Influence of steaming and acid-leaching treatments on the hydrophobicity of HBEA zeolite determined under static conditions

A series of HBEA dealuminated samples was prepared by treatment with HCl or steaming of a parent sample. Samples were characterized by XRD, elemental analysis, nitrogen adsorption and pyridine adsorption–desorption followed by IR spectroscopy. The hydrophobicity coefficient, determined by separated static adsorption of water and toluene was used as a quantitative measurement of the hydrophobic properties. It is shown that dealumination causes drastic increase of the hydrophobicity of the different samples. The increase of the hydrophobic character is rather higher for steamed samples than for the acid-leached ones. For the same number of Brønsted sites, the water uptake on the steamed samples corresponds to 11 molecules by unit cell whereas it is 17 for the acid-leached samples. The low hydrophobic character of acid-leached samples is attributed to the creation of hydroxyl nests during acid treatment.