CRYSTALLIZATION OF NaY ZEOLITE IN THE PRESENCE OF “CRYSTAL DIRECTION AGENT”AND RECRYSTALLIZATION OF NaA INTO NaY IN THE REACTION MIXTURE

The process of nucleation and crystal growth of NaY zeolite over a temperature rangeof 55°--100℃ in the presence of "crystal direction agent " are studied. The apparent ac-tivation energy for nucleation and that for crystal growth are evaluated. The mechanism ofthe recrystallization of NaA into NaY is investigated by adding NaA zeolite to the reactionmixture in which the crystallization of NaY zeolite is proceeding. The recrystallization ofNaA zeolite does not occur until the NaY crystallization from the reaction mixture is com-pleted. Thus the process of recrystallization of NaA into NaY might be shown as follows: Amorphous aluminosilicate gel→NaY NaA→NaY NaA Scanning electron microscopic observations and the recrystallization curves show that therecrystallization of NaA into NaY is getting n with a degradation and dissolution of surfacecrystals on the NaA zeolite and that the nucleation and crystal growth of NaY take placeimmediately at the surface of NaA crystals.     

Isomorphous Substitution of Metallic Elements for Zeolite Y in the Aqueous Solution

The substitutions of Ti, Fe and Zr into zeolite Y in the aqueous solutions of (NH4)2TiF6, (NH4)3ZrF7 and (NH4)3FeF6 were systematically Investigated. It was found that Ai atoms in the framework can be replaced by some metallic elements and the extent of substitution depends on the M/A1 ratio of the solution. The maximum allowable M/A1 ratio of the aqueous solution Is related with the radius of the M atom and the stability constant of the MFnm- complex. The substituted zeolite samples with crystallinity greater than 80% were characterized by means of XRD, IR, DTA, TPR and NH3-TPD measurements. The incorporation of Ti, Fe and Zr into the zeolite leads to an increase in the unit cell parameter, a lowering of thermal stability and a red shift of the asymmetric stretching frequency. The extent of these changes is apparently related with the ionic radius of the metallic element and the degree of substitution. The results of various characterization methods show that the het-eroatoms are readily Introduced int     

Dehydrogenation activities of highly dispersed transition metal oxides on NaY zeolite

Highly dispersed α-Fe_2O_3/NaY,NiO/NaY,and CuO/NaY catalyst systems were pre-pared by impregnation method.Dispersion thresholds of the transition metal oxides on NaY" zeolitewere determined by XRD phase analysis.The dispersion capacities of the transition metal oxides on NaYzeolite are much lower than that estimated on the basis of a closed packed monolayer in the micropores.The catalytic activity and selectivity of the highly dispersed oxide catalyst systems for ethylben-zene and cyclohexane dehydrogenation reactions were reported.     

Baeyer-Villiger oxidation of ketones with hydrogen peroxide catalyzed by Sn-aniline complex

Sn-aniline complex was prepared by a simple procedure.Cyclic and acyclic ketones were oxidized into lactones or esters with very high selectivity and yield with 30% hydrogen peroxide in the presence of Sn-aniline complex.     

Preparation of a novel composite electrode based on N-doped TiO_2-coated Na Y zeolite membrane and its photoelectrocatalytic performance

For the first time the preparation of the N-doped TiO_2-coated NaY zeolite membrane(N-doped TiO_2/NaY zeolite membrane) as an electrode material for photoelectrocatalysis has been achieved and reported.The XRD, SEM, UV–vis and XPS techniques were used to characterize the structure of the N-doped TiO_2/NaY zeolite membrane. The results verified that the surface of the N-doped TiO_2/NaY zeolite membrane was coated by TiO_2 nanoparticles of ca. 20 nm size and exhibited a distinct red-shift in the UV–vis spectra compared to N-doped TiO_2. The photoelectrocatalysis performance of the N-doped TiO_2/NaY zeolite membrane electrode was evaluated by phenol degradation. The results revealed it is a promising novel electrode material for application of photoelectrocatalysis in the removal of organic contaminants in waste water.     

Synthesis and Crystal Structure of a 1-D Copper(Ⅱ) Polymer with 1-Hexylimidazole and Oxalate

A novel Cu(Ⅱ) complex has been prepared by means of self-assembly of CuCl2,1-hexylimidazole L and oxalic acid(H2OX) in the presence of triethylamine,and structurally characterized by X-ray diffraction analysis.In complex 1,1-D polymer chains are formed through pentacoordinated Cu(Ⅱ),oxalate and bridging chlorine atoms.In the crystal packing of 1,the imidazole ring head-to-tail π-π stacking interactions exist between 1-D polymer chains and extend the 1-D polymer chains into 2-D supramolecular layers.The fluorescence emission spectra of L and 1 were described.     

PURIFICATION AND CHARACTERIZATION OF A DNA POLYMERASE-TEMPLATE COMPLEX IN MOUSE ASCITES TUMOR CELLS

A DNA polymerase-template complex found in mouse Erhlich ascites tumor cells waspurified by twice discontinuous gradient centrifugations and agarose gel filtration. Afterpurification, the specific activity of the complex increased about 500-fold. The size of thecomplex was found to be 510,000 daltons. The shape of the complex was globular under electronmieroscope. Its diameter was between 100--110 A. The complex was isolated into two mainenzyme proteins and a homogeneous DNA template by DEAE cellulose chromatography. Themain enzyme had a molecular weight of 300,000 daltons and a sedimentation coefficient of9.5s. The endogenous template DNA showed a single zone in polyacrylamide gel electropho-resis analysis. The sedimentation coefficient was determined to be 3.8s.     

Nd-doped barium titanate ceramics with various Ti/Ba ratios prepared by sol-gel method

The Nd-doped BaTiO3 nanocrystalline powders and ceramics with different Ti/Ba ratios were prepared by sol-gel method. Phases and microstructures of the Nd-doped BaTiO3 based powders and ceramics were characterized by XRD, SEM and TEM methods. The results revealed that the powders synthesized by sol-gel method were nanometer scale (30-60 nm) and were mainly composed of cubic BaTiO3 with a small amount of BaCO3. After sintering at high temperature, both cubic BaTiO3 and BaCO3 were transformed into tetrahedron BaTiO3 phase. The dielectric properties of the ceramics were also determined and the influence of Ti/Ba ratio on the dielectric properties was discussed. The Tc did not change with the variation of Ti/Ba ratio, while theεmax increased firstly and then decreased. The excess TiO2 is benefit for the modification of ceramics' microstructure and dielectric properties.     

Electrons Transfer Between Mercaptoacetic Acid and ZnO Nanocrystal Thin Film

ZnO nanoorystals thin film were prepared by means of the self-assembly mothed. The complex films of mercaptoacetic acid(MPA) and ZnO nanocrystals(ZNCs) were prepared by means of the self-assembly technique. The interaction between the MPA and ZnO within the MPA and ZnO nanocrystal thin film decreases the photoluminescence intensity of the ZnO. The interaction was manifested by the X-ray photoelectron spectra. The intensity change of the photoluminescence of the ZnO is discussed on the basis of taking into account the process of electron transfer on the interface between the ZnO and MPA. The electron transfer of ZnO depends on the distance between the ZnO and MPA.     

COMPLEX ACTION OF SILVER-FORM CLINOPTILOLITE

By means of chemical analysis, X-ray diffraction and scanning electron micrograph, this article studies complex action which occurs on silver-form clinoptilolite and its meta-glass reacts with solutions of halogenide (except fluoride), sulphide, etc. This complex action includes the "connecting growth" crystallization of the solid sample surface and the internal salt occlusion. Compounded anions have replaceable property, and cations entered into solid sample with the anions also have replaceable property. Complex sequence is S~(2-)>I~->Br~->Cl~- and irreversible. The complex anions can be eluted by some oxidizer and the property has important significance for production.