| Abstract
| - Titania/silica gels covered by a carbon layer using pyrolysis of cyclohexene at 973 K and containingdifferent amounts of titania (CTiO2) and carbon deposit (CC) have been studied by means of pyrolysiskinetics, nitrogen adsorption/desorption, TEM, IR spectroscopy, differential thermogravimetry, andtheoretical methods. The pyrolysis rate depends on the concentration and the characteristics of a titaniaphase, as anatase, which forms at a lower synthetic temperature in comparison with rutile, catalyzes thisprocess more strongly than rutile does. The adsorbent mesoporosity decreases with increasing concentrationsof titania and carbon covering the oxide surface mainly in mesopores, but in the case of C/SiO2, carboncan be also grafted onto the outer surface of silica. The microporosity (maximal for binary systems C/SiO2or TiO2/SiO2) of carbon/titania/silica gels is relatively low and changes slightly with increasing depositconcentration. The influence of carbon on the specific surface area of the adsorbents is weaker than thatof titania due to not only the difference in the morphology of these deposits per se but also the types oftheir distributions and contacts between grafted matters and substrate surfaces. Carbon deposit reducesthe amount of adsorbed water to a greater extent than titania does. Theoretical modeling of C/TiO2/SiO2and pyrolysis of cyclohexene has been performed using different quantum chemical methods and molecularmechanics.
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