Continuous Synthesis of 5-Hydroxymethylfurfural from Glucose Using a Combination of AlCl3 and HCl as Catalyst in a Biphasic Slug Flow Capillary Microreactor

5-Hydroxymethylfurfural (HMF) was synthesized from glucose in a slug flow capillary microreactor, using a combination of AlCl3 and HCl as the homogeneous catalyst in the aqueous phase and methyl isobutyl ketone as the organic phase for in-situ HMF extraction. After optimization, an HMF yield of 53% was obtained at a pH of 1.5, 160 °C and a residence time of 16 min, and it could be further increased to 66.2% by adding 20 wt% NaCl in the aqueous phase. Slug flow operation in the microreactor greatly promoted mixing/reaction in the aqueous droplet and facilitated HMF extraction to the organic slug, enabling the reaction to run (largely) under kinetic control and an enhanced HMF yield by suppressing its further rehydration, degradation and/or polymerization. Confining reaction in the aqueous droplet prevented humin deposition on the microreactor wall. In line with the literature, [Al(OH)2]+ was confirmed by ESI-MS as the catalytically active species, and is responsible for the glucose isomerization to fructose under various pH values. The ratio between AlCl3 and HCl was optimized for the highest HMF yield and the best results were obtained with 40 mM AlCl3 and 40 mM HCl. Compared with batch results, a higher HMF yield was obtained in the microreactor at the same reaction time mainly due to a higher heating rate therein. The aqueous catalyst was recycled and reused three times without a noticeable performance loss. Thus, the present recyclable and stable homogenous catalyst system, combined with biphasic microreactor operation, is an attractive concept for the glucose conversion to HMF.</p

Catalytic hydrotreatment of Alcell lignin fractions using a Ru/C catalyst

We here report the catalytic hydrotreatment of three different Alcell lignin fractions using a Ru/C catalyst in a batch reactor set-up (400 °C, 4 h, 100 bar H2 intake, 5 wt% catalyst on lignin). The fractions, obtained by a solvent fractionation scheme from Alcell lignin, differ in composition and molecular weight. The resulting product oils were characterized by various techniques, such as GC-MS-FID, GC × GC-FID, GPC, and 13C-NMR, to gain insight into the relationship between the feed and product yield/composition on a molecular level. The lowest molecular weight fraction (Mw = 660 g mol-1) gave the highest product oil yield after catalytic hydrotreatment (>70 wt% on lignin fraction). The main differences in molecular composition for the product oils were observed and are related to the chemical structure of the different feed fractions and less on the molecular weight. The highest amounts of valuable alkylphenolics (8.4 wt% on intake) and aromatic compounds (4.2 wt% on intake) in the product oils were obtained with the lowest molecular weight fraction. This fraction also contained the highest amounts of aliphatic hydrocarbons after the hydrotreatment reaction (14.0 wt% on intake), which were primarily linked to the presence of extractives in the Alcell lignin feed, that accumulate in this low molecular weight fraction during solvent fractionation

Laboratory gram-scale pyrolysis reactor

The invention relates to an apparatus and method for pyrolyzing a feedstock in an open container. The apparatus comprises a downer reactor with an entry located at the top end of the downer for feeding and an exit located at the bottom end of the downer for removing the container from the downer, the downer being divided into at least three vertically arranged zones by at least two locking systems on either side of a middle pyrolysis zone, wherein the at least two locking systems are configured to simultaneously close for sealing the pyrolysis zone, wherein the at least two locking systems are further configured to let through the container in an open position, the apparatus comprising heating means, cooling means and pressurizing means configured to adjust the temperature and pressure of at least the pyrolysis zone independently from the other zones

Laboratory gram-scale pyrolysis reactor

The invention relates to an apparatus and method for pyrolyzing a feedstock in an open container. The apparatus comprises a downer reactor with an entry located at the top end of the downer for feeding and an exit located at the bottom end of the downer for removing the container from the downer, the downer being divided into at least three vertically arranged zones by at least two locking systems on either side of a middle pyrolysis zone, wherein the at least two locking systems are configured to simultaneously close for sealing the pyrolysis zone, wherein the at least two locking systems are further configured to let through the container in an open position, the apparatus comprising heating means, cooling means and pressurizing means configured to adjust the temperature and pressure of at least the pyrolysis zone independently from the other zones