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  • 1
    Electronic Resource
    Electronic Resource
    Compositional control of PbTiO3 thin films by plasma enhanced metalorganic chemical vapor deposition (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 2511-2513 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: PbTiO3 thin films on the Si substrates were prepared by plasma enhanced chemical vapor deposition (PECVD) using Ti(O-i-C3H7)4, Pb(C2H5)4, and oxygen. The composition of PECVD PbTiO3 thin films was intensively influenced by the input flow rate ratio of precursors while it was independent of the deposition temperatures. As-deposited PECVD PbTiO3 thin film showed a uniform distribution of the Pb, Ti, and C component throughout the bulk of film. When an annealing process was performed at 750 °C under the O2 ambient for 1 h, the Pb/(Pb+Ti) ratio of thin films was reduced from 0.567 to 0.509.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110465
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  • 2
    Electronic Resource
    Electronic Resource
    Ethylene and Propylene Polymerization over Chiral ansa-Dichloro[o-phenylenedimethylenebis(.eta.5-1-indenyl)]zirconium [Zr{C6H4(CH2-1-C9H6)2-1,2}Cl2] (1995)
    s.l. : American Chemical Society
    Macromolecules 28 (1995), S. 4801-4805 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00118a003
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  • 3
    Electronic Resource
    Electronic Resource
    Residual Oil Hydrodesulfurization Using Dispersed Catalysts in a Carbon-Packed Trickle Bed Flow Reactor (1995)
    s.l. : American Chemical Society
    Energy & fuels 9 (1995), S. 2-9 
    Details
    ISSN: 1520-5029
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ef00049a001
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  • 4
    Electronic Resource
    Electronic Resource
    Comparison of ethylene polymerization catalyzed over Cr(VI)/silica and Cr(II)/silica catalysts (1992)
    Springer
    Polymer bulletin 29 (1992), S. 205-212 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Ethylene polymerization and the morphology of produced high density polyethylene (HDPE) catalyzed over. Cr(VI)/silica and Cr(II)/silica were studied. Cr/silica catalyst with Cr loading of 1 wt % has been prepared by impregnating an aqueous solution of CrO3 onto silica having specific surface area of 301 m2/g and pore volume of 1.64 ml/g. The rate profiles and the morphologies of polyethylene polymerized over Cr(VI) and Cr(II)/silica were different. The process of active site formation influences the rate profiles. The shape of polyethylene particles polymerized with Cr(II)/silica resembled the original shape of catalyst particles. However, Cr(VI)/silica catalyst particles were fractured inhomogeneously during the polymerization. The variation of molecular weight and molecular weight distribution at various polymerization times indicated that the formation of active sites of Cr(VI)/silica was accomplished gradually during polymerization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558058
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  • 5
    Electronic Resource
    Electronic Resource
    Deactivation characteristics inn-heptane reforming reaction catalyzed over small Pt, Ir and Pt-Ir bimetallic clusters in NaY (1993)
    Springer
    Catalysis letters 19 (1993), S. 239-245 
    Details
    ISSN: 1572-879X
    Keywords: Pt ; Ir ; Pt-Ir bimetallic cluster ; NaY zeolite ; deactivation ; n-heptane reforming reaction ; TPO ; coke
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The deactivation characteristics of highly dispersed (about 1 nm) Pt, Ir and Pt-Ir bimetallic clusters in NaY were studied by hydrogen chemisorption, coke analysis and temperature programmed oxidation of used catalyst inn-heptane reforming reaction. As the Ir content was increased, the amount of coke decreased. Most of coke was located around the metal cluster and this coke decreased the selectivity of dehydrocyclization inn-heptane reaction. The higher activity and more improved activity maintenance of Pt-Ir/NaY bimetallic catalysts than those of Pt/NaY are related to the less amount of coke formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00771760
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  • 6
    Electronic Resource
    Electronic Resource
    The existence of dual Cu site involved in the selective catalytic reduction of NO with propene on Cu/ZSM-5 (1996)
    Springer
    Catalysis letters 42 (1996), S. 177-184 
    Details
    ISSN: 1572-879X
    Keywords: SCR ; NO ; propene ; Cu/ZSM-5 ; nitro species ; -NCO species ; reaction intermediates ; DRIFT spectroscopy ; IR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In order to establish the role of surface species in the selective catalytic reduction (SCR), in situ IR studies were carried out using a DRIFT (diffuse reflectance infrared Fourier transform) cell in gas mixtures of various C3H6/NO ratios containing excess oxygen. The location and mobility of Cu ions were investigated by recording the relevant bands of CO adsorbed on Cu/ZSM-5. The nitro species coordinated on Cu2+ and the -NCO surface complex as possible intermediates were observed in the reduction of NO with propene on Cu/ZSM-5 between 350 and 400°C. The reactivities of these species toward NO, O2 and propene were examined. The nitro species can react with propene very rapidly to form N2 without the formation of NCO species. NCO also reacts with NO2 and/ or NO at 350°C. IR spectra of CO adsorbed on cuprous ions show that two kinds of Cu ions, which are responsible for the activation of NO and propene respectively, exist on Cu/ZSM-5. From these results, a dual site mechanism involving nitro species and -NCO species as intermediates is suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00810685
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  • 7
    Electronic Resource
    Electronic Resource
    Polymerization of aqueous lactic acid to prepare high molecular weight poly(lactic acid) by chain-extending with hexamethylene diisocyanate (1995)
    Springer
    Polymer bulletin 35 (1995), S. 415-421 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In order to synthesize the high molecular weight poly(lactic acid) [PLA], Hexamethylene diisocyanate [HDI] was used as a chain extender connecting the terminal group of polymers. Poly(lactic acid) of high molecular weight, 76000 (MW) and 33000 (Mn), was obtained by using antimony trioxide catalyst after chain-extending with HDI. Without chain-extending, the molecular weight of PLA was about 7000 (Mn). Tm in the 2nd-scan DSC thermogram was not found when PLA was chain-extended with HDI. In order to check the degree of crystallization of polymers, annealing of these polymers was carried out at 120 °C. Peaks of XRD (X-Ray Diffraction) were sharpened as the duration of annealing was lengthened. The analysis of polymers reacted with HDI by 1H-NMR showed the broad peaks at 1.32 and 3.14 ppm assigned to HDI units. The molecular weight of polymers increased with the increase in the mole ratio of-NCO/-OH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297606
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  • 8
    Electronic Resource
    Electronic Resource
    Polymerization of propylene by highly active catalysts synthesized with Mg(OEt)2/benzoyl chloride/TiCl4 (1990)
    Springer
    Polymer bulletin 23 (1990), S. 35-42 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Active centers have been studied in the polymerization of propylene using highly active Mg(OEt)2/Benzoyl chloride/TiCl4 catalysts activated with AlEt3. The method for the measurement of active centers is based on the inhibiting effect of CO on polymerization. The activity of the present catalysts, which is higher than that of TiCl3 or MgCl2-supported catalyst, is mainly due to the higher concentration of active centers by one order of magnitude. In order to investigate the stability of active centers during polymerization the number of active centers are compared at various polymerization times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00983961
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  • 9
    Electronic Resource
    Electronic Resource
    The role of lanthanum oxide on Pd‐only three‐way catalysts prepared by co‐impregnation and sequential impregnation methods (2000)
    Springer
    Catalysis letters 70 (2000), S. 35-41 
    Details
    ISSN: 1572-879X
    Keywords: Pd‐only three‐way catalyst ; lanthanum oxide ; cerium oxide ; co‐impregnation ; XPS ; XRD ; thermal aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of lanthanum oxides on the catalytic performance and the physicochemical properties of Pd‐only three‐way catalysts prepared by co‐impregnation and sequential impregnation methods was studied by using hydrogen chemisorption, BET surface area, X‐ray diffraction and X‐ray photoelectron spectroscopy. It was found that the roles of La closely depended on the order of La introduction in the preparation of the Pd catalysts. Pd–La/Al2O3 prepared by co‐impregnation of La and Pd, kept its superior activity in spite of the significant loss of surface area of the alumina support after thermal aging at 1273 K, indicating that the primary role of La was a Pd stabilizer through the intimate interaction between La and Pd. However, on Pd/La/Al2O3, in which Pd was consecutively impregnated after the impregnation of La, La preferentially interacted with the alumina support as a form of LaxAlyO2, resulting in the stabilization of the alumina support during thermal aging. XPS results indicated that lanthanum oxide suppressed the formation of PdO interacting with alumina during thermal aging. In the case of Pd/La–Ce/Al2O3, the formation of the solid solution of (CexLa1−x)O2 was not strong enough to maintain the high activity and the good textural property after thermal aging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019083704188
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  • 10
    Electronic Resource
    Electronic Resource
    Selective alkylation of aniline with methanol over metallosilicates (1994)
    Springer
    Catalysis letters 26 (1994), S. 169-180 
    Details
    ISSN: 1572-879X
    Keywords: aniline alkylation ; metallosilicate ; acidity ; NNDMA selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The selective alkylation of aniline with methanol was investigated over various metallosilicates synthesized in two different media: alkaline medium (NaOH) and fluorine medium (NH4F). Through the elemental analysis, XRD, and29Si MAS NMR, it was thought that all the metallosilicates had MFI zeolite structure and the metals were incorporated in metallosilicate framework successfully. Temperature programmed desorption (TPD) of NH3 and aniline alkylation suggested that the selectivity for N,N-dimethylaniline (NNDMA) is high when the metallosilicates have a large number of medium acid sites (567–673 K), which means that the medium acid sites play an important role in the production of NNDMA. It was also known that metallosilicates synthesized in fluorine medium have strong acid sites (〉 773 K) and were deactivated more rapidly than those synthesized in alkaline medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00824042
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