Improved conversion of bamboo shoot shells to furfuryl alcohol and furfurylamine by a sequential catalysis with sulfonated graphite and biocatalysts

Improved biotransformation of lignin-valorized vanillin into vanillylamine in a sustainable bioreaction medium

Lignin is a critical biopolymer for creating a large number of highly valuable biobased compounds. Vanillin, one of lignin-derived aromatics, can be used to synthesize vanillylamine that is a key fine chemical and pharmaceutical intermediate. To produce vanillylamine, a productive whole-cell-catalyzed biotransformation of vanillin was developed in deep eutectic solvent - surfactant - H2O media. One newly created recombinant E. coli 30CA cells expressing ω-transaminase and L-alanine dehydrogenase was employed to transform 50 mM and 60 mM vanillin into vanillylamine in the yield of 82.2% and 8.5% under 40 °C, respectively. The biotransamination efficiency was enhanced by introducing surfactant PEG-2000 (40 mM) and deep eutectic solvent ChCl:LA (5.0 wt%, pH 8.0), and the highest vanillylamine yield reached 90.0% from 60 mM vanillin. Building an effective bioprocess was utilized for transamination of lignin-derived vanillin to vanillylamine with newly created bacteria in an eco-friendly medium, which had potential application for valorization of lignin to value-added compounds.

An efficient chemoenzymatic cascade strategy for transforming biomass into furfurylamine with lobster shell-based chemocatalyst and mutated ω-transaminase biocatalyst in methyl isobutyl ketone-water

To date, an efficient process for manufacturing valuable furan compounds from available renewable resources has gained great attention via a chemoenzymatic route. In this study, a sulfonated tin-loaded heterogeneous catalyst CLUST-Sn-LS using lobster shell as biobased carrier was prepared to convert corncob (75.0 g/L) into furfural (122.5 mM) at 170 °C for 30 min in methyl isobutyl ketone (MIBK)-H₂O biphasic system (2:1, v/v). To improve furfurylamine yield, a novel recombinant E. coli TFTS harboring robust mutant Aspergillus terreus ω-transaminase [hydrophilic threonine (T) at position 130 was site-directed mutated to hydrophobic phenylalanine (F)] was constructed to transform 300-500 mM furfural into furfurylamine (90.1-93.6 % yield) at 30 °C and pH 7.5 in MIBK-H₂O. Corncob was converted to furfurylamine in MIBK-H₂O with a high productivity of 0.461 g furfurylamine/(g xylan). This constructed chemoenzymatic method coupling bio-based chemocatalyst CLUST-Sn-LS and mutant ω-transaminase biocatalyst in a biphasic system could efficiently convert lignocellulose into furfurylamine.

Chemoenzymatic catalytic synthesis of furfurylamine from hemicellulose in biomasses

Recently, efficient synthesis of furan-based chemicals from biomacromolecule via chemoenzymatic approaches have been widely recognized. In this work, an efficient conversion of biomacromolecule (e.g., xylan in biomass) to furfurylamine (FLA) was developed in a tandem reaction by bridging with chemocatalysis and biocatalysis. Various biomasses (e.g., corncob, bagasse, bamboo shoot shell, corn stalk, rice straw stalk, reed, water bamboo and sunflower stalk) could produce different titer of furfural due to the diverse xylan content in biomass. After being catalyzed by shrimp shell-supported solid acid catalyst (Sn-DAT-SS) in deep eutectic solvent choline chloride:ethylene glycol (ChCl:EG) - water (10:90, v/v) at 170 °C after 30 min, corncob gave the highest furfural yield of 52.4 %. The potential catalytic mechanism for Sn-DAT-SS-catalyzing the conversion of biomass into furfural in ChCl:EG - water was proposed. It was found that by-products (formic acid, levulinic acid, 5-hydroxymethylfurfural) and soluble sugars (glucose, xylose, arabinose, cellobiose) produced during the conversion of biomass to furfural had certain inhibition effects on the biotransamination of furfural to FLA. Biomass-derived furfural (36.7-92.3 mM) could be fully aminated to FLA by E. coli CCZU-XLS160 cells harboring ω-transaminase after 24-72 h. The established chemoenzymatic strategy for converting biomacromolecules into valuable furan-based products was successfully developed in an eco-friendly system.

Valorization of Waste Lignocellulose to Furfural by Sulfonated Biobased Heterogeneous Catalyst Using Ultrasonic-Treated Chestnut Shell Waste as Carrier

Recently, the highly efficient production of value-added biobased chemicals from available, inexpensive, and renewable biomass has gained more and more attention in a sustainable catalytic process. Furfural is a versatile biobased chemical, which has been widely used for making solvents, lubricants, inks, adhesives, antacids, polymers, plastics, fuels, fragrances, flavors, fungicides, fertilizers, nematicides, agrochemicals, and pharmaceuticals. In this work, ultrasonic-treated chestnut shell waste (UTS-CSW) was utilized as biobased support to prepare biomass-based heterogeneous catalyst (CSUTS-CSW) for transforming waste lignocellulosic materials into furfural. The pore and surface properties of CSUTS-CSW were characterized with BET, SEM, XRD, and FT-IR. In toluene–water (2:1, v:v; pH 1.0), CSUTS-CSW (3.6 wt%) converted corncob into furfural yield in the yield of 68.7% at 180 °C in 15 min. CSUTS-CSW had high activity and thermostability, which could be recycled and reused for seven batches. From first to seventh, the yields were obtained from 68.7 to 47.5%. Clearly, this biobased solid acid CSUTS-CSW could be used for the sustainable conversion of waste biomasses into furfural, which had potential application in future.

Improved one-pot synthesis of furfural from corn stalk with heterogeneous catalysis using corn stalk as biobased carrier in deep eutectic solvent-water system

Using acid-treated corn stalk (CS) as biobased carrier, heterogeous SO₄^2-/SnO₂-CS catalyst was firstly prepared to catalyze CS into fufural in deep eutectic solvent-water system. The physical properties of SO₄^2-/SnO₂-CS were captured by FT-IR, NH₃-TPD, XRD, XPS, and BET. SO₄^2-/SnO₂-CS (1.2 wt%) could be used to catalyze CS (75.0 g/L) with MgCl₂ (15.0 g/L) to produce furfural (102.3 mM) in the yield of 68.2% for 0.5 h at 170 °C in ChCl:EG-water (20:80, v:v). Moreover, enhanced synthesis of furfural was explored based on the structure changes of CS, furfural yields and formation of byproducts. Finally, the potential catalytic mechanism for catalyzing CS into furfural and byproducts was proposed using SO₄^2-/SnO₂-CS as catalyst in ChCl:EG-water containing MgCl₂. In summary, this established ChCl:EG-water system and optimized catalytic condition facillitated to synthesize furfural from biomass with biobased solid acid catalyst.