Effect of Hydrothermal Carbonization Conditions on the Physicochemical Properties and Gasification Reactivity of Energy Grass

Abstract

In this study, Erianthus arundinaceus energy grass was examined by conducting hydrothermal carbonization (HTC) using a laboratory-scale autoclave in the temperature range of (180–240 °C) and the retention time of (0–120 min). The parent material and hydrochars were investigated in terms of mass yield, proximate and elemental analyses, the higher heating value (HHV), X-ray diffraction, Fourier transform infrared, and X-ray fluorescence (XRF) analyses. Furthermore, CO2 gasification was conducted on the pyrolysis char prepared from the parent material and the hydrochars using thermogravimetric analysis. It was found that increasing the HTC temperature and residence time caused the mass yield to decrease and the HHV to increase. Hydrochar crystallinity increased with HTC temperature up to 210 °C as a result of the deformation of the amorphous components, while under 240 °C, the crystallinity declined from its peak at 210 °C due to the commencing of cellulose degradation. The XRF analysis showed that the alkali index was increased due to increasing temperature and residence time. Gasification reactivity of the pyrolyzed hydrochar prepared at 180 °C was enhanced due to longer residence time (120 min), while those from very short residence time (0 min) showed a weaker reactivity than the parent material. Changing the HTC temperature showed minimal effect on the reactivity. At higher HTC temperature (240 °C), the catalytic activity was restricted by the highly ordered structure. This was not the case at 180 °C and long residence time of 120 min, where the reactivity was mainly controlled by the increased minerals.

Formation of Soluble Furanic and Carbocyclic Oxy-Organics during the Hydrothermal Carbonization of Glucose

“…Catalytic hydrothermal biorefinery process is an efficient method to convert the renewable lignocellulosic biomass into liquid fuels and fine chemicals and has been widely studied during the past decades. − During the catalytic hydrothermal biorefinery process, the polysaccharides in the biomass undergo hydrolysis to form monosaccharides such as glucose and xylose, which could be selectively converted to a series of valuable downstream platform chemicals such as furfural, 5-hydroxymethylfurfural (HMF), − levulinic acid, , and lactic acid. , However, the formation of great amounts of byproducts during the hydrothermal degradation of carbohydrates, especially the solid hydrochar (HC) − (or the so-called humins in some literature studies − ), sharply decreases the yields of these desired platform chemicals. On the other hand, hydrothermal carbonization (HTC) is one efficient process to convert the biomass into solid HC, which could be used as a solid fuel , or novel carbon-based material precursor. , Therefore, the knowledge of the hydrothermal degradation routes of carbohydrate and the formation mechanism of HCs is an important foundation for both catalytic hydrothermal biorefinery process and HTC process.…”

Pretreatment of Biomass by Selected Type-III Deep Eutectic Solvents and Evaluation of the Pretreatment Effects on Hydrothermal Carbonization

“…The ash wt % remained the same for ChCl:Urea pretreatment and untreated HTCs, except for MPTB:EG pretreatment. This could happen when some inorganics in the cross-linked matrix were leached out to the process liquid during HTC but were readsorbed to the pores during condensation. ,, The pretreated hydrochars showed 53.8–72.6 wt % elemental carbon and 21.7–39.8 wt % elemental oxygen, whereas the untreated hydrochars showed only 52.5–63.3 wt % elemental carbon and 31.1–40.9 wt % elemental oxygen (Table ). Moreover, the pretreated H-220s showed ∼5–5.6 wt % higher elemental carbon than untreated H-220 but very close to untreated H-260 (since ∼3.7–4.4 wt % less elemental carbon) (Table ).…”

A Comprehensive Review on Hydrothermal Carbonization of Biomass and its Applications

“…HTC is a process where the reaction time was found to be the crucial factor, which affects the yield of the hydrochar production [1][2][3]120]. As per the study, in a supercritical state, the degradation and hydrolysis rate of biomass is very high.…”