Experimental and computer simulation sorption and spectroscopic studies were evaluated in-order to be able to answer two puzzling questions. (1) How can a Si/Al ~40 ratio commercial H⁺ exchanged Y zeolite (H–Y), CBV 780, adsorb only nearly as little H₂O as a Si/Al ~ 4330 ratio ZSM-5? (2) Why another Si/Al ~ 40 ratio commercial H–Y, CBV 901, adsorbs much less H₂O than CBV 780 and even less than the mentioned highly siliceous ZSM-5? These zeolites have not been chemically treated to be hydrophobic, only their patented synthesis and post-treatment conditions differ. Results indicate that the crystallites of CBV 901 are covered with a defect and aluminum free siliceous nano-layer, which prevents any H₂O penetration into the bulk. The external surface of CBV 780 crystallites has about the same little amount of Al as its bulk, presumably less than 4 Al per unit cell. Due to the low number of Al-associated Brønsted acidic hydroxyls (BA-OH), on which H₂O preferably adsorbs, little water adsorption takes place in the micropores. On the other hand the surface of the large mesopore defects of CBV 780 must be enriched in with Al to get the measured overall Si/Al ~40 ratio in this material, which provides enough BA-OH sites for adsorbing H₂O molecules as a prelude to mesopore filling, that manifests itself in a Type II sorption isotherm.

为了能够回答两个令人困惑的问题，对实验和计算机模拟吸附和光谱学研究进行了评估。（1）如何以Si / Al〜40比率的商用H ⁺交换Y沸石（H–Y）CBV 780吸附的H ₂ O几乎只有Si / Al〜4330比率的ZSM-5？（2）为什么另一种Si / Al〜40比率的商用H–Y CBV 901吸附的H ₂ O比CBV 780少得多，甚至比上述高硅质ZSM-5少呢？这些沸石尚未经过化学处理以具有疏水性，只是它们获得专利的合成方法和后处理条件不同。结果表明，CBV 901的微晶被缺陷和无铝硅质纳米层覆盖，可以防止任何H ₂O渗透到主体中。CBV 780晶体的外表面与其堆积的铝量几乎相同，大概每单位晶胞少于4 Al。由于H ₂ O优选吸附在其上的与铝缔合的布朗斯台德酸性羟基（BA-OH）的数量较少，因此微孔中几乎不发生水吸附。另一方面，CBV 780的大中孔缺陷表面必须富含Al，才能获得该材料中测得的总Si / Al〜40比率，这为吸附H ₂ O分子提供了足够的BA-OH位。中孔填充的前奏，表现为II型吸附等温线。