Documents disponibles écrits par cet auteur

Design of an Oxygen Reduction Catalyst for Direct Methanol Fuel Cells / Jing Xu in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10251-10253 Titre : Design of an Oxygen Reduction Catalyst for Direct Methanol Fuel Cells Type de document : texte imprimé Auteurs : Jing Xu, Auteur ; Jinhua Yang, Auteur ; Jim Yang Lee, Auteur Année de publication : 2011 Article en page(s) : pp. 10251-10253 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fuel  cell  Catalyst  Conception Résumé : First principle calculations were used to screen the activity of core-shell oxygen reduction reaction (ORR) electrocatalysts for use in direct methanol fuel cells (DMFCs). Density functional theory (DFT) calculations indicate that the subsurface addition of 3d transition metals improves the activity of a Pd3Pt electrocatalyst by reducing its oxygen binding energy. Optimal activity close to the maximum of the ORR volcano curve is predicted for Pd3Fe@Pd3Pt and Pd3Mn@Pd3Pt core-shell catalysts. To validate the theoretical predictions, a series of Pd3M@Pd3Pt/C electrocatalysts (M = Ni, Co, Fe, and Cr) was prepared by galvanic replacement. Optimal activity and high methanol tolerance were observed for Pd3Fe@Pd3Pt. Compared with commercial Pt catalysts, the Pd3M@Pd3Pt structured catalysts utilize less platinum and yet display favorable ORR activity and selectivity. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447914 [article] Design of an Oxygen Reduction Catalyst for Direct Methanol Fuel Cells [texte imprimé] / Jing Xu, Auteur ; Jinhua Yang, Auteur ; Jim Yang Lee, Auteur . - 2011 . - pp. 10251-10253. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10251-10253 Mots-clés : Fuel  cell  Catalyst  Conception Résumé : First principle calculations were used to screen the activity of core-shell oxygen reduction reaction (ORR) electrocatalysts for use in direct methanol fuel cells (DMFCs). Density functional theory (DFT) calculations indicate that the subsurface addition of 3d transition metals improves the activity of a Pd3Pt electrocatalyst by reducing its oxygen binding energy. Optimal activity close to the maximum of the ORR volcano curve is predicted for Pd3Fe@Pd3Pt and Pd3Mn@Pd3Pt core-shell catalysts. To validate the theoretical predictions, a series of Pd3M@Pd3Pt/C electrocatalysts (M = Ni, Co, Fe, and Cr) was prepared by galvanic replacement. Optimal activity and high methanol tolerance were observed for Pd3Fe@Pd3Pt. Compared with commercial Pt catalysts, the Pd3M@Pd3Pt structured catalysts utilize less platinum and yet display favorable ORR activity and selectivity. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447914

Kinetic study of H2 oxidation in the preferential oxidation of CO on a nanosized Au / CeO2 catalyst / Jing Xu in Industrial & engineering chemistry research, Vol. 49 N° 9 (Mai 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp. 4149–4155 Titre : Kinetic study of H2 oxidation in the preferential oxidation of CO on a nanosized Au / CeO2 catalyst Type de document : texte imprimé Auteurs : Jing Xu, Auteur ; Ping Li, Auteur ; Xingfu Song, Auteur Année de publication : 2010 Article en page(s) : pp. 4149–4155 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Kinetic  Oxidation  Catalyst Résumé : Kinetic study of H2 oxidation in the preferential oxidation (PROX) of CO was implemented over a nanosize Au/CeO2 catalyst in a temperature range 313−353 K. The Langmuir−Hinshelwood mechanism was proposed to be mainly responsible for H2 oxidation, and CO oxidation can be accelerated by coadsorbed H at low temperatures. On the other hand, the water in the system has proved to suppress both CO and H2 oxidation by increasing the energy bars. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of CO adsorption on the Au surface indicates that linear CO−Au bond can be weakened in the presence of H2; meanwhile, water can be a poison taking effects via the bonding of water and the lattice oxygen at the interface of Au/CeO2. The irreversible loss of activity during reaction may be caused by the reconstruction of Au particles, at least in part. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100325y [article] Kinetic study of H2 oxidation in the preferential oxidation of CO on a nanosized Au / CeO2 catalyst [texte imprimé] / Jing Xu, Auteur ; Ping Li, Auteur ; Xingfu Song, Auteur . - 2010 . - pp. 4149–4155. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 9 (Mai 2010) . - pp. 4149–4155 Mots-clés : Kinetic  Oxidation  Catalyst Résumé : Kinetic study of H2 oxidation in the preferential oxidation (PROX) of CO was implemented over a nanosize Au/CeO2 catalyst in a temperature range 313−353 K. The Langmuir−Hinshelwood mechanism was proposed to be mainly responsible for H2 oxidation, and CO oxidation can be accelerated by coadsorbed H at low temperatures. On the other hand, the water in the system has proved to suppress both CO and H2 oxidation by increasing the energy bars. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of CO adsorption on the Au surface indicates that linear CO−Au bond can be weakened in the presence of H2; meanwhile, water can be a poison taking effects via the bonding of water and the lattice oxygen at the interface of Au/CeO2. The irreversible loss of activity during reaction may be caused by the reconstruction of Au particles, at least in part. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100325y

Second-law thermodynamic comparison and maximal velocity ratio design of shell-and-tube heat exchangers with continuous helical baffles / Qiu-Wang Wang in Journal of heat transfer, Vol. 132 N° 10 (Octobre 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 10 (Octobre 2010) . - pp. [101801-1/9] Titre : Second-law thermodynamic comparison and maximal velocity ratio design of shell-and-tube heat exchangers with continuous helical baffles Type de document : texte imprimé Auteurs : Qiu-Wang Wang, Auteur ; Gui-Dong Chen, Auteur ; Jing Xu, Auteur Année de publication : 2010 Article en page(s) : pp. [101801-1/9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Continuous  helical  baffles  Segmental  baffles  Entropy  generation  number  Ex-ergy  losses  Second-law  thermodynamic  analysis  Shell-and-tube  heat  exchangers Index. décimale : 536 Chaleur. Thermodynamique Résumé : Shell-and-tube heat exchangers (STHXs) have been widely used in many industrial processes. In the present paper, flow and heat transfer characteristics of the shell-and-tube heat exchanger with continuous helical baffles (CH-STHX) and segmental baffles (SG-STHX) were experimentally studied. In the experiments, these STHXs shared the same tube bundle, shell geometrical structures, different baffle arrangement, and number of heat exchange tubes. Experimental results suggested that the CH-STHX can increase the heat transfer rate by 7–12% than the SG-STHX for the same mass flow rate although its effective heat transfer area had 4% decrease. The heat transfer coefficient and pressure drop of the CH-STHX also had 43–53% and 64–72% increase than those of the SG-STHX, respectively. Based on second-law thermodynamic comparisons in which the quality of energy are evaluated by the entropy generation number and exergy losses, the CH-STHX decreased the entropy generation number and exergy losses by 30% and 68% on average than the SG-STHX for the same Reynolds number. The analysis from nondimensional correlations for Nusselt number and friction factor also revealed that if the maximal velocity ratio R>2.4, the heat transfer coefficient of CH-STHX was higher than that of SG-STHX, and the corresponding friction factor ratio kept at constant fo,CH/fo,SG=0.28. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Second-law thermodynamic comparison and maximal velocity ratio design of shell-and-tube heat exchangers with continuous helical baffles [texte imprimé] / Qiu-Wang Wang, Auteur ; Gui-Dong Chen, Auteur ; Jing Xu, Auteur . - 2010 . - pp. [101801-1/9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 10 (Octobre 2010) . - pp. [101801-1/9] Mots-clés : Continuous  helical  baffles  Segmental  baffles  Entropy  generation  number  Ex-ergy  losses  Second-law  thermodynamic  analysis  Shell-and-tube  heat  exchangers Index. décimale : 536 Chaleur. Thermodynamique Résumé : Shell-and-tube heat exchangers (STHXs) have been widely used in many industrial processes. In the present paper, flow and heat transfer characteristics of the shell-and-tube heat exchanger with continuous helical baffles (CH-STHX) and segmental baffles (SG-STHX) were experimentally studied. In the experiments, these STHXs shared the same tube bundle, shell geometrical structures, different baffle arrangement, and number of heat exchange tubes. Experimental results suggested that the CH-STHX can increase the heat transfer rate by 7–12% than the SG-STHX for the same mass flow rate although its effective heat transfer area had 4% decrease. The heat transfer coefficient and pressure drop of the CH-STHX also had 43–53% and 64–72% increase than those of the SG-STHX, respectively. Based on second-law thermodynamic comparisons in which the quality of energy are evaluated by the entropy generation number and exergy losses, the CH-STHX decreased the entropy generation number and exergy losses by 30% and 68% on average than the SG-STHX for the same Reynolds number. The analysis from nondimensional correlations for Nusselt number and friction factor also revealed that if the maximal velocity ratio R>2.4, the heat transfer coefficient of CH-STHX was higher than that of SG-STHX, and the corresponding friction factor ratio kept at constant fo,CH/fo,SG=0.28. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]