The adsorption of methanol in HZSM-5 at low temperatures has long been regarded as an associative process involving hydrogen bonding to the acidic zeolite hydroxyl groups. Recent studies employing inelastic neutron scattering spectroscopy (INS) have reported that complete dissociation to methoxylate the zeolite occurs at 298 K, and infrared evidence for a partial dissociation at 298 K has also been described. Here we investigate the apparent contradictions between different techniques, using a combination of INS, infrared spectroscopy and solid-state NMR spectroscopy, including isotopic substitution experiments. Different possible explanations are proposed and considered; we conclude that at room temperature methanol is very largely associatively adsorbed, although the presence of some small extent (>1%) of methoxylation cannot be ruled out.

长期以来，HZSM-5 中甲醇在低温下的吸附一直被认为是涉及氢键与酸性沸石羟基的缔合过程。最近使用非弹性中子散射光谱 (INS) 的研究报告说，沸石甲氧基化的完全离解发生在 298 K，并且还描述了在 298 K 下部分离解的红外证据。在这里，我们结合使用 INS、红外光谱和固态核磁共振光谱，包括同位素取代实验，研究了不同技术之间的明显矛盾。提出并考虑了不同的可能解释；我们得出结论，尽管不能排除存在一定程度的甲氧基化 (>1%)，但在室温下甲醇在很大程度上被缔合吸附。