Benchmark Thermochemistry of N-Methylaniline

© 2015 American Chemical Society. In this work, the standard molar enthalpy of formation in the gaseous state of highly pure N-methylaniline, δfHm° (g, 298.15 K) = 90.9 ± 2.1 kJ·mol-1, has been obtained from the calorimetrically measured energy of combustion converted into the enthalpy of formation, δfHm° (liq, 298.15 K) = 35.9 ± 2.1 kJ·mol-1, and from the molar enthalpy of vaporization, δlgHm = 55.0 ± 0.2 kJ·mol-1, derived from vapor pressure measurements by transpiration method. The enthalpy of formation of N-methylaniline calculated using the quantum chemical G4 method was in excellent agreement with the experimental value. The frequencies of normal vibrations were obtained from the experimental and calculated spectra. Thermodynamic properties of N-methylaniline in the ideal gas state were calculated from molecular and spectral data in the temperature range 100-1500 K

Benchmark thermochemistry of methylbenzonitriles: Experimental and theoretical study

© 2015 Elsevier Ltd. All rights reserved. The gas-phase enthalpies of formation of 2-, 3-, and 4-methylbenzonitrile at T = 298.15 K were studied by combustion calorimetry, and their vaporization enthalpies were determined using the transpiration method. The composite ab initio methods W1-F12 and G4 were used to calculate the gas-phase enthalpies of formation for these three methylbenzonitriles. These theoretical values were found to be in excellent agreement with the corresponding experimental data. The analysis of these data revealed that the interaction between cyano and methyl groups is slightly stabilizing. Using the experimental data a set of group-additivity terms, which allows to estimate thermochemical properties for methyl and cyano substituted benzenes, was proposed. These terms, together with theoretical data, were subsequently used to reassess the thermochemical properties of 2,6-dimethylbenzonitrile and 2,4,6-trimethylbenzonitrile

Catalytic Hydrogen Evolution of NaBH4_4 Hydrolysis by Cobalt Nanoparticles Supported on Bagasse-Derived Porous Carbon

As a promising hydrogen storage material, sodium borohydride (NaBH4) exhibits superior stability in alkaline solutions and delivers 10.8 wt.% theoretical hydrogen storage capacity. Nevertheless, its hydrolysis reaction at room temperature must be activated and accelerated by adding an effective catalyst. In this study, we synthesize Co nanoparticles supported on bagasse-derived porous carbon (Co@xPC) for catalytic hydrolytic dehydrogenation of NaBH$_4$. According to the experimental results, Co nanoparticles with uniform particle size and high dispersion are successfully supported on porous carbon to achieve a Co@150PC catalyst. It exhibits particularly high activity of hydrogen generation with the optimal hydrogen production rate of 11086.4 mL$_{H2}$∙min$^{H2}$∙g$_{Co}$$^{H2}$ and low activation energy (E$_{a}$) of 31.25 kJ mol$^{H2}$. The calculation results based on density functional theory (DFT) indicate that the Co@xPC structure is conducive to the dissociation of [BH$_{4}$]$^{-}$, which effectively enhances the hydrolysis efficiency of NaBH$_4$. Moreover, Co@150PC presents an excellent durability, retaining 72.0% of the initial catalyst activity after 15 cycling tests. Moreover, we also explored the degradation mechanism of catalyst performance

Benchmark Thermochemistry of N-Methylaniline

© 2015 American Chemical Society. In this work, the standard molar enthalpy of formation in the gaseous state of highly pure N-methylaniline, δfHm° (g, 298.15 K) = 90.9 ± 2.1 kJ·mol-1, has been obtained from the calorimetrically measured energy of combustion converted into the enthalpy of formation, δfHm° (liq, 298.15 K) = 35.9 ± 2.1 kJ·mol-1, and from the molar enthalpy of vaporization, δlgHm = 55.0 ± 0.2 kJ·mol-1, derived from vapor pressure measurements by transpiration method. The enthalpy of formation of N-methylaniline calculated using the quantum chemical G4 method was in excellent agreement with the experimental value. The frequencies of normal vibrations were obtained from the experimental and calculated spectra. Thermodynamic properties of N-methylaniline in the ideal gas state were calculated from molecular and spectral data in the temperature range 100-1500 K

Benchmark Thermochemistry of N-Methylaniline

© 2015 American Chemical Society. In this work, the standard molar enthalpy of formation in the gaseous state of highly pure N-methylaniline, δfHm° (g, 298.15 K) = 90.9 ± 2.1 kJ·mol-1, has been obtained from the calorimetrically measured energy of combustion converted into the enthalpy of formation, δfHm° (liq, 298.15 K) = 35.9 ± 2.1 kJ·mol-1, and from the molar enthalpy of vaporization, δlgHm = 55.0 ± 0.2 kJ·mol-1, derived from vapor pressure measurements by transpiration method. The enthalpy of formation of N-methylaniline calculated using the quantum chemical G4 method was in excellent agreement with the experimental value. The frequencies of normal vibrations were obtained from the experimental and calculated spectra. Thermodynamic properties of N-methylaniline in the ideal gas state were calculated from molecular and spectral data in the temperature range 100-1500 K

Benchmark Thermochemistry of N-Methylaniline

© 2015 American Chemical Society. In this work, the standard molar enthalpy of formation in the gaseous state of highly pure N-methylaniline, δfHm° (g, 298.15 K) = 90.9 ± 2.1 kJ·mol-1, has been obtained from the calorimetrically measured energy of combustion converted into the enthalpy of formation, δfHm° (liq, 298.15 K) = 35.9 ± 2.1 kJ·mol-1, and from the molar enthalpy of vaporization, δlgHm = 55.0 ± 0.2 kJ·mol-1, derived from vapor pressure measurements by transpiration method. The enthalpy of formation of N-methylaniline calculated using the quantum chemical G4 method was in excellent agreement with the experimental value. The frequencies of normal vibrations were obtained from the experimental and calculated spectra. Thermodynamic properties of N-methylaniline in the ideal gas state were calculated from molecular and spectral data in the temperature range 100-1500 K

Thermochemical properties of pyrazine derivatives as seminal liquid organic hydrogen carriers for hydrogen storage

This work contributes to our primary interest in applications of experimental and computational thermochemistry methods for providing the basic data required in chemical-process design. Pyrazine derivatives are considered as a seminal liquid organic hydrogen carriers. The standard molar enthalpies of vaporisation/sublimation of pyrazine derivatives were derived from the vapour pressure temperature dependences measured by the static and transpiration method. Enthalpies of fusion of the solid compounds were measured using DSC. Thermodynamic data on solid–gas, liquid–gas, and solid–liquid phase transitions available in the literature were collected and combined with own experimental results. We have evaluated and recommended the set of vaporisation and formation enthalpies of pyrazine derivatives at 298.15 K as the reliable benchmark properties for further thermochemical calculations. Gas phase molar enthalpies of formation of pyrazine derivatives calculated by the high-level quantum-chemical method G4 were in agreement with the recommended experimental data. Compilation of experimental and theoretical results derived in this work is useful for optimisation of hydrogenation/dehydrogenation reactions involved in the hydrogen storage technologies

Benchmark thermochemistry of methylbenzonitriles: Experimental and theoretical study

© 2015 Elsevier Ltd. All rights reserved. The gas-phase enthalpies of formation of 2-, 3-, and 4-methylbenzonitrile at T = 298.15 K were studied by combustion calorimetry, and their vaporization enthalpies were determined using the transpiration method. The composite ab initio methods W1-F12 and G4 were used to calculate the gas-phase enthalpies of formation for these three methylbenzonitriles. These theoretical values were found to be in excellent agreement with the corresponding experimental data. The analysis of these data revealed that the interaction between cyano and methyl groups is slightly stabilizing. Using the experimental data a set of group-additivity terms, which allows to estimate thermochemical properties for methyl and cyano substituted benzenes, was proposed. These terms, together with theoretical data, were subsequently used to reassess the thermochemical properties of 2,6-dimethylbenzonitrile and 2,4,6-trimethylbenzonitrile

Benchmark thermochemistry of methylbenzonitriles: Experimental and theoretical study

© 2015 Elsevier Ltd. All rights reserved. The gas-phase enthalpies of formation of 2-, 3-, and 4-methylbenzonitrile at T = 298.15 K were studied by combustion calorimetry, and their vaporization enthalpies were determined using the transpiration method. The composite ab initio methods W1-F12 and G4 were used to calculate the gas-phase enthalpies of formation for these three methylbenzonitriles. These theoretical values were found to be in excellent agreement with the corresponding experimental data. The analysis of these data revealed that the interaction between cyano and methyl groups is slightly stabilizing. Using the experimental data a set of group-additivity terms, which allows to estimate thermochemical properties for methyl and cyano substituted benzenes, was proposed. These terms, together with theoretical data, were subsequently used to reassess the thermochemical properties of 2,6-dimethylbenzonitrile and 2,4,6-trimethylbenzonitrile