Bimolecular Decomposition Pathways for Carboxylic Acids of Relevance to Biofuels

Clark, Jared; Nimlos, Mark R.; Robichaud, David J.

doi:10.1021/jp509285n

Cited by 17 publications

(17 citation statements)

References 55 publications

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“… 5,6 Here we developed a novel approach to produce renewable mcl -LAO based on the early studies that propylene can be produced from polyhydroxybutyric acid (PHB) as a thermal degradation product, where the hydroxybutyrate units undergo an intramolecular β-elimination to produce crotonic acid, which is then converted into propylene via decarboxylation. 7 A recent research also reported propylene production from cyanobacterial biomass rich in PHB via HTL, 8 consistent with these thermochemical reactions. We hypothesized that mcl -LAO could be produced from medium chain-length polyhydroxyalkanoic acid ( mcl -PHA) via a similar series of reactions.…”

Section: Introductionsupporting

confidence: 60%

Co-production of fully renewable medium chain α-olefins and bio-oilviahydrothermal liquefaction of biomass containing polyhydroxyalkanoic acid

Dong

Xiong

et al. 2018

RSC Adv.

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Section: Introductionsupporting

confidence: 60%

Co-production of fully renewable medium chain α-olefins and bio-oilviahydrothermal liquefaction of biomass containing polyhydroxyalkanoic acid

Dong

Xiong

et al. 2018

RSC Adv.

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“…According to previous studies, a carboxylic acid molecule can be catalyzed by the carboxylic acid group of another carboxylic acid molecule. 38 The detailed catalytic reaction path is shown in Figure 5A-C. Reaction path 1 is that the carboxylic acid molecule forms an eight-membered ring transition state configuration with the carboxyl group of another carboxylic acid molecule to form the enone product (P1).…”

Section: Bimolecular Mutual Catalytic Reactionmentioning

confidence: 99%

“…36 Clark et al theoretically calculated the single-molecule and bimolecular pyrolysis pathways of carboxylic acids related to biofuels. 37,38 The results show that the mutual catalytic dehydration between molecules is more dominant than the dehydration reaction of single molecules. Therefore, the pyrolysis process of unsaturated fatty acids can be clearly understood by combining experiments with density functional theory.…”

Section: Introductionmentioning

confidence: 97%

“…Woo et al analyzed the ketonization reaction mechanism of caproic acid molecules through DFT calculations, and the results showed that the ketonization reaction was obtained by the first condensation of two caproic acid molecules and then decarboxylation 36 . Clark et al theoretically calculated the single‐molecule and bimolecular pyrolysis pathways of carboxylic acids related to biofuels 37,38 . The results show that the mutual catalytic dehydration between molecules is more dominant than the dehydration reaction of single molecules.…”

Section: Introductionmentioning

confidence: 99%

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Study on the pyrolysis mechanism of unsaturated fatty acid: A combined density functional theory and experimental study

Jiang

Yuan

Cheng

et al. 2021

Intl J of Energy Research

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Summary In this study, oleic acid was used as a model compound to discuss the mechanism of thermal conversion of unsaturated fatty acids to hydrocarbons, so as to promote the goal of obtaining renewable chemicals and fuels from unsaturated fatty acids. In‐situ detection techniques such as TG‐FTIR and Py‐GC/MS combined with density functional theory were applied to study the reaction mechanism of oleic acid molecules in the conditions of slow pyrolysis and fast pyrolysis. As the temperature rises, the hydrogen bond is broken, and the vibration peak of oleic acid shows obvious dehydrogenation under slow pyrolysis, and the same situation exists under fast pyrolysis. As the temperature increases, the pyrolysis process of oleic acid molecules changed from the dominant role of bimolecular mutual catalysis to that of free radical reaction. The results of Py‐GC/MS showed that methyl, ethyl, and hydrogen radicals are the main active substances under the conditions of high temperature and fast pyrolysis of unsaturated fatty acid. This work demonstrates the feasibility of producing renewable hydrocarbons by pyrolysis of unsaturated fatty acids and proposed influenced factors to control product distribution. Novelty Statement Density functional theory (DFT) combined with experiments was used in present study to supplement the understanding of the pyrolysis mechanism of fatty acids in bio oil pyrolysis, and the control factors of controlling the distribution of fatty acid pyrolysis products were proposed.

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“…Other rate constants in the literature are calculated from theory, estimation methods, or similarity arguments 3 . Clark et al 42,43 . calculated barrier heights and rate constants for the unimolecular and bimolecular pathways of many acids including propionic acid.…”

Section: Introductionmentioning

confidence: 99%

Diol isomer revealed as a source of methyl ketene from propionic acid unimolecular decomposition

Rogers

Lockwood

Nguyen

et al. 2021

Int J of Chemical Kinetics

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Carboxylic acids are important combustion intermediates, especially regarding the combustion of oxygenates such as ethyl esters. The purpose of this study is to discern the unimolecular decomposition pathways of one such carboxylic acid, propionic acid, using microreactor flow experiments with line‐tunable photoionization mass spectrometry and infrared spectroscopy, along with high‐level electronic structure calculations (CCSD(T)/cc‐pV∞Z//M06‐2X/cc‐pVTZ level of theory) and master equation theory. Microreactor experiments were performed at 300–1500 K, pressures decreasing from roughly 300 Torr to vacuum pressure, and around 100 μs residence times. Primary products are methyl ketene, ketene, ethylene, and methyl radical. Theory suggests the two lowest energy bond fissions are active at these conditions and responsible for the production of ketene, methyl radical, and some ethylene. Importantly, theory revealed the significance of the isomerization of propionic acid to propene‐1,1‐diol, and the subsequent dehydrogenation reaction of the diol as an alternative explanation for the unimolecular formation of methyl ketene. This is predicted to be the dominant thermal decomposition pathway at lower temperatures (up to ∼850 K). Line‐tunable VUV photons allowed for isomer resolution of the products and showed no evidence of the diol of propionic acid surviving until detection, suggesting propene‐1,1‐diol decomposes either to methyl ketene and water rapidly, fragments upon ionization to a distonic ion inseparable from methyl ketene through our detection methods, or never stabilizes as propionic acid well‐skips directly to methyl ketene. Infrared spectroscopy showed no evidence of the decarboxylation of propionic acid at these conditions. Updated rate constants and branching ratios for propionic acid decomposition are calculated and provided for future modeling studies.

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Bimolecular Decomposition Pathways for Carboxylic Acids of Relevance to Biofuels

Cited by 17 publications

References 55 publications

Co-production of fully renewable medium chain α-olefins and bio-oilviahydrothermal liquefaction of biomass containing polyhydroxyalkanoic acid

Co-production of fully renewable medium chain α-olefins and bio-oilviahydrothermal liquefaction of biomass containing polyhydroxyalkanoic acid

Study on the pyrolysis mechanism of unsaturated fatty acid: A combined density functional theory and experimental study

Diol isomer revealed as a source of methyl ketene from propionic acid unimolecular decomposition

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