Die Verbrennungs- und Bildungswärme von Kohlenoxyd und Methan

Roth, W. A.; Banse, Hildegard

doi:10.1002/srin.193200313

Cited by 8 publications

(3 citation statements)

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“…As in the case of CO 2 , all determinations used in the TN were recalculated and/or rechecked from the original data. The determinations included in the Core TN were extracted from Roth and Banse (−213.33 ± 0.50 kcal/mol at 20 °C = −892.6 ± 2.1 kJ/mol), Rossini ,, and Prosen and Rossini (−889.849 ± 0.350 kJ/mol at 30 °C), and Pittam and Pilcher (−890.699 ± 0.430 kJ/mol at 25 °C), as well as the newer determinations by Dale et al (−890.61 ± 0.21 kJ/mol at 25 °C) and by Alexandrov et al , (−890.43 ± 0.35 kJ/mol at 25 °C).…”

Section: Core (Argonne) Thermochemical Networkmentioning

confidence: 99%

Introduction to Active Thermochemical Tables: Several “Key” Enthalpies of Formation Revisited

et al. 2004

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The concept behind active thermochemical tables (ATcT) is presented. As opposed to traditional sequential thermochemistry, ATcT provides reliable, accurate, and internally consistent thermochemistry by utilizing the thermochemical network (TN) approach. This involves, inter alia, a statistical analysis of thermochemically relevant determinations that define the TN, made possible by redundancies in the TN, such as competing measurements and alternate network pathways that interrelate the various chemical species. The statistical analysis produces a self-consistent TN, from which the optimal thermochemical values are obtained by simultaneous solution in error-weighted space, thus allowing optimal use of all of the knowledge present in the TN. ATcT offers a number of additional features that are not present nor possible in the traditional approach. With ATcT, new knowledge can be painlessly propagated through all affected thermochemical values. ATcT also allows hypothesis testing and evaluation, as well as discovery of weak links in the TN. The latter provides pointers to new experimental or theoretical determinations that will most efficiently improve the underlying thermochemical body of knowledge. The ATcT approach is illustrated by providing improved thermochemistry for several key thermochemical species.

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Section: Core (Argonne) Thermochemical Networkmentioning

confidence: 99%

Introduction to Active Thermochemical Tables: Several “Key” Enthalpies of Formation Revisited

et al. 2004

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“…Suffice it to say here that the determinations influencing the ATcT result for the bond dissociation enthalpy of toluene into benzyl and H ͓reaction ͑18a͔͒ are those listed in the recent IUPAC recommendation for the thermochemistry of benzyl. 94 The manifold of C͑A͒TN interdependencies determining the bond dissociation enthalpy of toluene into phenyl and methyl ͓reaction ͑18b͔͒ is substantially more complex, but the ATcT sensitivity analysis indicates that the current result is heavily dominated by the negative-ion-cycle determination of the bond dissociation energy of benzene, 21,22 the positive-ion-cycle determinations of the bond dissociation energy of methane, [121][122][123][124] and the calorimetric determinations of the combustion enthalpies of methane, [125][126][127][128][129][130][131][132] and liquid benzene [133][134][135] and toluene, 133,135,136 coupled to the determinations of the vaporization enthalpies of benzene [137][138][139][140] and toluene. [137][138][139][140][141] The entropy changes of reactions ͑18a͒ and ͑18b͒, needed to relate reaction enthalpies to corresponding free energies, and the temperature dependences of the enthalpy and free energy of both reactions are based on the partition functions ͑and their various derivatives͒ for toluene, benzyl, phenyl, methyl, and hydrogen atom, contained in ATcT.…”

Section: B Pyrolysis Of Aromatic Fuelsmentioning

confidence: 99%

Unimolecular thermal fragmentation ofortho-benzyne

Zhang

Maccarone

Nimlos

et al. 2007

The Journal of Chemical Physics

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The ortho-benzyne diradical, o-C(6)H(4) has been produced with a supersonic nozzle and its subsequent thermal decomposition has been studied. As the temperature of the nozzle is increased, the benzyne molecule fragments: o-C(6)H(4)+Delta--> products. The thermal dissociation products were identified by three experimental methods: (i) time-of-flight photoionization mass spectrometry, (ii) matrix-isolation Fourier transform infrared absorption spectroscopy, and (iii) chemical ionization mass spectrometry. At the threshold dissociation temperature, o-benzyne cleanly decomposes into acetylene and diacetylene via an apparent retro-Diels-Alder process: o-C(6)H(4)+Delta-->HC triple bond CH+HC triple bond C-C triple bond CH. The experimental Delta(rxn)H(298)(o-C(6)H(4)-->HC triple bond CH+HC triple bond C-C triple bond CH) is found to be 57+/-3 kcal mol(-1). Further experiments with the substituted benzyne, 3,6-(CH(3))(2)-o-C(6)H(2), are consistent with a retro-Diels-Alder fragmentation. But at higher nozzle temperatures, the cracking pattern becomes more complicated. To interpret these experiments, the retro-Diels-Alder fragmentation of o-benzyne has been investigated by rigorous ab initio electronic structure computations. These calculations used basis sets as large as [C(7s6p5d4f3g2h1i)H(6s5p4d3f2g1h)] (cc-pV6Z) and electron correlation treatments as extensive as full coupled cluster through triple excitations (CCSDT), in cases with a perturbative term for connected quadruples [CCSDT(Q)]. Focal point extrapolations of the computational data yield a 0 K barrier for the concerted, C(2v)-symmetric decomposition of o-benzyne, E(b)(o-C(6)H(4)-->HC triple bond CH+HC triple bond C-C triple bond CH)=88.0+/-0.5 kcal mol(-1). A barrier of this magnitude is consistent with the experimental results. A careful assessment of the thermochemistry for the high temperature fragmentation of benzene is presented: C(6)H(6)-->H+[C(6)H(5)]-->H+[o-C(6)H(4)]-->HC triple bond CH+HC triple bond C-C triple bond CH. Benzyne may be an important intermediate in the thermal decomposition of many alkylbenzenes (arenes). High engine temperatures above 1500 K may crack these alkylbenzenes to a mixture of alkyl radicals and phenyl radicals. The phenyl radicals will then dissociate first to benzyne and then to acetylene and diacetylene.

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“…It is known that the CO 2 reduction process involves multiple proton-coupled electron transfer steps to produce a wide variety of products, such as CO ( E 0 = −0.52 V vs NHE at pH = 7), CH 3 OH ( E 0 = −0.38 V vs NHE at pH = 7) and CH 4 ( E 0 = −0.24 V vs NHE at pH = 7), as well as even higher hydrocarbons, − while the distribution of final products is usually determined by the kinetic and thermodynamic parameters of the CO 2 reduction pathways. Among the C1 products of the CO 2 reduction reaction, CH 4 is the highest reduced product, and it is found to have the highest standard heat of combustion (−891 kJ mol –1 ). − Thus, CH 4 is the best and the cleanest C1 product having the potential to replace the nonrenewable energy sources like fossil fuels. However, maintaining high efficiency and good selectivity during the conversion of CO 2 to CH 4 is extremely challenging not only because it is an eight-electron transfer process but also because each reduction step has sluggish kinetics.…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic CO₂ Reduction Based on a Re(I)-Integrated Conjugated Microporous Polymer: Role of a Sacrificial Electron Donor in Product Selectivity and Efficiency

et al. 2023

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One of the major challenges in photocatalytic CO2 reduction is achieving control over the selective formation of a single product while maintaining a high conversion efficiency. Here, we report the synthesis and characterization of a conjugated microporous polymer (TEB-BPY) formed by C–C coupling between 1,3,5-triethynylbenzene and 5,5′-dibromo-2,2′-bipyridine. Further, [Re(CO)5Cl] covalently integrated with the polymer, and the resulting metalated Re@TEB-BPY polymer was used as a catalyst for the visible-light-driven CO2 reduction. Re@TEB-BPY displays photoconversion of CO2 to CO with a production rate of 91.7 μmol g–1 h–1 and a selectivity of ∼68% in the presence of triethylamine (TEA) as the sole sacrificial electron donor. Interestingly, CH4 is produced as a major product instead of CO when CO2 reduction was performed using 1-benzyl-1,4-dihydronicotinamide (BNAH) as a sacrificial electron donor in the presence of TEA as a base. In this reaction, Re@TEB-BPY produces CH4 as the major product with a rate of 2.05 mmol g–1 h–1 (selectivity of ∼96% and apparent quantum efficiency of 0.22%). From an in situ diffuse reflectance FTIR spectroscopy (DRIFTS) study together with DFT calculations, a possible catalytic cycle for CO2 reduction to CO or CH4 is constructed. Theoretical calculations along with control experiments further reveal that TEA acts mainly as a base in the presence of BNAH to suppress the back electron transfer process, resulting in enhanced photocatalytic activity.

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Die Verbrennungs- und Bildungswärme von Kohlenoxyd und Methan

Cited by 8 publications

References 0 publications

Introduction to Active Thermochemical Tables: Several “Key” Enthalpies of Formation Revisited

Introduction to Active Thermochemical Tables: Several “Key” Enthalpies of Formation Revisited

Unimolecular thermal fragmentation ofortho-benzyne

Photocatalytic CO₂ Reduction Based on a Re(I)-Integrated Conjugated Microporous Polymer: Role of a Sacrificial Electron Donor in Product Selectivity and Efficiency

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Die Verbrennungs- und Bildungswärme von Kohlenoxyd und Methan

Cited by 8 publications

References 0 publications

Introduction to Active Thermochemical Tables: Several “Key” Enthalpies of Formation Revisited

Introduction to Active Thermochemical Tables: Several “Key” Enthalpies of Formation Revisited

Unimolecular thermal fragmentation ofortho-benzyne

Photocatalytic CO2 Reduction Based on a Re(I)-Integrated Conjugated Microporous Polymer: Role of a Sacrificial Electron Donor in Product Selectivity and Efficiency

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Product

Resources

About

Photocatalytic CO₂ Reduction Based on a Re(I)-Integrated Conjugated Microporous Polymer: Role of a Sacrificial Electron Donor in Product Selectivity and Efficiency