Lignin is an abundant biopolymer with a high carbon content and high aromaticity. Despite its potential as a raw material for the fuel and chemical industries, lignin remains the most poorly utilised of the lignocellulosic biopolymers. Effective valorisation of lignin requires careful fine‐tuning of multiple “upstream” (i.e., lignin bioengineering, lignin isolation and “early‐stage catalytic conversion of lignin”) and “downstream” (i.e., lignin depolymerisation and upgrading) process stages, demanding input and understanding from a broad array of scientific disciplines. This review provides a “beginning‐to‐end” analysis of the recent advances reported in lignin valorisation. Particular emphasis is placed on the improved understanding of lignin's biosynthesis and structure, differences in structure and chemical bonding between native and technical lignins, emerging catalytic valorisation strategies, and the relationships between lignin structure and catalyst performance.

With these guidelines, we aim to unite the lignin-first biorefining research field around best practices for performing or reporting feedstock analysis, reactor design, catalyst performance, and product yields.

The discovery and investigation of novel and efficient pathways for the conversion of biomass into fuels and chemicals are among the big challenges facing heterogeneous catalysis nowadays. However, not all experience gained in the transformation of hydrocarbons over the last 100 years can directly be transferred to biomass conversion. In this article, we will discuss how the specific properties of biomass pose new requirements on the processes and on the solids that are used as catalysts for their conversion. Due to the importance of lignocellulosic materials, which constitute ca. 95% of the total plant biomass, we will focus mostly on the desired properties of solid catalysts for the conversion of these polymeric biomolecules. Research in this field is very intense presently and novel transformations and catalysts are being discovered at a high rate. This paper thus focuses on the concepts that govern biomass transformation instead of giving a complete and comprehensive survey of the literature, which would be outdated within a short time.