to comply with current regulations, they are not effective enough to meet the more stringent legislative restrictions in the future (Tang and Hong 2014). Biodesulfurization (BDS) is a desulfurization method of using specific microorganisms to remove sulfur from organosulfur compounds, such as DBT and alkylated DBTs, through a metabolic pathway by selective cleavage of carbon-sulfur bonds (Mohebali and Ball 2016). BDS process has been attracting increasing attention due to its potential for removal of sulfur from polycyclic aromatic sulfur hydrocarbons in mild conditions. Furthermore, BDS has low operating costs and can significantly reduce greenhouse emissions compared with HDS. BDS is considered a promising technology that can be employed together with HDS (Stanislaus, Marafi, and Rana 2010; Martinez et al. 2016). In literature, DBT is widely used as a model target compound to study deep biodesulfurization of liquid fuel. In this study, Gordonia sp. SC-10 capable of desulfurizing DBT through C-S cleavage pathway was used for biodesulfurization of model oil. Effects of initial 2-hydroxybiphenyl (2-HBP) concentration, oil-water ratio and initial sulfur content in model oil on bacterial growth and biodesulfurization efficiency were investigated in this study.
Ultrasound assisted photocatalytic oxidative desulfurization of model diesel fuel
Published in Petroleum Science and Technology, 2018
Meng Zhao, Pingfang Han, Xiaoping Lu
Diesel fuels are complex mixtures of alkanes, cycloalkanes, and hydrocarbons with a carbon number range of C9–C28 (Jiang, et al. 2011), which exhaust gas(SOx) causing air pollution. For the increasingly environmental concern and stringent legal requirements, the removal of sulfur compounds from fuels has attracted more and more attention. A conventional method for removing sulfur from fuel named hydrodesulfurization (HDS) is presently the most used industrial process, which has a great efficient in removing sulfides, disulfides and light thiophenic sulfur compounds (Li et al. 2015). However, HDS technique must be operated at high temperature and high pressure and consumes large amounts of hydrogen gas. On the other hand, HDS is less efficient in removing refractory sulfur compounds such as di-benzo-thiophene and other alkyl-substituted derivatives of dibenzothiophene (Song and Ma 2003). Photocatalytic oxidative desulfurization process is the most promising alternative to HDS for the removal of sulfur. In this process, photocatalytic oxidative desulfurization shows great advantage in lowering the sulfur level and reducing the operational costs owing to the mild temperature and pressure condition (Robertson et al. 2006 and Zarrabi et al. 2015). Through this technique, benzothiophene(DBT), dibenzothiophene(BT), and their corresponding alkyl derivatives can be oxidized into the corresponding sulfoxides and sulfones, which could be removed from the diesel fuel using solvent extraction method. On the basis of photocatalytic oxidative desulfurization, the application of ultrasound can enhance the mass transfer in heterogeneous systems and improve kinetics, which can speed up the reaction rate due to strong cavitational activity (Kauer 2017). In this series of catalytic process, it is crucial to select the most appropriate photocatalyst. The most common photocatalysts and semiconductors are the transition metal oxides which have unique characteristics. CdO is applied as a semiconductor photocatalyst to oxidize DBT and its derivations in diesel because it has got an outstanding features based on having a band gap of 2.3 eV, which not only has the unique optical properties but also has selective catalytic properties that can be beneficial to crack high molecular weight concentration of sulfur compound. This catalyst is prepared by ultrasound assisted chemical precipitation technique and the obtained sample is employed to produce low sulfur diesel fuel via the ultrasound assisted photocatalytic oxidative desulfurization process of model diesel. Meanwhile, the effect of catalyst dosage, reaction temperature, oxidation time, oxidant to diesel fuel ratio, time of the extraction process and the comparison of ultrasound-assisted desulfurization and non-ultrasonic assisted desulfurization are investigated. The sulfoxides and sulfones obtained by photocatalytic oxidative desulfurization are removed by solvent extraction, eventually. Through a series of research, the optimum desulfurization method and conditions would be excogitated aming at improving the efficiency of desulphurization and reducing the sulfur content in model diesel.