Gold nanoparticles (AuNps) were anchored on alkynyl carbamate-functionalized support materials having the suitable features for application as catalysts in continuous-flow packed bed reactors. The functionalization step was carried out by grafting with the difunctional organosilane [3-(2-propynylcarbamate)propyl]triethoxysilane (PPTEOS) three commercial micrometer-sized oxide supports, i.e. silica, alumina, and titania. The alkynyl-carbamate moieties were capable of straightforwardly reducing the gold precursor HAuCl4 yielding the supported AuNps systems Au/SiO2@lYne, Au/Al2O3@Yne, and Au/TiO2@Yne. A comparison among the three materials revealed that silica allowed the highest organic functionalization (12 wt %) as well as the highest gold loading (3.7 wt %). Moreover, a TEM investigation showed only for Au/SiO2@Yne the presence of homogeneously distributed spherically shaped AuNP, (average diameter nm). Au/ SiO2@Yne is an efficient catalyst, both in batch and flow conditions, in the oxidation of a large variety of alcohols using H202 as the oxidizing agent at a temperature of 90 degrees C. Furthermore, under flow conditions, the catalyst worked for over 50 h without any significant decrease in the catalytic activity. The catalytic activity of the three catalysts was evaluated and compared in the oxidation of 1-phenylethanol as a model substrate. We found that the flow approach plays a strategic role in preserving the physical and chemical integrity of the solid catalysts during its use, with remarkable consequences for the reaction conversion (from 2% in batch to 80% in flow) in the case of Au/TiO2@Yne.

Supported Gold Nanoparticles for Alcohols Oxidation in Continuous Flow Heterogeneous Systems

Massi, A.;Zaghi, A.
Ultimo
2017

Abstract

Gold nanoparticles (AuNps) were anchored on alkynyl carbamate-functionalized support materials having the suitable features for application as catalysts in continuous-flow packed bed reactors. The functionalization step was carried out by grafting with the difunctional organosilane [3-(2-propynylcarbamate)propyl]triethoxysilane (PPTEOS) three commercial micrometer-sized oxide supports, i.e. silica, alumina, and titania. The alkynyl-carbamate moieties were capable of straightforwardly reducing the gold precursor HAuCl4 yielding the supported AuNps systems Au/SiO2@lYne, Au/Al2O3@Yne, and Au/TiO2@Yne. A comparison among the three materials revealed that silica allowed the highest organic functionalization (12 wt %) as well as the highest gold loading (3.7 wt %). Moreover, a TEM investigation showed only for Au/SiO2@Yne the presence of homogeneously distributed spherically shaped AuNP, (average diameter nm). Au/ SiO2@Yne is an efficient catalyst, both in batch and flow conditions, in the oxidation of a large variety of alcohols using H202 as the oxidizing agent at a temperature of 90 degrees C. Furthermore, under flow conditions, the catalyst worked for over 50 h without any significant decrease in the catalytic activity. The catalytic activity of the three catalysts was evaluated and compared in the oxidation of 1-phenylethanol as a model substrate. We found that the flow approach plays a strategic role in preserving the physical and chemical integrity of the solid catalysts during its use, with remarkable consequences for the reaction conversion (from 2% in batch to 80% in flow) in the case of Au/TiO2@Yne.
2017
Ballarin, B.; Barreca, D.; Boanini, E.; Cassani, M. C.; Dambruoso, P.; Massi, A.; Mignani, A.; Nanni, D.; Parise, C.; Zaghi, A.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2377450
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