Toward Accurate and Efficient Predictions of Entropy and Gibbs Free Energy of Adsorption of High Nitrogen Compounds on Carbonaceous Materials

Abstract

The adsorption of high nitrogen compounds (HNCs) on the selected adsorption sites of carbonaceous materials from the gas phase has been investigated by ab initio quantum chemical methods at the density functional level applying both periodic and cluster approaches with M06-2X and BLYP functionals including dispersion forces (BLYP-D2). Among the possible structures of the adsorption complexes, the most stable systems possess nitrogen-containing heterocycles in a parallel orientation toward the modeled carbon surface. The adsorption enthalpies, calculated using the rigid rotor-harmonic oscillator approach (RRHO), were in good agreement with available experimental data. This approach was shown to provide sufficiently accurate adsorption enthalpies from the gas phase for the HNC−carbon systems. The vibrational, rotational, and translation contributions to the adsorption entropy were also analyzed by the approach extended beyond the RRHO scheme. The effects of anharmonic vibrations and internal rotations of the adsorbate on the adsorption sites of the modeled carbon surface were estimated. The Gibbs free energies calculated using the RRHO approach were adjusted to take into account the heterogeneity of the carbon surfaces and underestimation of the adsorption enthalpies at the BLYP-D2(PBC) level. The corrected Gibbs free energy values of adsorption are negative for all of the investigated HNC−carbon systems, and they agree well with available experimental data. This suggests an effective adsorption of selected high nitrogen compounds on carbonaceous materials from the gas phase at 298.15 K. Partition coefficients for distribution of high nitrogen compounds on modeled carbon surfaces were also predicted in good agreement with the experimental results.

Computational study of the thermodynamic stabilities of hydrogen-bonded complexes in solution

“…The M06-2X calculations of both Cramer and Truhlar et al and ours did not include basis set superposition error (BSSE) corrections as did with the original M06-2X model development. We noted that Leszczynski and coworkers added −3 kcal/mol correction (−2 kcal/ mol for enthalpy and −1 kcal/mol for TΔS) for the adsorption free energies from the M06-2X/6-31+G(d,p) calculations to compare with experimental values favorably [23]. We will further justify our computational procedures in the beginning of the following section.…”

“…Leszczynski and coworkers have made efforts to accurately predict thermodynamic parameters for intermolecular complexes including adsorption of polycyclic aromatic hydrocarbons and nitroaromatic compounds with carbon surfaces in water by using Minnesota density functionals, M05-2X and M06-2X with 6-31+G(d,p), cc-pVDZ, and cc-pVTZ basis sets and the PCM model with scalings [21][22][23][24]. Cramer, Truhlar and coworkers carried out a comprehensive computational study of natural and substituted H-bonded nucleobase dimers formed by adenine (A), thymine (T), guanine (G), cytosine (C), and uracil (U) in the gas phase, chloroform and water solution [25].…”

Noncovalent Interaction of Graphene with Heterocyclic Compounds: Benzene, Imidazole, Tetracene, and Imidazophenazines

“…However, this increase is not very significant, while adding amino‐groups in back sites enhances this energy more significantly . Note that the adsorption of such benzene derivatives as nitrogen compounds (HNCs) on graphene has also been studied …”

“…[20] Note that the adsorption of such benzene derivatives as nitrogen compounds( HNCs) on graphene has also been studied. [33][34][35][36] The interaction energy between aromatic hydrocarbonsa nd graphene increases upon substitution with both electron-donating and -withdrawing groups, as identified by DFT calculations. [25,27,28] It was shown that -CN and -OH groups added to anthracene and pyrene molecules are effectives ubstituents for enhancing binding to graphene.…”

Theoretical Study on the Reactions Originating from Solid Char(N): Radical Preference and Possible Surface N2 Formation Reactions

“…Recently, quantum chemistry calculation has offered a very useful method in the modeling of the carbonaceous reactions due to its possibility to characterize the surface intermediates and to obtain accurate kinetic data for the rates of reactions between these species. − When combined with appropriate experimental techniques (for example, SVUV-PIMS, MBMS, LIF, GC–MS), quantum chemistry calculation can both identify the radicals and reactive intermediates and quantify their concentrations as a function of temperature and time. , The adsorption of nitrogen species onto the carbonaceous surface has been investigated, and the thermodynamically most favorable structures are in a parallel orientation toward the modeling surface . Maclagan et al suggested that the proton affinities increase with increasing model size of the carbonaceous surface .…”