Detailed Chemical Kinetic Modeling of Vapor-Phase Reactions of Volatiles Derived from Fast Pyrolysis of Lignin

Abstract

The vapor-phase reactions of nascent volatiles derived from the fast pyrolysis of lignin were investigated both experimentally and numerically. Lignin residue after enzymatic hydrolysis was pyrolyzed in a two-stage tubular reactor at 773− 1223 K. The nascent volatiles formed in the first stage underwent vapor-phase reactions in situ in the second stage. A detailed chemical kinetic model that consists of more than 500 species and 8000 elementary reactions was used to simulate the vaporphase reactions of volatiles derived from fast pyrolysis of lignin. The contribution of tar in the vapor-phase reactions was considered in global reactions, which improves the predictive capability of the kinetic model. The experimental data and numerical predictions of 31 products were compared and analyzed to understand the mechanism of vapor-phase reactions of lignin. The model predictions were in good agreement with the experimental observations. Reaction pathway analysis for the formation of aromatic hydrocarbons was performed. Cyclopentadienyl radicals produced from phenol decomposition were suggested as important intermediates in the formation of aromatic hydrocarbons during lignin pyrolysis.

Computational Study on the Thermal Decomposition of Phenol‐Type Monolignols

“… Rate constants of channels 1, 7, and 16 were calculated with VTST, otherwise with CTST. Kinetic parameters for channel 5 have been already included in the DCKM of secondary vapor‐phase reactions established by our group . …”

“…In case of the secondary homogeneous vapor‐phase cracking, our research group has established a DCKM involving thousands of elementary reaction channels and hundreds of chemical species . The DCKM was employed to conduct the numerical simulation of the vapor‐phase reactions of volatiles derived from fast pyrolysis of lignin at 773−1223 K . However, our established DCKM has not yet involved kinetic parameters for the monolignol decomposition processes in the vapor phase.…”

Measuring biomass fast pyrolysis kinetics: State of the art

“…The micropyrolyzer reactors are usually coupled with gas chromatography (GC) techniques like GC-MS, GC-TOF-MS (time-of-flight mass spectrometer), or GC-FID ( Figure 2; Choi, Lee, Proano-Aviles, Lindstrom, Johnston, & Brown, 2017;Ronsse et al, 2012). U-shaped two-stage tubular reactors, separated by quartz wool, have been reported by Norinaga et al (Kousoku, Norinaga, & Miura, 2014;Norinaga et al, 2013;Qi et al, 2017;Yang et al, 2013;Yang, Appari, Kudo, Hayashi, & Norinaga, 2015;Yang, Furutani, Kudo, Hayashi, & Norinaga, 2016) for intrinsic gas-phase pyrolysis kinetic studies of cellulose and lignin model compound such as catechol, resorcinol, and hydroquinone pyrolysis. Pyroprobe reactors consist of a horizontal tubular reactor, wherein the sample is introduced using a quartz sample holder.…”

Detailed kinetic mechanism of gas-phase reactions of volatiles released from biomass pyrolysis

“…Here the comparisons are limited to recent experimental data, which give more attention to the secondary gas phase reactions of released species. Norinaga et al [59] and Yang et al [60] studied the kinetics of secondary vapor-phase decomposition of volatiles generated from the fast pyrolysis of cellulose and lignin in a two-stage tubular reactor, while minimizing volatile-char interactions. Avicel cellulose with particle sizes ranging from 74 to 105 μm was used by Norinaga, while the lignin samples used by Yang had particle sizes in the range of 75−150 μm.…”