Adsorption of the butene isomers in faujasite: A combined ab-initio theoretical and experimental study

The adsorption behavior of the butene isomers on NaY zeolite is studied experimentally and compared with quantum chemical predictions. The adsorption experiments were carried out with the pulse chromatographic method, the calculations were performed both on the HF as on the DFT-B3LYP level in combination with the 6-31G* and the 6-311+G** basis set. The results of the calculations are in line with the experimental ones for the cation-butene isomer interaction in the gas phase; the same adsorption trend in the zeolite cluster, however, could not be recovered. The calculated interaction energies for a Na+ zeolite cluster are close to the experimental ones with a magnitude of deviation of only 2 kcal/mol, showing the reliability of the model chosen. The trends obtained are discussed in the framework of the HSAB principle and purely electrostatic and inductive interactions.