摘要:

AbstractThe thermal behavior, mechanism and kinetic parameters of the exothermic decomposition reaction of 3,3‐bis(azidomethyl)oxetane/tetrahydrofuran (BAMO/THF) copolymer in a temperature‐programmed mode have been investigated by means of DSC, TG‐DTG, fast and lower thermolysis/FTIR and TG‐MS. The reaction mechanism was proposed. The apparent activation energy and pre‐exponential constant of exothermic decomposition reaction of the compound at 0.1 MPa are 167.04 kJ*mol−1and 1014.41s−1, respectively. The corresponding critical temperatures of thermal explosion obtained from the onset temperatureTc, and the peak temperatureTpare 223.20 and 245.78°C, respectively. The kinetic equation of the exothermic decomposition process of BAMO/THF at 0.1 MPa could be expressed as:\documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{{\rm d}\alpha }}{{{\rm d}T}} = 10^{15.19} \left[{ - \ln (1 - \alpha)} \right]^{\frac{2}{3}} e^{ - 2.009 \times 10^4 /T} $

ISSN:1001-604X    

DOI:10.1002/cjoc.20040221102

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractThe adsorption and diffusion of N atoms on the three low‐index Cu planes were studied using 5‐parameter Morse potential (5‐MP) method, and the best theory‐experiment agreement was obtained. N atom of Cu(100) surface sit on the fourfold hollow site with the vertical height of 0.018 nm closely coplanar with the topmost copper layer, and the four CuN bond lengths are 0.182 nm and the fifth CuN distance is 0.199 nm. For Cu(111) system, the existence of aberrant Cu(100) reconstructed structure is approved at higher coverage, and at low coverage the structure is almost an ideal Cu(111) surface structure. With respect to Cu(110) system, the N atoms are adsorbed at LB and H3sites, not at SB site. The diffusion passage and diffusion barrier of adsorbed N atoms were a

ISSN:1001-604X    

DOI:10.1002/cjoc.20040221103

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractElectrolytic fixation of CO2was investigated by electrocarboxylation of organic halides (a), and four esters (I, II, III, IV) were obtained in moderate yields. Electrochemical reduction esterifications of RX in the presence of CO2were carried out on nanocrystalline TiO2‐Pt electrode. The electrochemical behavior of RX in the presence of CO2was investigated by the technique of cyclic voltammetry, and the probable reaction mechanism was propose

ISSN:1001-604X    

DOI:10.1002/cjoc.20040221104

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractA study was made of magnetic field effects (MFEs) on the photoreduction reaction of 2‐methyl‐1, 4‐naphthoquinone (MNQ) in Brij 35 micellar solution containing 4‐lauroylamino‐TEMPO (2,2,6,6‐tetramethylpiperidine‐l‐oxyl) radical (L‐R) under magnetic fields below 1.75 T by a nanosecond laser flash photolysis technique. The triplet MNQ mainly underwent the hydrogen abstraction from Brij 35 molecule to give a radical pair. The escaped radical yield increased with magnetic fields from 0 to 0.62 T and then saturated from 0.62 to 1.75 T. MFEs for both system can be explained by the relaxation mechanism. However, it was supposed that additional radical, L‐R affected the MFEs mainly through enhancing the spin‐spin interactions of radical pairs. The effect of the micelle size on MFEs of the studying syst

ISSN:1001-604X    

DOI:10.1002/cjoc.20040221105

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractSeveral 2.0 wt% nickel catalysts supported on nanometer bimodal mesoporous aluminosilicate (NBMAS), AlHMS and AlMCM‐41 were prepared by means of the wetness impregnation method. The characterization techniques such as Py‐FTIR and H2chemisorption showed that the amount of Brönsted acid sites decreased in the order of Ni/AlHMS>Ni/AlMCM‐41>Ni/NBMAS, while the nickel dispersion differed a little. In the catalyticn‐dodecane hydroconversion, the highest conversion was obtained over Ni/NBMAS, and the lowest isomerization selectivity occurred over Ni/AIHMS. For the cracked products, the symmetrical carbon number distribution centered at C6was obtained on the Ni/AlMCM‐41 catalyst due to the well balanced metall/acid functions, whereas the Ni/AlHMS and Ni/NBMAS catalysts led to more C3‐C5and C1+C11products,

ISSN:1001-604X    

DOI:10.1002/cjoc.20040221106

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractDFT/B3LYP method with SDD basis set has been applied to the systems of (Me2AlN3). (n =1–3). (Me2AlN3)2was found to exhibit the planar Al2N2ring structure. (Me2AlN3)3involving a six‐membered Al3N3ring was found to exhibit two minima with very similar binding energies (‐265.52 and −256.10 kJ*mol−1). Compared to the monomer, both the structural changes and charge&transfers for the clusters are large. Frequency calculations were carried out on each optimized structure and its JR spectra were discussed. Thermodynamic properties reveal that the dimer is the main component in the systems of the (Me2AlN3)

ISSN:1001-604X    

DOI:10.1002/cjoc.20040221107

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractIn this paper, the effect of catalytic support and sulfiding method on the chemical state of supported Co‐MO catalysts is studied by XPS. After sulfidation within‐situmethod, the majority of molybdenum in CNT supported CoMo catalyst is transferred to a species with a formal chemical state Mo(IV) in MoS2phase, and the rest to Mo(V) which consists of Mo coordinated both to O and S, such as MoO2S22‐‐and MoO3S2‐−. In case of CoMo/γ‐Al2O3catalyst sulfided within‐situmethod, a fraction of molybdenum is transferred to formal state Moo in the form of MoS2, but there is still a mount of unreduced Mo(VI) phase which is difficult to be sulfided. In CoMo/CNT catalytic system sulfided withex‐situmethod, Mo(IV) in the form of MoS2is detected along with a portion of unreduced Mo(VI) phase, suggesting that not all the Mo phases are reduced and sulfided byex‐situmethod. As for CoMo/γ‐Al2O3, a portion of molybdenum is sulfided to intermediate reduced state Mo(V) which consists of Mo coordinated both to O and S. such as MoO2S2–2and MoO3S2–, in addition, there is still a fraction of unreduced Mo(VI) phase. XPS analyses results suggest that CNT support facilitates the reduction and sulfidation of active species to a large extent, and that alumina support strongly interacts with active species, hereby producing a fraction of phase which resists complete sulfiding. Catalytic measurements of catalysts in the HDS of dibenzothiophene (DBT) show that CoMo/CNT catalysts are of higher HDS activity and selectivity than CoMo/γ‐A2O3catalyst, which is in good relation with the sulfiding behavior

ISSN:1001-604X    

DOI:10.1002/cjoc.20040221108

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractA new thermokinetic reduced extent method for studying of the reversible Competitive inhibition of single substrate enzyme‐catalyzed reactions was proposed in this paper. The reaction that arginase‐catalyzed hydrolysis ofL‐arginine toL‐ornithine and urea and the inhibition of this reaction by the product, L‐ornithine, and exogenousL‐lysine were studied at 37 °C in 40 mmol−L−1sodium barbiturate‐HC1 buffer solution (pH=9.4). Michealis constantKmfor arginine and maximum velocityVmof the reaction were determined to be 5.14 mmol.L−1and 1.13X 10−‐2mmol‐L−1.s‐1, respectively. The product inhibition constantKpand inhibitory constantK1ofL‐lysine were determined to be 1.18 and 5.6 mmol.L−1, respectively. All the results have better repeatability and self‐consistency and are in agreement with literature values. This new method using more direct thermal information from the process would give more reliable kinetic information than

ISSN:1001-604X    

DOI:10.1002/cjoc.20040221109

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractHartree‐Fock‐Roothaan (HFR) calculations for ground states of some atoms,i.e. He, Be, Ne, Ar, and Kr have been performed using minimal basis sets of Slater type orbitals (STOs) with integer and noninteger principal quantum numbers (integern‐STOs and nonintegern‐STOs). The obtained total energies for these atoms using minimal basis sets of integern‐STOs are in good agreement with those in the previous literature. On the other hand, for the case of minimal basis sets of nonintegern‐STOs, although the calculated total energies of these atoms agree well with the results in Literature, some striking results have been obtained for atoms Ar and Kr. Our computational results for the energies of atoms Ar and Kr are slightly better than those in literature. by amount of 0.00222 and 0.000054 a.u., respectively. The improvement in the energies of atoms Ar and Kr may result from the efficient calculations of one‐center two‐electron integrals over nonintegern‐STOs. For some atomic ions in their ground state, HFR calculations have been carried out using minimal basis sets of nonintegern‐STOs. The obtained total energies for these atomic ions are substantially lower than those avai

ISSN:1001-604X    

DOI:10.1002/cjoc.20040221110

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY

摘要:

AbstractTwo coordination compounds of rare earth perchlorates with alanine and imidazole, [RE(Ala)n(Im)(H2O)]‐(ClO4)3(s) (RE=La,n=3; RE=Nd,n=2), have been prepared and characterized. The standard molar enthalpies of reaction for the following two reactions, LaCl3*7H2O(s) + 3Ala(s)+Im(s)+3NaClO4(s)=[La(Ala)3(Im)(H2O)]‐(Cl04)3(S) f 3NaCI(s) + 6H2O(1) (1) and NdCl36H2O(s) + 2Ala(s) + Im(s) + 3NaClO4(s) = [Nd(Ala)2(Im)(H2O)]‐(ClO4)3(s)+3NaCl(s)+5H2O(1) (2), were determined by solution‐reaction calorimetry, at T=298.15 K, as 36.168±0.642 kJ.mol−1and 48.590±0.934 kJ.mol−1respectively. From the results and other auxiliary quantities, the standard molar enthalpies of formation of [La(Ala)3(Im)(H2O)](Cl04)3(s) and [Nd(Ala)2(Im)(H2O)] (Cl04)3(s) were derived, ΔfH ⊖m{[La(Ala)3(Im)(H2O)](ClO4)3, s) =(−2984.8 ± 1.0) kJ.mol‐land ΔfH ⊖m{[Nd(Ala)2(Im)(H2O)]‐(ClO4)3,s) =(−23

ISSN:1001-604X    

DOI:10.1002/cjoc.20040221111

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:2004

数据来源: WILEY