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2 results on '"Pedro H C, Camargo"'

1. Hot Electrons, Hot Holes, or Both? Tandem Synthesis of Imines Driven by the Plasmonic Excitation in Au/CeO2 Nanorods

Author

Ivo F. Teixeira, Mauricio S. Homsi, Rafael S. Geonmonond, Guilherme F. S. R. Rocha, Yung-Kang Peng, Ingrid F. Silva, Jhon Quiroz, and Pedro H. C. Camargo

Subjects
tandem, oxidative coupling, Au NPs, CeO2 nanorods, localized surface plasmon resonance, nanocatalysis, Chemistry, QD1-999
Abstract

Solar-to-chemical conversion via photocatalysis is of paramount importance for a sustainable future. Thus, investigating the synergistic effects promoted by light in photocatalytic reactions is crucial. The tandem oxidative coupling of alcohols and amines is an attractive route to synthesize imines. Here, we unravel the performance and underlying reaction pathway in the visible-light-driven tandem oxidative coupling of benzyl alcohol and aniline employing Au/CeO2 nanorods as catalysts. We propose an alternative reaction pathway for this transformation that leads to improved efficiencies relative to individual CeO2 nanorods, in which the localized surface plasmon resonance (LSPR) excitation in Au nanoparticles (NPs) plays an important role. Our data suggests a synergism between the hot electrons and holes generated from the LSPR excitation in Au NPs. While the oxygen vacancies in CeO2 nanorods trap the hot electrons and facilitate their transfer to adsorbed O2 at surface vacancy sites, the hot holes in the Au NPs facilitate the α-H abstraction from the adsorbed benzyl alcohol, evolving into benzaldehyde, which then couples with aniline in the next step to yield the corresponding imine. Finally, cerium-coordinated superoxide species abstract hydrogen from the Au surface, regenerating the catalyst surface.

Published
2020
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2. Exploiting the Synergetic Behavior of PtPd Bimetallic Catalysts in the Selective Hydrogenation of Glucose and Furfural

Author

Pedro H. C. Camargo, Sébastien Paul, Priscilla M. de Souza, Anderson G. M. da Silva, Lishil Silvester, Robert Wojcieszak, Cibele G. Fernandes, Thenner S. Rodrigues, Universidade Federal do Rio de Janeiro (UFRJ), Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille, Data Aware Large Scale Computing (DATAMOVE ), Inria Grenoble - Rhône-Alpes, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire d'Informatique de Grenoble (LIG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Universidade de São Paulo (USP), Laboratoire de catalyse de Lille - UMR 8010 (LCL), Université de Lille, Sciences et Technologies-Centrale Lille-Centre National de la Recherche Scientifique (CNRS), ENSCL, CNRS, Centrale Lille, Univ. Artois, Université de Lille, Unité de Catalyse et Chimie du Solide - UMR 8181 [UCCS], Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), and Universidade de São Paulo = University of São Paulo (USP)

Subjects
lcsh:Chemical technology, 010402 general chemistry, Furfural, 01 natural sciences, Catalysis, Furfuryl alcohol, lcsh:Chemistry, chemistry.chemical_compound, Hydrogenolysis, Furan, sorbitol, Pd, [CHIM]Chemical Sciences, lcsh:TP1-1185, Physical and Theoretical Chemistry, Bimetallic strip, Tetrahydrofuran, Pt, bimetallic, hydrogenation, furfural, X-ray photoelectronspectroscopy (XPS), 010405 organic chemistry, X-ray photoelectron spectroscopy (XPS), [CHIM.CATA]Chemical Sciences/Catalysis, ESPECTROSCOPIA, 0104 chemical sciences, lcsh:QD1-999, chemistry, Chemical engineering, Selectivity
Abstract

International audience; Mono and bimetallic catalysts based on Pt and Pd were prepared by a co-precipitation method. They were tested in liquid phase hydrogenation reactions of glucose and furfural at low temperature and pressure. The bimetallic PtPd/TiO2 catalyst proved to be an efficient material in selectively hydrogenating glucose to sorbitol. Moreover, high furfural conversion was attained under relatively soft conditions, and the furfuryl alcohol selectivity was strongly affected by the chemical composition of the catalysts. Furfuryl alcohol (FA) was the major product in most cases, along with side products such as methylfuran (MF), furan, and traces of tetrahydrofuran (THF). These results showed that the PtPd bimetallic sample was more active relative to the monometallic counterparts. A correlation between the catalytic results and the physicochemical properties of the supported nanoparticles identified key factors responsible for the synergetic behavior of the PtPd system. The high activity and selectivity were due to the formation of ultra-small particles, alloy formation, and the Pt-rich surface composition of the bimetallic particles supported on the TiO2 nanowires.

Published
2019
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