Thermally-activated Al(OH)3: phase transformations and porosity

Thermochemically activated aluminum trihydroxide (Al (OH)3) is an important intermediate for ceramics, construction materials, catalysts, etc. Functional properties of materials based on Al (OH)3 depend on its phase composition and porosity. A series of thermochemically activated Al (OH)3 calcined at temperatures from 120 to 800 °C were studied by low-temperature N2 sorption, XRD and thermal analysis. It was shown that transformation of gibbsite to boehmite occurs below 300 °C and is accompanied by increasing of specific surface area and pore volume. Transformation of boehmite to γ-Al2O3 proceeds above 400 °C. The sample calcined at 500 °C was shown to consist of monophase γ-Al2O3 with specific surface area of 206 m2/g and pore volume of 0.55 cm3/g

Thermally-activated Al(OH)3: phase transformations and porosity

Thermochemically activated aluminum trihydroxide (Al (OH)3) is an important intermediate for ceramics, construction materials, catalysts, etc. Functional properties of materials based on Al (OH)3 depend on its phase composition and porosity. A series of thermochemically activated Al (OH)3 calcined at temperatures from 120 to 800 °C were studied by low-temperature N2 sorption, XRD and thermal analysis. It was shown that transformation of gibbsite to boehmite occurs below 300 °C and is accompanied by increasing of specific surface area and pore volume. Transformation of boehmite to γ-Al2O3 proceeds above 400 °C. The sample calcined at 500 °C was shown to consist of monophase γ-Al2O3 with specific surface area of 206 m2/g and pore volume of 0.55 cm3/g

Insights into formation of Pt species in Pt/CeO2 catalysts: Effect of treatment conditions and metal-support interaction

The features of the formation of Pt species on the CeO2 surface from adsorbed [PtCl6-yOy] complexes in Pt/CeO2 catalysts depending on the Pt content (0.5, 1.0 and 2.0 wt.%) and treatment conditions (direct Pt precursor reduction, oxidative and reductive treatments) are studied by XRD, CO pulse chemisorption, H2-TPR, UV–vis DRS, and Raman spectroscopy. The temperature of oxidative decomposition of the Pt precursor is shown to be the key factor that defines the state and size of the Pt species formed. High pretreatment temperature (500 °C) provides Pt incorporation into ceria lattice and yields smaller Pt particles after reduction providing strong Pt–CeO2 interaction, while the reduction of the samples dried at 120 °C results in the pronounced agglomeration of the formed Pt species to yield Pt particles weakly bonded with the ceria