Electronic Modification of Carbon Support Materials for Heterogeneous Catalysts by Heteroatom Functionalization
Most industrial production processes for chemical products make use of a heterogeneous catalyst. Such catalysts are important for the sustainable synthesis of chemical substances. Most of these catalysts are metallic nanoparticles (i.e., particles with dimensions of just a few nanometers). Due to their specific electronic structure and high number of available surface atoms they can induce the desired chemical conversions. To avoid agglomeration of the nanoparticles under reaction conditions, they are often immobilized on porous inorganic substrates, so-called “supports”. Carbon nanomaterials are attractive as support materials for metallic nanoparticles because they combine high surface area, high thermal stability, and high chemical inertness. Surface functional groups on the supports can act as anchoring sites for the metal particles and thus increase their stability during the catalytic conversion. In addition, heteroatoms (e.g., nitrogen, boron, sulfur, or oxygen) can modify the electronic properties of the carbon framework and the catalytically active metal particles. We investigate the effects of nitrogen doping in carbon materials with tailored structure on the activity, selectivity, and stability of catalysts. Such modification can affect the metal particles themselves but also the transport of reactants/products as well as the bulk properties of the catalyst particles on a micrometer scale. We aim for profound understanding into the influence of the support materials’ electronic properties on the catalyst performance to make heterogeneously catalyzed processes more energy efficient and sustainable to achieve real “green chemistry” catalysis.