Monolithic supports based on biomorphic SiC for the catalytic combustion of hydrogenElectronic supplementary information (ESI) available. See DOI: 10.1039/c6ra09127j

• Main Authors: Arzac, G. M, Ramírez-Rico, J, Gutiérrez-Pardo, A, Jiménez de Haro, M. C, Hufschmidt, D, Martínez-Fernández, J, Fernández, A
• Format: Journal Article
• Published: 13.07.2016
• ISSN: 2046-2069
• DOI: 10.1039/c6ra09127j

Catalytic hydrogen combustion was studied with H 2 /air mixtures in conditions that simulate the H 2 concentration of the exhaust gases from fuel cells (3-4% v/v H 2 in air). Pt-impregnated monoliths based on porous biomorphic SiC (bio-SiC) substrates were employed for the first time for this reaction. Capillary forces were exploited for the incipient impregnation of supports with H 2 PtCl 6 solutions. Freeze drying permitted us to obtain a homogeneous distribution of the active phase reducing accumulation at the monolith's outer shell. The supports and catalysts were characterized from a structural and thermal point of view. Catalytic tests were performed in a homemade reactor fed with up to 1000 ml min −1 H 2 /air mixtures and a diffusional regime (non-isothermal) was achieved in the selected conditions. Catalyst loading was tested in the range of 0.25-1.5 wt% Pt and 100% conversion was achieved in all cases. Temperatures were recorded at different points of the monoliths during the reaction showing anisotropic thermal behavior for selected bio-SiC substrates. These effects are of interest for heat management applications and were explained in correlation with thermal conductivity measurements performed on the supports. Pt-impregnated monoliths were also tested in less than 100% conversion conditions (1% v/v H 2 in air) and in powder form in kinetic conditions for comparative purposes. Application of biomorphic porous SiC monoliths as Pt catalysts supports for the catalytic combustion of hydrogen. Anisotropic thermal behaviour is highlighted.