The poisoning level of Pt/C catalysts used in PEM fuel cells by the hydrogen feed gas impurities: The bonding strength

11 Postole, Georgeta Auroux, AlineProton exchange membrane fuel cells (PEMFCs) most likely will us reformed fuel as the primary source for the anode feed despite it nearly always contains carbon monoxide or ammonia. In this paper, the microcalorimetry technique was employed to study and compare the poisoning effect of pollutants such as CO and NH3 on three commercial carbon-supported platinum catalysts with high Pt loading, aimed to be used in PEMFCs applications. Microcalorimetric measurements were performed at 80 degrees C and the results were compared with those obtained from hydrogen adsorption in similar conditions. All the catalysts exhibited significantly higher differential heats of CO adsorption in comparison with NH3 and hydrogen adsorption, indicating that carbon monoxide will be primarily adsorbed in case of co-adsorption, while ammonia and hydrogen will compete in the adsorption process on the same type of active sites. The irreversibly (chemically) amount of adsorbed molecules on Pt/C surfaces decreases in the order: CO >> NH3 > H-2. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved

Catalytic steam reforming of methane over doped and undoped ceria - the impact of H2S

internationalInternational audienc

The poisoning level by various pollutants of Pt/c commercial catalysts used in PEMFC

internationa

Sulfur-promoted CeO2 and Ir/CeO2 catalysts for steam reform-ing of methane under water-deficient conditions. [+ Affiche]

Internationa

Development of a Novel Method for the Fabrication of Nanostructured Zr(x)Ni(y) Catalyst to Enhance the Desorption Properties of MgH2

© 2020 by the authors. The present work involves the development of a novel method for the fabrication of zirconium nickel (Zr(x)Ni(y)) alloy used as a nanocatalyst to improve the hydrogen storage properties of the Mg/MgH2 system. The catalyst was fabricated through the high-pressure reactor and activated under hydrogen prior to being mechanically milled with the MgH2 for 5 h under argon. The microstructure characterisation of the samples was determined via SEM-EDX (scanning electron microscope analysis–energy dispersive X-ray spectroscopy), XRD (X-ray diffraction) and FE-HRTEM (field emission high resolution transmission electron microscopy), and the desorption characteristic of the nanocomposite (10 wt.% Zr(x)Ni(y)–MgH2) was determined via TPD (temperature-programmed desorption). The nanostructured MgH2 powder milled with 10 wt.% of the activated Zr(x)Ni(y) based nanocatalyst resulted in a faster hydrogen release—5.9 H2-wt.% at onset temperature 210 °C/peak temperature 232 °C. The observed significant improvement in the hydrogen desorption properties was likely to be the result of the impact of the highly dispersed catalyst on the surface of the Mg/MgH2 system, the reduction in particle size during the ball milling process and/or the formation of Mg0.996Zr0.004 phase during the milling process.</jats:p

Calorimetric study of the reversibility of CO pollutant adsorption on high loaded Pt/carbon catalysts used in PEM fuel cells

ENERGIE+AAU:GPO:SBENon

Etude de l’impact de la nanostructuration de MgH2 sur les propriétés de stockage de l’hydrogène

SSCI-VIDE+ATARI+ASK:GPO:AAU:BGLNational audienceA. Kamaruddin, G. Postole, A. Auroux, B. GaleyUniversité Lyon 1, CNRS, UMR 5256, IRCELYON, Institut de recherches sur la catalyse et l’environnement de Lyon, 2 avenue Albert Einstein, F-69626 Villeurbanne, FranceL’hydrogène est mondialement reconnu comme un vecteur énergétique à fort potentiel et comme un substituant possible aux carburants fossiles. Mais une utilisation à grande échelle nécessite un moyen fiable et sûr de le stocker [1]. Le stockage sous forme solide dans des hydrures métalliques est très prometteur grâce à leur grande capacité massique et volumique. Néanmoins, l’utilisation industrielle est encore limitée par une haute stabilité thermodynamique et une cinétique de sorption lente. De nombreuses recherches ont été menées pour améliorer la cinétique et réduire la température de désorption mais les progrès faits à ce jour ne sont pas suffisants pour atteindre les exigences d’un couplage avec une pile à combustible basse température [2]. Le but du travail réalisé est d’améliorer la cinétique d’hydrogénation et de déshydrogénation du système Mg/MgH2, tout en gardant sa grande capacité de stockage réversible. Les échantillons ont été préparés par broyage planétaire, puis caractérisés par DRX et MEB. Deux techniques d’analyse thermique complémentaires ont ensuite été utilisées pour étudier l’impact du broyage sur les propriétés de déshydrogénation de MgH2 : DSC (Differential Scanning Calorimetry) et DTP (Désorption en Température Programmée). Grâce à des mesures à différentes vitesses de chauffe l’énergie d’activation des échantillons a été calculée. Enfin, afin d’analyser l’impact de la nanostructuration sur les propriétés d’hydrogénation du magnésium et sur la réversibilité du système formé, un appareil volumétrique de type Sievert a été utilisé.Remerciements : les auteurs remercient l’ANR (Agence Nationale de Recherche) pour le support financier (subvention 3H2/2016). [1] Ş. E. C. Şener et al. Renewable and Sustainable Energy Reviews 2018, 81, 2335-2342.[2] V.A. Yartis et al. International Journal of Hydrogen Energy 2019, 44, 7809–59

Solution combustion synthesis of noble metal-loaded ceria catalysts and application to hydrogen production and purification for fuel cells

National @ ECI2D+TSN:GPO:FMO:LPIInternational audienceMesoporous ceria powders doped with up to 2 wt% platinum-group metals (Pt, Pd, Ir, Rh, Ru) were synthesized in one step by the ambient air combustion of an aqueous solution of ceric ammonium nitrate (CAN), chloride or nitrate metal precursor, and glycine or oxalyl dihydrazide used as fuels [1, 2] (Fig. 1). The structural properties of the powders, and the influence of such parameters as metal loading and thermochemical post-treatments, were investigated combining aberration-corrected HRTEM, SEM, in situ XRD, XPS, DRIFTS, and Raman spectroscopy. The materials, whose texture appeared spongy at the micrometer scale and depended on the fuel nature, exhibited ca. 30 nm-sized ceria crystallites with a layered structure at the nanoscale. Comparisons with pure ceria showed that the presence of the metal inhibited ceria grain coarsening. The powders were successfully employed as catalysts for the production of hydrogen from the steam reforming of methane (SRM) in water-deficient conditions, and for the purification of hydrogen through the preferential oxidation of CO (PROX).For SRM, 0.1 wt% Ir-CeO2 exhibited the best performances. Due to its higher Ir dispersion and stronger Ir-CeO2 interaction, the combustion-synthesized material was more active and stable than its conventionally prepared counterpart [3, 4]. Moreover, it was not permanently deactivated by the introduction of H2S in the reactant feed [4]. After reducing treatments, Ir nanoparticles anchored at the surface of ceria grains were imaged (Fig. 1), and their size (ca. 2 nm) and morphology did not evolve upon further heating at up to 900 °C. A complete picture of the Ir-CeO2 interface could be established, with the presence of Irx+-O2--Ce3+ entities along with oxygen vacancies [3].For CO oxidation and PROX, systematic comparisons between the samples, which exhibited similar metal nanoparticle sizes, allowed us to rank the Pt-group metals [5]. Rh-CeO2 appeared as the most active system in H2-free CO oxidation. The presence of H2 boosted the CO oxidation activity of all catalysts, except that of Rh-CeO2, which promoted the decomposition of CO and the subsequent formation of methane. Pt-CeO2, which was the most active and selective PROX catalyst, was further investigated by changing the nature of the fuel and the metal precursor. Although the catalyst activities were influenced by such parameters, the selectivities were strikingly unaffected.[1] V. M. Gonzalez-Delacruz, F. Ternero, R. Pereniguez, A. Caballero, and J. P. Holgado, Appl. Catal. A 384 (2010) 1-9.[2] M. S. Hegde, G. Madras, and K. C. Patil, Acc. Chem. Res. 42 (2009) 704-712.[3] T.S. Nguyen, G. Postole, S. Loridant, F. Bosselet, L. Burel, M. Aouine, L. Massin, P. Gélin, F. Morfin, L. Piccolo, J. Mater. Chem. A 2 (2014) 19822-19832.[4] G. Postole, T.S. Nguyen, M. Aouine, P. Gélin, L. Cardenas, L. Piccolo, Appl. Catal. B 166-167 (2015) 580-591.[5] T.S. Nguyen, F. Morfin, M. Aouine, F. Bosselet, J.L. Rousset, L. Piccolo, Catal. Today (2015), in press

enhancing kinetic properties of magnesium hydride for hydrogen storage applications

SSCI-VIDE+ATARI+KAM:VFO:AAU:GPONational audienceMagnesium hydride MgH2 is a non-naturally occurring compound that can be synthesized through direct hydrogenation of Mg metal which is abundant in nature, inexpensive, and non- toxic.In the present work, we are trying to lower the hydrogen adsorption/desorption (A/D) temperature of MgH2 to a reasonable level to allow its widespread use as a viable hydrogen storage medium, while still keeping its advantages over other forms of storage, namely safety and economics. Nanosizing and catalysis are the parameters used to improve the kinetic properties of hydrogen (A/D) processes of MgH2.Ball-milling process is applied in this study for MgH2 nanostructuring. The main goal of such approach is to raise the value of the specific area, which in turn may lead to a decrease in the energy needed to start desorbing the hydrogen content since the molecules which are at or close to the surface react more readily than those which are trapped deep inside particle agglomerates.The analytical method used to follow the hydrogen desorption kinetics of the processed MgH2 samples is Temperature Programmed Desorption (TPD) via a Thermo-Fischer TPDRO 1100 apparatus. The fresh and ball-milled powders are characterized by using techniques such as XRD, XPS, SEM. The results obtained show that freshly milled MgH2 sample presents improved properties with a H2 desorbing peak centered at 406°C against 417°C for the commercial powder. Interestingly the milled sample stored during two or three weeks desorb H2 at even lower temperatures but with multiple peaks which may indicate that during the storage of the ball-milled powder, small agglomerates begun to form thus impacting the particle size and distribution

On the promoting effect of H2S on the catalytic H-2 production over Gd-doped ceria from CH4/H2O mixtures for solid oxide fuel cell applications

ENERGIE:MATERIAUX:SURFACES+GPO:FBS:GBR:NSP:PGEIn order to understand the exceptional tolerance of ceria to high sulfur levels in the fuel for further SOFC applications, the interaction of sulfur with a commercial Ce0.9Gd0.1O2-x (CGO, from Praxair) and its influence on H-2 production from CH4/H2O mixture was studied. The activity tests were performed at 750 C, in the presence of H2S and under gradual internal reforming conditions (large excess of CH4 with respect to water vapor, 10:1). The presence of H2S in the reactant mixture promoted the catalytic activity of CGO. The nature of various species formed by sulfur-ceria interaction is discussed based on CH4-TPR, XRD, XPS, and in situ FTIR results. H2S reacts with ceria fraction in CGO and generates new catalytic sites with improved reactivity toward CH4. The formation and stabilization of oxygen vacancies by S-insertion in ceria lattice are evidenced and directly related to the improved activity. The detrimental effect of Ce2O2S phase, when formed, on the catalytic activity of doped ceria is confirmed. (C) 2014 Elsevier Inc. All rights reserved