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The effects of acid and Al concentration, type of Al salt, treatment temperature and time of removal of Mg from sepiolite have been investigated, as has the use of modified sepiolite as an active fluid catalytic cracking (FCC) matrix. The samples were characterized by N2 adsorption and X-ray diffraction. Mg removal from sepiolite increased with increasing acid and Al ion concentration, treatment time and temperature. The temperature had the greatest impact on Mg removal. After acid and Al modification, 29% of the Mg was removed. When using the modified sepiolites as active matrices in FCC catalysts, the specific surface area, pore volume and mesoporous pore volume of the catalysts increased and they exhibited excellent performance in resisting the effects of heavy-metals as a result of the introduction of Mg oxide from the modified sepiolite.
Ca0.98Eu0.02Al1−4δ/3Si1+δN3 (δ = 0–0.36) red-emitting phosphors were prepared by carbothermal reduction and nitridation method with stable and inexpensive CaCO3 as Ca source. Optimal nominal composition was obtained at δ = 0.18, showing intense emission peaked at 625 nm and high external quantum efficiency of 71%. The emission wave length could be successfully tuned from 630 to 606 nm with increasing δ value. Ca0.98Eu0.02Al1−4δ/3Si1+δN3 phosphors provided two coordinated environments for Eu2+ ions, resulting in two fitted Gaussian peaks. Energy transfer from Eu2+ sites in Si-rich environments to those in Si/Al-equivalent modes has been confirmed by analysis of the decay curve of each peak. The decay behaviors suggested that energy transfer effect slowed with higher δ value. Finally, warm white light was created by combining as-prepared red-emitting Ca0.98Eu0.02Al0.76Si1.18N3 and yellow-emitting YAG:Ce3+ phosphors with a blue-emitting chip, exhibiting a color rendering index Ra of 91 at a low correlated color temperature of 3500 K with a luminous efficiency of 79 lm/W.
Nanocomposite powders of Ni–Al2O3 (5 and 10 vol% Ni) were prepared from porous alumina preforms with high specific area (100 m2 g?1) impregnated with nickel nitrate. Samples were obtained by reduction under a controlled oxygen partial pressure either directly or through an intermediate step, giving nickel aluminum spinel. In both cases, homogeneous dispersions of nickel particles in the alumina matrix were achieved. The Ni particle size ranged from 10 to 100 nm, depending on the preparation conditions and temperature.
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