Biorefinery platforms – Sugars


BIOREFINERY PLATFORMS

Concept

- The sugar platform is defined as any combination of C5 (5 carbon atoms; xylose, pentose and ribose are the most common pentose sugars), C6 (6 carbon atoms; glucose, fructose and galactose are the most common hexose sugars) and/or C12 sugars (molecules containing two hexose sugar units) that exists within a pathway from biomass feedstock towards final biobased products.
- These simple sugars are reactive molecules that can be converted biologically or chemically into fuels, chemicals, materials. food and animal feed.
- Larger molecules such as oligosaccharides and polysaccharides are not included within the sugar platform.
- The traditional processes are based on utilizing sucrose (composed of glucose and fructose) derived from sugar crops (sugar beet or sugar cane) or glucose obtained after hydrolysis of starch (founded in wheat, corn barley, rye, triticale…).
- In advanced biorefineries, utilizing lignocellulosic biomass as feedstock, the biomass will typically undergo first pretreatment followed by enzymatic hydrolysis in order to release the sugars. Glucose will be produced from the cellulose whereas hydrolysis of the hemicellulose will result in a mixture of C5/C6 sugars. The composition of the hemicellulose fraction is very feedstock dependent.

Figure 1. Sugars platforms

Processing pathways and applications

- Fermentation. Glucose serves as the primary substrate for many biological fermentation processes providing access to a variety of important chemical building blocks (alcohols, organic acids, lipids and hydrocarbons) but also very high value fine chemicals (amino acids, vitamins, antibiotics, enzymes…). The mixed sugar platform in a lignocellulosic biorefinery can in theory produce the same products as glucose. The conversion can be using bacteria, fungi or yeast, genetically modified or not, in a variety of process conditions. The product of interest can also be produced intra-cell or extra-cell.
- Chemical processes. The sugars can also be converted by catalytic processes to useful chemical building blocks. The sugars can undergo selective dehydration, hydrogenation and oxidation reactions to give useful products. Some examples: sorbitol, furfural, glucaric acid, hydroxymethylfurfural (HMF) and levulinic acid.
- Thermochemical processes. Aqueous Phase Reforming (APR) enables the transformation of sugars into mixtures of drop-in hydrocarbons. The APR process catalytically converts sugars in an aqueous solution into hydrogen, CO2 and a mixture of alkanes, acids, ketones and aromatics. A series of condensation reactions then lengthen the carbon chains in the mixture of hydrocarbons. This mixture then undergoes hydroprocessing, isomerisation and distillation.

References

- E4tech, RE-CORD and WUR (2015) “From the Sugar Platform to biofuels and biochemicals”. Final report for the European Commission, contract No. ENER/C2/423-2012/SI2.673791. 
- IEA Bioenergy Task 42 (2020). “Biobased chemicals. A 2020 update”.

Popular Posts

Glucaric acid biorefineries

New HVO plant enters into operation in China

Shell to build an HVO biorefinery in Rotterdam

Hydrotreated Vegetable Oils (HVO) Biorefineries – The rise of renewable diesel

Topsoe’s HydroFlex and H2bridge technologies selected by Tidewater for its renewable diesel biorefinery in Canada