Resumo

RIOS, LUIS et al. TEXTURAL AND CHEMICAL CHARACTERIZATION OF CRYSTALLINE Ti-SiO2 CATALYSTS USED IN THE EPOXIDATION OF FATTY ESTERS. Dyna rev.fac.nac.minas [online]. 2006, vol.73, n.148, pp.95-101. ISSN 0012-7353.

Discrete Ti^IV centers dispersed in a SiO2 matrix acts as strong electron acceptors, therefore, they are useful in activating molecules or moieties which are electron-rich.  The amount, dispersion, accessibility and coordination of these centers determine their chemical efficiency.  Several Ti-MCM-41 materials where characterized using DRX, FT-IR, UV-Vis and nitrogen adsorption to evaluate the dispersion, coordination and accessibility of Ti centers as well as the crystallinity, porosity and surface area of the SiO2 matrix.  This study allows a correlation between the chemical environment of titanium, textural properties of the catalyst and its performance in the activation of O-O bonds present in peroxides, used for the epoxidation of plant oils.  Results suggest that the presence of crystalline pores, in the epoxidation of oleic acid methylester with TBHP catalyzed by Ti-MCM-41, is not necessary, because the reaction occurs in large extension on the external surface area.  The important issue is to have the titanium centers finely dispersed on a relatively high surface area.  Temperature should be below 70°C to minimize the ketone formation.

Palavras-chave : Ti-SiO2; Ti-MCM-41; epoxidation; oils.