Lignin to Monoaromatics with a Carbon-Nanofiber-Supported Ni-CeO2-x Catalyst Synthesized in a One-Pot Hydrothermal Process

The synthesis of effective heterogeneous catalysts is one of the main challenges toward hydrothermal processing of wood-derived biomass into marketable sustainable chemicals. Many of these catalysts are based on noble metals and are normally synthesized using multiple steps in time-consuming processes. Here, we have developed a one-pot catalyst synthesis method for Ni-CeO2-x supported on carbon nanofibers. In situ H-2 production through formic acid decomposition enabled the synthesis of catalysts in their reduced form, with ceria as Ce3+ and presence of metallic Ni. This catalyst promoted Kraft lignin conversion in supercritical water at short reaction times with a 79 wt % yield of a bio-oil composed of nearly 69 wt % of monoaromatics. Thus, lignin breakdown was achieved without resourcing to noble metal catalysts, molecular H-2, or cosolvents, with a decrease in catalyst synthesis time and unit operations and with an attractive yield of a chemically uniform product fraction.

Automated summary

A one-pot catalyst synthesis method has been developed for Ni-CeO2-x supported on carbon nanofibers, allowing for the conversion of Kraft lignin in supercritical water with a high yield of 79% bio-oil, primarily composed of monoaromatics. This approach achieved lignin breakdown without the need for noble metal catalysts, molecular H-2, or cosolvents, resulting in reduced catalyst synthesis time and unit operations and a desirable yield of a chemically uniform product fraction.