Lignocellulosic Biomass Conversion by Sequential Combination of Organic Acid and Base Treatments

Abstract

The present work aims at exploring a new hydrolysis approach using sequential combinations of organic acid [oxalic acid (OA)] and base [tetramethylammonium hydroxide (TMAH)] to convert lignocellulosic biomass at mild conditions (150−215 °C, 1−2 h, and 1 atm N2) using a spruce wood sample in a batch reactor. In the single-step tests, hydrolysis with OA can convert biomass to yield sugars and furanic compounds. Hydrolysis with TMAH mainly depolymerizes lignin to produce phenolic compounds but also converts some polysaccharides in biomass possibly by the peeling reaction and/or alkaline hydrolysis. A sequential combination of OA and TMAH can significantly increase the conversion of the biomass compared to single- or two-step reactions with either the acid or the base. The analysis of liquid products by chemical derivatization followed by gas chromatography equipped with a flame ionization detector (GC−FID) and the characterization of the solid residues by pyrolysis−gas chromatography−mass spectrometry (Py−GC...