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]  inIndustrial & 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

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Preferential oxidation of CO in H2 stream on Au/TiO2 catalysts / Palanivelu Sangeetha in Industrial & engineering chemistry research, Vol. 48 N° 12 (Juin 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5666–5670 Titre : Preferential oxidation of CO in H2 stream on Au/TiO2 catalysts : effect of preparation method Type de document : texte imprimé Auteurs : Palanivelu Sangeetha, Auteur ; Li-Hsin Chang, Auteur ; Chen, Yu-Wen, Auteur Année de publication : 2009 Article en page(s) : pp. 5666–5670 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Au/TiO2 catalysts Deposition-precipitation methods Inductively coupled plasma-mass spectrometry X-ray diffraction Transmission electron microscopy photoelectron spectroscopy Résumé : A series of Au/TiO2 catalysts were prepared by either photodeposition or deposition−precipitation methods. The catalysts were characterized by inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The catalytic performance of these catalysts was investigated by preferential oxidation of carbon monoxide in a hydrogen stream. A high gold dispersion and narrow size distribution was obtained for Au/TiO2 catalysts prepared by both photodeposition or deposition−precipitation methods. The photodeposition method facilitates the preparation of gold particles as small as 1.5 nm on the support, whereas in the deposition−precipitation method, the gold particles were found to be around 2−3 nm. The catalyst prepared by the photodeposition method showed higher CO conversion and CO selectivity than those prepared by the deposition−precipitation method. The selectivity of CO reacting with O2 decreased with increasing reaction temperature due to H2 competing with CO at high temperatures. Au/TiO2 catalysts prepared by the photodeposition method showed relatively higher CO selectivity below 65 °C when compared with the deposition−precipitation method. The differences in activity could be attributed to the difference in chemical state of gold particles and the particle size of gold. The catalyst prepared by photodeposition had a smaller particle size (1.5 nm). It had higher CO conversion at low temperature ( En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900403s [article] Preferential oxidation of CO in H2 stream on Au/TiO2 catalysts : effect of preparation method [texte imprimé] / Palanivelu Sangeetha, Auteur ; Li-Hsin Chang, Auteur ; Chen, Yu-Wen, Auteur . - 2009 . - pp. 5666–5670. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 12 (Juin 2009) . - pp. 5666–5670 Mots-clés : Au/TiO2 catalysts Deposition-precipitation methods Inductively coupled plasma-mass spectrometry X-ray diffraction Transmission electron microscopy photoelectron spectroscopy Résumé : A series of Au/TiO2 catalysts were prepared by either photodeposition or deposition−precipitation methods. The catalysts were characterized by inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The catalytic performance of these catalysts was investigated by preferential oxidation of carbon monoxide in a hydrogen stream. A high gold dispersion and narrow size distribution was obtained for Au/TiO2 catalysts prepared by both photodeposition or deposition−precipitation methods. The photodeposition method facilitates the preparation of gold particles as small as 1.5 nm on the support, whereas in the deposition−precipitation method, the gold particles were found to be around 2−3 nm. The catalyst prepared by the photodeposition method showed higher CO conversion and CO selectivity than those prepared by the deposition−precipitation method. The selectivity of CO reacting with O2 decreased with increasing reaction temperature due to H2 competing with CO at high temperatures. Au/TiO2 catalysts prepared by the photodeposition method showed relatively higher CO selectivity below 65 °C when compared with the deposition−precipitation method. The differences in activity could be attributed to the difference in chemical state of gold particles and the particle size of gold. The catalyst prepared by photodeposition had a smaller particle size (1.5 nm). It had higher CO conversion at low temperature ( En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900403s

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