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Preparation and Catalysis of Supported Nano-platinum Catalysts

Author: HanMing
Tutor: YangPing
School: Suzhou University
Course: Physical and chemical
Keywords: Catalytic hydrogenation Benzaldehydes Supported platinum catalyst Rare earth Ceria
CLC: O643.36
Type: Master's thesis
Year: 2011
Downloads: 142
Quote: 1
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Abstract


MgAl2O4, Al2O3 and CeO2 were synthesized and used as carriers for preparing a series of supported nano-platinum catalysts. Then the catalysts were applied in hydrogenation of benzaldehydes. Some corresponding researches were done as follows:（1） Platinum nanoparticles, synthesized via ethanol reduction of hexachloroplatinic acid in the presence of poly-（N-vinyl-2-pyrrolidone）, were anchored on magnesium aluminate spinel using a colloidal deposition method. The samples were characterized using the following methods: transmission electron microscopy, powder X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The results revealed that platinum nanoparticles, with an average diameter of 2.8 nm, are homogenously dispersed on the surface of the carrier. Under very mild conditions, supported Pt/MgAl2O4 catalysts demonstrated excellent catalytic activity and high selectivity in the hydrogenation reaction of benzaldehydes to benzyl alcohols. The reaction kinetics for the catalytic hydrogenation of 3-phenoxybenzaldehyde to 3-phenoxybenzyl alcohol on a Pt/MgAl2O4 catalyst can be described by equation r = k. c. pH, and the apparent activation energy is 35.6 kJ mol-1.（2） Rare earths （La, Ce, Pr, Nd, Sm, Eu and Gd） promoted Pt/Al2O3 catalysts were synthesized by two methods. The in?uence of the preparation method and the dopants on the activity and stability of the catalysts were investigated. Transmission electron microscopy, powder X-ray diffraction and X-ray photoelectron spectroscopy were used to observe the characteristics of the prepared catalysts. The results reveal the beneficial role of La, Ce, Pr, Nd and Sm doping in increasing catalytic activity of hydrogenation of 3-phenoxybenzaldehyde, while the addition of Gd and Eu exhibited a negative effect. The main reason for the differences in 3-phenoxybenzaldehyde hydrogenation activity of these platinum catalysts depends on the nature of the modifier.（3） Cerium oxide nanoparticles and nanosized rod-shaped CeO2 and microsized spherical CeO2 structures have been synthesized by a one-pot, template-free hydrothermal method. The samples were characterized using the following methods: scanning electron microscopy, powder X-ray diffraction, and nitrogen adsorption-desorption measurements. CeO2 products of different morphologies and specific surface area can be selectively produced. Furthermore, the applications of the CeO2 as carriers were explored. 0.5 wt% Pt nanoparticles loaded on CeO2（I） exhibited highest catalytic activity on hydrogenation of 3-phenoxybenzaldehyde.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
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