THE KINETICS OF H2O2 DECOMPOSITION HAVE BEEN INVESTIGATED USING ZRO2 SUPPORTED WITH TRANSITION METAL IONS INCLUDING CUII, AGI , HGII, COII, MNII, NIII AND FEIII. AT PH = 6.8, THE REACTION RATE EXHIBITS A ®RST ORDER DEPENDENCE ON THE INITIAL H2O2 CONCENTRATION AT LOW CONCENTRATIONS. THE ORDER OF ACTIVITY OF THE DI€ERENT CATALYSTS IS STRONGLY DEPENDENT ON THE [H2O2]0 USED. ... إقراء المزيد

ABSTRACT BULK STRUCTURE AND SURFACE TEXTURE OF BATIO3 MATERIALS SYNTHESIZED AT LOW TEMPERATURE USING SOL-GEL TECHNIQUE HAVE BEEN INVESTIGATED. THE MATERIALS WERE PRODUCED BY THE PYROLYSIS OF AN XEROGEL PRECURSOR OF THE TENTATIVE FORMULA BATIO3-X(CH3COO)2X, WHICH WAS PREPARED USING 1:1 MOLAR RATIO OF BARIUM ACETATE AND TITANIUM OXYACETATE SOLUTION. THE PRESENT METHOD AVOIDS USING ALKALI-METAL HYDROXIDES (AS A HYDROLYZING AGENT), ... إقراء المزيد

TRANSMISSION ELECTRON MICROSCOPY (TEM) STUDIES AND NITROGEN GAS ADSORPTION DATA WERE USED TO INVESTIGATE TEXTURAL CHARACTERISTICS OF TITANIAS PREPARED VIA CALCINATION, AT 400°C/3 H, OF THE HYDROLYSIS PRODUCTS OF TITANIUM(IV) ISOPROPOXIDE IN N-HEPTANE OR ISOPROPANOL SOLVENT. A VARIETY OF TITANIAS (ANATASE FORM) WERE PRODUCED WITH DIFFERENT TEXTURAL CHARACTERISTICS. THE NATURE OF THESE PRODUCTS WAS CONTROLLED LARGELY BY THE SYNTHESIS PARAMETERS ... إقراء المزيد

TRANSMISSION ELECTRON MICROSCOPY SHOWED THAT XEROGEL OF LONG AND SHORT FIBROUS BOEHMITE SAMPLES, ALO(OH), WERE RESPECTIVELY PRODUCED VIA HYDROLYSIS OF ALUMINIUM ALKOXIDE AT SLOW AND HIGH STIRRING RATES. THERMOGRAVIMETRY, DIFFERENTIAL SCANNING CALORIMETRY, AND X-RAY DIFFRACTOMETRY, SHOWED THE TWO XEROGELS TO PRODUCE SIMILAR CALCINATION PRODUCTS, AT 400±C AND UP TO 1000±C, FOR THE CHEMICAL AND PHASE COMPOSITION OF THE MATERIAL BULK. ... إقراء المزيد

Abstract Ti(OPr’), vapor was pyrolyzed in dry nitrogen atmosphere using a simple tubular flow reactor at 400 and 800°C. Well-defined spheroidal anatase TiO, particles showing mesoporous surfaces of 30 m2 g-r and assuming two different morphologies (fused and composite) were produced at the low temperature (ca. 4OO”Q whereas deformed spheroidal particles of rutile-structured TiO, and surfaces of 12 mZ g ... إقراء المزيد

TIO2 POWDERS WERE OBTAINED BY CALCINATION OF BASE HYDROLYSIS PRODUCTS OF TITANIUM(IV) ISOPROPOXIDE, TI(OPRI)4 AT 400°C FOR 3 H. THE HYDROLYSIS WAS CARRIED OUT AT ROOM TEMPERATURE IN TWO DIFFERENT SOLVENTS, NAMELY ISOPROPANOL AND N-HEPTANE, AND IN THE PRESENCE OF LOW AND HIGH AMMONIA CONTENTS. X-RAY POWDER DIFFRACTOMETRY SHOWED THE RESULTING TIO2 POWDERS TO CONSIST OF ANATASE CRYSTALLITES, IRRESPECTIVE OF ... إقراء المزيد