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Catalytic performance of silica - supported silver nanoparticles for liquid - phase oxidation of ethylbenzene / Raji Vadakkekara in Industrial & engineering chemistry research, Vol. 51 N° 16 (Avril 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 16 (Avril 2012) . - pp. 5691-5698 Titre : Catalytic performance of silica - supported silver nanoparticles for liquid - phase oxidation of ethylbenzene Type de document : texte imprimé Auteurs : Raji Vadakkekara, Auteur ; Mousumi Chakraborty, Auteur ; Parimal A. Parikh, Auteur Année de publication : 2012 Article en page(s) : pp. 5691-5698 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Oxidation  Liquid  phase  Nanoparticle  Catalytic  reaction Résumé : In this study silver nanoparticles were prepared by chemical reduction method using silver nitrate as metal precursor, starch as protecting agent, and sodium borohydride (NaBH4) as a reducing agent. Formation of silver nanoparticles was monitored using UV-vis absorption spectroscopy and dynamic light scattering (DLS). They were supported on silica by dispersing silica powder in the suspension of destabilized silver nanoparticles. Samples containing different proportions of silver were thus prepared. This method is at variance from the conventionally employed method, i.e., impregnation of silver salt from its solution on support. Ag/SiO2 samples were characterized by UV-vis absorption spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), inductive coupled plasma optical emission spectroscopy (ICP-OES), and N, adsorption-desorption. Superior catalytic performance of the catalyst prepared by the present method could be observed in a test reaction of ethylbenzene oxidation affording high selectivity to acetophenone as compared to the catalyst prepared by the conventional reported methods. The 5 wt % Ag/SiO2 catalyst was found not much susceptible to sintering as could be inferred from the comparable performance of the regenerated and fresh catalysts. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25834482 [article] Catalytic performance of silica - supported silver nanoparticles for liquid - phase oxidation of ethylbenzene [texte imprimé] / Raji Vadakkekara, Auteur ; Mousumi Chakraborty, Auteur ; Parimal A. Parikh, Auteur . - 2012 . - pp. 5691-5698. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 16 (Avril 2012) . - pp. 5691-5698 Mots-clés : Oxidation  Liquid  phase  Nanoparticle  Catalytic  reaction Résumé : In this study silver nanoparticles were prepared by chemical reduction method using silver nitrate as metal precursor, starch as protecting agent, and sodium borohydride (NaBH4) as a reducing agent. Formation of silver nanoparticles was monitored using UV-vis absorption spectroscopy and dynamic light scattering (DLS). They were supported on silica by dispersing silica powder in the suspension of destabilized silver nanoparticles. Samples containing different proportions of silver were thus prepared. This method is at variance from the conventionally employed method, i.e., impregnation of silver salt from its solution on support. Ag/SiO2 samples were characterized by UV-vis absorption spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), inductive coupled plasma optical emission spectroscopy (ICP-OES), and N, adsorption-desorption. Superior catalytic performance of the catalyst prepared by the present method could be observed in a test reaction of ethylbenzene oxidation affording high selectivity to acetophenone as compared to the catalyst prepared by the conventional reported methods. The 5 wt % Ag/SiO2 catalyst was found not much susceptible to sintering as could be inferred from the comparable performance of the regenerated and fresh catalysts. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25834482

Rhodium supported Hβ zeolite for the hydrogenation of toluene / Kalpesh B. Sidhpuria 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. 4034–4042 Titre : Rhodium supported Hβ zeolite for the hydrogenation of toluene Type de document : texte imprimé Auteurs : Kalpesh B. Sidhpuria, Auteur ; Parimal A. Parikh, Auteur ; Pratap Bahadur, Auteur ; Raksh V. Jasra, Auteur Année de publication : 2008 Article en page(s) : p. 4034–4042 Note générale : Bibliogr. p. 4041-4042 Langues : Anglais (eng) Mots-clés : Noble  metal  Rh;  Toluene  --  hydrodearomatization;  Fourier  transform  infrared  spectra;  Chemical  analysis Résumé : Noble metal Rh supported on a large pore high acidic zeolite Hβ has been explored as a hydrodearomatization catalyst. The detail kinetic study of hydrodearomatization of toluene over a 1 wt % Rh/Hβ was done in a continuous-downflow stainless steel catalytic fixed bed reactor at varied space time, toluene feed rate, hydrogen partial pressure, hydrogen to toluene mole ratio, temperature, and in the presence of dibenzothiophene. The time on stream data and reaction order with respect to toluene were measured and was found to be of first order. Fourier transform infrared (FTIR) spectra and chemical analysis of fresh and spent catalyst suggested the presence of surface carbon species and weight percent carbon was found to be 4.43%. It was observed that toluene conversion was increased on increasing H2 partial pressure and H2/feed mole ratio. The conversion is dependent on temperature and shows a well-defined maximum. The decrease of the catalyst activity in the presence of dibenzothiophene is mainly attributed to the adsorption and decomposition of dibenzothiophene (DBT) on the metal sites, which results in a loss of metal surface available for the reaction to take place and a higher coke formation reducing the fraction of acid sites available for toluene hydrodearomatization. A nonlinear semiempirical kinetic model was also developed to have the best fit with 12% error. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8001793 [article] Rhodium supported Hβ zeolite for the hydrogenation of toluene [texte imprimé] / Kalpesh B. Sidhpuria, Auteur ; Parimal A. Parikh, Auteur ; Pratap Bahadur, Auteur ; Raksh V. Jasra, Auteur . - 2008 . - p. 4034–4042. Bibliogr. p. 4041-4042 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°12 (Juin 2008) . - p. 4034–4042 Mots-clés : Noble  metal  Rh;  Toluene  --  hydrodearomatization;  Fourier  transform  infrared  spectra;  Chemical  analysis Résumé : Noble metal Rh supported on a large pore high acidic zeolite Hβ has been explored as a hydrodearomatization catalyst. The detail kinetic study of hydrodearomatization of toluene over a 1 wt % Rh/Hβ was done in a continuous-downflow stainless steel catalytic fixed bed reactor at varied space time, toluene feed rate, hydrogen partial pressure, hydrogen to toluene mole ratio, temperature, and in the presence of dibenzothiophene. The time on stream data and reaction order with respect to toluene were measured and was found to be of first order. Fourier transform infrared (FTIR) spectra and chemical analysis of fresh and spent catalyst suggested the presence of surface carbon species and weight percent carbon was found to be 4.43%. It was observed that toluene conversion was increased on increasing H2 partial pressure and H2/feed mole ratio. The conversion is dependent on temperature and shows a well-defined maximum. The decrease of the catalyst activity in the presence of dibenzothiophene is mainly attributed to the adsorption and decomposition of dibenzothiophene (DBT) on the metal sites, which results in a loss of metal surface available for the reaction to take place and a higher coke formation reducing the fraction of acid sites available for toluene hydrodearomatization. A nonlinear semiempirical kinetic model was also developed to have the best fit with 12% error. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8001793