31P Solid-State NMR-Enabled Development of a Pt/Aluminum Tripolyphosphate Catalyst for Selective C─O Bond Hydrogenolysis of Phenols.

Understanding the active structure of phosphate-based supports is essential for designing catalysts for selective C─O bond hydrogenolysis. Herein, 31P solid-state NMR analysis revealed that the support in our previously reported Pt/Al(PO3)3 catalyst was actually an aluminum condensed phosphate mixture (ACPM), rather than a single aluminum metaphosphate (AMP) phase, consisting of aluminum metaphosphate (AMP), aluminum cyclohexaphosphate (ACP), and aluminum tripolyphosphate (ATPP), with the ATPP phase located on the catalyst surface. Guided by these findings, a Pt/ATPP catalyst was developed, showing high selectivity for the hydrogenolysis of 4-heptylphenol to heptylbenzene. Mechanistic studies suggested that the Lewis acid sites on ATPP contribute to the enhanced selectivity by facilitating C─O bond activation, a key step in phenol hydrogenolysis.