Mar 2007, Volume 1 Issue 1
    

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  • Synthesis, characterization and catalytic properties of mesoporous MCM-48 containing zeolite secondary building units
    LI Qiang, ZHANG Ying, DOU Tao, LI Yuping, WANG Shan, SUN Famin
    2007, 1(1): 1-5. https://doi.org/10.1007/s11705-007-0001-0
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    Mesoporous aluminosilicate MCM-48 containing zeolite secondary building units in the pore wall has been synthesized in alkaline media with a two-step procedure. The aluminosilicate precursors comprising zeolite secondary building units were first synthesized by carefully controlling reaction conditions and then were assembled using cotemplates of gemini surfactant [C18H37N(CH3)2(CH2)3N(CH3)2C18H37]2+ (18-3-18) and triethanolamine (TEA). X-ray Diffraction (XRD) patterns of the as-made samples indicated that highly ordered mesostructured MCM-48 was formed. Transmission Electron Microscopy (TEM) images further verified the formation of MCM-48 with uniform cubic pore channel system having the pore opening diameter of about 25 Å. Compared with the conventionally synthesized MCM-48, the as-synthesized MCM-48 sample showed an adsorption band at 520 600 cm-1 in its FT-IR spectrum, which was assigned to five-membered ring vibration from zeolite structure. This suggested the presence of zeolite building units in the pore wall. N2 adsorption data showed that the material had a much higher specific surface area (1 200 m2/g) than the conventional MCM-48(1 100 m2/g). Finally, the catalytic performance of the as-made MCM-48 was evaluated by hydrogenation dealkylation reaction of heavy aromatic hydrocarbons. Catalytic results showed that the as-made MCM-48 catalyst exhibited higher conversion than the conventional MCM-48 catalyst. The as-made mesostructured MCM-48 may have a potential catalytic application in the conversion of bulky molecules.
  • Properties of La1-xCexCoO3 system perovskite-type catalysts for diesel engine exhaust removal
    GONG Cairong, FAN Guoliang, HOU Yanfeng, ZHANG Zhongrong, SONG Chonglin, HUANG Qifei
    2007, 1(1): 6-10. https://doi.org/10.1007/s11705-007-0002-z
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    A series of complex oxide La1-xCexCoO3 catalysts was synthesized at a low temperature through a combustion process, in which x is among 0, 0.1, 0.2, 0.4 and 0.6 corresponding to the quantity of La3+ partial substitution by Ce4+. The catalysts were characterized for phase composition using chemical analysis and X-ray diffraction. The catalytic activity of the catalysts in removal of NOx, total hydrocarbon (THC) and particulate matter (PM) from diesel exhaust gases were examined in detail using temperature-programmed reaction technique. The results show that after partial substitution of La3+ with Ce4+, the oxygen vacancy concentration increases significantly and a Co3+-Co2+ system is formed. Consequently, the catalytic activity in the removal of THC and NOx is significantly improved. But for the PM, the effect is not so obvious. The possible catalytic mechanism for this was presented. It is also worth noting that the doped catalysts showed good stability.
  • Biodiesel production by the transesterification of cottonseed oil by solid acid catalysts
    CHEN He, PENG Baoxiang, WANG Dezheng, WANG Jinfu
    2007, 1(1): 11-15. https://doi.org/10.1007/s11705-007-0003-y
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    Methyl esters (biodiesel) were produced by the transesterification of cottonseed oil with methanol in the presence of solid acids as heterogeneous catalysts. The solid acids were prepared by mounting H2SO4 on TiO2 · nH2O and Zr(OH)4, respectively, followed by calcining at 823K. TiO2-SO42- and ZrO2-SO42- showed high activity for the transesterification. The yield of methyl esters was over 90% under the conditions of 230°C, methanol/oil mole ratio of 12:1, reaction time 8 h and catalyst amount (catalyst/oil) of 2% (w). The solid acid catalysts showed more better adaptability than solid base catalysts when the oil has high acidity. IR spectral analysis of absorbed pyridine on the samples showed that there were Lewis and BrØnsted acid sites on the catalysts.
  • Effect of glow discharge plasma on rhodium-based catalyst for oxygenates synthesis
    HUANG Lihong, CHU Wei, XU Junqiang, HONG Jingping, YI Min
    2007, 1(1): 16-19. https://doi.org/10.1007/s11705-007-0004-x
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    Rhodium-based catalysts were prepared by impregnation, treated with glow discharge plasma, characterized by X-ray diffraction, X-ray photoelectron spectroscopy, H2 temperature-programmed reduction, H2 temperature-programmed desorption and CO temperature-programmed desorption, and investigated for oxygenate synthesis from CO hydrogenation. Based on the characterization results, plasma treatment endowed the samples with smaller particle size, higher dispersion of active components, and an enrichment of active components on the surface as well. As a result, the reducibility and adsorption properties were modified. In catalytic tests, the catalytic activity for CO hydrogenation over the samples treated by plasma was improved remarkably: the conversion of CO and the yield of oxygenates increased at most by a factor of 78.62% and 51.96%, respectively, while the selectivity of ethanol and methanol in the oxygenates was enhanced as well.
  • Preparation and influence of performance of anodic catalysts for direct methanol fuel cell
    WANG Zhenbo, YIN Geping, SHI Pengfei
    2007, 1(1): 20-25. https://doi.org/10.1007/s11705-007-0005-9
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    This research aims at increasing the utilization of platinum-ruthenium alloy (Pt-Ru) catalysts and thus lowering the catalyst loading in anodes for methanol electrooxidation. The direct methanol fuel cell s (DMFC) anodic catalysts, Pt-Ru/C, were prepared by chemical reduction with a reducing agent added in two kinds of solutions under different circumstances. The reducing agent was added in hot solution with the protection of inert gases or just air, and in cold solution with inert gases. The catalysts were treated at different temperatures. Their performance was tested by cyclic voltammetry and potentiostatic polarization by utilizing their inherent powder microelectrode in 0.5 mol/L CH3OH and 0.5 mol/L H2SO4 solution. The structures and micro-surface images of the catalysts were determined and observed by X-ray diffraction and transmission electron microscopy, respectively. The catalyst prepared in inert gases showed a better catalytic performance for methanol electrooxidation than that prepared in air. It resulted in a more homogeneous distribution of the Pt-Ru alloy in carbon. Its size is small, only about 4.5 nm. The catalytic performance is affected by the order of the reducing agent added. The performance of the catalyst prepared by adding the reductant at constant temperature of the solution is better than that prepared by adding it in the solution at 0?C and then heating it up to the reducing temperature. The structure of the catalyst was modified, and there was an increase in the conversion of ruthenium into the alloyed state and an increase in particle size with the ascension of heat treatment temperature. In addition, the stability of the catalyst was improved after heat treatment.
  • Effect of steady shear on multi-axial texture of symmetric diblock copolymers
    XU Hui, LIU Honglai, HU Ying
    2007, 1(1): 26-34. https://doi.org/10.1007/s11705-007-0006-8
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    The effect of steady shear on multi-axial texture of symmetric diblock copolymer was investigated by using dynamic density functional theory. Through modifying the periodic boundary condition, the parallel-transverse biaxial texture and perpendicular-parallel-transverse triaxial texture have been observed. In the formation of the multi-axial texture, there are two critical velocities μ*per-par and µ*par-tra, at which the transition between the perpendicular and the parallel lamellar morphology, and the transition between the parallel and the transverse lamellar morphology occur, respectively. The two critical velocities increase as the interaction parameter increases, but they almost remain constant at different shear rates. Furthermore, the rotation from the transverse lamellae to the parallel lamellae induced by the shear strain, and the increase of lamellar spacings of the three lamellae after removing the shear, have also been observed by the time evolution of the morphologies. These phenomena are consistent with experimental work.
  • Experimental study of the influence of acid wash on cellulose pyrolysis
    WANG Shurong, LIU Qian, LUO Zhongyang, CEN Kefa, LIAO Yanfen
    2007, 1(1): 35-39. https://doi.org/10.1007/s11705-007-0007-7
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    The analysis of microstructure and polymerization degree showed that acid wash altered the cellulose morphology and decreased the polymerization degree significantly. A series of experiments were done to study the effect of acid wash on cellulose rapid pyrolysis. Experimental results showed that under acid pretreatment, the yield of bio-oil decreased while the production of gas and char increased. With an increase in acid concentration, this trend would be further enhanced. Sulphuric acid limited the formation of bio-oil more effectively than hydrochloric acid and phosphoric acid. According to the GC-MS analysis of bio-oil, high-concentration acid wash restrained the formation of levoglucosan by catalyzing dehydration process and cross linking reaction.
  • Fabrication and performance of PEN SOFCs with proton-conducting electrolyte
    ZHONG Li, LUO Jingli, Karl Chuang
    2007, 1(1): 40-44. https://doi.org/10.1007/s11705-007-0008-6
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    A positive-electrolyte-negative (PEN) assembly solid oxide fuel cell (SOFC) with a thin electrolyte film for intermediate temperature operation was fabricated. Instead of the traditional screen-printing method, both anode and cathode catalysts were pressed simultaneously and formed with the fabrication of nano-composite electrolyte by press method. This design offered some advantageous configurations that diminished ohmic resistance between electrolyte and electrodes. It also increased the proton-conducting rate and improved the performance of SOFCs due to the reduction of membrane thickness and good contact between electrolyte and electrodes. The fabricated PEN cell generated electricity between 600?C and 680?C using H2S as fuel feed and air as oxidant. Maximum power densities 40 mW " cm-2 and 130 mW " cm-2 for the PEN configuration with a Mo-Ni-S-based composite anode, nano-composite electrolyte (Li2SO4+Al2O3) film and a NiO-based composite cathode were achieved at 600?C and 680?C, respectively.
  • Preparation and characterization of SO42-/TiO2 and S2O82-/TiO2 catalysts
    MA Xuedan, GUO Daishi, JIANG Qizhong, MA Zifeng, MA Zhengfei, YE Weidong, LI Chunbo
    2007, 1(1): 45-49. https://doi.org/10.1007/s11705-007-0009-5
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    Nanosized solid superacids SO42-/TiO2 and S2O82-/TiO2, as well as MCM-41-supported SO42-/ZrO2, were prepared. Their structures, acidities, and catalytic activities were investigated and compared using XRD, N2 adsorption-desorption, and in situ FTIR-pyridine adsorption, as well as an evaluation reaction with pseudoionone cyclization. The results showed that SO42-/TiO2 and S2O82-/TiO2 possess not only nanosized particles with diameters <7.0 nm, a BET surface greater than 140 cm2/g and relatively regular mesostructures with pores around 4.0 nm, but also a pure anatase phase and strong acidity. Different from the Lewis acid nature of SO42-/ZrO2/MCM-41, SO42-/TiO2 and S2O82-/TiO2 exhibit mainly Br¢nsted acidities. The strongest Br¢nsted acid sites were produced on SO42-/TiO2 promoted with H2SO4, while Lewis acid sites on S2O82-/TiO2 even stronger than those on SO42-/ZrO2/MCM-41 were generated when persulfate solution was used as sulfating agent. Because of their distinct acid natures, SO42-/TiO2 and S2O82-/TiO2 exhibited catalytic activities for the cyclization of pseudoionone that were much higher than that of SO42-/ZrO2/MCM-41. It can be concluded that the existence of more Br¢nsted acid sites was favorable for proton participation in the cyclization reaction.
  • Thermal decomposition of poly(ethylene terephthalate)/mesoporous molecular sieve composites
    RUN Mingtao, ZHANG Dayu, WU Sizhu, WU Gang
    2007, 1(1): 50-54. https://doi.org/10.1007/s11705-007-0010-z
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    The nonisothermal and isothermal degradation processes of poly (ethylene terephthalate)/mesoporous molecular sieve (PET/MMS) composites synthesized by in-situ polymerization were studied by using thermogravimetric analysis in nitrogen. The nonisothermal degradation of the composite is found to be the first-order reaction. An iso-conversional procedure developed by Ozawa is used to calculate the apparent activation energy (E), which is an average value of about 260 kJ/mol with the weight conversion from 0% to 30%, and is higher than that of neat PET. Isothermal degradation results are confirmed with the nonisothermal process, in which PET/MMS showed higher thermal stability than neat PET. The polymer in mesoporous channels has more stability due to the protection of the inorganic pore-wall. These results indicate that mesoporous MMS in PET/MMS composites improve the stability of the polymer.
  • Large-scale synthesis of isolated Mn2O3 nanotube/fiber with ferric nitrate as catalyst
    ZHANG Aifei, LIU Jiping, L? Guangshu
    2007, 1(1): 55-58. https://doi.org/10.1007/s11705-007-0011-y
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    Isolated Mn2O3 nanotubes and nanofibers were prepared very easily at a large scale with the liquid-phase catalysis method. The Mn2O3 nanotubes had dimensions of 30 50 nm (exterior diameter) and 0.2 1.0 ?m (length), approximately. The 2O3 nanofibers had dimensions of 10 30 nm (diameter) and 0.4 2.0 ?m (length), approximately. Nano-2O3 with different microstructures including nanotubes, nanofibers and nanoparticles could be selectively synthesized by controlling the contents and proportions of potassium permanganate and ferric nitrate. Ferric nitrate was an ideal catalyst for the preparation of 2O3 nanotube/fiber. When cobalt nitrate or nickel nitrate was used as catalyst, only amorphous nano-2O3 was synthesized. X-ray diffraction (XRD) result shows that the 2O3 nanotube has a crystalline structure different from o-2O3, t-2O3, h-2O3 and ?-2O3.
  • Direct synthesis of diphenyl carbonate over heterogeneous catalyst: effects of structure of substituted perovskite carrier on the catalyst activities
    WU Guangwen, JIN Fang, WU Yuxin, ZHANG Guangxu, LI Dinghuo, WANG Cunwen, MA Peisheng
    2007, 1(1): 59-64. https://doi.org/10.1007/s11705-007-0012-x
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    The perovskite-type compound LaMnO3 was substituted for the part of La in position A and for the part of Mn in position B by citrate method. The phases were detected by X-ray diffraction. Powder morphologies were scanned by scanning electron microscopy. The valence of atoms was determined by X-ray photoelectron spectroscopy. It was found that the perovskite can form crystal defect and increase the proportion of high valence B element by doping. Active component Pd was loaded on various perovskite supports for synthesis of diphenyl carbonate. The results showed that the activities of catalysts in which supports have crystal defect by substitution were higher. It can be concluded that perovskite with defect structure by doping could lead to the formation of oxygen vacancy where the lattice oxygen became exchangeable with the oxygen gas. Also, this improved the redox process of the carrier by transferring electrons and activities of catalysts.
  • Synthesis of a new iron (III) porphyrin acrylate-styrene copolymer and its catalysis for hydroxylation of cyclohexane
    YU Hancheng, LI Xixian, HUANG Jinwang, JI Liangnian, CHEN Xianli
    2007, 1(1): 65-67. https://doi.org/10.1007/s11705-007-0013-9
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    A new iron (III) porphyrin acrylate-styrene copolymer, P[(PorFe)A-S], was synthesized by the reaction of iron (III) porphyrin acrylate with styrene and characterized by UV-Vis, Infrared spectra (IR), inductively coupled plasma-atomic emission spectrometry (ICP) and molecular weight determination. Its catalytic activity in the hydroxylation of cyclohexane for model cytochrome P450 in the P[(PorFe)A-S]-O2 ascrobate-thiosalicylic acid system has been studied. It was found that the P[(PorFe)A-S] has a higher catalytic activity than non-supported iron (III) porphyrin and its high catalytic activity remained in reuse. The catalytic activity of P[(PorFe)A-S] was discussed in the view of the microenvironment of iron (III) porphyrin. It is proposed that the atalytic activity of the P[(PorFe)A-S] may be further enhanced by construction of a homophase catalytic system containing the iron (III) porphyrin acrylate-styrene copolymer.
  • Solution properties and self-association of multi-blocks like copolymer P(AM/AA) prepared by template copolymerization
    ZHANG Yuxi, WU Feipeng, LI Miaozhen, WANG Erjian
    2007, 1(1): 68-71. https://doi.org/10.1007/s11705-007-0014-8
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    The association and properties of multi-block like copolymers (TP) of acrylamide (AM) and acrylic acid (AA) prepared by template copolymerization in aqueous solution were studied. The results showed that the copolymers of this type exhibited a significant structure effect compared with that of similar random copolymers (CP) obtained by copolymerization in the absence of template. Decreasing the value of pH or adding Ca2+ ion to the copolymer solution will make phase separation occur. The TEM images demonstrated that the phase separation caused by Ca2+ ion was due to the formation of extensively intermolecular cross-linking. With the increase of the pH value of copolymer solution, the changes of the solution viscosity was similar with that of homopolyacrylic acid, which originally increased and then decreased. But the increase range of template copolymer was higher than that of homopolyacrylic acid. TEM images indicated that at the maximal viscosity the copolymer obtained in the presence of template formed coiled aggregates.
  • Synthesis and thermosensitive behavior of dextran graft copolymers containing poly (N-vinylcaprolactam) side chains
    SHI Huangying, CHEN Wenjuan, ZHANG Liming
    2007, 1(1): 72-75. https://doi.org/10.1007/s11705-007-0015-7
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    New graft copolymers were synthesized by grafting N-vinylcaprolactam onto dextran. Their composition and structure were investigated by elemental analyses, infrared spectra and thermogravimetric analyses. By optical transmittance measurements, it was found that the aqueous solutions of these graft copolymers showed a temperature-dependent transmittance change due to the introduction of thermosensitive poly (N-vinylcaprolactam) graft chains. Moreover, the lower critical solution temperature (LCST) of the graft copolymer in aqueous solution was dependent on its grafting extent and concentration. The LCST value was found to increase with the increase of the grafting extent and decrease with the increase of the copolymer concentration. With these stimuli-response properties, such polysaccharide derivative may hold potential applications in biomedicine and biotechnology.
  • Preparation and properties of nano SiO2 core-shell structured additives and their nanocomposite with polypropylene
    KE Yangchuan, SUN Mingzhuo, SONG Yanxin, YANG GuangFu
    2007, 1(1): 76-80. https://doi.org/10.1007/s11705-007-0016-6
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    To improve the performance of traditional nucleation additives and their compatibility with other additives, as well as to solve complex problems in practical applications, SiO2 precursors were reactively grafted in situ with the symmetrical hydroxyl groups of the nucleation agents. With this approach, the dissymmetrical part of the nucleation agents plays an important role. As a result, the prepared composite additive the nanoparticle precursor (NPP0) produces excellent results. The NPP0-PP composite has a transparency of over 93%, haze lower than 15%, and a heat distortion temperature (HDT) of 142?C, which is more than the 110?C of the pure PP matrix. In addition, it maintains over 90% of the mechanical properties with a deformation coefficient less than 1%. This indicates a strong nanoeffect.
  • Investigation on multiple-melting behavior of nano-CaCO3/polypropylene composites
    LIN Zhidan, ZENG Chunlian, MAI Kancheng
    2007, 1(1): 81-86. https://doi.org/10.1007/s11705-007-0017-5
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    The multiple melting-peak behavior of polypropylene (PP) in nano-CaCO3/PP composites and modified nano-CaCO3/PP composites were investigated under the condition of isothermal crystallization and nonisothermal crystallization. The result indicated that the addition of nano-CaCO3 markedly increased the crystallization temperatures of PP and induced the formation of the β-crystal of PP. The crystallization temperatures of nano-CaCO3/PP composites modified by reactive monomers were further increased, but the melting-peak intensity of the β-crystal of PP was not greatly influenced. While in the presence of dicumyl peroxide, nano-CaCO3/PP composites modified by reactive monomers led to the significant increase in the melting-peak intensity of the β-crystal of PP. The double melting-peak of PP was observed, which was attributed to the formation of two kinds of different crystallization forms of α-crystal or β-crystal during the crystallization of PP. With the increase of crystallization temperatures, the double melting-peak moved toward the high-temperature side. The intensity of high-temperature melting peak was higher than that of low-temperature melting peak in nano-CaCO3/PP composites. While in modified nano-CaCO3/PP composites crystallized at higher temperature, the intensity of high-temperature melting peak was lower than that of low-temperature melting peak. The isothermal crystallization time had little effect on the melting temperatures.
  • Advances in chemical synthesis and application of metal-metalloid amorphous alloy nanoparticulate catalysts
    WU Zhijie, LI Wei, ZHANG Minghui, TAO Keyi
    2007, 1(1): 87-95. https://doi.org/10.1007/s11705-007-0018-4
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    This paper reviews the advances in the chemical synthesis and application of metal-metalloid amorphous alloy nanoparticles consisting of transition metal (M) and metalloid elements (B, P). After a brief introduction on the history of amorphous alloy catalysts, the paper focuses on the properties and characterization of amorphous alloy catalysts, and recent developments in the solution-phase synthesis of amorphous alloy nanoparticles. This paper further outlines the applications of amorphous alloys, with special emphasis on the problems and strategies for the application of amorphous alloy nanoparticles in catalytic reactions.
  • Preparation and application of magnetic microsphere carriers
    ZHANG Bo, XING Jianmin, LIU Huizhou
    2007, 1(1): 96-101. https://doi.org/10.1007/s11705-007-0019-3
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    Magnetic microsphere carriers have received considerable attention, primarily because of their wide applications in the fields of biomedicine and bioengineering. In this paper, preparation methods, surface modification and application of magnetic carriers are reviewed. Emphasis will be placed on recent biological and biomedical developments and trends such as enzyme immobilization, cell isolation, protein purification, target drugs and DNA separation.