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Au/CuOx-TiO2 catalysts for preferential oxidation of CO in hydrogen sStream / Palanivelu Sangeetha in Industrial & engineering chemistry research, Vol. 49 N° 5 (Mars 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 5 (Mars 2010) . - pp. 2096–2102 Titre : Au/CuOx-TiO2 catalysts for preferential oxidation of CO in hydrogen sStream Type de document : texte imprimé Auteurs : Palanivelu Sangeetha, Auteur ; Zhao, Bin, Auteur ; Chen, Yu-Wen, Auteur Année de publication : 2010 Article en page(s) : pp. 2096–2102 Note générale : Industrial Chemisty Langues : Anglais (eng) Mots-clés : Catalysts;  Au/CuOx-TiO2;  Preferential  Oxidation Résumé : A series of Au/CuOx−TiO2 catalysts with various Cu/Ti atomic ratios were prepared by deposition−precipitation method. The catalysts were characterized by inductively coupled plasma−mass spectrometry, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The preferential oxidation of CO in H2 stream (PROX) on these catalysts was carried out in a fixed bed microreactor with a gas mixture (CO:O2:H2:He = 1.33:1.33:65.33:32.01 by volume ratios) was fed with a space velocity of 30000 mL/(g·h). Au/CuOx−TiO2 with various Cu/Ti atomic ratios showed similar gold particle size (2.3−2.5 nm). The gold in the starting material was almost totally loaded on the CuOx−TiO2 support at pH = 7. Au/CuOx−TiO2 catalysts with gold content of 1 wt % and calcined at 180 °C had superior catalytic activity and selectivity for CO oxidation at temperature of 80 °C. Au/CuOx−TiO2 (Cu/Ti = 4.8/95.2) had a CO conversion of 100% at 80 °C, and CO selectivity reaches 68%. Gold particles were well dispersed and stable on the support. Even after PROX reaction at 80 °C for a long time, most of the particles still maintained at 2.4 nm. The CO conversion slightly decreased from 100% to 95%, and CO selectivity was nearly the same. Au/CuOx−TiO2 is a highly effective and thermally stable catalyst for PROX reaction compared with Au/TiO2 catalyst. Note de contenu : Bibliogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901233e [article] Au/CuOx-TiO2 catalysts for preferential oxidation of CO in hydrogen sStream [texte imprimé] / Palanivelu Sangeetha, Auteur ; Zhao, Bin, Auteur ; Chen, Yu-Wen, Auteur . - 2010 . - pp. 2096–2102. Industrial Chemisty Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 5 (Mars 2010) . - pp. 2096–2102 Mots-clés : Catalysts;  Au/CuOx-TiO2;  Preferential  Oxidation Résumé : A series of Au/CuOx−TiO2 catalysts with various Cu/Ti atomic ratios were prepared by deposition−precipitation method. The catalysts were characterized by inductively coupled plasma−mass spectrometry, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The preferential oxidation of CO in H2 stream (PROX) on these catalysts was carried out in a fixed bed microreactor with a gas mixture (CO:O2:H2:He = 1.33:1.33:65.33:32.01 by volume ratios) was fed with a space velocity of 30000 mL/(g·h). Au/CuOx−TiO2 with various Cu/Ti atomic ratios showed similar gold particle size (2.3−2.5 nm). The gold in the starting material was almost totally loaded on the CuOx−TiO2 support at pH = 7. Au/CuOx−TiO2 catalysts with gold content of 1 wt % and calcined at 180 °C had superior catalytic activity and selectivity for CO oxidation at temperature of 80 °C. Au/CuOx−TiO2 (Cu/Ti = 4.8/95.2) had a CO conversion of 100% at 80 °C, and CO selectivity reaches 68%. Gold particles were well dispersed and stable on the support. Even after PROX reaction at 80 °C for a long time, most of the particles still maintained at 2.4 nm. The CO conversion slightly decreased from 100% to 95%, and CO selectivity was nearly the same. Au/CuOx−TiO2 is a highly effective and thermally stable catalyst for PROX reaction compared with Au/TiO2 catalyst. Note de contenu : Bibliogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901233e

Hydrogenation of p-chloronitrobenzene on tungsten-modified NiCoB catalyst / Zhao, Bin in Industrial & engineering chemistry research, Vol. 49 N° 4 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1669–1676 Titre : Hydrogenation of p-chloronitrobenzene on tungsten-modified NiCoB catalyst Type de document : texte imprimé Auteurs : Zhao, Bin, Auteur ; Chou, Chun-Jen, Auteur ; Chen, Yu-Wen, Auteur Année de publication : 2010 Article en page(s) : pp 1669–1676 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hydrogenation  Tungsten  Catalyst. Résumé : NiCoB has been reported to be a good catalyst for the hydrogenation of p-chloronitrobenzene (p-CNB). However, it aggregates easily. In this study, a series of tungsten-modified NiCoB catalysts with various tungsten contents were synthesized by the chemical reduction method using NaBH4 as the reducing agent. The products were characterized by X-ray diffraction (XRD), N2 sorption, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The catalysts were tested for the liquid-phase hydrogenation of p-CNB. Ni, Co, W, and B were present in both elemental and oxidized states. The addition of tungsten could influence the surface composition of the catalyst. The electronic structures of Ni, Co, W, and B were also changed with changing content of tungsten. XPS showed that the elemental states of Ni, Co, W, and B formed an amorphous nanoalloy. The interactions of these species affected their electron densities and further influenced their catalytic activities. The tungsten oxide located among the NiCoB particles could act as a spacer that separates the NiCoB particles from their neighbors and inhibits aggregation. Compared to the unmodified NiCoB catalyst, the catalytic activity of tungsten-modified NiCoB exhibited an obvious increase, along with a slight decrease in the selectivity of p-chloroaniline (p-CAN). The differences in the atom radius and electronegativity of tungsten from those of the other elements in the alloy resulted in the formation of active sites for the catalytic reaction. The concentration of boron on the catalyst surface decreased with increasing tungsten concentration, which was responsible for the slight decrease in the selectivity of p-CAN. Considering the electronic effects, the structural effects, and the amount of B3+ (Lewis acid), good catalytic performance in the hydrogenation of p-CNB was achieved by modifying the NiCoB catalysts with the proper amount of tungsten. Tungsten species not only acted as a spacer to prevent NiCoB particles from aggregating, but also donated partial electrons to Ni and Co. An overdose of tungsten would cover the surface of Ni and result in low activity. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901606b [article] Hydrogenation of p-chloronitrobenzene on tungsten-modified NiCoB catalyst [texte imprimé] / Zhao, Bin, Auteur ; Chou, Chun-Jen, Auteur ; Chen, Yu-Wen, Auteur . - 2010 . - pp 1669–1676. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1669–1676 Mots-clés : Hydrogenation  Tungsten  Catalyst. Résumé : NiCoB has been reported to be a good catalyst for the hydrogenation of p-chloronitrobenzene (p-CNB). However, it aggregates easily. In this study, a series of tungsten-modified NiCoB catalysts with various tungsten contents were synthesized by the chemical reduction method using NaBH4 as the reducing agent. The products were characterized by X-ray diffraction (XRD), N2 sorption, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The catalysts were tested for the liquid-phase hydrogenation of p-CNB. Ni, Co, W, and B were present in both elemental and oxidized states. The addition of tungsten could influence the surface composition of the catalyst. The electronic structures of Ni, Co, W, and B were also changed with changing content of tungsten. XPS showed that the elemental states of Ni, Co, W, and B formed an amorphous nanoalloy. The interactions of these species affected their electron densities and further influenced their catalytic activities. The tungsten oxide located among the NiCoB particles could act as a spacer that separates the NiCoB particles from their neighbors and inhibits aggregation. Compared to the unmodified NiCoB catalyst, the catalytic activity of tungsten-modified NiCoB exhibited an obvious increase, along with a slight decrease in the selectivity of p-chloroaniline (p-CAN). The differences in the atom radius and electronegativity of tungsten from those of the other elements in the alloy resulted in the formation of active sites for the catalytic reaction. The concentration of boron on the catalyst surface decreased with increasing tungsten concentration, which was responsible for the slight decrease in the selectivity of p-CAN. Considering the electronic effects, the structural effects, and the amount of B3+ (Lewis acid), good catalytic performance in the hydrogenation of p-CNB was achieved by modifying the NiCoB catalysts with the proper amount of tungsten. Tungsten species not only acted as a spacer to prevent NiCoB particles from aggregating, but also donated partial electrons to Ni and Co. An overdose of tungsten would cover the surface of Ni and result in low activity. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901606b

Hydrogenation of p-chloronitrobenzene over mo-modified NiCoB nanoalloy catalysts / Ming-Hung Lin in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7037–7043 Titre : Hydrogenation of p-chloronitrobenzene over mo-modified NiCoB nanoalloy catalysts : effect of Mo content Type de document : texte imprimé Auteurs : Ming-Hung Lin, Auteur ; Zhao, Bin, Auteur ; Chen, Yu-Wen, Auteur Année de publication : 2009 Article en page(s) : pp. 7037–7043 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : p-chloronitrobenzene  HydrogenationNiCoB  alloy  catalyst Résumé : NiCoB alloy catalyst has been reported to be a good catalyst for the hydrogenation of p-chloronitrobenzene to p-chloroaniline. The objective of this study was to investigate the effects of Mo content on the catalytic properties of NiCoB in the hydrogenation of p-chloronitrobenzene. A series of Mo-doped NiCoB nanoalloy catalysts with various Mo contents were prepared by chemically reacting nickel acetate, cobalt acetate, ammonium heptamolybdate, and sodium borohydride in a 50 vol % water/methanol solution at 298 K under an N2 gas curtain with vigorous stirring. The Ni/Co atomic ratio was fixed at 10. An excess amount of NaBH4 was used [B/(Ni + Co) atomic ratio = 3] to fully reduced Ni and Co cations. The catalysts were characterized with nitrogen sorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalysts were tested for liquid-phase hydrogenation of p-chloronitrobenzene at 353 K and 1.2 MPa H2 pressure. Even adding a small amount of Mo had significant effect on activity and selectivity of NiCoB. The activity increased with an increase of Mo content until a Mo/Ni atomic ratio of 0.6 and then decreased. The catalyst with the atomic ratio of Mo/Ni = 0.6 had the highest surface area and the highest activity and selectivity of p-chloroaniline. The particle size of Mo−NiCoB decreased with an increase of Mo content. The crystallization temperature extended upward with the increase in Mo content, indicating that the molybdenum species suppressed the growth of the crystalline structure of NiCoB and helped the NiCoB catalyst maintain its amorphous state. Molybdenum was mainly in the form of hydroxide and acted as a spacer to prevent NiCoB from aggregation/agglomeration. Adding the proper amount of molybdenum in NiCoB catalysts increased the surface area, activity, and selectivity. An overdose of molybdenum had an opposite effect on the NiCoB catalyst. The optimum atomic ratio of Mo/Ni was 0.6. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900019d [article] Hydrogenation of p-chloronitrobenzene over mo-modified NiCoB nanoalloy catalysts : effect of Mo content [texte imprimé] / Ming-Hung Lin, Auteur ; Zhao, Bin, Auteur ; Chen, Yu-Wen, Auteur . - 2009 . - pp. 7037–7043. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7037–7043 Mots-clés : p-chloronitrobenzene  HydrogenationNiCoB  alloy  catalyst Résumé : NiCoB alloy catalyst has been reported to be a good catalyst for the hydrogenation of p-chloronitrobenzene to p-chloroaniline. The objective of this study was to investigate the effects of Mo content on the catalytic properties of NiCoB in the hydrogenation of p-chloronitrobenzene. A series of Mo-doped NiCoB nanoalloy catalysts with various Mo contents were prepared by chemically reacting nickel acetate, cobalt acetate, ammonium heptamolybdate, and sodium borohydride in a 50 vol % water/methanol solution at 298 K under an N2 gas curtain with vigorous stirring. The Ni/Co atomic ratio was fixed at 10. An excess amount of NaBH4 was used [B/(Ni + Co) atomic ratio = 3] to fully reduced Ni and Co cations. The catalysts were characterized with nitrogen sorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalysts were tested for liquid-phase hydrogenation of p-chloronitrobenzene at 353 K and 1.2 MPa H2 pressure. Even adding a small amount of Mo had significant effect on activity and selectivity of NiCoB. The activity increased with an increase of Mo content until a Mo/Ni atomic ratio of 0.6 and then decreased. The catalyst with the atomic ratio of Mo/Ni = 0.6 had the highest surface area and the highest activity and selectivity of p-chloroaniline. The particle size of Mo−NiCoB decreased with an increase of Mo content. The crystallization temperature extended upward with the increase in Mo content, indicating that the molybdenum species suppressed the growth of the crystalline structure of NiCoB and helped the NiCoB catalyst maintain its amorphous state. Molybdenum was mainly in the form of hydroxide and acted as a spacer to prevent NiCoB from aggregation/agglomeration. Adding the proper amount of molybdenum in NiCoB catalysts increased the surface area, activity, and selectivity. An overdose of molybdenum had an opposite effect on the NiCoB catalyst. The optimum atomic ratio of Mo/Ni was 0.6. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900019d