Chemical Research in Chinese Universities

Table of Content

24 August 1991, Volume 7 Issue 3

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Articles

Synthesis, Characterization and Catalytic Properties of Zeolite [B, Al, Ga, Fe]-ZSM-5

Liu Xinsheng, Yu Jihong, Kan Qubin, Ding Hong

1991, 7(3): 135-142.

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Zeolite [B,Al, Ga, Fe]-ZSM-5, containing several heteroatoms, was synthesized for the first time under. hydrothermal conditions. Characterization of the sample using various techniques such as XRD, IR, ESR, TG-DTA, SEM and XRF indicates that the heteroatoms are located in the framework, similar to the situations of the heteroatoms present in the zeolites [B]^-, [Al]^-, [Ga]^- and [Fe]-ZSM-5. The study of the catalytic properties for reactions of cracking and dehydrogenation of ethylbenzene reveals that the heteroatoms function independently and there are no mutual interactions between the heteroatoms.

Preparation and Characterization of Chromium (Ⅲ)-Containing α-and β-Tungstosilicates(Ⅱ)

Peng Jun, Qu Lunyu, Xu Yihua, Peng Weixian, Zhao Yongnian

1991, 7(3): 143-147.

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Two new compounds of A- type α-and β-K_4.5H_2.5[SiW₉Cr₃(OH₂)₃O₃₇]·xH₂O were synthesized. The two kinds of isomers of α-and β-SiW_12-xCr_x(x=2, 3) were identified by Second-derivative IR spectroscopy and cyclic voltammetry. The numbers of electrons involved in reductions were obtained by controlled potential electrolyses of the isomers.

A Further Investigation into Intramolecular Process of Mg(Ⅱ)-, Sc(Ⅲ)-, Y(Ⅲ)-, In (Ⅲ)-and Pb(Ⅲ)-CyDTA Complexes by the Method of Dynamic NMR

Song Ruifang, Ba Yong, Qiu Zuwen

1991, 7(3): 148-155.

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The intramolecular process of Mg (Ⅱ) -, Sc (Ⅲ) -, Y (Ⅲ) -, In(Ⅲ)-and Pb (Ⅱ)-trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA) complexes was studied by the method of proton dynamic NMR(DNMR). The top limit of. the experimental temperature range of deuterium oxide solutions was extended from 100℃ to 167 ℃ instead of the previous 100 ℃ by using sealed, thick-walled tubes to observe experimental phenomena further. It was found that another intramolecular process, i. e. B, R (Bonded State, Rotational State) conversion, exists in these complexes formed by polyaminepolycarboxylic ligands in addition to △,A conversion and nitrogen inversion. A quantitative treatment was proposed to estimate the relative populations of acetate groups in B and Rstates.

Structure and Catalytic Behaviour of Saponite and Its Cross-Linking Product

Jiang Dazhen, Liu Ziyang, Sun Tie, Ren Beiyuan, Min Enze, He Mingyuan

1991, 7(3): 156-161.

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Synthetic saponites have been intercalated with hydroxyl aluminium oligomers and characterized with several techniques. The basal 001 peak of the pillared saponite (PS) is 1. 8 nm. The amount of the aluminium in the tctrahedral sheet is correlative with cross-linking density. The sheet-to-pillar linkage mode may be Si-O-Alp^Ⅵ. The acid sites in pillared saponite may locate either at surface of clay or at that of pillar. The cumene conversion is relative to accessible acid sites on the surface of PS. The pillar density in the PS has an effect on the pore structure which is correlative with shape selectivity during the reaction between ethanol and ammonia.

Surface Photovoltage Studies of Moisture Sensitive Characteristic of Copper Tetrasulfonato-Phthalocyanine

Liu Wang, Xiao Liangzhi, Liang Yuexia, Tian Ke, Wang Dejun, Li Tiejin

1991, 7(3): 162-166.

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The surface photovoltaic characteristic of copper tetrasulfonato- phthalocyanine (CuTsPc) in water vapor was studied by surface photovoltage spectroscopy (SPS). It was found that the adsorption of water vapor caused some marvelous changes of the photovoltaic response, that is, the SPS signal diminished rapidly and even reversed; the bands were widened and displayed a bathochromic shift. The dependence of surface photovoltage on the vapor pressure indicates that the reversed signal reaches to a maximum when the vapor pressure is 4.7×10² Pa. The time response velocity, reversibility, selectivity and reproducibili-ty were examined as well. All results obtained show that CuTsPc is of great significance in the manufacture of moisture sensitive devices. In addition, the mechanism of moisture sensitivity is discussed.

Ab initio Study on the Tautomerization Mechanism and the Kinetics of Formamide

Su Zhongmin, Cui Ruihai, Lin Xianjie, Zhao Chengda

1991, 7(3): 167-171.

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The tautomerism of formamide has been investigated by ab initio calculation using RHF/4-31G basis set. The change in some physical properties along the reaction path is presented. In the study of molecular reaction kinetics, we have calculated all the kinetic parameters according to statistical thermodynamics and transition state theory. The combination of kinetics analysis with IRC analysis has indicated that the tautomerism is concerted but the geometric changes are nonsynchronous; the lifetime of the transition state is short and the transition state is tight type; the formamide is more stable than formimidic acid; the kinetic rate constant of backward reaction is larger than that of the forward reaction in the range of temperature studied.

Catalytic Performance and IR Characterization of Co-Mo/Al₂O₃ and Ru-Co-Mo/Al₂O₃ Catalysts in Hydrodesulfurization

Xiao Fengshou, Xin Qin, Guo Xiexian

1991, 7(3): 172-173.

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The Mechanism of Phase Transition of Molecular Sieve VPI-5 into AlPO₄-8

Xu Yihua, Xiao Fengshou, Yao Shangqing, Liu Xinsheng, Pang Wengqin

1991, 7(3): 174-175.

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