Pang Wenqin

Synthesis and Characterization of Fapo-5 Crystallized From Clear Homogeneous Solutions

Abstract Ferroaluminophosphate number 5 molecular sieve (FAPO-5) was hydrothermally synthesized from clear homogeneous solutions. EPR, Mossbauer, XPS and electron probe microanalysis (EPMA) investigations evidence that iron is only substituted for aluminum but not for phosphorus atoms. The distribution of iron atoms in the sample is rich in the center and both Fe(III) and Fe(II) exist in the FAPO-5 crystals. FAPO-5 exhibits higher catalytic activity and selectivity for the ethylbenzene dehydrogenation, compared to those of AlPO 4 -5 and FAPSO-5.

The Synthesis of Zeolite NaA from Homogeneous Solutions and Studies of its Properties

The authors first synthesized zeolite NaA from homogeneous solutions at 100°, 90°, 80°, 60°C and room temperature, respectively. With the prolongation of crystallization, zeolite NaA was converted into NaX and NaHS type zeolites and into NaHS completely at last. We have studied the morphology, IR spectra, thermal stability, and 29 Si MAS-NMR measurements, and preliminarily investigated the mechanism of the formation of NaA type zeolite based on the results of 27 Al- and 29 Si-NMR spctra.

Crowth of Single Crystals of Borozeosilite and Titanozeosilite

Abstract B-, Ti MFI-type zeolite single crystals known as Borozeosilite and Titanozeosilite were synthesized by hydrothermal crystallization in a non-alkaline medium in the presence of fluoride. The growth of the single crystals was investigated by means of Si NMR and TMS-GC methods. X-ray structure analysis was performed on the crystals, and precise atom positions were determined. The cell parameters are a=19.976, b=19.843, c=13.339 and a=20.046, b=19.950, c=13.405A for Borozeosilite and Titanozeosilite, respectively, which corresponds to isomorphous substitution of silicon by boron or titanium in the zeolite framework.

The Synthesis, Crystallization and Structure of Heteroatom Containing ZSM-5 Type Zeolite (M-ZSM-5)

In this report we summarize the syntheses, the crystallization kinetic model, the crystal structure and the characterization of Heteroatom containing ZSM-5 (M-ZSM-5) type zeolites (M=Ga, In, R.E., Si, Ge, Sn, Ti(IV, III) Zr, V(V, IV, III,), Cr, Mo, W, Mn and Fe). Much of discussion which follows will be related to the more recent available results obtained in our laboratory.

Synthesis of large single crystals of pentasil-type silica zeolites from non-alkaline medium

Large single crystals of pentasil-type silica zeolites (Silicalite-I and ZSM-39) have been synthesized with choline cation, 1,4-diazabicyclo[2.2.2]octane, and tetramethylammonium cation as templates from non-alkaline medium.

Hydrothermal synthesis and structural investigation of sodium zirconium silicophosphates

The hydrothermal reactions of NaZr2(PO4)3 with Na2SiO3 in excess NaOH at 300°C have been investigated. The pure precursor phases have been obtained at the reactant ratio of NaZr2(PO4)3∶Na2SiO3 from 1∶1 to 1∶3.2. When the reactant ratio reached 1∶3.5 in the case of a large excess of NaOH, Na4Zr2(SiO4)3 was obtained. The structures of the precursor phases were studied by X-ray diffraction, infrared and magic angle spinning nuclear magnetic resonance spectroscopy. The results showed that these NASICON-like phases were similar to 6.06 phase designated by Clearfieldet al., which were converted into sodium zirconium silicophosphates on heating to 1000°C. All NASICON phases prepared by this process were pure phases and free ZrO2 remained. The structure and ionic conductivity of these NASICONs have been investigated and the results compared with literature data. The compounds in some of the range of composition appear to have a maximum ionic conductivity at 300°C (0.2 Ω−1 cm−1). This method provides a very effective and convenient route for preparing all compounds in the NASICON family.

Luminescent properties of RE-silicalite-I and RE-ZSM-5 zeolites synthesized by direct hydrothermal crystallization

Rare earth ions were introduced into silicalite-I and ZSM-5 by direct hydrothermal crystallization either in a non-alkaline aqueous medium containing fluoride or in an alkaline medium. The excitation and emission spectra of europium, cerium and terbium ions in the zeolites were investigated.

ZEOLITES SYNTHESIZED FROM NONALKALINE MEDIA

ABSTRACT Hydrothermal crystallization of zeolites and clathrass, at 100~200°C from non-alkaline media containing F– anions and organic template has been investigated. Under such conditions Zeolite P, ZSM-39, Theta-1, ZSM-5, a novel zeolite (CJS-1) and two novel clathrasils(CJS-2 and CJS-3) could be prepared. The conditions and various effects on the synthesis were systematically investigated. The large single crystals of Zeolite P, ZSM-39, CJS-2 and CJS-3 were obtained. The ZSM-5 single crystals were synthesized using seven kinds of organic amines.

Hydrothermal synthesis and characterization of sodium dititanim triphosphate

Sodium dititanium triphosphate has ben synthesized hydrothermally from teh Na2O–TiO2–P2O5–P2O5–H2O system, and characterized by X-ray powder diffraction and Raman and IR spectrosocopy.

Synthesis and characterization of a novel zeolite, CJS-1

A novel zeolite, CJS-1, has been synthesized from pip–Al2O3–SiO2–HF–H2O systems (pip = piperazine) and characterized by means of X-ray powder diffraction, scanning electron microscopy, thermal analysis, and gas adsorption.