The Experts below are selected from a list of 1635 Experts worldwide ranked by ideXlab platform
Q. Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Effects of magnetic fields on improving mass transfer in flue gas Desulfurization using a fluidized bed
Heat and Mass Transfer, 2015Co-Authors: Q. Zhang, Xiaobo WangAbstract:The effects of magnetic fields on improving the mass transfer in flue gas Desulfurization using a fluidized bed are investigated in the paper. In this research, the magnetically fluidized bed (MFB) is used as the reactor in which ferromagnetic particles are fluidized with simulated flue gas under the influence of an external magnetic field. Lime slurry is continuously sprayed into the reactor. As a consequence, the Desulfurization Reaction and the slurry drying process take place simultaneously in the MFB. In this paper, the effects of ferromagnetic particles and external magnetic fields on the desulphurization efficiency are studied and compared with that of quartz particles as the fluidized particles. Experimental results show that the ferromagnetic particles not only act as a platform for lime slurry to precipitate on like quartz particles, but also take part in the Desulfurization Reaction. The results also show that the specific surface area of ferromagnetic particles after Reaction is enlarged as the magnetic intensity increases, and the external magnetic field promotes the oxidation of S(IV), improving the mass transfer between sulphur and its sorbent. Hence, the efficiency of desulphurization under the effects of external magnetic fields is higher than that in general fluidized beds.
-
Removal of SO2 Using a Magnetically Fluidized Bed in the Semi‐Dry Flue Gas Desulfurization Process: Roles of Ferromagnetic Particles and Applied Magnetic Field in the Desulfurization Reaction
Chemical Engineering & Technology, 2008Co-Authors: Q. ZhangAbstract:A new semidry flue gas Desulfurization (FGD) process is proposed. The process uses a magnetically fluidized bed (MFB) as the reactor in which ferromagnetic particles are fluidized with simulated flue gas under the influence of an external magnetic field. A slurry of lime is continuously sprayed into the reactor by an atomizer fixed at the top of the bed. As a consequence, the Desulfurization Reaction and slurry drying take place simultaneously in a same reactor. Experiments with a laboratory-scale apparatus were carried out to investigate the roles of the ferromagnetic particles and the magnetic field applied in the Desulfurization Reaction. The results show that when ferromagnetic particles are used as the fluidization material, both sulfite (SO32–) salts and sulfate (SO42–) salts are found in the Desulfurization products. When quartz particles are used, only sulfite (SO32–) salts are found. This suggests that the Fe(III) ions and Fe(II) ions result from the ferromagnetic particles dissolving in the liquid phase. In addition, the ions act as catalysts in the oxidation of S(IV) to S(VI) and react with SO2 producing FeSO3 and Fe2(SO4)3 as the products. On the other hand, the level of the sulfate (SO42–) salts in the products increases with increasing intensity of applied field intensity, which suggests that the oxidation of S(IV) can be enhanced by the applied magnetic field. The oxidation of S(IV) can increase the solubility of SO2, and therefore, intensify the Reaction between SO2 and Ca(OH)2, leading to an increased SO2 removal efficiency.
-
removal of so2 using a magnetically fluidized bed in the semi dry flue gas Desulfurization process roles of ferromagnetic particles and applied magnetic field in the Desulfurization Reaction
Chemical Engineering & Technology, 2008Co-Authors: Q. ZhangAbstract:A new semidry flue gas Desulfurization (FGD) process is proposed. The process uses a magnetically fluidized bed (MFB) as the reactor in which ferromagnetic particles are fluidized with simulated flue gas under the influence of an external magnetic field. A slurry of lime is continuously sprayed into the reactor by an atomizer fixed at the top of the bed. As a consequence, the Desulfurization Reaction and slurry drying take place simultaneously in a same reactor. Experiments with a laboratory-scale apparatus were carried out to investigate the roles of the ferromagnetic particles and the magnetic field applied in the Desulfurization Reaction. The results show that when ferromagnetic particles are used as the fluidization material, both sulfite (SO 3 2- ) salts and sulfate (SO 4 2- ) salts are found in the Desulfurization products. When quartz particles are used, only sulfite (SO 3 2- ) salts are found. This suggests that the Fe(III) ions and Fe(II) ions result from the ferromagnetic particles dissolving in the liquid phase. In addition, the ions act as catalysts in the oxidation of S(IV) to S(VI) and react with SO 2 producing FeSO 3 and Fe 2 (SO 4 ) 3 as the products. On the other hand, the level of the sulfate (SO 4 2- ) salts in the products increases with increasing intensity of applied field intensity, which suggests that the oxidation of S(IV) can be enhanced by the applied magnetic field. The oxidation of S(IV) can increase the solubility of SO 2, and therefore, intensify the Reaction between SO 2 and Ca(OH) 2 , leading to an increased SO 2 removal efficiency.
Eoin M. Scanlan - One of the best experts on this subject based on the ideXlab platform.
-
Native Chemical Ligation,Thiol–Ene Click: A Methodology for the Synthesis of Functionalized Peptides
Journal of Organic Chemistry, 2013Co-Authors: Lyn Markey, Silvia Giordani, Eoin M. ScanlanAbstract:The sequential combination of native chemical ligation and thiol–ene radical chemistry (NCL-TEC) on the resulting cysteine thiol has been investigated as a methodology for rapidly accessing functionalized peptides. Three sequential cycles of native chemical ligation and subsequent thiyl radical Reactions (including a free-radical-mediated Desulfurization Reaction) were carried out on a peptide backbone demonstrating the iterative nature of this process. The versatility of the thiyl radical Reaction at cysteine was demonstrated through the introduction of a number of different side chains including an amino acid derivative, a carbohydrate group, and an alkyl azide. Conditions were developed that allowed the sequential NCL-TEC process to proceed in high yield.
-
native chemical ligation thiol ene click a methodology for the synthesis of functionalized peptides
Journal of Organic Chemistry, 2013Co-Authors: Lyn Markey, Silvia Giordani, Eoin M. ScanlanAbstract:The sequential combination of native chemical ligation and thiol–ene radical chemistry (NCL-TEC) on the resulting cysteine thiol has been investigated as a methodology for rapidly accessing functionalized peptides. Three sequential cycles of native chemical ligation and subsequent thiyl radical Reactions (including a free-radical-mediated Desulfurization Reaction) were carried out on a peptide backbone demonstrating the iterative nature of this process. The versatility of the thiyl radical Reaction at cysteine was demonstrated through the introduction of a number of different side chains including an amino acid derivative, a carbohydrate group, and an alkyl azide. Conditions were developed that allowed the sequential NCL-TEC process to proceed in high yield.
Baojian Shen - One of the best experts on this subject based on the ideXlab platform.
-
hydroDesulfurization of dibenzothiophene over niw snalpo4 5 al2o3 catalyst the tuning effect of snalpo4 5 to the Desulfurization Reaction pathway
Applied Catalysis A-general, 2018Co-Authors: Qian Wang, Xinyue Zhang, Qianqian Yu, Lei Li, Yandan Wang, Baojian ShenAbstract:Abstract SnAlPO4-5 molecular sieves were hydrothermally synthesized using SnCl2·2H2O as the tin source, and were verified that divalent tin was incorporated into the framework by isomorphous substitution of trivalent aluminum, and increasing the numbers of Bronsted and Lewis acid sites relative to those in AlPO4-5. The molecular sieves were used to fabricate hybrid supports with alumina and then were loaded with active metals to obtain NiW catalysts. The hydroDesulfurization (HDS) of dibenzothiophene (DBT) were evaluated for the catalytic activity of the catalysts. Because of the higher number of weak acid sites, much greater average number of slab layers and higher dispersion of WS2, the HDS rate of DBT at 280 °C is improved from 49.6% for the NiW/(AlPO4-5+Al2O3) catalyst to 82.2% for the NiW/(Sn0.12AlPO4-5+Al2O3) catalyst. Moreover, the highly active NiW/(Sn0.12AlPO4-5+Al2O3) catalyst obviously increases the product of the direct Desulfurization route in the DBT HDS, which is beneficial for reducing hydrogen consumption in the industrial applications.
Lyn Markey - One of the best experts on this subject based on the ideXlab platform.
-
Native Chemical Ligation,Thiol–Ene Click: A Methodology for the Synthesis of Functionalized Peptides
Journal of Organic Chemistry, 2013Co-Authors: Lyn Markey, Silvia Giordani, Eoin M. ScanlanAbstract:The sequential combination of native chemical ligation and thiol–ene radical chemistry (NCL-TEC) on the resulting cysteine thiol has been investigated as a methodology for rapidly accessing functionalized peptides. Three sequential cycles of native chemical ligation and subsequent thiyl radical Reactions (including a free-radical-mediated Desulfurization Reaction) were carried out on a peptide backbone demonstrating the iterative nature of this process. The versatility of the thiyl radical Reaction at cysteine was demonstrated through the introduction of a number of different side chains including an amino acid derivative, a carbohydrate group, and an alkyl azide. Conditions were developed that allowed the sequential NCL-TEC process to proceed in high yield.
-
native chemical ligation thiol ene click a methodology for the synthesis of functionalized peptides
Journal of Organic Chemistry, 2013Co-Authors: Lyn Markey, Silvia Giordani, Eoin M. ScanlanAbstract:The sequential combination of native chemical ligation and thiol–ene radical chemistry (NCL-TEC) on the resulting cysteine thiol has been investigated as a methodology for rapidly accessing functionalized peptides. Three sequential cycles of native chemical ligation and subsequent thiyl radical Reactions (including a free-radical-mediated Desulfurization Reaction) were carried out on a peptide backbone demonstrating the iterative nature of this process. The versatility of the thiyl radical Reaction at cysteine was demonstrated through the introduction of a number of different side chains including an amino acid derivative, a carbohydrate group, and an alkyl azide. Conditions were developed that allowed the sequential NCL-TEC process to proceed in high yield.
Kenji Maruhashi - One of the best experts on this subject based on the ideXlab platform.
-
Isolation of Carotenoid-deficient Mutant from Alkylated Dibenzothiophene Desulfurizing Nocardioform Bacteria, Gordonia sp. TM414
Current Microbiology, 2004Co-Authors: Toru Matsui, Kenji MaruhashiAbstract:The dibenzothiophene-desulfurizing nocardioform bacteria, Gordonia sp. TM414, was isolated from oil-contaminated soil. To avoid coloration of the oil layer after the Desulfurization Reaction, which could decrease the quality of the oil, two colorless knock-out mutants, TPc and TPd, were isolated by using a broad-host-range transposon complex. Genomic sequence analysis revealed that the same gene was disrupted in these mutants and that the transposon-inserted gene was assigned as the gene for phytoene desaturase, crt I. The crt I mutants also showed Desulfurization activity comparable to that of the parent strain in a model-oil/aqueous bi-phasic Reaction, suggesting that the carotenoid production is not responsible for the bi-phasic Desulfurization Reaction that requires hydrophobic substrate incorporation from the organic phase.
-
Desulfurization of 2,4,6,8-tetraethyl dibenzothiophene by recombinant Mycobacterium sp. strain MR65
Biotechnology Letters, 2003Co-Authors: Kimiko Watanabe, Ken-ichi Noda, Jin Konishi, Kenji MaruhashiAbstract:Recombinant Mycobacterium sp. strain MR65 harboring dszABCD genes was used to desulfurize alkyl dibenzothiophenes (C_x-DBTs) in n -hexadecane. The specific Desulfurization activity for 2,4,6,8-tetraethyl DBT (C_8-DBT) by DszC enzyme was about twice that for 4,6-dipropyl DBT (C_6-DBT). However, the degradation rate of 2,4,6,8-tetraethyl DBT in n -hexadecane by resting cells of strain MR65 was only about 40% of that of 4,6-dipropyl DBT. These results indicated that the Desulfurization ability for Cx-DBTs by resting cells depends on carbon number substituted at positions 4 and 6 and that the rate-limiting step in the Desulfurization Reaction of highly alkylated C_x-DBTs is the transfer process from the oil phase into the cell.
-
analyses of microbial Desulfurization Reaction of alkylated dibenzothiophenes dissolved in oil phase
Biotechnology and Bioengineering, 2003Co-Authors: Hideki Okada, Nobuhiko Nomura, Tadaatsu Nakahara, Koichi Saitoh, Hiroo Uchiyama, Kenji MaruhashiAbstract:The kinetics of the oil/water two-phase Reaction system was analyzed, and the Reaction was carried out with the Desulfurization of alkylated dibenzothiophenes (Cx-DBTs) using the desulfurizing microorganism Mycobacterium sp. G3. In the water-phase Reaction system, the Desulfurization activities were constant with respect to species of Cx-DBTs as substrates. However, the Desulfurization activities in the oil/water two-phase Reaction system against DBT, 4,6-dimethyl DBT, 4,6-diethyl DBT, 4,6-dipropyl DBT, and 4,6-dibutyl DBT were 49.0, 45.9, 11.5, 1.35, and 0.00 μmol g DCW−1 h−1, respectively. The kinetic parameters for the degradation of DBT, 4,6-dimethyl DBT, and 4,6-diethyl DBT were also obtained (Vmax values 90.0, 68.7, and 22.7 μmol g DCW−1 h−1 and Km values 0.21, 0.70, and 3.03 mM, respectively). The reason for the decrease in activity against Cx-DBTs of high molecular weight was a decrease in the Vmax value and an increase in the Km value, the latter being a particularly serious problem. Furthermore, the hydrophobicity of the substrate was evaluated as the capacity factor measured by high-performance liquid chromatography (HPLC). The correlation between substrate hydrophobicity and Desulfurization activity indicated that the Desulfurization Reaction in the oil/water two-phase Reaction system is greatly influenced by the hydrophobicity of the substrates. In addition, the influence of the solvent on Desulfurization activity was examined, and it was found that not only the hydrophobicity of substrates, but also that of solvents, affected the Desulfurization Reaction. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 489–497, 2003.
-
Analysis of dibenzothiophene metabolic pathway in Mycobacterium strain G3.
Journal of Bioscience and Bioengineering, 2002Co-Authors: Hideki Okada, Nobuhiko Nomura, Tadaatsu Nakahara, Kenji MaruhashiAbstract:The dibenzothiophene (DBT) metabolic pathway in Mycobacterium strain G3, which is classified as a desulfurizing microorganism with the 4S pathway, was analyzed. 2-Hydroxybiphenyl (HBP), which is an end metabolite in the DBT Desulfurization Reaction, and 2-methoxybiphenyl (MBP) were found in the Reaction mixture, and the methoxylation pathway from HBP to MBP was clarified. Although the substrate in the methoxylation Reaction was HBP, there was no relationship between expression of the methoxylation activity and that of the Desulfurization activity. Then, 4,6-dimethyl DBT, 4,6-diethyl DBT and benzo[b]naphtho[2,1-d]thiophene were metabolized to their methoxy forms via the Desulfurization pathway. We established the methoxylation pathway in Mycobacterium G3.
-
Analyses of substrate specificity of the desulfurizing bacterium Mycobacterium sp. G3.
Journal of Bioscience and Bioengineering, 2002Co-Authors: Hideki Okada, Nobuhiko Nomura, Tadaatsu Nakahara, Kenji MaruhashiAbstract:Abstract The substrate specificity of Mycobacterium sp. G3 with Desulfurization activity against dibenzothiophene (DBT) was investigated. Desulfurization Reactions were carried out using a concentrated cell suspension of G3. The conversion from 4,6-dipropyl DBT, one of the sulfur-containing compounds that is difficult to desulfurize in diesel oil, to 2-hydroxy-3,3′-dipropylbiphenyl as an end -product of the Desulfurization Reaction was found in the water Reaction system and in the oil/water two-phase Reaction system. 4,6-Dibutyl DBT and 4,6-dipentyl DBT were metabolized to the hydroxybiphenyl form via the sulfone form in the water Reaction system. These results indicate that G3 has high membrane permeability and superior substrate specificity for high molecular weight alkyl DBTs, which are represented by 4,6-dipentyl DBT as C10-DBT. Furthermore, G3 could desulfurize diesel oil, and the sulfur concentration was decreased from 116 mg l −1 to 48 mg l −1 within 24 h.