Over A bio-based circular economy: refining lignocellulose and the role of catalysis

By professor Bert F. Sels (KU Leuven)

Abstract

In a circular economy, chemicals and products are re-used and recycled as much as possible. However, a 100% recuperation is impossible, and therefore chemicals production remains a necessity. In order to reduce the CO₂ footprint, utilization of renewable feedstock to fill such feedstock deficiency may be gradual way towards sustainable chemicals and products, provided that bio-refining is sustainable (e.g., utilization of renewable energy and CO₂ capturing when necessary) and cost-effective. Biorefineries are key in such an idealized circular (bio) economy.

The goal of a ‘bio-refinery’, in analogy to the petro-refinery, is to fractionate a raw renewable carbon resource into specific and purified product mixtures, creating valuable streams which can be processed further by the chemical industry. The most abundant and probably most promising sustainable resource is lignocellulose, which is the structural material of plant biomass. Many biorefinery schemes focus on (hemi)cellulose valorisation, while the complex lignin fraction is regarded as a waste product that can be implemented in low-value applications, but is mostly burned for energy recuperation. In pursuing more added value, the production of platform chemicals or fuels from lignin clearly remains one of the foremost challenges in current biomass conversion. 

But also, whatever success we reach with lignin, since biomass contains large amounts of carbohydrates, their utilization into useful products remains essential for every lignocellulosic biorefinery. This contribution will therefore also show creation of novel chemical platforms, in addition to the well-known furanics, which may strongly contribute to the creation of a genuine bio-based chemical and biofuel industry, showing lower CO₂ footprints. Chemocatalysis can play a leading role in the chemical transformations, but may not yet be mature enough to enter the final steps to commercialization.

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