Abstract
BackgroundRecently, exploring fermentative or chemical pathways that convert biomass-derived sugars to fuels/chemicals has attracted a lot of interest from many researchers. We are investigating a hydrocarbon pathway from mixed sugars via 5-hydroxymethyl furfural (HMF) and furfural intermediates. To achieve this goal, we must first convert glucose and xylose to HMF and furfural in favorable yields. Current processes to produce HMF/furfural generally involve the use of acid catalysts in biphasic systems or solvents such as ionic liquids. However, the yield from transforming glucose to HMF is lower than the yield of furfural from xylose.ResultsIn this study, we present an efficient chemical pathway simultaneously transforming glucose and xylose to HMF and furfural via ketose intermediates, i.e., fructose and xylulose, which were generated from glucose and xylose via enzymatic isomerization. In the enzymatic isomerization, by adding sodium borate to complex with the ketoses, xylose conversion reached equilibrium after 2 h with a conversion of 91% and glucose conversion reached 84% after 4 h. By enzymatically isomerizing the aldoses to ketoses, the following dehydration reactions to HMF and furfural could be performed at low process temperatures (i.e., 110–120 °C) minimizing the side reactions of the sugars and limiting the degradation of furfurals to humins and carboxylic acids. At 120 °C, pH 0.5, and 15 min reaction time, mixed ketose sugars were converted to HMF and furfural in yields of 77% and 96%, respectively (based on starting aldose concentrations).ConclusionTaken together, our results demonstrate that this combined biological and chemical process could be an effective pathway to simultaneously convert biomass-derived glucose and xylose to HMF and furfural, for use as intermediates in the production of hydrocarbons.
Highlights
Exploring fermentative or chemical pathways that convert biomass-derived sugars to fuels/ chemicals has attracted a lot of interest from many researchers
Wang et al Biotechnol Biofuels (2019) 12:253 the conditions needed for converting glucose to hydroxymethyl furfural (HMF) are much more severe than those required for converting xylose to furfural, such that if these conditions were applied to a mixture of pentose and hexose sugars it is likely that any furfural produced would be substantially degraded
Enzymatic isomerization of glucose and xylose with and without borate The simultaneous isomerization of glucose and xylose to fructose and xylulose can be catalyzed by a bifunctional enzyme, i.e., a glucose isomerase
Summary
Exploring fermentative or chemical pathways that convert biomass-derived sugars to fuels/ chemicals has attracted a lot of interest from many researchers. It is well known that glucose and xylose are the two main sugars making up the Current processes to produce HMF/furfural generally involves the use of acid catalysts in aqueous media or solvents such as ionic liquids and the chemical transformation has mostly utilized only one type of sugar, i.e., glucose or xylose, [3,4,5,6,7] rarely both sugars simultaneously. Considering the large amount of glucose in biomass, an effective way to co-transform glucose/xylose to HMF/furfural with high yields is important In this context, to overcome the obstacles for utilizing mixed sugars in a dehydration/condensation/hydrodeoxygenation pathway, we must convert the C6 sugars into HMF under much less severe conditions than have typically been used
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
