Hydrodeoxygenation of Lignin-derived Phenols into Cycloalkanes by Atomically Dispersed Pt-Polyoxometalate Catalysts

We report atomically dispersed Pt sites anchored on polyoxometalate cesium salts as robust and durable catalysts for upgrading lignin into hydrocarbons at relatively mild conditions. Experimental results and DFT calculations cross-validate the catalytic performance, considering the porosity, acidity, H2 storage capacity, and HOMO-LUMO energy gap of these catalysts. The optimal Pt0.4/CsPW-H2 catalyst enables the hydrodeoxygenation (HDO) of a diverse range of lignin-derived phenolics into hydrocarbons with up to 97% yield at the conditions of 150 °C and 0.1 to 2MPa H2. A lignin oil from the reductive catalytic fractionation (RCF) of Eucalyptus wood can be transformed into cyclohexanes with a 32.7wt% yield under a solvent-free condition. This catalyst demonstrates excellent reusability in the HDO of 4-propyl guaiacol for 20 cycles, achieving a 15095 molpropylcyclohexane molPt-1 total turnover number (TON). This work broadens the horizons of designing highly efficient catalytic systems aimed at sustainably producing liquid fuels from lignin.