The Significant\nDifferences in Solvation Thermodynamics\nof C1–C3 Oxygenates in Hydrophilic versus Hydrophobic Pores\nof a Hydrophilic Ti-FAU Zeolite Model

The rates of catalytic reactions have been observed to\nbe dramatically\ndifferent in zeolites, depending on whether they are hydrophobic or\nhydrophilic. Hypotheses aimed at explaining this behavior have pointed\nto various solvent and zeolite properties as having an influence on\nentropy. Herein, the influence of various solvent and adsorbate properties\non the solvation energies, entropies, and free energies of 11 C<sub>1</sub>–C<sub>3</sub> oxygenates in hydrophobic and hydrophilic\npores within a hydrophilic model of Ti-FAU zeolite is tested. The\nresults indicate significant variation in the solvation thermodynamics\ndepending on the adsorbate type as well as if it is bound within a\nhydrophobic or hydrophilic pore. Further, while solvation energies\nare related to solvent–adsorbate interactions, solvation entropies\nhave multiple contributions, and these differ depending on whether\nthe adsorbate is in a hydrophobic or hydrophilic pore. Specifically,\nsolvation entropies in hydrophobic pores are related to solvent structural\nproperties, whereas solvation entropies in hydrophilic pores are related\nto adsorbate polarity. The large range of results obtained from two\ndifferent pores within one zeolite model with minimal unique adsorption\nsites suggests that solvation behavior in zeolites is complicated\nand that the phenomena that control the observed performance depend\non the zeolite, reaction, and solvent.