Synthesis of furoic acid from biomasses by sequential catalysis with fish scale-rice husk-based heterogeneous chemocatalyst and dehydrogenase biocatalyst

Abstract

In this work, furfural was effectively converted to furoic acid (FCA) by using biological macromolecules as raw materials in tandem reaction with chemical biological catalysts. Firstly, a biochar-based heterogeneous catalyst Sn-FS-RH was prepared using equal mass of fish scale (FS) and rice husk (RH) as carriers. Different biomasses (such as poplar wood, winter bamboo shoot shell, corn cob, corn straw, reed leaf, peanut shell, rape straw, and potato shell) were transformed into furfural with Sn-FS-RH in deep eutectic solvent choline chloride:Maleic acid (ChCl:MLA)-H2O (10:90, v/v; 170 °C), and the furfural yield from corn cob-derived xylose reached the highest (70.5% yield, based on xylose) after 15 min of catalysis. The mechanism of Sn-FS-RH-catalyzed the transformation of lignocellulose to furfural was interpreted in ChCl:MLA-H2O. One liter of xylose-hydrolysate was obtained after acid hydrolysis of biomass. The preparation of FUR was generally carried out in a 10 liter of autoclave reactor containing 75 g biomass, 36 g Sn-FS-RH catalyst, 100 g ChCl:MLA, and 20 g ZnCl2. The reactor was stirred at 170 ℃ for 15 min at 500 rpm. It was observed that the by-products (formic acid, levulinic acid, and 5-hydroxymethylfurfural) formed in the transformation of lignocellulose to furfural had somewhat inhibitory effect on the formation of furoic acid from furfural bioconversion. After 24–72 h, Escherichia coli HMFOMUT cells containing dehydrogenase could transform fully furfural derived from different biomass (30–90 mM) into furoic acid. This two-step chemoenzymatic strategy was an efficient way to transform biomacromolecules into biofurans in a sustainable medium.