Five biomass-based materials: sesame straw (SS), corn cobs (CC), bamboo powder (BP), wheat straw (WS), and furfural residue (FR), were sulfonated using sulfuric acid, as well as some commercial sulfonated catalysts, like Amberlyst, Nafion were compared for the production of ethyl levulinate (EL) from furfuryl alcohol (FAL). Remarkably, under optimum conditions (50 mg of 8% SO3H-FR at 170 °C for 5 h), 100% FAL conversion and 90% EL yield were achieved, along with stable recyclability in continuous flow. Dynamic evolution of GC in the function of reaction time under different temperatures was performed, indicating that FAL conversion to ethoxymethylfuran (EMF) occurs under a lower temperature (150 °C) and short time (45 min). On the contrary, the intermediates 5, 6, and 7 required a higher temperature for EL formation with the concomitant release of diethyl ether (DEE). Comprehensive characterizations demonstrated significant changes in the chemical composition of sulfur- or nitrogen-containing functional groups after sulfonation. In particular, the −S–O types (especially −SO3H) play a more critical role in EL production than the sulfur content alone. The adsorption energies and charge density differences of FAL (Eads) on pristine FR and the sites of −SO3H, −SO4, pyrrolic N, pyridinic N, and their complexes were compared. The FAL adsorption energy followed the order: Eads (complex) > Eads (−SO4) > Eads (−SO3H) > Eads (pyrrolic N) > Eads (pyridinic N)>Eads (pristine), indicating a synergistic adsorption effect among these functional groups in FR. Additionally, the electron transfer capacity was significantly enhanced after −SO3H doping.
Yang Yifei,Jia Litao,Meng Yan,Hou Bo,Li Debao,Sun Yuhan
Abstract Ordered mesoporous carbon supported cobalt-based catalysts (Co/MC) were synthesized via incipient wetness impregnation with different amounts of furfuryl alcohol (FA) as carbon precursor. The characterizations of obtained Co/MC were subjected to N 2 adsorption, XRD, XPS, TEM, H 2 -TPR, H 2 -TPD and H 2 -TPSR. The results indicate that the reducibility and dispersion of Co active species vary significantly due to the difference of FA amount. By simply tuning the FA content from 25 to 100 wt%, the reduction temperature of deriving metallic Co shifts gradually to lower. The catalytic performance of Co/MC was evaluated for Fischer–Tropsch (FT) synthesis. The observed FT activity exhibits a volcano-type curve with the amount of FA due to the effect of both reducibility and dispersion of active species. As the precursor concentration overweighs 50 wt%, the ability of CO to dissociate over the active surface and the selectivity to the C 5+ products level off after experiencing an initial increase. Substantially, the catalysts with higher concentration of FA render the larger crystallites having an average size of more than 6 nm, which facilitates the CO hydrogenation by way of carbon chain propagation. It seems that the sample with FA content of 50 wt% is optimum in terms of FT activity and C 5+ selectivity. Graphical Abstract By simply tuning the carbon precursor furfuryl alcohol (FA) content from 25 to 100 wt%, the textural property of mesoporous carbon varies significantly, which further induces the different reducibility and dispersion of Co active species and the temperature of deriving metallic Co shifts gradually to lower. The catalytic performance of as-synthesized catalysts was evaluated for Fischer–Tropsch synthesis (FTS). The observed FT activity exhibits a volcano-type curve with the amount of FA due to the effect of both reducibility and dispersion of active species. At the FA concentration of support over 50 wt%, the selectivity to the C 5+ heavy molecular maintain invariant after experiencing an initial increase. It seems that the sample with respect to 50 wt% FA is optimum in terms of FT activity and C 5+ selectivity.
Chemoenzymatic cascade catalysis using deep eutectic solvent-silica heterogeneous catalyst and reductase biocatalyst was constructed for synthesizing furfuryl alcohol from biomass in one-pot manner. A novel heterogeneous catalyst B:LA-SG(SiO 2 ) was firstly prepared by immobilizing deep eutectic solvent Betaine:Lactic acid on silica with sol–gel method using tetraethyl orthosilicate as silicon source. High furfural yield (45.3%) was achieved from corncob with B:LA-SG(SiO 2 ) catalyst (2.5 wt%) in water at 170 ˚C for 0.5 h. Possible catalytic mechanism for converting biomass into furfural was proposed. Moreover, one newly constructed recombinant E. coli KF2021 cells containing formate dehydrogenase and reductase was utilized to transform corncob-valorized furfural into furfuralcohol at 97.7% yield at pH 7.5 and 40 ˚C via HCOONa-driven coenzyme regeneration. Such a hybrid process was constructed for tandem chemocatalysis and biocatalysis in a same reactor, potentially reducing the operation cost, which had potential application for valorization of biomass to value-added furans.
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