Abstract
A series of binary oxide systems with Ca/Si molar ratios of 0.05, 0.1, 0.25, 0.5 and 1.0 have been synthesized by the sol-gel technique from tetraethyl orthosilicate (TEOS) and metallic calcium powder. Upon calcination, a side effect of wollastonite formation as a result of the reaction between the components of the material has been observed in the two calcium-richest systems. The increase in calcium content produces an effect of porosity promotion. At high calcium contents, the homogeneity of the systems is limited by the ability of silica to disperse the calcium component. The properties of these systems are determined by the silica surface coverage with a large amount of the scattered CaCO3 fine microcrystallites (calcite), resulting from the phase segregation. The gels were characterized by X-ray powder diffraction, low temperature nitrogen adsorption, transmission and scanning electron microscopy (TEM, SEM and SEM/EDS), thermogravimetric analysis (TGA), and FT-IR spectra, to describe the parameters important from the point of view of their application as a support for metal-based catalysts.
Highlights
Thanks to their chemical and physical properties, silica and calcium oxide are the subject of several studies [1]
A Ni-Cu catalyst supported on a CaO-SiO2 system obtained by the sol-gel method exhibits high conversion and H2 selectivity in the steam reforming of methanol [10]
1.0 composition is there an insufficient amount of acid to react with the whole metallic calcium added and the pH value is basic
Summary
Thanks to their chemical and physical properties, silica and calcium oxide are the subject of several studies [1] They are used in absorption, catalysis, and as highly efficient catalysts obtained by the sol-gel process in the production of biodiesel [2]. Na2 O) in the form of glasses are known, which, thanks to their biological compatibility, can be combined with human tissues (bone tissue regeneration) These properties are determined both by the composition of such materials and their preparation method [4]. CaO-based systems are useful for hydrogen production from biomass, acting as a CO2 sorbent In these processes, CaO-SiO2 have been used successfully as an active phase support, increasing the specific surface area and porosity of the metallic catalyst [9]. A Ni-Cu catalyst supported on a CaO-SiO2 system obtained by the sol-gel method exhibits high conversion and H2 selectivity in the steam reforming of methanol [10]
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