Volume I: Results of Screening for Potential Candidates from Sugars and Synthesis Gas
This report identifies twelve building block chemicals that can be produced from sugars via biological or chemical conversions. The twelve building blocks can be subsequently converted to a number of high-value bio-based chemicals or materials.
Building block chemicals, as considered for this analysis, are molecules with multiple functional groups that possess the potential to be transformed into new families of useful molecules.
The twelve sugar-based building blocks are 1,4-diacids (succinic, fumaric and malic), 2,5-furan dicarboxylic acid, 3-hydroxy propionic acid, aspartic acid, glucaric acid, glutamic acid, itaconic acid, levulinic acid, 3-hydroxybutyrolactone, glycerol, sorbitol, and xylitol/arabinitol.
The synthesis for each of the top building blocks and their derivatives was examined as a two-part pathway. The first part is the transformation of sugars to the building blocks. The second part is the conversion of the building blocks to secondary chemicals or families of derivatives. Biological transformations account for the majority of routes from plant feedstocks to building blocks, but chemical transformations predominate in the conversion of building blocks to molecular derivatives and intermediates.
The challenges and complexity of these pathways, as they relate to the use of biomass derived sugars and chemicals, were briefly examined in order to highlight R&D needs that could help improve the economics of producing these building blocks and derivatives. Not surprisingly, many of the transformations and barriers revealed in this analysis are common to the existing biological and chemical processing of sugars.
The final selection of 12 building blocks began with a list of more than 300 candidates. The shorter list of 30 potential candidates was selected using an iterative review process based on the petrochemical model of building blocks, chemical data, known market data, properties, performance of the potential candidates and the prior industry experience of the team at PNNL and NREL. This list of 30 was ultimately reduced to 12 by examining the potential markets for the building blocks and their derivatives and the technical complexity of 2 the synthesis pathways.
A second-tier group of building blocks was also identified as viable candidates. These include gluconic acid, lactic acid, malonic acid, propionic acid, the triacids, citric and aconitic; xylonic acid, acetoin, furfural, levoglucosan, lysine, serine and threonine.
Recommendations for moving forward include examining top value products from biomass components such as aromatics, polysaccharides, and oils; evaluating technical challenges in more detail related to chemical and biological conversions; and increasing the suites of potential pathways to these candidates.