An integrated process for the production of platform chemicals and diesel miscible fuels by acid-catalyzed hydrolysis and downstream upgrading of the acid hydrolysis residues with thermal and catalytic pyrolysis

Role of pretreatment with acid and base on the distribution of the products obtained via lignocellulosic biomass pyrolysis

Analysis of chemicals distribution in pyrolysis liquid following different content of acid and base in pretreatment.

The effect of hydrogen peroxide concentration and solid loading on the fractionation of biomass in formic acid

This study investigated the fractionation of biomass using a decomposing mixture of hydrogen peroxide-formic acid as a pretreatment for the biorefining of Miscanthus × giganteus and of sugarcane bagasse. The main parameters investigated were the hydrogen peroxide concentration (2.5, 5.0 and 7.5 wt%) and biomass loading (5.0 and 10.0 wt%). At the highest hydrogen peroxide concentration used (7.5 wt%), the energy released by the decomposition of the H2O2 could heat the reaction mixture up to 180 °C in a short time (6-16 min). As a result, highly delignified pulps, with lignin removal as high as 92 wt%, were obtained. This delignification process also solubilised a significant amount of pentosan (82-98 wt%) from the initial biomass feedstock, and the resulting pulp had a high cellulosic content (92 wt%). The biomass loading only affected the reaction rate of hydrogen peroxide decomposition. Various analytical methods, including Fourier transform infrared spectroscopy, and thermogravimetric and elemental analyses, characterized the lignin obtained.

Kinetics of levulinic acid and furfural production from Miscanthus × giganteus

This study investigated the kinetics of acid hydrolysis of the cellulose and hemicellulose in Miscanthus to produce levulinic acid and furfural under mild temperature and high acid concentration. Experiments were carried out in an 8L-batch reactor with 9%-wt. biomass loading, acid concentrations between 0.10 and 0.53 M H2SO4, and at temperatures between 150 and 200°C. The concentrations of xylose, glucose, furfural, 5-hydroxymethylfurfural and levulinic acid were used in two mechanistic kinetic models for the prediction of the performance of ideal continuous reactors for the optimisation of levulinic acid and the concurrent production of furfural. A two-stage arrangement was found to maximise furfural in the first reactor (PFR - 185°C, 0.5M H2SO4, 27.3%-mol). A second stage leads to levulinic acid yields between 58% and 72%-mol at temperatures between 160 and 200°C.

Degradation mechanism of monosaccharides and xylan under pyrolytic conditions with theoretic modeling on the energy profiles

Xylan and three monosaccharides (mannose, galactose, and arabinose) were selected as model compounds to investigate the mechanism of hemicellulose pyrolysis. The evolution of several typical pyrolysis products were observed by thermogravimetric analysis coupled to Fourier transform infrared spectroscopy. Monosaccharides underwent similar pyrolysis routes involving ring opening and secondary decomposition. Breakage of the O-acetyl groups and 4-O-methylglucuronic acid units in xylan branches resulted in its different pyrolysis behavior for the formation of acetic acid, CO2, and CO. The detailed reaction pathways of the monosaccharides were studied using density functional theory calculations. Furfural formation was more favorable than the formation of 1-hydroxy-2-propanone and 4-hydroxydihydrofuran-2(3H)-one during xylose degradation. However, in the pyrolysis of mannose and galactose, formation of 5-hydroxymethyl-2-furaldehyde was preferred because of the high energy barrier of the dissociation of the hydroxymethyl group. Meanwhile, the breakage of O-acetyl groups leading to acetic acid formation easily occurred because of its lower energy barrier.