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Effect of sodium ions in synthesis of titanium silicalite-1 on its catalytic performance for cyclohexanone ammoximation
Pengxu YAO,Yaquan WANG,Teng ZHANG,Shuhai WANG,Xiaoxue WU
Front. Chem. Sci. Eng.. 2014, 8 (2): 149-155.
https://doi.org/10.1007/s11705-014-1409-y
Titanium silicalite-1 (TS-1) has been hydrothermally synthesized with tetrapropylammonium hydroxide (TPAOH) as the template in the presence of various amounts of Na+, characterized by inductively coupled plasma, X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and ultro-violet-visible spectroscopy and studied in cyclohexanone ammoximation. The characterization results show that with the increase of Na+ concentration in the synthesis, both the crystal sizes of TS-1and extra framework Ti increase but framework Ti decreases. The addition of Na+ below 3 mol-% of TPAOH in the synthesis does not influence the catalytic properties with above 98% conversion of cyclohexanone and 99.5% selectivity to cyclohexanone oxime. However, at the concentrations of Na+≥3 mol-% of TPAOH in the synthesis, the catalysts are deactivated faster with the increase of Na+ addition, which can be attributed to more high molecular weight byproducts deposited in the large TS-1 particles and the loss of the frame-work titanium. The results of this work are of great importance for the industry.
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Hydrotreating of light gas oil using a NiMo catalyst supported on activated carbon produced from fluid petroleum coke
N. Rambabu,Sandeep Badoga,Kapil K. Soni,A.K. Dalai,J. Adjaye
Front. Chem. Sci. Eng.. 2014, 8 (2): 161-170.
https://doi.org/10.1007/s11705-014-1430-1
Nitric acid functionalized steam activated carbon (NAFSAC) was prepared from waste fluid petroleum coke (FPC) and used as a support material for the synthesis of a NiMo catalyst (2.5 wt-% Ni and 13 wt-% Mo). The catalyst was then used for the hydrotreatment of light gas oil. The support and catalysts were characterized by Brunauer-Emmett-Teller (BET) gas adsorption method, X-ray diffraction, H2-temperature programmed reduction, NH3-temperature programmed desorption, CO-chemisorption, mass spetrography, scanning electron microscopy (SEM), Boehm titration, and Fourier transform infrared spectroscopy (FTIR). The SEM results showed that the carbon material retained a needle like structure after functionalization with HNO3. The Boehm titration, FTIR, and BET results confirmed that the HNO3 functionalized material had moderate acidity, surface functional groups, and mesoporosity respectively. The produced NAFSAC had an inert nature, exhibited the sink effect and few metal support interactions, and contained functional groups. All of which make it a suitable support material for the preparation of a NiMo hydrotreating catalyst. Hydrotreating activity studies of the NiMo/NAFSAC catalyst were carried out under industrial operating conditions in a laboratory trickle bed reactor using coker light gas oil as the feedstock. A parallel study was performed on the hydrotreating activity of NiMo/γ-Al2O3 as a reference catalyst. The hydrodesulfurization and hydrodenitrogenation activities of the NiMo/NAFSAC catalyst were 62% and 30%, respectively.
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Synthesis of vinylferrocene and the ligand-exchange reaction between its copolymer and carbon nanotubes
Ran SHI,Hai WANG,Ping TANG,Yuezhen BIN
Front. Chem. Sci. Eng.. 2014, 8 (2): 171-178.
https://doi.org/10.1007/s11705-014-1428-8
To improve the dispersibility of carbon nanotubes (CNTs), poly(vinylferrocene-co-styrene) (poly(Vf-co-St)), was grafted onto the surface of CNTs by a ligand-exchange reaction. Poly(Vf-co-St) was obtained by a radical copolymerization reaction using styrene and vinylferrocene as the monomers. The vinylferrocene was synthesized from ferrocene via a Friedel-Crafts acylation. The molecular weight, molecular weight distribution, and amount of Vf in the poly(Vf-co-St) were 1.32 × 104, 1.69 and 17.6% respectively. The degree of grafting of the copolymer onto the CNTs surface was calculated from thermogravimetric analysis and varied from 27.1% to 79.7%. The addition of the poly(Vf-co-St) greatly promoted the dispersibility of the modified CNTs in anhydrous alcohol. The electrical conductivity of composites prepared from the polymer-grafted CNTs and copolymer (acrylonitrile, 1,3-butadiene and styrene, ABS) strongly depended on the degree of grafting. These results show that the amount of polymer grafted onto the surface of CNTs can be controlled and that the electrical properties of composites prepared with these grafted polymers can be tuned.
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WO3 nanomaterials synthesized via a sol-gel method and calcination for use as a CO gas sensor
Diah SUSANTI,A.A. Gede Pradnyana DIPUTRA,Lucky TANANTA,Hariyati PURWANINGSIH,George Endri KUSUMA,Chenhao WANG,Shaoju SHIH,Yingsheng HUANG
Front. Chem. Sci. Eng.. 2014, 8 (2): 179-187.
https://doi.org/10.1007/s11705-014-1431-0
Carbon monoxide is a poisonous and hazardous gas and sensitive sensor devices are needed to prevent humans from being poisoned by this gas. A CO gas sensor has been prepared from WO3 synthesized by a sol-gel method. The sensor chip was prepared by a spin-coating technique which deposited a thin film of WO3 on an alumina substrate. The chip samples were then calcined at 300, 400, 500 or 600 °C for 1 h. The sensitivities of the different sensor chips for CO gas were determined by comparing the changes in electrical resistance in the absence and presence of 50 ppm of CO gas at 200 °C. The WO3 calcined at 500 °C had the highest sensitivity. The sensitivity of this sensor was also measured at CO concentrations of 100 ppm and 200 ppm and at operating temperatures of 30 and 100 °C. Thermogravimetric analysis of the WO3 calcined at 500 °C indicated that this sample had the highest gas adsorption capacity. This preliminary research has shown that WO3 can serve as a CO gas sensor and that is should be further explored and developed.
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Modification of polycarbonateurethane surface with poly(ethylene glycol) monoacrylate and phosphorylcholine glyceraldehyde for anti-platelet adhesion
Jing YANG,Juan LV,Bin GAO,Li ZHANG,Dazhi YANG,Changcan SHI,Jintang GUO,Wenzhong LI,Yakai FENG
Front. Chem. Sci. Eng.. 2014, 8 (2): 188-196.
https://doi.org/10.1007/s11705-014-1414-1
Poly(ethylene glycol) monoacrylate (PEGMA) is grafted onto polycarbonateurethane (PCU) surface via ultraviolet initiated photopolymerization. The hydroxyl groups of poly(PEGMA) on the surface react with one NCO group of isophorone diisocyanate (IPDI) and another NCO group of IPDI is then hydrolyzed to form amino terminal group, which is further grafted with phosphorylcholine glyceraldehyde to establish a biocompatible hydrophilic structure on the surface. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirm the successful grafting of both PEG and phosphorylcholine functional groups on the surface. The decrease of the water contact angle for the modified film is caused by synergic effect of PEG and phosphorylcholine, which both have the high hydrophilicity. Furthermore, the number of platelets adhered is relative low on the synergetically modified PCU film compared with the PCU film modified only by poly(PEGMA). Our synergic modification method using both PEG and phosphorylcholine may be applied in surface modification of blood-contacting biomaterials and some relevant devices.
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Oxidation-extraction desulfurization of model oil over Zr-ZSM-5/SBA-15 and kinetic study
Chuanzhu LU,Hui FU,Huipeng LI,Hua ZHAO,Tianfeng CAI
Front. Chem. Sci. Eng.. 2014, 8 (2): 203-211.
https://doi.org/10.1007/s11705-014-1420-3
ZSM-5/SBA-15 composite molecular sieves were synthesized using post-synthesis method and characterized by X-ray diffraction and N2 adsorption-desorption. The oxidative-extration desulfurization of model oil was investigated by using hydrogen peroxide as the oxidant, tetrabutyl ammonium bromide as phase transfer catalyst, dimethyl sulfoxide as extractant, and Zr-ZSM-5/SBA-15, Ag-ZSM-5/SBA-15, Ce-ZSM-5/SBA-15 as catalyst. Under the optimal conditions, the desulfurization rate decreases in the order: Zr-ZSM-5/SBA-15>Ce-ZSM-5/SBA-15>Ag-ZSM-5/SBA-15. The highest desulfurization rate is 84.53% under the catalysis of Zr-ZSM-5/SBA-15. Kinetics analysis shows that the reaction is pseudo-first-order with the activation energy of 44.23 kJ/mol.
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2,5-Dialkoxylphenyl-1,3,4-oxadiazoles as efficient organogelators and their self-assembling property
Zipei SUN,Xuelin DONG,Yan ZHAI,Ziyan Li,Yaodong HUANG
Front. Chem. Sci. Eng.. 2014, 8 (2): 219-224.
https://doi.org/10.1007/s11705-014-1418-x
Four 2,5-dialkoxylphenyl-1,3,4-oxadiazoles are shown to be efficient organogelators. These compounds readily form stable gels in many organic solvents and their gelation property as well as supramolecular structures were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), 1H nuclear magnetic resonance (1H NMR), and ultraviolet-visible spectroscopy (UV-vis). The results indicate that the gelator molecules self-assemble into gels with elongated fibrous networks and layer structures, and van der Waals interaction is the main driving force.
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Application of membrane separation technology in post-combustion carbon dioxide capture process
Mo LI,Xiaobin JIANG,Gaohong HE
Front. Chem. Sci. Eng.. 2014, 8 (2): 233-239.
https://doi.org/10.1007/s11705-014-1408-z
Membrane separation technology is a possible breakthrough in post-combustion carbon dioxide capture process. This review first focuses on the requirements for CO2 separation membrane, and then outlines the existing competitive materials, promising preparation methods and processes to achieve desirable CO2 selectivity and permeability. A particular emphasis is addressed on polyimides, poly (ethylene oxide), mixed-matrix membrane, thermally-rearranged polymer, fixed site carrier membrane, ionic liquid membrane and electrodialysis process. The advantages and drawbacks of each of materials and methods are discussed. Research threads and methodology of CO2 separation membrane and the key issue in this area are concluded
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