Direct conversion of lignocellulosic biomass into aromatic monomers over supported metal catalysts in supercritical water

[Display omitted] •Biomass could be converted into aromatic monomers in supercritical water.•Pt/C, Rh/C, or Pd/C catalysts increased the aromatic monomer yields.•Yields of aromatic monomers increased with increasing amount of water.•Pt/C and Rh/C catalysts increased activity with reuse for up to three cycles. With the goal of contributing to the valorization of lignocellulosic biomass, we investigated the conversion of Japanese cedar and bagasse into aromatic monomers over charcoal-supported metal catalysts in supercritical water. Over Ru/C, Japanese cedar was converted into gaseous products such as methane and carbon dioxide. Pd/C, Pt/C, and Rh/C were active for the conversion of Japanese cedar into aromatic monomers, and the monomer yields over these catalysts decreased in the order Pt/C > Rh/C > Pd/C when the conversion reaction was carried out at 673 K for 1 h. Bagasse, an herbaceous biomass, could also be converted into aromatic monomers by reaction over Pt/C, Rh/C, or Pd/C at 673 K for 1 h. Catalyst reusability experiments revealed that the activities of Pt/C and Rh/C for Japanese cedar conversion increased with reuse, up until the third reuse.