Synthesis and characterization of SiO2-MgO binary oxide system obtained by sol-gel method in anhydrous conditions

Binary SiO2-MgO oxide systems were synthesized by the sol-gel method and self-combustion method with no addition of water to the starting reaction system, using three types of precursors. The series of SiO2-MgO samples of Si to Mg molar ratios of: 1:0.0, 1:0.1, 1:0.5, 1:1.0, 1:2.0 were characterized by TGA, XRPD, low-temperature nitrogen adsorption and TPD methods. Changes in structural parameters and surface properties caused by modification of silica with amorphous magnesium oxide were identified. High thermal stability of the amorphous oxide systems was evidenced by XRPD measurements, while the results obtained by TPD revealed that modification of weakly acidic SiO2 gel surface with MgO changed its surface character into basic. According to the results of textural analysis, the mesoporous binary oxides obtained showed large surface area and monomodal pore distribution (in the majority of samples) irrespective of the method of synthesis. Furthermore, the CO2 sorption properties of the sorbents were investigated by thermal gravimetric analysis (TGA) at room temperature.