# Depolymerisation of γ‐Valerolactone Organosolv Lignins with Unsupported Molybdenum‐Based Catalysts

## TL;DR

This paper shows how to efficiently break down lignin into useful oils and aromatic compounds using molybdenum catalysts and ethanol under high-pressure conditions.

## Contribution

The study introduces an efficient depolymerisation method for γ-valerolactone organosolv lignins using unsupported molybdenum-based catalysts.

## Key findings

- Over 90% yields of low-molecular-weight lignin oils were achieved with minimal char formation.
- Aromatic monomer yields ranged from 7–16 wt%.
- Product properties can be tuned by adjusting depolymerisation conditions like temperature and catalyst.

## Abstract

Lignin is an attractive feedstock for a wide variety of applications ranging from aromatic chemicals and transportation fuels to resins and coatings. Emerging biorefinery concepts, like the organosolv process, enable the separation of all the lignocellulose components, and moreover, produce lignins of high quality and purity susceptible to valorisation by depolymerisation. In this work, we focus on the depolymerisation of lignins obtained by γ‐valerolactone (GVL) organosolv fractionation of four biomass feedstocks, eucalyptus, white birch, sugarcane bagasse and Scots pine. We demonstrate that lignins extracted with the GVL process are depolymerised using unsupported molybdenum‐based catalysts under reductive conditions in supercritical ethanol. As a result, over 90% yields of low‐molecular‐weight lignin oils are obtained with minimal char formation, yields of the aromatic monomers being 7–16 wt%. Furthermore, the design of experiments method is used to analyse the effect of depolymerisation conditions, catalyst, hydrogen loading and temperature, on the yields and properties of the product fractions. Notably, we show that the properties of the lignin oils and monoaromatics can be tuned towards the targeted application by modifying the depolymerisation conditions.

Lignins from γ‐valerolactone organosolv fractionation were depolymerised in ethanol using unsupported molybdenum catalysts. Over 90% yields of low‐molecular‐weight lignin oil were obtained with minimal char formation, yields of the aromatic monomers being 7–16 wt%. Furthermore, we show how the product properties, like molecular weight and hydroxyl content, can be tuned by modifying the depolymerisation conditions.© 2026 WILEY‐VCH GmbH