Issue 18, 2017

The effect of surface chemistry on the performances of Pd-based catalysts supported on activated carbons

Abstract

In this work we investigated in detail the effects of nitric acid on the surface chemistry of two carbons, activated by steam and by phosphoric acid, meant to identify the nature and the concentration of the oxidized surface species. To this aim, the oxidized carbons were characterized by means of a large number of complementary techniques, including micro-Raman spectroscopy, N2 physisorption, Boehm titration method, 13C solid state nuclear magnetic resonance, X-ray photoelectron spectroscopy, diffuse reflectance infrared and inelastic neutron scattering spectroscopy. Carboxylic and carboxylate groups are mainly formed, the latter stabilized by the extended conjugation of the π electrons and being more abundant on small and irregular graphitic platelets. We demonstrated that the presence of oxygen-containing groups acts against the palladium dispersion and causes the appearance of an appreciable induction time in hydrogenation reactions. The carbon with more oxygenated surface species (and in particular more carboxylate groups) must be chosen in the hydrogenation of polar substrates, while it is detrimental to the hydrogenation of nonpolar substrates.

Graphical abstract: The effect of surface chemistry on the performances of Pd-based catalysts supported on activated carbons

Supplementary files

Article information

Article type
Paper
Submitted
18 May 2017
Accepted
12 Aug 2017
First published
14 Aug 2017

Catal. Sci. Technol., 2017,7, 4162-4172

The effect of surface chemistry on the performances of Pd-based catalysts supported on activated carbons

A. Lazzarini, R. Pellegrini, A. Piovano, S. Rudić, C. Castan-Guerrero, P. Torelli, M. R. Chierotti, R. Gobetto, C. Lamberti and E. Groppo, Catal. Sci. Technol., 2017, 7, 4162 DOI: 10.1039/C7CY01005B

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