Tuning coordinated supported catalysts: Carboxylic acid-based ligands to improve ceria-supported Pt catalysts for hydrosilylation

Abstract

Ligand-coordinated supported catalysts (LCSCs) with highly-dispersed metal centers are of growing interest to bring the high selectivity and metal utilization efficiency of isolated, well-defined metal centers to a solid support for recyclability and stability. Pt LCSCs with bidentate N-based ligands have shown high activity, selectivity, and stability in hydrosilylation catalysis. Here, we tuned Pt LCSCs with carboxylic acid-based ligands as “anchoring ligands” with bidentate N-based ligand or as “coordination ligand.” X-ray photoemission spectroscopy and inductively coupled plasma mass spectrometry were performed after the test reaction, hydrosilylation of 1-octene, to evaluate the leaching of Pt. Using trimesic acid (TMA) as the “anchoring ligand” reduced Pt leaching from 34% after only 1 batch to ~25% after 4 batches. Using TMA as the “coordination ligand” creates a catalyst with 7 times higher turnover number than previous LCSCs. Two other carboxylic acid-based ligands were explored, both creating active and selective Pt hydrosilylation LCSCs.