Documents disponibles écrits par cet auteur

Hydrogenation of dimethyl oxalate using extruded Cu/SiO2 catalysts / Li Zhao in Industrial & engineering chemistry research, Vol. 51 N° 43 (Octobre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 43 (Octobre 2012) . - pp. 13935-13943 Titre : Hydrogenation of dimethyl oxalate using extruded Cu/SiO2 catalysts : Mechanical strength and catalytic performance Type de document : texte imprimé Auteurs : Li Zhao, Auteur ; Yujun Zhao, Auteur ; Shengping Wang, Auteur Année de publication : 2013 Article en page(s) : pp. 13935-13943 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Catalytic  reaction  Strength  Catalyst  Hydrogenation Résumé : In this work, the extrusion process of Cu/SiO2 catalysts prepared by the ammonia-evaporation (AE) method has been investigated and optimized in order to obtain materials with convenient catalytic and mechanical properties for their application in the gas-phase hydrogenation reaction of dimethyl oxalate (DMO) to ethylene glycol (EG). Thereby, a variety of Cu/SiO2 extrudates were prepared with different Cu loading, It has been observed that a special microstructure including defects, flaws, and discontinuities plays a significant role on the mechanical strength. Larger CuO grains may act as fracture origins, which negatively affect the mechanical strength. The 20Cu/SiO2 extrudate with high Cu dispersion and high porosity is optimized for hydrogenation of DMO to EG, achieving a 98% conversion of DMO and 85% selectivity of EG under the liquid hourly space velocity (LHSV) of 1.0 h―1. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26593320 [article] Hydrogenation of dimethyl oxalate using extruded Cu/SiO2 catalysts : Mechanical strength and catalytic performance [texte imprimé] / Li Zhao, Auteur ; Yujun Zhao, Auteur ; Shengping Wang, Auteur . - 2013 . - pp. 13935-13943. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 43 (Octobre 2012) . - pp. 13935-13943 Mots-clés : Catalytic  reaction  Strength  Catalyst  Hydrogenation Résumé : In this work, the extrusion process of Cu/SiO2 catalysts prepared by the ammonia-evaporation (AE) method has been investigated and optimized in order to obtain materials with convenient catalytic and mechanical properties for their application in the gas-phase hydrogenation reaction of dimethyl oxalate (DMO) to ethylene glycol (EG). Thereby, a variety of Cu/SiO2 extrudates were prepared with different Cu loading, It has been observed that a special microstructure including defects, flaws, and discontinuities plays a significant role on the mechanical strength. Larger CuO grains may act as fracture origins, which negatively affect the mechanical strength. The 20Cu/SiO2 extrudate with high Cu dispersion and high porosity is optimized for hydrogenation of DMO to EG, achieving a 98% conversion of DMO and 85% selectivity of EG under the liquid hourly space velocity (LHSV) of 1.0 h―1. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26593320

Kinetics study for ion - exchange - resin catalyzed hydrolysis of methyl glycolate / Yan Xu in Industrial & engineering chemistry research, Vol. 51 N° 36 (Septembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 36 (Septembre 2012) . - pp. 11653-11658 Titre : Kinetics study for ion - exchange - resin catalyzed hydrolysis of methyl glycolate Type de document : texte imprimé Auteurs : Yan Xu, Auteur ; Wenjing Dou, Auteur ; Yujun Zhao, Auteur Année de publication : 2012 Article en page(s) : pp. 11653-11658 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Hydrolysis  Catalytic  reaction  Ion  exchange  resin  Kinetics Résumé : The hydrolysis of methyl glycolate catalyzed by commercial cation-exchange resin was studied in a stirred tank batch reactor. It was found that 001×7 resin was an effective catalyst for the hydrolysis of methyl glycolate. The effects of catalyst loading, initial reactant ratio and temperature have been examined in detail. The kinetics of glycolate hydrolysis was evaluated by the use of the pseudohomogeneous model, which was found to represent the kinetics fairly well, due to the total dissociation of the active sulfonic acid group in swollen polymer resin in the presence of water. The kinetics was expressed in terms of activities and the activity coefficients were estimated by using the group contribution method UNIFAC. The activation energy was found to be 59.26 kJ/mol for 001x7 resin, indicating surface reaction is the rate-controlling step. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26350331 [article] Kinetics study for ion - exchange - resin catalyzed hydrolysis of methyl glycolate [texte imprimé] / Yan Xu, Auteur ; Wenjing Dou, Auteur ; Yujun Zhao, Auteur . - 2012 . - pp. 11653-11658. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 36 (Septembre 2012) . - pp. 11653-11658 Mots-clés : Hydrolysis  Catalytic  reaction  Ion  exchange  resin  Kinetics Résumé : The hydrolysis of methyl glycolate catalyzed by commercial cation-exchange resin was studied in a stirred tank batch reactor. It was found that 001×7 resin was an effective catalyst for the hydrolysis of methyl glycolate. The effects of catalyst loading, initial reactant ratio and temperature have been examined in detail. The kinetics of glycolate hydrolysis was evaluated by the use of the pseudohomogeneous model, which was found to represent the kinetics fairly well, due to the total dissociation of the active sulfonic acid group in swollen polymer resin in the presence of water. The kinetics was expressed in terms of activities and the activity coefficients were estimated by using the group contribution method UNIFAC. The activation energy was found to be 59.26 kJ/mol for 001x7 resin, indicating surface reaction is the rate-controlling step. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26350331

Selective hydrogenation of benzene to cyclohexene on a Ru/Al2O3/cordierite monolithic catalyst / Yujun Zhao in Industrial & engineering chemistry research, Vol. 47 n°14 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4641-4647 Titre : Selective hydrogenation of benzene to cyclohexene on a Ru/Al2O3/cordierite monolithic catalyst : effect of mass transfer on the catalytic performance Type de document : texte imprimé Auteurs : Yujun Zhao, Auteur ; Jin Zhou, Auteur ; Jianguo Zhang, Auteur ; Deyi Li, Auteur Année de publication : 2008 Article en page(s) : p. 4641-4647 Note générale : Bibliogr. p. 4647 Langues : Anglais (eng) Mots-clés : Benzene  --  hydrogenation;  Monolithic  fixed-bed  reactor Résumé : A Ru/Al2O3/cordierite monolithic catalyst was prepared, characterized, and examined in selective hydrogenation of benzene to cyclohexene in a monolithic fixed-bed reactor with an aqueous solution of ZnSO4. The Carberry number and Wheeler−Weisz group were calculated to analyze the effects of external and internal diffusions of H2, benzene, and cyclohexene. According to the results of calculations, the water film, solubility, and diffusion coefficients of the three reactants (H2, benzene, and cyclohexene) play important roles in the mass-transfer rate. Under proper reaction conditions, the effects of the external mass transfer of H2 and benzene on the reaction rate are negligible. For the hydrogenation of cyclohexene, the diffusion of cyclohexene from the organic phase to the catalyst is the limiting step in the presence of water, which is the most important factor for obtaining high cyclohexene selectivity. The absence of pore diffusion of the three reactants, which is attributed to the thin eggshell distribution of in the catalyst, is another important factor for the higher cyclohexene selectivity. In addition, the optimum reaction conditions were found to be 413-423 K and 5 MPa. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071574g [article] Selective hydrogenation of benzene to cyclohexene on a Ru/Al2O3/cordierite monolithic catalyst : effect of mass transfer on the catalytic performance [texte imprimé] / Yujun Zhao, Auteur ; Jin Zhou, Auteur ; Jianguo Zhang, Auteur ; Deyi Li, Auteur . - 2008 . - p. 4641-4647. Bibliogr. p. 4647 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°14 (Juillet 2008) . - p. 4641-4647 Mots-clés : Benzene  --  hydrogenation;  Monolithic  fixed-bed  reactor Résumé : A Ru/Al2O3/cordierite monolithic catalyst was prepared, characterized, and examined in selective hydrogenation of benzene to cyclohexene in a monolithic fixed-bed reactor with an aqueous solution of ZnSO4. The Carberry number and Wheeler−Weisz group were calculated to analyze the effects of external and internal diffusions of H2, benzene, and cyclohexene. According to the results of calculations, the water film, solubility, and diffusion coefficients of the three reactants (H2, benzene, and cyclohexene) play important roles in the mass-transfer rate. Under proper reaction conditions, the effects of the external mass transfer of H2 and benzene on the reaction rate are negligible. For the hydrogenation of cyclohexene, the diffusion of cyclohexene from the organic phase to the catalyst is the limiting step in the presence of water, which is the most important factor for obtaining high cyclohexene selectivity. The absence of pore diffusion of the three reactants, which is attributed to the thin eggshell distribution of in the catalyst, is another important factor for the higher cyclohexene selectivity. In addition, the optimum reaction conditions were found to be 413-423 K and 5 MPa. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071574g