MICROCALORIMETRIC STUDY OF THE ACIDITY OF TUNGSTIC HETEROPOLYANIONS

被引：81
作者：
LEFEBVRE, F
LIUCAI, FX
AUROUX, A
机构：
[1] Institut de Recherches sur la Catalyse, Laboratoire Propre du CNRS Conventionné, Université Claude-Bernard Lyon I, 69626 Villeurbanne Cédex
来源：
JOURNAL OF MATERIALS CHEMISTRY | 1994年 / 4卷 / 01期
关键词：
D O I：
10.1039/jm9940400125
中图分类号：
O64 [物理化学（理论化学）、化学物理学];
学科分类号：
070304 ; 081704 ;
摘要：
The number and strength of the acid centres of tungstic heteropolyacids have been determined by absorption calorimetry of ammonia. The initial heats are in the order H3PW12O40>H(4)SiW(12)O40>H6P2W21O71(H2O)(3)>H6P2W18O62, varying from 200 to 155 kJ mol(-1). An increase in the number of protons in Keggin heteropolyanions decreases the acidic strength. Moreover, the influence of the activation temperature on the acidity has been studied and confirms that there is a drastic modification of the solid at ca. 350 degrees C. The heat capacities of the heteropolyanions and of the corresponding ammonium salts, the thermokinetic parameters of ammonia absorption and the heat capacities of the acids and ammonium salts have been related to the porosity of the various samples.
引用
收藏
页码：125 / 131
页数：7
相关论文
共 30 条
[1]  
AUROUX A, 1990, CALORIM ANAL THERM, V20, P103
[2]  
AUROUX A, 1982, STUDIES SURFACE SCI, V10, P305
[3]   DODECATUNGSTOPHOSPHORIC ACID HEXAHYDRATE, (H5O2+)3(PW12O403-) - TRUE STRUCTURE OF KEGGINS PENTAHYDRATE FROM SINGLE-CRYSTAL X-RAY AND NEUTRON-DIFFRACTION DATA [J].
BROWN, GM ;
NOESPIRLET, MR ;
BUSING, WR ;
LEVY, HA .
ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE CRYSTAL ENGINEERING AND MATERIALS, 1977, 33 (APR15) :1038-1046
[4]  
GHOSH AK, 1986, J CATAL, V101, P328
[5]   CATALYSIS BY HETEROGENEOUS SUPPORTED HETEROPOLY ACID [J].
IZUMI, Y ;
HASEBE, R ;
URABE, K .
JOURNAL OF CATALYSIS, 1983, 84 (02) :402-409
[6]  
KAPUSTIN GI, 1990, KINET CATAL+, V31, P896
[7]  
Kozhevnikov I. V., 1987, RUSS CHEM REV+, V56, P811, DOI DOI 10.1070/RC1987V056N09ABEH003304
[8]   HOMOGENEOUS CATALYSTS BASED ON HETEROPOLY ACIDS (REVIEW) [J].
KOZHEVNIKOV, IV ;
MATVEEV, KI .
APPLIED CATALYSIS, 1983, 5 (02) :135-150
[9]   P-31 MAS NMR-STUDY OF H3PW12O40 SUPPORTED ON SILICA - FORMATION OF (EQUIVALENT-TO-SIOH2+)(H2PW12O40-) [J].
LEFEBVRE, F .
JOURNAL OF THE CHEMICAL SOCIETY-CHEMICAL COMMUNICATIONS, 1992, (10) :756-757
[10]  
LEFEBVRE F, 1992, UNPUB
123