Spectro-thermal investigation of the decomposition intermediates developed throughout reduction of ammonium paratungstate

被引：18

作者：

Fouad, NE ^{[1
]}

Nohman, AKH ^{[1
]}

Zaki, MI ^{[1
]}

机构：

[1] Menia Univ, Fac Sci, Dept Chem, Menia 61519, Egypt

来源：

THERMOCHIMICA ACTA | 2000年 / 343卷 / 1-2期

关键词：

ammonium paratungstate; tungsten bronze; tungsten oxides; reduction; TG;

D O I：

10.1016/S0040-6031(99)00339-1

中图分类号：

O414.1 [热力学];

学科分类号：

摘要：

The thermal decomposition course of ammonium paratungstate (APT) in hydrogen was studied using thermogravimetric and differential thermal analyses. X-ray diffractometry, infrared spectroscopy and diffuse reflectance spectroscopy were used to characterize and identify the intermediate solid products. It was found that ammonium paratungstate decomposes to tungsten metal W-0 through five main steps encompassing different tungsten intermediate compounds. Ammonium tungsten bronze (NH4)(0.33)WO3, which precedes the formation of WO3, is relatively the most stable intermediate (250-550 degrees C) encountered through reduction of APT to tungsten metal W-0. The influence of hydrogen spillover on the reduction behavior commences to be effective just after formation of the bronze intermediate. (C) 2000 Elsevier Science B.V. All rights reserved.

引用

收藏

页码：139 / 143

页数：5

相关论文

共 10 条

[1] Insertion of hydrogen into hexagonal tungsten bronzes A(0.3)WO(3) (A=K,NH4 and Cs) [J].

Bludska, J ;

Jakubec, I .

ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS, 1996, 194 :69-72

[2] ROLE OF WO3 IN MIXED V2O5-WO3/TIO2 CATALYSTS FOR SELECTIVE CATALYTIC REDUCTION OF NITRIC-OXIDE WITH AMMONIA [J].

CHEN, JP ;

YANG, RT .

APPLIED CATALYSIS A-GENERAL, 1992, 80 (01) :135-148

[3] PREPARATION AND CHARACTERIZATION OF A HEXAGONAL AMMONIUM TUNGSTEN BRONZE PHASE (NH4)XWO3 [J].

DICKENS, PG ;

HALLIWEL.AC ;

MURPHY, DJ ;

WHITTING.MS .

TRANSACTIONS OF THE FARADAY SOCIETY, 1971, 67 (579) :794-&

[4] THERMOGRAVIMETRY OF WO3 REDUCTION IN HYDROGEN - KINETIC CHARACTERIZATION OF AUTOCATALYTIC EFFECTS [J].

FOUAD, NE ;

ATTYIA, KME ;

ZAKI, MI .

POWDER TECHNOLOGY, 1993, 74 (01) :31-37

[5] THERMOANALYTICAL RESOLUTION OF HYDROGEN-INFLUENCED REDUCTIVE EVENTS IN THE DECOMPOSITION COURSE OF AMMONIUM PARATUNGSTATE [J].

FOUAD, NE ;

NOHMAN, AKH ;

ZAKI, MI .

THERMOCHIMICA ACTA, 1994, 239 :137-145

[6] Impacts of hydrogen spillover on the reduction behavior of tungsten oxide: Isothermal and non-isothermal approaches [J].

Fouad, NE .

JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS, 1997, 44 (01) :13-28

[7]

Gier T. E., 1968, INORG CHEM, V7, P1646

[8] THERMAL-DECOMPOSITION AND THE CREATION OF REACTIVE SOLID-SURFACES .5. THE GENESIS COURSE OF THE WO3 CATALYST FROM ITS AMMONIUM PARATUNGSTATE PRECURSOR [J].

MANSOUR, SAA ;

MOHAMED, MA ;

ZAKI, MI .

THERMOCHIMICA ACTA, 1988, 129 (02) :187-196

[9] NON-ISOTHERMAL KINETIC AND THERMODYNAMIC PARAMETERS OF AMMONIUM PARATUNGSTATE DECOMPOSITION - A THERMOANALYTIC STUDY [J].

MOHAMED, MA ;

MANSOUR, SAA ;

ZAKI, MI .

THERMOCHIMICA ACTA, 1989, 138 (02) :309-317

[10] LOW-TEMPERATURE HYDROTHERMAL REDUCTION OF AMMONIUM PARATUNGSTATE [J].

REIS, KP ;

RAMANAN, A ;

WHITTINGHAM, MS .

JOURNAL OF SOLID STATE CHEMISTRY, 1991, 91 (02) :394-396