Toward Replacing Ethylene Oxide in a Sustainable World: Glycolaldehyde as a Bio‐Based C₂ Platform Molecule

Abstract

Fossil‐based platform molecules such as ethylene and ethylene oxide currently serve as the primary feedstock for the C2‐based chemical industry. However, in the search for a more sustainable chemical industry, fossil‐based resources may preferentially be replaced by renewable alternatives, provided there is realistic economic feasibility. This Review compares and critically discusses several production routes toward bio‐based structural analogues of ethylene oxide and the required adaptations for their implementation in state‐of‐the‐art C2‐based chemical processes. For example, glycolaldehyde, a structural analogue obtainable from carbohydrates by atom‐economic retro‐aldol reactions, may replace ethylene oxide's leading role. This alternative chemical route may not only allow the carbon footprint of conventional chemicals production to be lowered, but the introduction of a bio‐based pathway may also contribute to safer production processes. Where possible, challenges, drawbacks, and prospects are highlighted.

Perspectives for the Upgrading of Bio‐Based Vicinal Diols within the Developing European Bioeconomy

“…Among the olefins reachable through a DODH reaction, ethylene ( 1 ) and buta‐1,3‐diene ( 2 ) can theoretically be produced from EG and ERY, respectively. Ethylene ( 1 ) is the most important olefin produced around the globe with 140 Mt per year (market size of 127 billion US$ in 2017 with a cost of 1.2–1.3 US$ per kg) through steam cracking of naphtha and is considered as one of the most polluting petrochemical process regarding greenhouse gas emissions [52] . More than half its production is dedicated to the manufacturing of the most widely used plastic, namely, polyethylene, and it also contributes to the manufacturing of polystyrene and polyvinyl chloride [53] .…”

“…[101] It stands as one of the most important bulk chemicals with a global production of 31 Mt in 2018 with a predicted annual growth rate of 3-4 %. [52,102] It is expected to reach a market volume of 58 billion US$ by the end of 2023. [103] Currently, 72 % of the production of 42 is dedicated to the preparation of glycols, with an annual volume of 26 Mt, as well as a non-negligible part going to the preparation of ethoxylates as surfactants.…”

A catalytic approach via retro-aldol condensation of glucose to furanic compounds

“…GA is a remarkable small molecule with both aldehyde and alcohol functionality, which has high potential to be a renewable alternative for petroleum-based ethylene oxide. 3 GA is prone to many side reactions due to its highly reactive nature, thus it is often sequentially stabilized after formation, such as by hydrogenation to ethylene glycol. 4 Other synthetic methods have also been developed for the transformation of GA, mainly including oxidation, aldol reaction, amination etc.…”

“…al. [3][4]5 Nevertheless, new transformations that create platform chemicals or building blocks for fine chemicals are greatly needed to boost contemporary biorefinery concepts toward a sustainable world.…”

Heterogeneous Base‐Catalyzed Conversion of Glycolaldehyde to Aldotetroses: Mechanistic and Kinetic Insight

“…Increasingly, attention has been devoted to the prospect of building bio‐sourced molecules up from the smallest possible carbohydrates such as the C2 aldose glycolaldehyde (GA) [2c,4] . GA can be derived by thermal conversions of glucose and other carbohydrates and such processes are currently being developed, including pyrolysis, gasification, catalytic retroaldol cleavage, use of supercritical water or thermal cracking in yields of up to 74 % [4b,5] . GA itself emerges as a precursor for polymer or pharmaceuticals production upon conversion to other C2 compounds such as ethylene glycol, ethanolamine, glyoxal, glycolic acid, or glyoxylic acid [2f,4b] …”