Documents disponibles écrits par cet auteur

Preferential oxidation of carbon monoxide in hydrogen stream over Au/MgOx-TiO2 catalysts / Li-Hsin Chang in Industrial & engineering chemistry research, Vol. 47 n°12 (Juin 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4098–4105 Titre : Preferential oxidation of carbon monoxide in hydrogen stream over Au/MgOx-TiO2 catalysts Type de document : texte imprimé Auteurs : Li-Hsin Chang, Auteur ; Chen, Yu-Wen, Auteur ; Natarajan Sasirekha, Auteur Année de publication : 2008 Article en page(s) : p. 4098–4105 Note générale : Bibliogr. p. 4104-4105 Langues : Anglais (eng) Mots-clés : Au/MgOx−TiO2  --  catalytic  activity;  Carbon  monoxide;  Impregnation  method;  Aqueous  solutions;  Deposition−precipitation Résumé : A series of Au/MgOx−TiO2 with various Mg/Ti molar ratios was prepared to study its catalytic activity for preferential oxidation of carbon monoxide in hydrogen-rich stream (PROX). An incipient wetness impregnation method was used to prepare the MgOx−TiO2 support, using aqueous solutions of Mg(NO3)2 on TiO2 calcined at 300 °C. A deposition−precipitation (DP) method was utilized to prepare Au/MgOx−TiO2, using HAuCl4 as the starting material. Au/MgOx and Au/TiO2 were also included for comparison. Investigation was carried out to study the effect of Mg/Ti molar ratio on the catalytic properties of gold supported catalysts. The catalysts were characterized by inductively couple plasma-mass spectrometry, X-ray diffraction, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. TEM results revealed the presence of nanosized gold particles and narrow particle size distribution on all the catalysts. MgOx was deposited on the TiO2 surface in the form of thin islands without definite shape. MgOx was mainly present as Mg(OH)2. Au particles were deposited on the surface of TiO2 in intimate contact with MgOx. The gold particle size was around 2.5 nm and was smaller than the MgOx particles. Since the surface area of TiO2 was small and the MgOx concentration was comparatively higher than Au concentration, Au should be in intimate contact with MgOx on the TiO2 surface. However, the exact status depends upon the Mg/Ti ratio and pH value during DP process to deposit gold. Au/MgOx−TiO2 with suitable amount of MgOx has higher CO conversion and higher selectivity of O2 to CO oxidation in the PROX reaction than Au/MgO and Au/TiO2. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071590d [article] Preferential oxidation of carbon monoxide in hydrogen stream over Au/MgOx-TiO2 catalysts [texte imprimé] / Li-Hsin Chang, Auteur ; Chen, Yu-Wen, Auteur ; Natarajan Sasirekha, Auteur . - 2008 . - p. 4098–4105. Bibliogr. p. 4104-4105 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4098–4105 Mots-clés : Au/MgOx−TiO2  --  catalytic  activity;  Carbon  monoxide;  Impregnation  method;  Aqueous  solutions;  Deposition−precipitation Résumé : A series of Au/MgOx−TiO2 with various Mg/Ti molar ratios was prepared to study its catalytic activity for preferential oxidation of carbon monoxide in hydrogen-rich stream (PROX). An incipient wetness impregnation method was used to prepare the MgOx−TiO2 support, using aqueous solutions of Mg(NO3)2 on TiO2 calcined at 300 °C. A deposition−precipitation (DP) method was utilized to prepare Au/MgOx−TiO2, using HAuCl4 as the starting material. Au/MgOx and Au/TiO2 were also included for comparison. Investigation was carried out to study the effect of Mg/Ti molar ratio on the catalytic properties of gold supported catalysts. The catalysts were characterized by inductively couple plasma-mass spectrometry, X-ray diffraction, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. TEM results revealed the presence of nanosized gold particles and narrow particle size distribution on all the catalysts. MgOx was deposited on the TiO2 surface in the form of thin islands without definite shape. MgOx was mainly present as Mg(OH)2. Au particles were deposited on the surface of TiO2 in intimate contact with MgOx. The gold particle size was around 2.5 nm and was smaller than the MgOx particles. Since the surface area of TiO2 was small and the MgOx concentration was comparatively higher than Au concentration, Au should be in intimate contact with MgOx on the TiO2 surface. However, the exact status depends upon the Mg/Ti ratio and pH value during DP process to deposit gold. Au/MgOx−TiO2 with suitable amount of MgOx has higher CO conversion and higher selectivity of O2 to CO oxidation in the PROX reaction than Au/MgO and Au/TiO2. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071590d

Preparation of NiFeB nanoalloy catalysts and their applications in liquid-phase hydrogenation of p-chloronitrobenzene / Chen, Yu-Wen in Industrial & engineering chemistry research, Vol. 48 N° 13 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6248–6255 Titre : Preparation of NiFeB nanoalloy catalysts and their applications in liquid-phase hydrogenation of p-chloronitrobenzene Type de document : texte imprimé Auteurs : Chen, Yu-Wen, Auteur ; Natarajan Sasirekha, Auteur Année de publication : 2009 Article en page(s) : pp. 6248–6255 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : NiFeB  nanoalloy  catalysts  Chemical  reduction  method  Metal  acetates  P-chloronitrobenzene  Hydrogenation Résumé : A series of NiFeB nanoalloy catalysts were prepared by chemical reduction method using metal acetates as the starting materials, and NaBH4 as the reducing agent. The amorphous metal materials, combining the features of amorphous and nanometer materials, have more surface atoms and a higher concentration of coordinately highly unsaturated sites. Sodium borohydride in excess amount was added dropwise into the mixture to ensure full reduction of metal cations. The catalysts were characterized with X-ray diffraction, nitrogen sorption, transmission electron microscopy, and X-ray photoelectron spectroscopy. The hydrogenation of p-chloronitrobenzene was carried out in a batch reactor at 1.2 MPa H2 pressure and 323−393 K. The Ni/Fe molar ratios in the starting materials affected the concentration of boron bounded to the nickel and iron metals, resulting in the difference in surface area, electronic structures of the metals, and the catalytic activities of the catalysts. The addition of iron in NiB catalyst could reduce the particle of the nickel metal, suppress the growth of crystalline structure of NiFeB, and help the NiFeB catalyst to maintain its amorphous state. On the basis of the electron transfer between elemental nickel and boron, Ni in NiFeB had more d-band electrons and higher electron density than in NiB; therefore, it also has higher activities of hydrogenation of the nitro group than does NiB. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801624a [article] Preparation of NiFeB nanoalloy catalysts and their applications in liquid-phase hydrogenation of p-chloronitrobenzene [texte imprimé] / Chen, Yu-Wen, Auteur ; Natarajan Sasirekha, Auteur . - 2009 . - pp. 6248–6255. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. 6248–6255 Mots-clés : NiFeB  nanoalloy  catalysts  Chemical  reduction  method  Metal  acetates  P-chloronitrobenzene  Hydrogenation Résumé : A series of NiFeB nanoalloy catalysts were prepared by chemical reduction method using metal acetates as the starting materials, and NaBH4 as the reducing agent. The amorphous metal materials, combining the features of amorphous and nanometer materials, have more surface atoms and a higher concentration of coordinately highly unsaturated sites. Sodium borohydride in excess amount was added dropwise into the mixture to ensure full reduction of metal cations. The catalysts were characterized with X-ray diffraction, nitrogen sorption, transmission electron microscopy, and X-ray photoelectron spectroscopy. The hydrogenation of p-chloronitrobenzene was carried out in a batch reactor at 1.2 MPa H2 pressure and 323−393 K. The Ni/Fe molar ratios in the starting materials affected the concentration of boron bounded to the nickel and iron metals, resulting in the difference in surface area, electronic structures of the metals, and the catalytic activities of the catalysts. The addition of iron in NiB catalyst could reduce the particle of the nickel metal, suppress the growth of crystalline structure of NiFeB, and help the NiFeB catalyst to maintain its amorphous state. On the basis of the electron transfer between elemental nickel and boron, Ni in NiFeB had more d-band electrons and higher electron density than in NiB; therefore, it also has higher activities of hydrogenation of the nitro group than does NiB. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801624a