Flores Gonzalez M.A.,Polytechnic University of Pachuca |
Villanueva-Ibanez M.,Polytechnic University of Pachuca |
Hernandez-Perez M.A.,Escuela Superior de Ingenieria Quimica e Industrias Extractivas ESIQIE
Materials Science Forum | Year: 2011
Rare-earth ion (Eu3+ and Tb3+)-doped and undoped aluminum oxide powders have been prepared via polyol mediated synthesis. The precursors were aluminium nitrate, rare-earth (RE: Tb, Eu) nitrate and diethylene glycol. The powders were generated using low-temperature (T max ∼ 200°C) and reaction time of 150 min. By controlling the acidity of the synthesis solution and the precursor concentration, sub-micrometric aggregates (about 300 nm) with spherical morphology were obtained. The powders of RE-doped Al2O3 were further investigated by photon correlation laser, X-ray diffraction, transmission electron microscope, scanning electron microscope, thermal analysis and photoluminescence emission spectra. The results showed that α-Al 2O3 is formed at a temperature significantly lower than the solid sate reaction route. The luminescence of Al2O3 doped with 5 at.% Eu was observed with emission band in 614 nm and Al 2O3 doped with 5 at.% Tb showed an emission band in 544 nm. © (2011) Trans Tech Publications, Switzerland.
Elizalde I.,Mexican Institute of Petroleum |
Ancheyta J.,Escuela Superior de Ingenieria Quimica e Industrias Extractivas ESIQIE
Fuel Processing Technology | Year: 2014
The kinetics of the hydrocracking of residue and catalyst deactivation were studied by using the continuous kinetic lumping approach. Catalyst activity decay was represented with an empirical equation. Experimental information was obtained in a continuous stirred tank reactor at liquid-hourly space velocity of 0.5 h- 1, three reactor temperatures (380, 400 and 410 C), 9.8 MPa of pressure, 5000 ft3/bbl of H2-to-oil ratio and 200 h of time on stream. The parameters of the continuous kinetic model showed dependence with time on stream and temperature. Due to the marked changes on catalyst activity during time on stream, it was proposed that some pore blockage occurs apart from catalyst deactivation by site coverage. © 2014 Elsevier B.V.