Comparative studies on porous material-supported Pd catalysts for catalytic oxidation of benzene, toluene, and ethyl acetate / Chi He in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6930–6936 Titre : Comparative studies on porous material-supported Pd catalysts for catalytic oxidation of benzene, toluene, and ethyl acetate Type de document : texte imprimé Auteurs : Chi He, Auteur ; Jinjun Li, Auteur ; Jie Cheng, Auteur Année de publication : 2009 Article en page(s) : pp. 6930–6936 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Molecular sieves-supported palladium catalysts Benzene elimination Toluene Ethyl acetate Résumé : The feasibility and mechanism of five molecular sieves-supported palladium catalysts in elimination of benzene, toluene, and ethyl acetate were investigated. The experimental results indicate that Pd particles are well dispersed on these porous supports with size of 2−10 nm, while mesoporous supports with a larger specific surface area and pore diameter lead to a better dispersion. The activity of freshly made catalysts obeys the following order: Pd/Beta > Pd/ZSM-5 > Pd/SBA-15 > Pd/MCM-48 > Pd/MCM-41. Although Pd/Beta has the highest activity for removal of these VOCs in the beginning, its activity quickly decreases. However, Pd/ZSM-5 and Pd/SBA-15 show a good stability, without activity loss in a 72 h test. Our research reveals that higher acidity can facilitate catalytic reaction and gives rise to higher activity, but it also enhances coke formation and decreases the catalyst stability. In addition, the porosity of supports has a certain impact on catalytic oxidation of VOCs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900412c [article] Comparative studies on porous material-supported Pd catalysts for catalytic oxidation of benzene, toluene, and ethyl acetate [texte imprimé] / Chi He, Auteur ; Jinjun Li, Auteur ; Jie Cheng, Auteur . - 2009 . - pp. 6930–6936. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 6930–6936 Mots-clés : Molecular sieves-supported palladium catalysts Benzene elimination Toluene Ethyl acetate Résumé : The feasibility and mechanism of five molecular sieves-supported palladium catalysts in elimination of benzene, toluene, and ethyl acetate were investigated. The experimental results indicate that Pd particles are well dispersed on these porous supports with size of 2−10 nm, while mesoporous supports with a larger specific surface area and pore diameter lead to a better dispersion. The activity of freshly made catalysts obeys the following order: Pd/Beta > Pd/ZSM-5 > Pd/SBA-15 > Pd/MCM-48 > Pd/MCM-41. Although Pd/Beta has the highest activity for removal of these VOCs in the beginning, its activity quickly decreases. However, Pd/ZSM-5 and Pd/SBA-15 show a good stability, without activity loss in a 72 h test. Our research reveals that higher acidity can facilitate catalytic reaction and gives rise to higher activity, but it also enhances coke formation and decreases the catalyst stability. In addition, the porosity of supports has a certain impact on catalytic oxidation of VOCs. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900412c

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Promoted and controllable self-assembly of hydrolyzed siloxane and triblock copolymer under organic polyhydroxy acids / Jin Jun Li in Industrial & engineering chemistry research, Vol. 48 N° 13 (Juillet 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6308–6314 Titre : Promoted and controllable self-assembly of hydrolyzed siloxane and triblock copolymer under organic polyhydroxy acids Type de document : texte imprimé Auteurs : Jin Jun Li, Auteur ; Zhen Mu, Auteur ; Chi He, Auteur Année de publication : 2009 Article en page(s) : pp. 6308–6314 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polyhydroxy organic acids Tartaric acid Citric Résumé : Large-molecule polyhydroxy organic acids such as tartaric acid and citric acid were found to significantly promote the cooperative formation of mesoporous silica SBA-15 with homogeneous well-defined hexagonal mesostructure under much weaker acidities without addition of volatile inorganic acids; therefore a novel environmental benign route for SBA-15 synthesis was developed. It is suggested that the polar groups of polyhydroxy acid molecules can greatly strengthen the assembly interactions between the silica species and the triblock copolymer by providing hydrogen bonding. More interestingly, by controlling the strength of hydrogen-bonding interaction that is dependent on the concentration of carboxylic acids, the particle size of the product can be tailored. The silica with small particle size synthesized with a small amount of polyhydroxy acids was favorable support of palladium catalyst for the complete oxidation of volatile organic compounds in atmosphere, probably due to the facilitated diffusion of reactant molecules. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900100g [article] Promoted and controllable self-assembly of hydrolyzed siloxane and triblock copolymer under organic polyhydroxy acids [texte imprimé] / Jin Jun Li, Auteur ; Zhen Mu, Auteur ; Chi He, Auteur . - 2009 . - pp. 6308–6314. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6308–6314 Mots-clés : Polyhydroxy organic acids Tartaric acid Citric Résumé : Large-molecule polyhydroxy organic acids such as tartaric acid and citric acid were found to significantly promote the cooperative formation of mesoporous silica SBA-15 with homogeneous well-defined hexagonal mesostructure under much weaker acidities without addition of volatile inorganic acids; therefore a novel environmental benign route for SBA-15 synthesis was developed. It is suggested that the polar groups of polyhydroxy acid molecules can greatly strengthen the assembly interactions between the silica species and the triblock copolymer by providing hydrogen bonding. More interestingly, by controlling the strength of hydrogen-bonding interaction that is dependent on the concentration of carboxylic acids, the particle size of the product can be tailored. The silica with small particle size synthesized with a small amount of polyhydroxy acids was favorable support of palladium catalyst for the complete oxidation of volatile organic compounds in atmosphere, probably due to the facilitated diffusion of reactant molecules. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900100g

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Supported nanometric Pd hierarchical catalysts for efficient toluene removal / Chi He in Industrial & engineering chemistry research, Vol. 51 N° 21 (Mai 2012)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 51 N° 21 (Mai 2012) . - pp. 7211–7222 Titre : Supported nanometric Pd hierarchical catalysts for efficient toluene removal : Catalyst characterization and activity elucidation Type de document : texte imprimé Auteurs : Chi He, Auteur ; Lingling Xu, Auteur ; Lin Yue, Auteur Année de publication : 2012 Article en page(s) : pp. 7211–7222 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Nanometric Catalysts Résumé : Micro-/mesoporous composite materials with coke-resistant ZSM-5 and three-dimensional large-pore KIT-6 as their micro- and mesoporous components, respectively, were synthesized using a simple in situ overgrowth approach. The hydrothermal stabilities and acidities of the biporous catalysts were found to be significantly enhanced. All composite materials acted as powerful catalysts for toluene oxidation. Among them, Pd/ZK-6% showed the highest catalytic activity, with 90% toluene decomposition at 203 °C, which is more than 30 °C lower than required for Pd/KIT-6. It can be anticipated that the specific surface area and acidity have a synergistic effect on the Pd dispersion. Overall, the catalytic activities were found to be primarily correlated with the specific surface area, support acidity, Pd dispersion, and toluene adsorption capability. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201243c [article] Supported nanometric Pd hierarchical catalysts for efficient toluene removal : Catalyst characterization and activity elucidation [texte imprimé] / Chi He, Auteur ; Lingling Xu, Auteur ; Lin Yue, Auteur . - 2012 . - pp. 7211–7222. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 21 (Mai 2012) . - pp. 7211–7222 Mots-clés : Nanometric Catalysts Résumé : Micro-/mesoporous composite materials with coke-resistant ZSM-5 and three-dimensional large-pore KIT-6 as their micro- and mesoporous components, respectively, were synthesized using a simple in situ overgrowth approach. The hydrothermal stabilities and acidities of the biporous catalysts were found to be significantly enhanced. All composite materials acted as powerful catalysts for toluene oxidation. Among them, Pd/ZK-6% showed the highest catalytic activity, with 90% toluene decomposition at 203 °C, which is more than 30 °C lower than required for Pd/KIT-6. It can be anticipated that the specific surface area and acidity have a synergistic effect on the Pd dispersion. Overall, the catalytic activities were found to be primarily correlated with the specific surface area, support acidity, Pd dispersion, and toluene adsorption capability. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201243c

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