(330f) Biomass to Bio-Chemicals: Extractive-Reaction Processes for the Production of 5-Hydroxymethylfurfural

Furanic compounds such as 5-hydroxymethylfurfural (HMF) have the potential to serve as biomass based substitutes of petroleum derived building blocks and are thus key intermediates in the production of biomass derived fuels and chemicals. HMF synthesis is based on the acid catalyzed dehydration of sugars, mainly hexoses, a reaction that is highly non-selective when taking place in aqueous media. In order to improve HMF yield, several laboratory scale reaction- separation processes have been reported, with their common characteristic being the presence of multiple processing steps and interconnected unit operations. Establishing their feasibility from an economic and energy efficiency perspective, and choosing the best processing path requires the evaluation of these processes from a systems perspective. Yet, studies in this direction are still scarce.

This work focuses on the design and optimization of processes that consider the solvent extraction approach as a way to improve HMF yield. These processes consist of a biphasic reactor in which HMF decomposition is prevented by the addition of an organic solvent that selectively removes the HMF produced in the aqueous phase. In order to improve HMF recovery, a liquid-liquid extractor usually needs to be coupled to the reactor (Roman-Leshkov et al., Science, 2006).  

Here, we develop a novel process in which extraction and reaction are combined in a single unit, the extractive-reactor. These type of extractive-reaction processes have been broadly applied to the production of metals and their application to the production of chemicals has been mentioned in the literature (Minottti et al., IECR, 1998).  The proposed process consists of a tubular biphasic reactor-extractor in which the aqueous (reactive) phase containing the sugar (fructose) and catalyst and the organic (extractive) phase are fed counter-currently. The HMF extracted by the organic phase is later on separated from the solvent by evaporation. Both the evaporated solvent and the aqueous solution containing unreacted fructose are recycled back to the extractive-reactor. For this process, we formulate an optimization problem in order to find the minimum cost of HMF that balances raw material, energy and capital costs.  The effect of different solvents, fructose prices and kinetic scenarios is also addressed.

The results obtained showed an improvement over those published in our previous work (Torres et al.,  Energy & Environmental Science, 2010) in which a continuous process consisting of a separate reactor and extractor was studied. A comparison of performance, capital and manufacturing costs of both optimal processes is presented at the end of the study.