Solid residue and by-product yields from acid-catalysed conversion of poplar wood to levulinic acid

Abstract

This study examines the yields of solid residue and by-product from the microwave-assisted acid hydrolysis of lignocellulosic poplar wood for levulinic acid production. The aim of this study was to optimise levulinic acid production via response surface methodology (RSM) and also investigate the effect of reaction conditions on other products such as furfural, solid residue, formic acid and acetic acid yields. A maximum theoretical levulinic acid yield of 62.1% (21.0 wt %) was predicted when reaction conditions were 188 °C, 126 min and 1.93 M sulphuric acid, with a corresponding solid residue yield of 59.2 wt %. Furfural from the hydrolysis of hemicellulose was found to have significantly degraded at the optimum levulinic acid yield conditions. The investigation of formic acid yields revealed lower formic acid yields than stoichiometrically expected, indicating the organic acid reactions under microwave-assisted hydrolysis of lignocellulose. The solid residue yields were found to increase significantly with increasing reaction time and temperature. The solid residue yields under all conditions exceeded that of levulinic acid and, therefore, should be considered a significant product alongside the high-value compounds. The solid residue was further examined using IR spectra, elemental analysis and XRF for potential applications. The overall results show that poplar wood has great potential to produce renewable chemicals, but also highlight all by-products must be considered during optimization.

Sequential Production of Levulinic Acid and Supercapacitor Electrode Materials from Cassava Rhizome through an Integrated Biorefinery Process

“…At an HCl concentration of 0.4 M and a retention time of 1 h, an increase in processing temperature from 150 to 200 °C diminished HY from 49.40 to 36.89% which was due to the degradation of hemicellulose, cellulose, and a part of lignin through hydrolysis and deoxygenation reactions. 38 Similar result trends were observed in the hydrothermal treatment of red seaweed (Gracilaria lemaneiformis), 39 poplar wood, 32 and hazelnut shells. 36 In the hydrothermal treatment of red seaweed, increasing the processing temperature from 160 to 200 °C decreased hydrochar yield from 31.4 to 20.8 wt %.…”

“…Opposite results were reported at 200 °C (Figure 2c), where an increase in retention time from 1 to 3 h saw a decrease in LA yield from 19.62 to 10.44%, which was caused by LA degradation. 32 In addition, Figure 2 demonstrates the effect of HCl concentration on LA yield. At 150 and 170 °C (Figure 2a,b), an increase in HCl concentration from 0.1 to 0.7 M increased LA yield continuously from 0.33 to 5.43 and 1.38 to 8.94%, respectively.…”

“…33 Several studies revealed that humins are formed in the production of LA from C6 carbohydrates under severe reaction conditions. 32,34,35 The catalytic hydrothermal process of CR at 200 °C for 1 h in 0.4 M HCl solution derived the maximum yield and selectivity of LA of 19.62 wt % and 54.85%, respectively. The yield was higher than that derived from the pristine biomass.…”

Integration of Catalytic Biofuel Production and Anaerobic Digestion for Biogas Production

“…Post reaction the SR was separated, washed with deioinsed water and dried at 60°C. The post aqueous reaction media was analysed using an HPLC as previously reported [8]. Levulinic acid and SR yields are reported on a dry mass basis and theoretical levulinic acid yield was calculated on structural sugar basis determined according to NREL standard 510-42618.…”

Performance of Brewery Digestate as a Potential Water Substitute in Concrete Applications

“…However, the brewery digestate has relatively little nitrate and phosphate. Biochar derived from a variety of feedstock thermochemical conversion technologies appears to be more environmentally friendly soil amenders than digestate [36], in terms of both carbon sequestration potential, limited toxics leaching and stimulating growth of microbial community into the soil.…”