Lactic acid as a platform chemical in the biobased economy: the role of chemocatalysis

TLDR

Upcoming bio‑refineries will manufacture future fuels, chemicals and materials, and lactic acid is a promising platform molecule that can bridge polysaccharide feedstock to added‑value products, though large‑scale production faces sustainability challenges such as gypsum waste and costly purification. This contribution critically reviews advances in homogeneous and heterogeneous chemocatalysis for producing and transforming lactic acid and other α‑hydroxy acids, highlighting their potential. The review focuses on chemocatalytic routes that convert sugars and glycerol into lactic acid and its esters using chemocatalysts, summarizing key developments in both homogeneous and heterogeneous systems.

Abstract

Upcoming bio-refineries will be at the heart of the manufacture of future transportation fuels, chemicals and materials. A narrow number of platform molecules are envisioned to bridge nature's abundant polysaccharide feedstock to the production of added-value chemicals and intermediate building blocks. Such platform molecules are well-chosen to lie at the base of a large product assortment, while their formation should be straightforward from the refined biomass, practical and energy efficient, without unnecessary loss of carbon atoms. Lactic acid has been identified as one such high potential platform. Despite its established fermentation route, sustainability issues – like gypsum waste and cost factors due to multi-step purification and separation requirements – will arise as soon as the necessary orders of magnitude larger volumes are needed. Innovative production routes to lactic acid and its esters are therefore under development, converting sugars and glycerol in the presence of chemocatalysts. Moreover, catalysis is one of the fundamental routes to convert lactic acid into a range of useful chemicals in a platform approach. This contribution attempts a critical overview of all advances in the field of homogeneous and heterogeneous catalysis and recognises a great potential of some of these chemocatalytic approaches to produce and transform lactic acid as well as some other promising α-hydroxy acids.