Transforming biomass and petroleum-based byproducts into transportation fuel is of high interest given the depletion of fossil carbon resources and the climate impact of the petroleum industry. A tandem catalysis method known as alkane metathesis may serve as an alternative to the current Fischer-Tropsch process for converting C3-C8 alkanes into C9-C19 chains for fuel, but previous reports of alkane metathesis suffer from poor selectivity and degradation of the catalytic species. We aim to modify both an iridium catalyst that can perform alkane dehydrogenation (step 1) and olefin hydrogenation (step 3) as well as a ruthenium catalyst that can perform olefin metathesis (step 2) by incorporating these complexes into polymeric scaffolds. We propose that embedding the iridium and ruthenium complexes within polymeric structures will help overcome the reported catalyst loading, stability, and incompatibility issues, as well as enhance overall reactivity and product selectivity. For both complexes, we have modified the ligand design to include vinylic groups so that the ligand precursors can be directly copolymerized with commercial vinylic monomers. Synthetic work is ongoing, though our initial results with the POCOP pincer ligand for iridium indicate that we can successfully incorporate it into a polymer and subsequently metalate it. Concurrently, we are using small molecule iridium and ruthenium complexes to benchmark the dehydrogenation and metathesis reactions, respectively, for later comparison to the polymer-supported complexes.

Towards tandem catalysis using Ir and Ru catalysts for alkane metathesis

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