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

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

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

Internationa

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

Thioresistant Ir-CeO2 methane steam reforming catalysts for solid-oxide fuel cell applications

International @ ENERGIE+GPO:TSN:PGE:LPIInternational audienceNon