Standard adsorption enthalpy

The dimensionless equilibrium constant of a simple reversible adsorption reaction is related to thermodynamic standard quantities - the standard adsorption enthalpy and the standard entropy of adsorption which are assumed to be temperature independent ... 

Fig. 22. Relative yields of the compounds l08TcO3Cl (O), 169Re03Cl ( ), and (most likely) 267Bh03Cl ( ) as a function of isothermal temperature. The error bars indicate a 68% confidence interval. The solid lines indicate the results of simulations with the microscopic model of I. Zvara [18] with the adsorption enthalpies given in the text. The dashed lines represent the calculated relative yield concerning the 68% confidence interval of the standard adsorption enthalpy of Bh03Cl from -66 to -81 kJ/mol. Figure reproduced from [55],...

The standard adsorption enthalpy can also be used to gain information on changes in the surface characteristics of the carbon materials. For this purpose, molecular probes with different sizes and shapes can be used n-hexane, benzene, cyclohexane and 2,2 DMB. All these molecules have six carbon atoms and are linear (n-hexane), cyclic (benzene and cyclohexane) and branched (2,2 DMB), and their mean molecular sizes range from 0.405nm (n-hexane) to 0.62nm (2,2 DMB). 

An empirical correlation between the standard adsorption enthalpy on quartz and the macroscopic standard sublimation enthalpy for chlorides and oxychlorides (Tiirler et al. 1999) allows estimating the standard sublimation enthalpy of BhOaCl as 89tig kJ/mol to be compared to the values of 49 12 kj/mol and 66 12 kj/mol for TcOaCl and ReOsCl, respectively (O Fig. 20.38). 

The IR spectra of Li-FER with adsorbed dihydrogen molecules showed a H-H stretching band located at 4090 cm" [06N1]. Three different types of Li site were found two of them adsorb H2. Periodic DFT calcirlatiorrs proved that orre of the hydrogen adsorbing sites is situated on the charmel wall and the other at the intersection of two perpendicirlar channels. These sites can adsorb one H2 and two H2 molecirles, respectively. The standard adsorption enthalpy of H2 in Li-FER was -4.1(8) kJ/mol. 

The adsorption of dihydrogen onto the zeohtes Na-ZSM-5 and K-ZSM-5 rendered the fundamental H-H stretching mode as IR active [05A1]. The corresponding IR adsorption bands were fonnd at 4101 and 4112 cm for H2/Na-ZSM-5 and H2/K-ZSM-5, respectively. By means of variable-temperature IR spectroscopy, the standard adsorption enthalpy and entropy were determined. 

Free standard adsorption enthalpy of adsorption, J/mol Free standard adsorption enthalpy with chemical reaction, J/mol... 

Fig. 28 Relative yields of HSO4 and OSO4 for each of the 12 detector pairs. Measured values are represented by bars Hs04 dark blue Os04 light blue. The solid black line indicates the temperature profile right-hand scale). The nmxima of the deposition distributions were evaluated as -44 6 °C for HSO4 and -82 7 °C for OSO4. Solid lines represent results of a simulation of the adsorption process with standard adsorption enthalpies of —46.0 kJ moP for Hs04 red line) and —39.0 kJ-moP for Os04 purple line)...

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