Furfural Production by Continuous Reactive Extraction in a Millireactor under the Taylor Flow Regime

Abstract

This study demonstrates the use of a millireactor as intensified technology for the continuous production of furfural via acid dehydration of xylose in a biphasic media. Very rapid extraction of furfural, aided by fast mass transfer rates, is key to preventing furfural subsequent degradation. Thus, by operating at elevated temperatures (i.e., 150–190 °C), it is possible to maintain high furfural selectivity (ca. 70%) at high xylose conversion (ca. 80%) and very short residence times (up to 2.5 min). A reaction mechanism is proposed based on the observed conversion-selectivity trends, and on the analysis of product distribution. The contribution of humins to the carbon balance is remarkably low due to the high furfural extraction rates achieved in the millireactor. Through first-principle reactor modeling, we further demonstrate the potential of combining intensified reactor technologies with the extractive synthesis of furfural and show that solvent optimization will be crucial to boost furfural selectivity above 80%.

Kinetic Model of Xylose Dehydration for a Wide Range of Sulfuric Acid Concentrations

“…of an intensified reactor with unconventionally high temperatures (i.e., 190 °C vs the conventional 150 °C) was key to a significant reduction in residence time (i.e., from 4−5 h to 3−6 min) and minimal humin formation. 9 Here, the use of process evaluation tools are key to optimize the delicate trade-off between the furfural yield and energy consumption that this process entails while also considering elements such as feed costs, energy, and environmental impact. To this end, robust kinetic models as the backbone of predictive mathematical platforms to reliably describe process performance as a function of operating conditions are essential.…”

Efficient synthesis of furfural from xylose over HCl catalyst in slug flow microreactors promoted by NaCl addition

“…the detailed discussion in Section S1 in the Supporting Information). Papaioannou et al 23 performed xylose conversion over the H 2 SO 4 catalyst in a continuous millireactor (inner diameter: 4.1 mm) at a short residence time of 2.5 min. The STY FF is satisfactory (19.9 mol min −1 m −3 ), but the furfural yield (ca.…”

“…21,22 Comparatively, few reports have been published on its application for furfural synthesis. One recent work is from Papaioannou et al 23 who demonstrated xylose conversion to furfural over the H 2 SO 4 catalyst in water-toluene biphasic systems in a slug flow millireactor (inner diameter: 4.1 mm). The furfural extraction aided by the strong inner circulation within aqueous droplets and organic slugs is claimed to greatly prevent furfural degradation.…”

Production of furans from C5 and C6 sugars in the presence of polar organic solvents

“…The concept of biphasic operation, based on the process of reactive extraction, exploits the continuous liquid-liquid extraction of the formed HMF or furfural into the organic phase. [78][79][80][81][82] The characteristics of these biphasic systems are variable in terms of catalysis and composition. 31,40,73,75 While homogeneous catalysis by mineral acids remains the preferred source, in several studies heterogeneous catalysis has also been successfully applied at biphasic conditions.…”