Kinetics of Isopropanol Decomposition and Reaction with H atoms from Shock Tube Experiments and Rate Constant Optimization using the Method of Uncertainty Minimization using Polynomial Chaos Expansions (MUM-PCE)

Published

September 28, 2020

Author(s)

Laura A. Mertens, Jeffrey A. Manion

Abstract

Recent interest in isopropanol (2-propanol, C3H¬7OH) combustion stems from its potential as a renewable biofuel. Here, we report shock tube investigations of isopropanol decomposition and reaction with H atoms at (918 to 1212) K and (158 to 484) kPa. Experiments were conducted with argon mixtures containing < 1% each of isopropanol and a radical scavenger (1,3,5- trimethylbenzene, 135TMB, which also serves as a reference compound for H atom kinetics). For studies of H-atom kinetics, an additional thermal H-atom precursor, either ethyl iodide (C2H5I) or hexamethylethane (HME) was added at < 0.1%. Propene was measured as the main product of molecular decomposition of isopropanol (R1498), while similar quantities of acetone and propene are found as the main products of H atom attack and are attributed to the respective abstraction of the tertiary and primary hydrogens of isopropanol (reactions R1504 and R1503). Traces of acetaldehyde were detected above approximately 1100 K. Rate constants for isopropanol decomposition and its reaction with H were extracted using the method of uncertainty minimization using polynomial chaos expansions (MUM-PCE) to optimize select parameters in chemical model based on the JetSurF 2.0 mechanism to the experimental data. We find: k1498 = 10(13.77 ± 0.27) exp( -(32 797 ± 970) K / T) s-1 at (979 to 1212) K and (286 to 484) kPa; k1503 = 10(6.01 ± 0.43) exp( -(3019 ± 920) K / T) cm3 mol-1 s-1 at (918 to 1142) K and (158 to 323) kPa; and k1504 = 10(5.84 ± 0.32) exp( -(1425 ± 773) K / T) cm3 mol-1 s-1 at (918 to 1142) K and (158 to 323) kPa. Rate constants for reaction of H with isopropanol are close to those determined in our laboratory for the reaction of H with isobutane, although branching ratios between tertiary and primary attack have small differences.

Citation

International Journal of Chemical Kinetics

Volume

53

Issue

1

Pub Type

Journals

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DOI Link

Keywords

kinetics, biofuels, combustion, hydrogen atoms, model optimization

Citation

Mertens, L. and Manion, J. (2020), Kinetics of Isopropanol Decomposition and Reaction with H atoms from Shock Tube Experiments and Rate Constant Optimization using the Method of Uncertainty Minimization using Polynomial Chaos Expansions (MUM-PCE), International Journal of Chemical Kinetics, [online], https://doi.org/10.1002/kin.21428 (Accessed April 27, 2024)