(455e) A Highly Selective Dehydration of D-Xylose and Wheat Straw C5-Sugars into Furfural By Using Supercritical CO2 as Catalyst: A Green and Efficient Approach

Crude oil is the principal feedstock for production of liquid fuels and also affords a platform for synthesis of a wide range of added-value chemicals and materials. Due to price fluctuation of crude oil-derived products coupled to increasing concerns about the impact of fossil emissions on environment, society is becoming more environmentally conscious. Thus, traditional chemical technologies for production of fuels and chemicals from biomass are being replaced with innovations. This includes the use of novel and green solvents. In this work, the selective dehydration of both D-xylose and lignocellulose-derived C₅-sugars into furfural, using supercritical CO₂ as catalyst and tetrahydrofuran (THF) as extracting solvent, is for the first time reported. The scrutinised approach involves the benefits from the use of auto-generated carbonic acid from dissolution of CO₂ in aqueous phase, assisted by THF, guiding to the improvement of furfural yield and reaction selectivity. This novel approach allowed to achieve a xylose conversion into furfural above 83 %mol, furfural yield of 70 %mol and selectivity up to 84 %mol at 180 ºC for 60 min with 50 bar of initial CO₂ pressure.¹ At aforementioned operational condition, furfural yields and selectivities up to 40 %mol and 44 %mol with respect to wheat straw hemicellulose hydrolysate were reached.² First, the influence of various operating conditions on pentose conversion and furfural yields were investigated. Then, various volumetric ratios of water and THF (v/v) were investigated to help define reaction conditions that favour the highest yield of furfural. In an effort to understand how addition of CO₂ improves furfural yield and its impact by the presence of THF, different pressures of CO₂were also investigated.

Acknowledgments

This work was supported by the Fundação para a Ciência e a Tecnologia (FCT/MEC, Portugal) through SFRH/BD/94297/2013, IF/00471/2015 grants and by BBRI - Biomass and Bioenergy Research Infrastructure (ROTEIRO/0189/2013) and the Associated Laboratory for Sustainable Chemistry−Clean Processes and Technologies−LAQV which is financed by national funds from FCT/MEC (UID/QUI/50006/2013) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007265).

References

1. A. R. C. Morais and R. Bogel-Lukasik, Green Chem., 2016, 18, 2331-2334.

2. A. R. C. Morais, M. D. J. Matuchaki, J. Andreaus and R. Bogel-Lukasik, Green Chem., 2016, 18, 2985-2994.