Properties of Ca.sub.2/TiO.sub.2 Composites Modified by Mechanochemical and Ultrasonic Methods

We study the influence of ultrasonic (1 h) and mechanochemical (4 h) treatments (UST and MCT, respectively) on the physicochemical properties of a Ca(OH).sub.2/TiO.sub.2 system with molecular ratio 1:1. The effect of refinement of the source components of the mixture after UST and the formation of the calcium-titanate phase after MCT were recorded by the X-ray phase diffraction method. By analyzing the porous structure, we reveal an increase in the specific surface area and the total volume of pores caused by the activation of powders. By the SEM method, we detected the formation of much smaller crystals as a result of UST and the appearance of elongated prismatic crystals after mechanochemical activation. The catalytic properties of Ca(OH).sub.2/TiO.sub.2 samples were studied for the reaction of selective oxidation of ethanol. It is shown that, at low temperatures, the main reaction product is acetaldehyde (S = 100% at 240°C). As the reaction temperature increases, we observe the formation of hydrogen with a maximum product yield of 32-38% and a productivity of 126 [Formula omitted].