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Preparation and characterization of spherical mesoporous CeO2−Al2O3 composites with high thermal stability / Chao Gao in Industrial & engineering chemistry research, Vol. 48 N° 14 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6544–6549 Titre : Preparation and characterization of spherical mesoporous CeO2−Al2O3 composites with high thermal stability Type de document : texte imprimé Auteurs : Chao Gao, Auteur ; Lin, Yan-Jun, Auteur ; Yang Li, Auteur Année de publication : 2009 Article en page(s) : pp. 6544–6549 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Spherical  mesoporous  CeO2−Al2O3  composites  Oil-drop  sol−gel  method  Thermal  stability Résumé : Spherical mesoporous CeO2−Al2O3 composites containing 2, 5, and 8 wt % ceria have been prepared by an oil-drop sol−gel method. A mixed alumina−ceria hydrosol and hexamethylenetetramine solution were mixed together and added dropwise into a hot oil column where spherical gel particles were formed due to surface tension. The spherical gel particles were then aged, washed, dried, and calcined at 600, 960, or 1200 °C. The resulting materials were characterized by X-ray diffraction, nitrogen adsorption−desorption, and temperature-programmed desorption of ammonia. At 1200 °C sintering of pure alumina is severe, whereas the presence of ceria prevents the alumina from sintering, so that the CeO2−Al2O3 composites have much larger BET surface areas than pure alumina. Addition of ceria also leads to an increase in the number of strong acid sites and the total number of acid sites compared with pure alumina. These results show that the spherical mesoporous CeO2−Al2O3 composites prepared in this way are suitable supports for high temperature catalytic processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9000508 [article] Preparation and characterization of spherical mesoporous CeO2−Al2O3 composites with high thermal stability [texte imprimé] / Chao Gao, Auteur ; Lin, Yan-Jun, Auteur ; Yang Li, Auteur . - 2009 . - pp. 6544–6549. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6544–6549 Mots-clés : Spherical  mesoporous  CeO2−Al2O3  composites  Oil-drop  sol−gel  method  Thermal  stability Résumé : Spherical mesoporous CeO2−Al2O3 composites containing 2, 5, and 8 wt % ceria have been prepared by an oil-drop sol−gel method. A mixed alumina−ceria hydrosol and hexamethylenetetramine solution were mixed together and added dropwise into a hot oil column where spherical gel particles were formed due to surface tension. The spherical gel particles were then aged, washed, dried, and calcined at 600, 960, or 1200 °C. The resulting materials were characterized by X-ray diffraction, nitrogen adsorption−desorption, and temperature-programmed desorption of ammonia. At 1200 °C sintering of pure alumina is severe, whereas the presence of ceria prevents the alumina from sintering, so that the CeO2−Al2O3 composites have much larger BET surface areas than pure alumina. Addition of ceria also leads to an increase in the number of strong acid sites and the total number of acid sites compared with pure alumina. These results show that the spherical mesoporous CeO2−Al2O3 composites prepared in this way are suitable supports for high temperature catalytic processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9000508

Preparation and properties of microspherical alumina with a magnetic core/shell structure / Jun-Ting Feng in Industrial & engineering chemistry research, Vol. 48 N°2 (Janvier 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p.692–697 Titre : Preparation and properties of microspherical alumina with a magnetic core/shell structure Type de document : texte imprimé Auteurs : Jun-Ting Feng, Auteur ; Lin, Yan-Jun, Auteur ; Feng Li, Auteur ; David G. Evans, Auteur Année de publication : 2009 Article en page(s) : p.692–697 Note générale : chemical engenireeng Langues : Anglais (eng) Mots-clés : Microspherical  --  Alumina Résumé : A series of Ni2+−Co2+−Fe2+−Fe3+−SO42− layered double hydroxide precursors with different Ni/Co ratios have been synthesized by a method involving separate nucleation and aging steps. After calcination at 900 °C, the corresponding Ni1-xCoxFe oxides were obtained. Vibrating sample magnetometry indicated that the Ni1-xCoxFe oxide samples not only had high specific saturation magnetization, but also low coercivity and remanence. Ni1-xCoxFe oxides showed the optimum combination of magnetic properties for x = 0.2. Silica was coated onto the surface of Ni0.8Co0.2Fe oxide particles, and the coated particles were used as magnetic cores to prepare magnetic Ni0.8Co0.2Fe oxide/SiO2/γ-Al2O3 particles by hydrolysis of aluminum isopropoxide. After repeating the hydrolysis twice more, Ni0.8Co0.2Fe oxide/SiO2/γ-Al2O3 particles with about 20 wt % Ni0.8Co0.2Fe oxide were obtained and shown to be suitable for practical applications as a magnetic catalyst or catalyst support by virtue of their efficacious magnetic properties and pore structure. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801098k [article] Preparation and properties of microspherical alumina with a magnetic core/shell structure [texte imprimé] / Jun-Ting Feng, Auteur ; Lin, Yan-Jun, Auteur ; Feng Li, Auteur ; David G. Evans, Auteur . - 2009 . - p.692–697. chemical engenireeng Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°2 (Janvier 2009) . - p.692–697 Mots-clés : Microspherical  --  Alumina Résumé : A series of Ni2+−Co2+−Fe2+−Fe3+−SO42− layered double hydroxide precursors with different Ni/Co ratios have been synthesized by a method involving separate nucleation and aging steps. After calcination at 900 °C, the corresponding Ni1-xCoxFe oxides were obtained. Vibrating sample magnetometry indicated that the Ni1-xCoxFe oxide samples not only had high specific saturation magnetization, but also low coercivity and remanence. Ni1-xCoxFe oxides showed the optimum combination of magnetic properties for x = 0.2. Silica was coated onto the surface of Ni0.8Co0.2Fe oxide particles, and the coated particles were used as magnetic cores to prepare magnetic Ni0.8Co0.2Fe oxide/SiO2/γ-Al2O3 particles by hydrolysis of aluminum isopropoxide. After repeating the hydrolysis twice more, Ni0.8Co0.2Fe oxide/SiO2/γ-Al2O3 particles with about 20 wt % Ni0.8Co0.2Fe oxide were obtained and shown to be suitable for practical applications as a magnetic catalyst or catalyst support by virtue of their efficacious magnetic properties and pore structure. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801098k

Synthesis and UV absorption properties of 5,5′-methylenedisalicylic acid-intercalated Zn−Al layered double hydroxides / Cui, Guo-Jing in Industrial & engineering chemistry research, Vol. 49 N° 2 (Janvier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 2 (Janvier 2010) . - pp 448–453 Titre : Synthesis and UV absorption properties of 5,5′-methylenedisalicylic acid-intercalated Zn−Al layered double hydroxides Type de document : texte imprimé Auteurs : Cui, Guo-Jing, Auteur ; Xu, Xiang-Yu, Auteur ; Lin, Yan-Jun, Auteur Année de publication : 2010 Article en page(s) : pp 448–453 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : UV  absorption  Methylenedisalicylic  Hydroxides. Résumé : A UV absorber, 5,5′-methylenedisalicylic acid (MDSA), has been intercalated into a ZnAl−NO3 layered double hydroxide (LDH) by an ion-exchange method. After intercalation of MDSA, the basal spacing in the LDH increased from 0.90 to 1.53 nm, suggesting that the MDSA anions were arranged in the interlayer galleries of ZnAl−MDSA LDH as a tilted monolayer arrangement of dianions. Infrared spectroscopy and thermogravimetry and differential thermal analysis (TGA−DTA) curves revealed the presence of a complex system of supramolecular host−guest interactions. The thermal stability of the intercalated UV absorbent was investigated by TGA−DTA, which showed that the thermostability was markedly enhanced after intercalation into the LDH host. After addition of 1 wt % ZnAl−MDSA LDH to polypropylene (PP), the resistance of the polymer to UV degradation was significantly improved. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901151c [article] Synthesis and UV absorption properties of 5,5′-methylenedisalicylic acid-intercalated Zn−Al layered double hydroxides [texte imprimé] / Cui, Guo-Jing, Auteur ; Xu, Xiang-Yu, Auteur ; Lin, Yan-Jun, Auteur . - 2010 . - pp 448–453. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 2 (Janvier 2010) . - pp 448–453 Mots-clés : UV  absorption  Methylenedisalicylic  Hydroxides. Résumé : A UV absorber, 5,5′-methylenedisalicylic acid (MDSA), has been intercalated into a ZnAl−NO3 layered double hydroxide (LDH) by an ion-exchange method. After intercalation of MDSA, the basal spacing in the LDH increased from 0.90 to 1.53 nm, suggesting that the MDSA anions were arranged in the interlayer galleries of ZnAl−MDSA LDH as a tilted monolayer arrangement of dianions. Infrared spectroscopy and thermogravimetry and differential thermal analysis (TGA−DTA) curves revealed the presence of a complex system of supramolecular host−guest interactions. The thermal stability of the intercalated UV absorbent was investigated by TGA−DTA, which showed that the thermostability was markedly enhanced after intercalation into the LDH host. After addition of 1 wt % ZnAl−MDSA LDH to polypropylene (PP), the resistance of the polymer to UV degradation was significantly improved. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901151c