Examinando por Autor "Frutos, Pilar de"

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Agglomeration of Ti-SBA-15 with clays for liquid phase olefin epoxidation in a continuous fixed bed reactor.
(ELSEVIER, 2008) Melero, Juan A.; Iglesias, Jose; Sainz-Pardo, Javier; Frutos, Pilar de; Blázquez, Sandra
Titanium-containing SBA-15 material has been agglomerated with bentonite clay to form macroscopic structured catalyst particles with the purpose of being used in continuous epoxidation processes on a fixed bed reactor. The binding conditions, the mass ratio catalyst to binding agent as well as the calcination temperature of the material were studied to improve as much as possible the catalytic behavior and mechanical strength of the titanium-based catalyst. The binded material has been finally tested in the liquid epoxidation of 1-octene with ethyl benzyl hydroperoxide in a continuous up-flow fixed bed reactor. Reaction results reveal a better catalytic performance of this catalyst, both regarding to the conversion of the olefin and efficient use of the oxidant, than conventional commercially available TiO2-SiO2, specially when pellet surface hydrophobization is performed by silylation treatment.
Direct synthesis of titanium substituted mesostructured materials using non-ionic surfactants and titanocene dichloride
(2005) Melero, Juan A.; Arsuaga, Jesús M.; Frutos, Pilar de; Iglesias, José; Sainz, Javier; Blázquez, Sandra
Titanium-substituted mesoporous molecular sieves have been successfully synthesized using non-ionic surfactants and titanocene dichloride under strong acidic conditions. Structure-textural parameters of the synthesized materials were characterized by using X-ray diffraction and nitrogen adsorption techniques. The increasing of the gel solution pH allows an enhancement of titanium within the mesostructure without damage of textural properties and presence of extra-framework species. The high accessibility and dispersion of titanium centres has been proved by means of NH3 adsorption and DR UV-Vis spectroscopy, being compared with TS-1 material. The synthesized materials show high activity and selectivity in the selective epoxidation of 1-octene with ethylbenzylhydroperoxide as oxidant. Moreover, silylated samples promoted an increase of epoxide selectivity.
Synthesis, characterization and catalytic activity of highly dispersed Mo-SBA-15
(ELSEVIER, 2007) Melero, J.A.; Iglesias, J.; Arsuaga, J.M.; Sainz-Pardo, J.; Frutos, Pilar de; Blázquez, Sandra
Molybdenum-containing SBA-15 materials have been prepared using a co-condensation method with a wide range of metal loadings under acidic conditions and using non-ionic surfactants. These materials display good catalytic activity in the epoxidation of olefins with alkyl hydroperoxides, being the catalytic activity correlated with the nature of supported molybdenum species. The immobilized metal species show different stabilities against leaching depending on their nature. Reutilization catalytic tests indicate that some fraction of the molybdenum show a high stability and it seems to be responsible for the major part of the catalytic activity of these materials. Stable molybdenum species use in a very efficient manner the alkyl hydroperoxide in the epoxidation of olefins whereas leached species leads to non-oxidative consumption of the oxidant and promote secondary reactions.