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Communication Dans Un Congrès Année : 2014

Fast and rational design of CO2-resistant hydrogenation catalysts by operando DRIFTS studies

J. Scalbert
  • Fonction : Auteur
C. Daniel
Y. Schuurman
Frédéric Meunier
  • Fonction : Auteur

Résumé

H2 can be produced from organic waste fermentation and CO2 is formed alongside in large concentrations in some cases. There is an interest in understanding any effects that CO2 could have on a catalytic reaction in which the biomass-derived H2 is used, as traces of CO2 may remain even after purification. An alumina-supported platinum catalyst used for toluene hydrogenation at low-temperature (i.e. 348 K) was fully and permanently deactivated upon CO2 introduction in a H2/toluene feed [1]. Strongly-bound carbonyl species were observed by operando diffuse reflectance FTIR spectroscopy (DRIFTS) and were shown to irreversibly poison the Pt surface sites. The DRIFTS operando data were crucial in revealing the origin of the deactivation, since no measurable concentration of CO could be observed in the reactor effluents. A Rh/alumina (with a Rh dispersion of 55%) was shown to be only partly deactivated by the introduction of 1.7% CO2 during the hydrogenation of toluene, contrary to the case of Pt/alumina. The Rh surface was only partially covered by carbonyl species derived from the CO2 (Fig. 1, left) and toluene could successfully compete for adsorption with some of the linearly adsorbed CO [2]. The DRIFTS data suggested that the most resistant sites were Rh atoms from low index plans. A Rh/silica with a Rh dispersion of 19% essentially showed no deactivation by CO2. No carbonyl could be observed under a feed containing 10 % CO2 (Fig. 1, left). Carbonyls formed from CO adsorption at 348 K were readily removed when toluene was introduced, while those were stable under Ar (Fig. 1, right). The exceptional resistance of the Rh/Silica was related to both (i) a lower ability to adsorb and dissociate CO2 and (ii) a large fraction of dense plan Rh atoms on which toluene successfully competes with CO for adsorption.
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Dates et versions

hal-01057869 , version 1 (25-08-2014)

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  • HAL Id : hal-01057869 , version 1

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J. Scalbert, C. Daniel, Y. Schuurman, Frédéric Meunier. Fast and rational design of CO2-resistant hydrogenation catalysts by operando DRIFTS studies. Tailor 2014 workshop, Apr 2014, St Paul de Vence, France. ⟨hal-01057869⟩
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