Synthesis and properties of catalyst based on semicrystalline calcium silicate hydrate with intercalated Co2+, Cu2+, and Cr3+ ions

Abstract

This work aims to synthesize a catalyst based on semicrystalline calcium silicate hydrate with intercalated multiple transition metal ions (Co2+, Cu2+, and Cr3+), and to determine its main properties. The hydrothermal method was employed to conduct the synthesis of the catalyst. The molar ratio of CaO/amorphous SiO2 = 1.5 was used. It was subsequently mixed with Co, Cu, and Cr nitrate solution (the concentration of each metal ion was 3.33 g/dm3). A suspension featuring the solution/solid ratio of 10.0:1.0 was then obtained. A 4 h- and 16 h-long sessions of hydrothermal treatment were performed in unstirred suspensions at 175 °C. The compounds (silicates containing metal ions and/or nitrate anion) with undescribed structure and composition were formed during hydrothermal treatment. The calcination of the synthetic catalyst led to the formation of the mixture consisting of calcium silicates and metal oxides. The results of nitrogen adsorption-desorption experiments showed that the temperature of calcination plays a crucial role in the porosity of the sample. It was determined that synthetic and calcined (550 °C) samples acted as catalysts for propanol oxidation reactions. 6 methods in total (atomic absorption spectroscopy, simultaneous thermal analysis, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and nitrogen adsorption-desorption) along with propanol oxidation experiments served to confirm the obtained results.