sulfur resistance of bi-metallic Ni catalysts

• Applicant: Privatdozent Dr.-Ing. Martin Seipenbusch
• Subject Area: Chemical and Thermal Process Engineering ; Mechanical Process Engineering
• Term: from 2016 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 323201401

The loss of catalytic activity due to poisoning of metallic surfaces with sulfur is problematic in many areas of application. Examples for this are the conversion of biomass into liquid fuels and chemicals, the catalytic reduction of higher polyaromatics in diesel fuel and the operation of solid oxide fuel cells. An increase of the sulfur resistance of heterogeneous catalysts is therefore of great interest.The aim of the proposed project is the testing of the hypothesis according to which a change in the electronic band structure of a metal catalyst can lead to an increase in sulfur resistance. This shall be accomplished by alloying a base metal with two other components. Literature search yielded two Ni-alloys of particular interest, which will be investigated as model system. For one this is Ni-Ru, for which a change in the density of states at the Fermi-level and at the same time an alteration of S-adsorption were theoretically shown. The second system is Ni-Sb, for which a strong increase in S-resistance was experimentally shown but no mechanistic explanation could be found. For both systems the effect of sulfur on the catalytic properties and the mechanisms of deactivation shall be studied making use of online characterization methods and the excellent possibilities for particle structuring offered by aerosol systems.From the definition of the project goals three core questions result:How does the adsorption of sulfur depend on the composition of alloyed particles?How does the electronic structure of alloyed metal particles change with composition?How does the catalytic activity of a test reaction change with time in the presence of sulfur and as a function of particle composition?The experimental procedure can be organized in three steps. The first step will comprise the generation of binary alloyed particles of controlled size and composition, which will be carefully characterized. For the latter online aerosol methods but additionally offline tools will be employed. A core online tool will be aerosol photoemission spectrometry (APES), which allows the characterization of the electronic structure of the particles. In a second step sulfur adsorption on the particle surfaces will be investigated, also relying in part on APES. The third step will focus on the investigation of the catalytic activity of the structures and their sulfur resistance in dependence on particle composition.

• DFG Programme: Research Grants