MESOPOROUS CERIA/ALUMINA, CEO2/AL2O3, COMPOSITES CONTAINING 10, 20 AND 30% (W/W) CERIA WERE PREPARED BY A NOVEL GEL MIXING METHOD. IN THE METHOD, CERIA GEL (FORMED VIA HYDROLYSIS OF AMMONIUM CERIUM(IV) NITRATE BY AQUEOUS AMMONIUM CARBONATE SOLUTION) AND ALUMINA GEL (FORMED VIA CONTROLLED HYDROLYSIS OF ALUMINUM _TRI_-ISOPROPOXIDE) WERE MIXED TOGETHER. THE MIXED GEL WAS SUBJECTED TO SUBSEQUENT DRYING AND CALCINATION FOR ... إقراء المزيد

CE-CONTAINING MCM-41 MATERIALS WERE PREPARED VIA A DIRECT, NONHYDROTHERMAL METHOD AT ROOM TEMPERATURE FROM _TETRA_-ETHOXYSILANE, _N_-HEXADECYL TRIMETHYL AMMONIUM BROMIDE, AMMONIA SOLUTION, AND CERIUM(IV) AMMONIUM NITRATE PRECURSORS. COMPOSITE MATERIALS CONTAINING THE NOMINATED RATIOS OF 5 AND 10% (W/W) CEO2/MCM-41 WERE TARGETED. THE OBTAINED MATERIALS WERE INVESTIGATED BY TGA, DSC, FTIR, DIFFUSE REFLECTANCE UV–VIS, XRD, N2 ADSORPTION/DESORPTION ISOTHERMS, AND SEM. RESULTS INDICATED ... إقراء المزيد

HUMIDITY SENSING CHARACTERISTICS OF NIO/AL2O3 NANOCOMPOSITES, PREPARED BY SOL-GEL METHOD, ARESTUDIED BY IMPEDANCE SPECTROSCOPY. MODELING OF THE OBTAINED IMPEDANCE SPECTRA WITH AN APPROPRIATE EQUIVALENT CIRCUIT ENABLES US TO SEPARATE THE ELECTRICAL RESPONSES OF THE TIGHTLY BOUNDCHEMISORBED WATER MOLECULES ON THE GRAIN SURFACES AND THE LOOSELY ASSOCIATED PHYSISORBED WATERLAYERS. DEPENDENCE OF THE DIELECTRIC PROPERTIES AND AC CONDUCTIVITY OF THE NANOCOMPOSITES ON ... إقراء المزيد

THE FORMATION AND ELECTRICAL PROPERTIES OF HIGH SURFACE AREA NIO/AL2O3 NANOCOMPOSITE MATERIALS WITH COMPOSITION RANGING FROM 5 TO 30% W/W HAVE BEEN STUDIED. THE TEMPERATURE DEPENDENCE OF THE DC ELECTRICAL RESISTIVITY WAS MONITORED IN THE TEMPERATURE RANGE 350–600 K. THE RESULTS REVEALED CORRELATION BETWEEN ELECTRICAL RESISTIVITY AND TEXTURAL PROPERTIES. THE CONDUCTIVITY RESULTS WERE DISCUSSED IN TERMS OF VARIABLE-RANGE-HOPPING MECHANISM. إقراء المزيد

OMPOSITE CERIA/SILICA MATERIALS OF 10 AND 20% (W/W) WERE PREPARED BY CALCINATION, AT 650 ◦C FOR 3 H, OF THE XEROGELS OBTAINED BY MIXING THE CORRESPONDING AMOUNT OF A CERIA PRECURSOR WITH FRESHLY PREPARED SOLS OF SPHERICAL SILICA PARTICLES (STÖBER PARTICLES) IN THEIR MOTHER LIQUORS. TWO DIFFERENT CERIA PRECURSORS WERE EXAMINED IN THIS INVESTIGATION. THE FIRST WAS A GEL PRODUCED ... إقراء المزيد

POROUS CERIA AGGREGATES OF SUBMICRON SIZE WERE OBTAINED FROM CERIUM(IV) ISOPROPOXIDE VIA A TWO-STEP SOL–GEL PROCESS. IN THE FIRST STEP, DISPERSION OF THE CERIUM(IV) ISOPROPOXIDE IN ISOPROPANOL MEDIA WAS ACHIEVED BY ULTRASONIC RADIATION, WHERE LIMITED HYDROLYSIS OCCURRED AND RESULTED IN THE FORMATION OF A STABLE DISPERSANT GEL PHASE. IN THE SECOND STEP, THE RESULTANT DISPERSIONS WERE MIXED UNDER STIRRING WITH ... إقراء المزيد

Humidity sensing properties measured by impedance spectroscopy (IS) and DC conductivity for a group of high surface area nanostructured 5 – 30% w/w NiO/Al2O3 composite materials are reported. The nanocomposites were prepared via a sol – gel method, which involved mixing of the respective sol – gel precursors and the subsequent drying and calcination at 873 K for 3 h. ... إقراء المزيد

A DIRECT SYNTHETIC ROUTE LEADING TO TITANIA PARTICLES DISPERSED ON NONPOROUS SPHERICAL SILICA PARTICLES HAS BEEN INVESTIGATED; 5, 10, AND 20% (W/W) TITANIA/SILICA SOLS MIXTURES WERE ACHIEVED VIA HYDROLYZATION OF TITANIUM TETRA-ISOPROPXIDE SOLUTION IN THE MOTHER LIQUOR OF A FRESHLY PREPARED SOL OF SPHERICAL SILICA PARTICLES (STOBER ¨ PARTICLES). TITANIA/SILICA MATERIALS WERE PRODUCED BY SUBSEQUENT DRYING AND CALCINATION OF THE ... إقراء المزيد

The formation of mesoporous spherical titania particles via hydrolysis of pure titanium tetra-isopropoxide in n-heptane solution upon the application of a slow stirring rate is described. Calcination of the dry hydrolysis product produced pure anatase at 400–600oC, and Ž 2 rutile at 8008C. Nitrogen adsorption results indicate high surface area S 132 m rg and uniform mesopores peaking at 10 ... إقراء المزيد

DIFFERENT RATIOS OF VANADIUM PENTOXIDE SUPPORTED ON ALUMINUM PHOSPHATE (1–30 MOL%) HAVE BEEN PREPARED BY AN IMPREGNATION METHOD. THE ORIGINAL AND CALCINED SAMPLES WERE CHARACTERIZED BY TG, DTG, DSC, X-RAY DIFFRACTION, IR SPECTRA, N2 ADSORPTION AND ELECTRICAL CONDUCTIVITY MEASUREMENTS. THE CATALYTIC DECOMPOSITION OF ETHANOL HAS BEEN CARRIED OUT AT 210 °C IN A FLOW SYSTEM AT 1 ATM USING AIR ... إقراء المزيد