Earth abundant metal catalysts stabilized by porous N-doped carbon

• Applicant: Professor Dr. Rhett Kempe
• Subject Area: Inorganic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 461481491

The replacement of rare noble metals by earth abundant metals has been demonstrated successfully for homogenous catalysts in recent years. Reusable and nano-structured hydrogenation and dehydrogenation catalysts, based on abundantly available metals, with a broad scope in organic synthesis have been developed to a much lesser extent. The main criticism arose from the observation that earth abundant metal are much less active in nanostructured catalyst in comparison to noble metals. Polymer based SiCN and SiC materials combine material specific characteristics such as thermal robustness and corrosion resistance with easy processing and possible shaping or structuring at low temperatures in diverse organic solvents. This easy processing also permits the synthesis of highly active catalysts.In four published manuscripts, in “Angewandte Chemie”, in “Nature Communication” (2x), and in “Nature Catalysis”, the potential of metal-SiCN nanocomposites as reusable catalysts and our expertise in 3d-metal catalysis (heterogeneous) have been demonstrated. In this project, we plan to show that nanostructured 3d-metal catalysts could be superior in activity and selectivity compared to noble metal catalysts and propose 1. the development of novel porous N-doped SiC supports and 2. the design of active and selective 3d-metal catalysts for hydrogenation and dehydrogenation reactions. Both aims are strongly linked since the support synthesis is the basis for developing novel highly active catalysts.Regarding 1.: SiCN and SiC have material specific advantages and disadvantages as porous supports for metal catalysts. SiCN gave significantly smaller and more reactive metal nanoparticles while the generation of high specific surfaces is a problem. The stabilization of especially small and reactive metal nanoparticles can be explained by the presence of N-atoms in the supports. They stabilize metal ions and clusters or particles via coordination during synthesis and catalysis to suppress growth of larger aggregates. SiC is easier to synthesize since the precursor polymers are not hydrolysis sensitive and higher specific surfaces can be generated. Unfortunately, the N-atoms which stabilize very small and highly reactive metal nanoclusters or particles are not present. A combination of the advantages would be porous N-doped SiC. Preliminary works support this hypothesis. Regarding 2.: In this subproject, we are interested in: a) the cobalt catalyzed reductive amination for the synthesis of primary amines under mild conditions, b) the hydrogenation of nitriles in the presence of functional groups easily to hydrogenate, and c) the design of selective (de)hydrogenation catalysts of so far rarely or never used 3d metals.

• DFG Programme: Research Grants