Recently, cost-effective production of highly value-added furan chemicals from abundant and renewable bioresources has gained much attentions via chemoenzymatic approach in environmentally-friendly reaction system. In this work, chemoenzymatic cascade reaction...

Recently, the cost-effective production of high value-added furan chemicals from inexpensive, abundant, and renewable bioresources has gained much attention via a chemoenzymatic approach in an environmentally friendly reaction system. Furfurylamine is an important furan-based chemical for the production of additives, fibers, perfumes, agrochemicals, and pharmaceuticals. This study attempted to develop one sustainable approach for the production of furfurylamine via chemoenzymatic cascade catalysis of biomass into furfurylamine using a chemocatalyst and a biocatalyst. Using alkali-treated shrimp shells as the biobased support, a tin-based heterogeneous chemocatalyst (Sn-DAT-SS) was first prepared to transform corncob into furfural in 52.4% yield in deep eutectic solvent choline chloride:ethylene glycol (ChCl:EG)–water (10:90, v/v) at 170 °C within 0.5 h. Sn-DAT-SS was easy to recover and has good reusability. Detailed investigation using Fourier transform infrared (FT-IR) spectroscopy, Brunauer–Emmett–Teller (BET) analysis, temperature-programmed desorption of NH3 (NH3-TPD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) indicated that the Lewis and Brönsted acid sites existed on the surface of Sn-DAT-SS. The possible catalytic mechanism of the Sn-DAT-SS-catalyzed transformation of corncob into furfural in ChCl:EG–water was presented. To biologically synthesize furfurylamine, newly constructed recombinant Escherichia coli CCZU-XLS160 whole-cells harboring ω-transaminase and l-alanine dehydrogenase were used to catalyze biomass-derived furfural using available inexpensive NH4Cl (2.0 mol NH4Cl/mol furfural) as the amine donor in ChCl:EG–water (10:90, v/v) at 35 °C and pH 7.5. Within 71.5 h, 92.3 mM furfural derived from corncob was wholly transformed into furfurylamine with a productivity of 0.39 g furfurylamine/g xylan in corncob in ChCl:EG–water (10:90, v/v). This work demonstrated an environmentally friendly chemoenzymatic strategy for utilizing lignocellulosic biomass into furfurylamine via tandem chemocatalysis and biocatalysis in green reaction media. It was feasible to obtain furfurylamine from a renewable source consisting of corncob and shrimp shells.

Heterogeneous tin-based sulfonated graphite (Sn-GP) catalyst was prepared with graphite as carrier. The physicochemical properties of Sn-GP were captured by FT-IR, XRD, SEM and BET. Organic acids with different pKa values were used to assist Sn-GP for transforming corncob (CC), and a linear equation (Furfural yield  = − 7.563 ×  pKa  + 64.383) (R2  =  0.9348) was fitted in acidic condition. Using sugarcane bagasse, reed leaf, chestnut shell, sunflower stalk and CC as feedstocks, co-catalysis of CC (75.0 g/L) with maleic acid (pKa  =  1.92) (0.5 wt%) and Sn-GP (3.6 wt%) yielded the highest furfural yield (47.3%) for 0.5 h at 170 °C. An effective furfural synthesis was conducted via co-catalysis with Sn-GP and maleic acid. Subsequently, E. coli CG-19 and TS completely catalyzed the conversion of corncob-derived FAL to furfurylalcohol and furoic acid, respectively. Valorisation of available renewable biomass to furans was successfully developed in tandem chemoenzymatic reaction. Graphical Abstract

5-Hydroxymethyl-2-furfurylamine (5-HMFA) as an important 5-HMF derivative has been widely utilized in the manufacture of diuretics, antihypertensive drugs, preservatives and curing agents. In this work, an efficient chemoenzymatic route was constructed for producing 5-(hydroxymethyl)furfurylamine (5-HMFA) from biobased D-fructose in deep eutectic solvent Betaine:Glycerol–water. The introduction of Betaine:Glycerol could greatly promote the dehydration of D-fructose to 5-HMF and inhibit the secondary decomposition reactions of 5-HMF, compared with a single aqueous phase. D-Fructose (200 mM) could be catalyzed to 5-HMF (183.4 mM) at 91.7% yield by SG(SiO2) (3 wt%) after 90 min in Betaine:Glycerol (20 wt%), and at 150 °C. E. coli AT exhibited excellent bio-transamination activity to aminate 5-HMF into 5-HMFA at 35 °C and pH 7.5. After 24 h, D-fructose-derived 5-HMF (165.4 mM) was converted to 5-HMFA (155.7 mM) in 94.1% yield with D-Ala (D-Ala-to-5-HMF molar ratio 15:1) in Betaine:Glycerol (20 wt%) without removal of SG(SiO2), achieving a productivity of 0.61 g 5-HMFA/(g substrate D-fructose). Chemoenzymatic valorization of D-fructose with SG(SiO2) and E. coli AT was established for sustainable production of 5-HMFA, which has potential application.

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