Title: Reactive Molecular Dynamics Simulations and Quantum Chemistry Calculations To Investigate Soot-Relevant Reaction Pathways for Hexylamine Isomers

Abstract

Sooting tendencies of a series of nitrogen-containing hydrocarbons (NHCs) have been recently characterized experimentally using the yield sooting index (YSI) methodology. In this work, we aim to identify soot-relevant reaction pathways for three selected C₆H₁₅N amines, namely, dipropylamine (DPA), di-isopropylamine (DIPA), and 3,3-dimethylbutylamine (DMBA) using ReaxFF molecular dynamics (MD) simulations and quantum mechanical (QM) calculations and to interpret the experimentally observed trends. ReaxFF MD simulations are performed to determine the important intermediate species and radicals involved in the fuel decomposition and soot formation processes. QM calculations are employed to extensively search for chemical reactions involving these species and radicals based on the ReaxFF MD results and also to quantitatively characterize the potential energy surfaces. Specifically, ReaxFF simulations are carried out in the NVT ensemble at 1400, 1600, and 1800 K, where soot has been identified to form in the YSI experiment. These simulations account for the interactions among test fuel molecules and pre-existing radicals and intermediate species generated from rich methane combustion, using a recently proposed simulation framework. ReaxFF simulations predict that the reactivity of the amines decrease in the order of DIPA > DMBA > DPA, independent of temperature. Both QM calculations and ReaxFF simulations predict that C₂H₄, C₃H₆,more » and C₄H₈ are the main non-aromatic soot precursors formed during the decomposition of DPA, DIPA, and DMBA, respectively, and the associated reaction pathways are identified for each amine. Both theoretical methods predict that sooting tendency increases in the order of DPA, DIPA, and DMBA, consistent with the experimentally measured trend in YSI. This work demonstrates that sooting tendencies and soot-relevant reaction pathways of fuels with unknown chemical kinetics can be identified efficiently through combined ReaxFF and QM simulations. Overall, predictions from ReaxFF simulations and QM calculations are consistent, in terms of fuel reactivity, major intermediates, and major non-aromatic soot precursors.« less

Authors:

Kwon, Hyunguk  ^[1];

• Search DOE PAGES for author "Kwon, Hyunguk"
• Search DOE PAGES for ORCID "0000-0001-6534-6051"

Etz, Brian D. ^[2]; Montgomery, Matthew J.  ^[3];

• Search DOE PAGES for author "Montgomery, Matthew J."
• Search DOE PAGES for ORCID "0000-0002-9307-2139"

Messerly, Richard ^[4]; Shabnam, Sharmin ^[1]; Vyas, Shubham  ^[5];

• Search DOE PAGES for author "Vyas, Shubham"
• Search DOE PAGES for ORCID "0000-0002-5849-8919"

van Duin, Adri C. T.  ^[1];

• Search DOE PAGES for author "van Duin, Adri C. T."
• Search DOE PAGES for ORCID "0000-0002-3478-4945"

McEnally, Charles S.  ^[3];

• Search DOE PAGES for author "McEnally, Charles S."
• Search DOE PAGES for ORCID "0000-0002-6820-921X"

Pfefferle, Lisa D. ^[3]; Kim, Seonah  ^[4];

• Search DOE PAGES for author "Kim, Seonah"
• Search DOE PAGES for ORCID "0000-0001-9846-7140"

Xuan, Yuan ^[1]

---

+ Show Author Affiliations

1. Pennsylvania State Univ., University Park, PA (United States)
2. National Renewable Energy Lab. (NREL), Golden, CO (United States); Colorado School of Mines, Golden, CO (United States)
3. Yale Univ., New Haven, CT (United States)
4. National Renewable Energy Lab. (NREL), Golden, CO (United States)
5. Colorado School of Mines, Golden, CO (United States)

Publication Date:

Mon May 04 00:00:00 EDT 2020

Research Org.:

Yale Univ., New Haven, CT (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Sustainable Transportation Office. Bioenergy Technologies Office; USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); National Science Foundation (NSF); US Air Force Office of Scientific Research (AFOSR)

OSTI Identifier:

1630117

Grant/Contract Number:  

EE0007983; AC36-99GO10337; MCB-090159; FA9550-17-1-0173

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory

Additional Journal Information:

Journal Volume: 124; Journal Issue: 21; Journal ID: ISSN 1089-5639

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

09 BIOMASS FUELS; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY