Theoretical Studies on the Unimolecular Decomposition of Ethylene Glycol

Ye, Lili; Zhao, Long; Zhang, Youmin; Qi, Fei

doi:10.1021/jp207978n

Cited by 30 publications

(27 citation statements)

References 71 publications

(108 reference statements)

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“…This can be attributed to the high-frequency factors of the latter two paths compared to the former one. At T ≥ 700 K, the contribution from the C β − O β bond fission increases gradually and starting competing with the fission of the C α -C β bond at T > 1600 K until they have an almost equal ratio at T = 2000 K. In general, the C α − C β bond fission is considered as the most dominated pathway for 2ME especially at T ≥ 500 K that matches with records from similar studies on oxygenated compounds 52,57,63,64 . Due to missing of kinetic data of n-butanol at CBS-QB3, the total rate of 2ME pyrolysis is compared with 2-butanol 57 at the CBS-QB3 at different temperatures.…”

Section: Resultssupporting

confidence: 84%

Thermochemistry and Kinetics of the Thermal Degradation of 2-Methoxyethanol as Possible Biofuel Additives

Abdel-Rahman

Al-Hashimi

Shibl

et al. 2019

Sci Rep

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Oxygenated organic compounds derived from biomass (biofuel) are a promising alternative renewable energy resource. Alcohols are widely used as biofuels, but studies on bifunctional alcohols are still limited. This work investigates the unimolecular thermal degradation of 2-methoxyethanol (2ME) using DFT/BMK and ab initio (CBS-QB3 and G3) methods. Enthalpies of the formation of 2ME and its decomposition species have been calculated. Conventional transition state theory has been used to estimate the rate constant of the pyrolysis of 2ME over a temperature range of 298–2000 K. Production of methoxyethene via 1,3-H atom transfer represents the most kinetically favored path in the course of 2ME pyrolysis at room temperature and requires less energy than the weakest Cα − Cβ simple bond fission. Thermodynamically, the most preferred channel is methane and glycoladhyde formation. A ninefold frequency factor gives a superiority of the Cα − Cβ bond breaking over the Cγ − Oβ bond fission despite comparable activation energies of these two processes.

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Section: Resultssupporting

confidence: 84%

Thermochemistry and Kinetics of the Thermal Degradation of 2-Methoxyethanol as Possible Biofuel Additives

Abdel-Rahman

Al-Hashimi

Shibl

et al. 2019

Sci Rep

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“…Ethylene glycol can be decomposed to vinyl alcohol (acetaldehyde) and methyl hydroxy through dehydration and cracking reactions in the studied working temperature range. 35 TPABr can also decompose and act as a free radical generator and release light gases. Considering the mentioned information, a portion of noncondensable gases probably came from DES decomposition and calculated gas yields may differ 4−6 wt % from real gas yields.…”

Section: Resultsmentioning

confidence: 99%

“…By heating the whole system, partial evaporation of EG happened and dissociation of either EG or TPABr heads launched above 300 °C. According to Qi et al, 35 ethylene glycol could be decomposed to steam and vinyl alcohol (acetaldehyde) through dehydration or methyl hydroxyl through C−C bond cracking in the 325−350 °C temperature range. The produced vinyl alcohol may also decompose to CH 4 and CO and produce hydrogen through the water gas−shift reaction.…”

Section: Resultsmentioning

confidence: 99%

Intensified Transformation of Low-Value Residual Fuel Oil to Light Fuels with TPABr:EG as Deep Eutectic Solvent with Dual Functionality at Moderate Temperatures

Razavian

Fatemi

2020

Energy Fuels

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The performance of two deep eutectic solvents (DESs) was comparatively inspected in upgrading of heavy residual fuel oil (Mazut) as a chemical additive at different processing temperatures and times of 300−350 °C and 105−420 min, respectively. DESs consisted of ethylene glycol possessing hydrogen-donating groups and tetrapropylammonium bromide (TPABr) or choline chloride (ChCl) possessing alkyl tails with different lengths. Characterization of upgraded liquids processed at 325 °C for 210 min showed that TPABr:EG was three times more effective than ChCl:EG in asphaltene conversion and produced a lighter fuel with higher maltene selectivity. Besides the asphaltene reduction (36%), it was more efficient in desulfurization, with a 12.8% reduction, than dry thermal upgrading, with 5.8% asphaltene and 1.9% sulfur reductions, respectively. Moreover, upgraded oil from the TPABr:EG-incorporated scenario revealed high stability toward regression, and viscosity was well preserved after 3 months. Aside from viscosity measurement, asphaltene determination, elemental CHNS, FTIR, and TGA analyses on upgraded oils, isolated asphaltenes from TPABr:EG-incorporated and dry thermal processes were further characterized by FTIR and NMR to pursue the upgrading events. It was realized that TPABr:EG boosted the structural changes in heavy asphaltenic islands by fragmentation and dealkylation of the heteromacromolecular rings. In fact, it intensified both side aliphatic chain shortening and aromatic core shrinkage appreciably compared to the dry thermal process. On the basis of all of the findings elucidating the dual radical generation and hydrogen donation functionality of TPABr:EG, a mechanism is proposed to shed light on the pathway of influence of this eutectic mixture in the intensification of upgrading heavy oil.

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“…En los dioles con los grupos hidroxilicos cercanos forman un producto cíclico de sustitución y para los compuestos con los grupos hidroxilicos separados los productos formados son de disociación (Eichmann, 1992). Aunque hay mayor número de reportes en la literatura, sobre la descripción de las interacciones inter e intramolecular de estos dioles, los estudios cinéticos han recibido menor atención (Ye, 2012). Así, un estudio reciente reporta la descomposición unimolécular del etilenglicol por cálculos teóricos (ab initio) con altos niveles de refinamiento por el método QCISD(T)/CBS//B3LYP/6-31G++G(d,p), donde se muestran resultados de la cinética y descomposición del etilenglicol, los cuales predicen la importancia de la eliminación de agua porque favorece la formación de moléculas como aldehídos y enoles.…”

Section: Introductionunclassified

“…Así, un estudio reciente reporta la descomposición unimolécular del etilenglicol por cálculos teóricos (ab initio) con altos niveles de refinamiento por el método QCISD(T)/CBS//B3LYP/6-31G++G(d,p), donde se muestran resultados de la cinética y descomposición del etilenglicol, los cuales predicen la importancia de la eliminación de agua porque favorece la formación de moléculas como aldehídos y enoles. Asimismo, las constantes de velocidad calculadas indican que las reacciones de eliminación de agua predominan a bajas temperaturas, mientras que en altas se presenta disociación con ruptura de enlace carbono-carbono (Ye, 2012). De igual forma, estudios experimentales de la pirolisis de algunos alcoholes polihidroxílicos, se realizaron utilizando un sistema estático de alto vacío y presentaron un mecanismo de reacción complejo (Chuchani et al, 1997).…”

Section: Introductionunclassified

Obtención de Dímeros por Termólisis de 1,2-Propanodiol

Milanés¹,

Robles²

2012

Inf. tecnol.

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ResumenLos compuestos dímeros 3-oxi-(bis)-2-propanol, 2-(2-hidroxipropoxi)-propanol y 2-oxi-(bis)propanol fueron obtenidos de la reacción de descomposición térmica del 1,2-propanodiol, realizada a 573.15 K y a su presión de vapor, utilizando un sistema de reacción a microescala, Los dímeros resultaron ser isómeros y fueron elucidados por cromatografía gaseosa acoplada a espectrometría de masas. Estos compuestos no han sido reportados en la literatura como productos de termólisis de polioles. La cinética y el mecanismo, fueron confirmados por cálculos computacionales utilizando el método de la Teoría del Funcional Densidad, DFT. El mecanismo propuesto transcurrió a través de un proceso concertado de una sola etapa, que pasa por un estado de transición cíclico de cuatro miembros, compatible con cálculos cinéticos y termodinámicos. Palabras clave: mecanismo de reacción, termólisis, dimerización, espectrometría de masas, 1,2propanodiol AbstractThe dimers 3-oxy-(bys)-2-propanol, 2-(2-hydroxypropoxy)-propanol and 2-oxy-(bys)-propanol were obtained from the thermal decomposition reaction of 1,2-propanediol, at 573.15 K and to its vapor pressure, and using microscale reaction system. The dimers resulted to be isomers and were elucidated by gas chromatography coupled to mass spectrometry. These compounds have not been reported in literature as products polyol thermolysis. The kinetic and the mechanism were validated by computational calculations using the Density Functional Theory, DFT. The proposed mechanism occurred in a single step concerted process that passes through a four member transition cyclical state that is compatible with kinetic and thermodynamic calculations.

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Theoretical Studies on the Unimolecular Decomposition of Ethylene Glycol

Cited by 30 publications

References 71 publications

Thermochemistry and Kinetics of the Thermal Degradation of 2-Methoxyethanol as Possible Biofuel Additives

Thermochemistry and Kinetics of the Thermal Degradation of 2-Methoxyethanol as Possible Biofuel Additives

Intensified Transformation of Low-Value Residual Fuel Oil to Light Fuels with TPABr:EG as Deep Eutectic Solvent with Dual Functionality at Moderate Temperatures

Obtención de Dímeros por Termólisis de 1,2-Propanodiol

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