Carbon Materials as Phase‐Transfer Promoters for Obtaining 5‐Hydroxymethylfurfural from Cellulose in a Biphasic System

Abstract

Different carbonaceous materials were tested as mass‐transfer promoters for increasing the yield of 5‐hydroxymethylfurfural (5‐HMF) in biphasic cellulose hydrolysis. The benefits of working with a biphasic system (water/methyl isobutyl ketone) under soft acid conditions were taken as starting point (no humins or levulinic acid production), with slow extraction kinetics as the weakest point of this approach. Carbon nanotubes (CNTs) and activated carbon (AC) were proposed to improve 5‐HMF liquid–liquid mass transfer. A kinetic analysis of the extraction process indicated the competition between 5‐HMF and glucose adsorption as the main cause of the poor results obtained with AC. In contrast, very promising results were obtained with CNTs, mainly at 1.5 wt % loading, with complete transfer of HMF and a high global mass‐transfer coefficient. The use of CNTs improved the amount of 5‐HMF in the organic phase by more than 270 %.

A Review of Conductive Carbon Materials for 3D Printing: Materials, Technologies, Properties, and Applications

“…The larger aspect ratio and specific surface area make CNTs disperse unevenly in the matrix, which agglomerates easily and causes stress concentration. The special structure endows CNTs with excellent mechanical [ 30 , 31 , 32 ], electrical [ 33 , 34 , 35 ], and chemical properties [ 36 , 37 ], which has been widely used in nano-electronic devices, field emission, composite reinforced materials, and so on [ 38 , 39 ]. Cheney et al [ 40 ] found that the introduction of ionic CNTs into epoxy matrix can improve the uneven distribution of CNTs.…”

Sustainable biomass hydrodeoxygenation in biphasic systems

“…20 shows the reaction of HMF in a water/MIBK system using carbon nanotubes and activated carbon as HMF mass transfer promoters. 195 At a concentration of 1.5 wt%, the carbon nanotubes resulted in a complete transfer of HMF and a high global mass transfer coefficient, increasing the HMF concentration in the organic phase by more than 270%. In addition, solid nanoparticles can be placed at the liquid–liquid interface to form Pickering emulsions to increase the contact area, where the solid particles act to stabilize the emulsion system, preferentially forming oil-in-water emulsions (O/W) for more hydrophilic solid particles and oil-in-water (W/O) emulsions for more hydrophobic solid particles.…”

“…Finally, amphiphilic catalysts enhance mass transfer by adsorbing non-hydrophilic molecules in the aqueous phase and desorbing them in the organic phase. 195,208 As previously mentioned, amphiphilic catalysts are placed at the interface of water-oil biphasic systems to form Pickering emulsions, thereby increasing the contact area. The selective conversion of FAL to CPO and LA has been investigated in the combined action of Ni/CNT p catalysts and biphasic solvent systems, as shown in Fig.…”

Carbon-Based Nanocatalysts (CnCs) for Biomass Valorization and Hazardous Organics Remediation

“…CNTs-based materials have rarely been used as catalysts to convert cellulose. On the other hands, CNTs were used as mass-transfer promoters in the presence of homogeneous acid catalysts [ 49 ]. Microcrystalline cellulose (5.83 g) in the presence of homogeneous catalyst HCl (200 ppm) and carbon nanotube (CNT, 386 ppm) were mixed in a solution of methyl-isobutyl-ketone (MIBK, 218 mL) and water (175 mL) at 140 °C and 10 bar for 2 h. An increased cellulose conversion of 43% was achieved, with the CNTs to play a key role since the conversion in their absence was only 20%.…”

“…As several equilibria steps are involved in the process, this extraction displaced all the reaction, also yielding to an increase in the productivity (270 times higher). In the same work, Faba et al also tested activated carbon as a mass-transfer promoter, although its efficiency was found negligible [ 49 ].…”