A novel Gaussian-DAEM-reaction model for the pyrolysis of cellulose, hemicellulose and lignin

Abstract

This work deals with the pyrolysis kinetics of cellulose, hemicellulose and lignin. Experiments were carried out in a thermogravimetric analyzer (TGA Q5000) in the inert atmosphere of nitrogen at a heating rate of 10 K min À1 . The single Gaussian distributed activation energy model (DAEM) was utilized to study the pyrolysis kinetics. Kinetic parameters such as the pre-exponential factor (k 0 ), mean activation energy (E 0 ) and standard variance (s) were computed by a pattern search algorithm. It was found that the calculated kinetic parameters using the single Gaussian-DAEM-reaction model could reproduce the differential thermogravimetric (DTG) curves of cellulose very well. However, there existed obvious deviations in the whole range of temperatures between the calculated and experimental data for hemicellulose and lignin.In order to describe the thermal decompositions of hemicellulose and lignin more accurately, a novel double Gaussian-DAEM-reaction model consisting of two parallel partial reactions was developed to describe the pyrolysis processes. Calculated results of the fitting procedure using the double Gaussian-DAEM-reaction model showed good agreement with experimental DTG data of hemicellulose and lignin.

TG-MS analysis and kinetic study for thermal decomposition of six representative components of municipal solid waste under steam atmosphere

“…1(a), the DTG curve in the pyrolysis stage presented one strong peak together with one shoulder peak, and two partial reactions were proposed to describe the pyrolysis behaviour in the previous work (Zhang et al, 2014b). As shown in Table 2, the M r of lignin at the final temperature of pyrolysis stage (T f , 825 K) was 64.3 wt.%, which was slightly larger than the sum of fixed carbon and ash contents (Table 1 and 57.32 wt.%).…”

Effect of Torrefaction on Biomass Physicochemical Characteristics and the Resulting Pyrolysis Behavior

“…Therefore, a DAEM with only one Gaussian function could predict a satisfactory simulation result for the activation energy distribution in cellulose pyrolysis. 33 However, the hemicellulose and lignin structures were branched and complicated, and during their pyrolysis, large numbers of fragments are produced that can be randomly polymerized to form char. Thus, condensation reactions play an important role in the pyrolysis of hemicellulose and lignin.…”

A Critical Review on Hemicellulose Pyrolysis

“…Hemicellulose pyrolysis has been extensively studied in the past two decades –,,. A number of experiments have been conducted to investigate the thermal decomposition of hemicellulose and the effects of operating conditions on the yields of pyrolysis products, such as pyrolysis temperature, particle size, residence time, atmosphere, and the presence of minerals (Table ).…”

“…However, the global kinetic models of hemicellulose pyrolysis are restricted to the specific starting materials and operating conditions reported by the authors, and therefore, have very poor potential for extrapolation to other applications. Additionally, the chemical structure of hemicellulose is often approximated as a xylose polymer, (C 5 H 8 O 4 ) n , in global kinetic models . However, real hemicelluloses are mixtures of heterogeneous polysaccharides that mainly consist of pentose, hexose, arabinose, and uronic acids, and thus, the formulation of native, extracted, or commercial hemicellulose (polysaccharides) can be very different from the theoretical formulae of a pentose polysaccharide, (C 5 H 8 O 4 ) n , or hexose polysaccharide, (C 6 H 10 O 5 ) m .…”