High temperature stability of n-decanethiol by adsorption on nickel powders used as reforming catalysts in solid oxide fuel cells (SOFC)

Solid Oxide Fuel Cells (SOFC) are among the most promising electricity producing technologies. Their successful implementation and versatility depends upon a number of still not fully solved technological issues; namely, the possibility of using both fossil and renewable energy vectors is one of the most significant. Such energy vectors, constituting a crucial SOFC feedstock, are the natural gas, the biogas and all forms of fossil and renewable liquid fuels like diesel, biodiesel, 'green' diesel. These fuels require a conversion step because SOFC can use only H2 and CO. This conversion step is achieved through catalytic reforming and/or partial oxidation. The most successful catalysts are ceramic-supported bimetallic composites. The presence of sulphur in the fuels is detrimental to the catalysts and constitutes one of the basic hurdles in scaling-up and adopting commercially these conversion technologies. In this paper, the authors, based on their previous work on the role of sulphur on micronic Ni powders used as CH4 reforming catalysts, study the behaviour of medium size thiols adsorbed at the surface of the Ni powders and treated thermally in a differential reactor set-up. The Diffuse Reflectance Infra-red Fourier Transform Spectroscopy (DRIFTS) analyses before and after adsorption and thermal treatments have shown that these Ni surfaces stabilize the adsorbed hydrocarbon chains and alter their catalytic properties during reforming. These results are quite surprising and open the field to a positive synergy between surface chemists and engineers in an effort to better control the efficiency and improve the tolerance to sulphur of these reforming catalysts.