Building a reactive molecular dynamics framework for cellulose pyrolysis studies

Research output: Contribution to conferenceConference AbstractScientific

Abstract

Much of the current interest in cellulose pyrolysis stems from technologies that enable the conversion of lignocellulosic biomass into commodity chemicals. Describing these reaction mechanisms is one of the fundamental associated challenges. Computational chemistry methods can complement the experimental knowledge. In our work, we used Reactive Molecular Dynamics (RMD) in conjunction with the ReaxFF force field, enabling formation and breaking of chemical bonds within a classical MD framework with an affordable computational cost. We carried out stochastic RMD simulations to study the high-temperature decomposition of an isolated cellulose molecule [1]. We conducted a total of 16900 simulations for chains with a degree of polymerization (DP) between 8 and 64, for several initial conformations, and in the temperature range of 1400 K to 2200 K. Each simulation was run until the first decomposition event was detected. From this data, the reaction rate constant could be obtained. We observed the decomposition to occur primarily through random cleavage of the glycosidic bonds. An activation energy of (171 ± 2) kJ mol-1 and a frequency factor of (1.07 ± 0.12) * 1015 s-1 were determined for this reaction. These values are within the range of values reported for the global mass loss kinetics of cellulose pyrolysis, and showed no dependence on the DP and on the initial conformation. We also observed the release of some of the characteristic low-molecular-weight products, such as glycolaldehyde, water, formaldehyde, and formic acid. Focusing on isolated molecules contributes to a bottom-up approach, in which we build towards condensed-phase pyrolysis simulations. The next steps may include studying secondary and tertiary decomposition reactions for an isolated chain, adding more chains to the system to include intra-chain interactions, extending the temperature range, and improving the bond information analysis. With these developments, the stochastic RMD approach could be used for detailed studies of cellulose pyrolysis, and used in the design, development and optimization of pyrolytic conversion processes.
Original languageEnglish
Publication statusPublished - 2017
MoE publication typeNot Eligible
Event4th International Cellulose Conference - Fukuoka, Japan
Duration: 17 Oct 201720 Oct 2017

Conference

Conference4th International Cellulose Conference
CountryJapan
CityFukuoka
Period17/10/1720/10/17

Fingerprint

Cellulose
Molecular dynamics
Pyrolysis
Decomposition
formic acid
Conformations
Polymerization
Computational chemistry
Information analysis
Molecules
Chemical bonds
Temperature
Formaldehyde
Reaction rates
Rate constants
Biomass
Activation energy
Molecular weight
Kinetics
Water

Keywords

  • cellulose
  • pyrolysis
  • molecular dynamics
  • ReaxFF
  • ProperTune

Cite this

Vaari, J., & Paajanen, A. (2017). Building a reactive molecular dynamics framework for cellulose pyrolysis studies. Abstract from 4th International Cellulose Conference, Fukuoka, Japan.
Vaari, Jukka ; Paajanen, Antti. / Building a reactive molecular dynamics framework for cellulose pyrolysis studies. Abstract from 4th International Cellulose Conference, Fukuoka, Japan.
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Vaari, J & Paajanen, A 2017, 'Building a reactive molecular dynamics framework for cellulose pyrolysis studies' 4th International Cellulose Conference, Fukuoka, Japan, 17/10/17 - 20/10/17, .

Building a reactive molecular dynamics framework for cellulose pyrolysis studies. / Vaari, Jukka; Paajanen, Antti.

2017. Abstract from 4th International Cellulose Conference, Fukuoka, Japan.

Research output: Contribution to conferenceConference AbstractScientific

TY - CONF

T1 - Building a reactive molecular dynamics framework for cellulose pyrolysis studies

AU - Vaari, Jukka

AU - Paajanen, Antti

N1 - Abstracts + extended 1 page abstracts only

PY - 2017

Y1 - 2017

N2 - Much of the current interest in cellulose pyrolysis stems from technologies that enable the conversion of lignocellulosic biomass into commodity chemicals. Describing these reaction mechanisms is one of the fundamental associated challenges. Computational chemistry methods can complement the experimental knowledge. In our work, we used Reactive Molecular Dynamics (RMD) in conjunction with the ReaxFF force field, enabling formation and breaking of chemical bonds within a classical MD framework with an affordable computational cost. We carried out stochastic RMD simulations to study the high-temperature decomposition of an isolated cellulose molecule [1]. We conducted a total of 16900 simulations for chains with a degree of polymerization (DP) between 8 and 64, for several initial conformations, and in the temperature range of 1400 K to 2200 K. Each simulation was run until the first decomposition event was detected. From this data, the reaction rate constant could be obtained. We observed the decomposition to occur primarily through random cleavage of the glycosidic bonds. An activation energy of (171 ± 2) kJ mol-1 and a frequency factor of (1.07 ± 0.12) * 1015 s-1 were determined for this reaction. These values are within the range of values reported for the global mass loss kinetics of cellulose pyrolysis, and showed no dependence on the DP and on the initial conformation. We also observed the release of some of the characteristic low-molecular-weight products, such as glycolaldehyde, water, formaldehyde, and formic acid. Focusing on isolated molecules contributes to a bottom-up approach, in which we build towards condensed-phase pyrolysis simulations. The next steps may include studying secondary and tertiary decomposition reactions for an isolated chain, adding more chains to the system to include intra-chain interactions, extending the temperature range, and improving the bond information analysis. With these developments, the stochastic RMD approach could be used for detailed studies of cellulose pyrolysis, and used in the design, development and optimization of pyrolytic conversion processes.

AB - Much of the current interest in cellulose pyrolysis stems from technologies that enable the conversion of lignocellulosic biomass into commodity chemicals. Describing these reaction mechanisms is one of the fundamental associated challenges. Computational chemistry methods can complement the experimental knowledge. In our work, we used Reactive Molecular Dynamics (RMD) in conjunction with the ReaxFF force field, enabling formation and breaking of chemical bonds within a classical MD framework with an affordable computational cost. We carried out stochastic RMD simulations to study the high-temperature decomposition of an isolated cellulose molecule [1]. We conducted a total of 16900 simulations for chains with a degree of polymerization (DP) between 8 and 64, for several initial conformations, and in the temperature range of 1400 K to 2200 K. Each simulation was run until the first decomposition event was detected. From this data, the reaction rate constant could be obtained. We observed the decomposition to occur primarily through random cleavage of the glycosidic bonds. An activation energy of (171 ± 2) kJ mol-1 and a frequency factor of (1.07 ± 0.12) * 1015 s-1 were determined for this reaction. These values are within the range of values reported for the global mass loss kinetics of cellulose pyrolysis, and showed no dependence on the DP and on the initial conformation. We also observed the release of some of the characteristic low-molecular-weight products, such as glycolaldehyde, water, formaldehyde, and formic acid. Focusing on isolated molecules contributes to a bottom-up approach, in which we build towards condensed-phase pyrolysis simulations. The next steps may include studying secondary and tertiary decomposition reactions for an isolated chain, adding more chains to the system to include intra-chain interactions, extending the temperature range, and improving the bond information analysis. With these developments, the stochastic RMD approach could be used for detailed studies of cellulose pyrolysis, and used in the design, development and optimization of pyrolytic conversion processes.

KW - cellulose

KW - pyrolysis

KW - molecular dynamics

KW - ReaxFF

KW - ProperTune

M3 - Conference Abstract

ER -

Vaari J, Paajanen A. Building a reactive molecular dynamics framework for cellulose pyrolysis studies. 2017. Abstract from 4th International Cellulose Conference, Fukuoka, Japan.