Requlation and Cotolysis of Strong Solid Acid Generated on Extra-Framework Aluminum

采用高铝含量的y型和丝光沸石型样品，精确测定了沸石的酸性与组成的关系。解吸氨的数量表明酸的量，在实验范围内与[Al]-[Na]原子的数量大致相同。这与传统上观察到的二次相邻铝种形成的关系大不相同。指出在沸石中，同形取代的铝原子即使在二级邻位上也会根据化学计量产生酸位。在对ZSM-5分子筛进行氨的程序升温解吸实验时，发现分子筛上有很强的酸性位点。该位点可归因于非框架铝，它与通常的框架酸位点相互作用。通过铝离子的浸渍，以牺牲沸石骨架中的酸位为代价，形成了强酸位。模板分子去除步骤的条件对HZSM-5中强酸位点的浓度有很大影响。在373 K的温度下，用氨水处理对固体酸度的影响也进行了研究，并确定了两种方法产生的酸位的相似性。从酸位的定量测量中发现，强酸位由两个Al阳离子组成。强酸性位点的存在提高了辛烷裂化的催化活性。超稳定Y型沸石经na_2h_2 -乙二胺四乙酸处理后，形成了酸强度分布窄、量大、对烷烃裂解有活性的强Bronsted酸位。

The relationship between the acidic property and the composition of a zeolite was precisely measured using Y-and mordenite-type samples with high aluminum contents. The number of the desorbed ammonia, showing the acid amount, was approximately same to the number of [Al]-[Na] atoms over the experimental range. This is quite different from the conventionally observed relationship where the secondary-neighboring aluminum species is formed. It is pointed out that the isomorphously substituted aluminum in zeolite generates the acid site according to the stoichiometry even when the aluminum atoms locate the secondary-neighboring sites.Very strong acid site was observed on the zeolite ZSM-5 in measurements of temperature programmed desorption of ammonia. The site was ascribable to the non-framework aluminum, which interacted with the usual framework acid site. By impregnation of aluminum cation, the strong acid site was created at the expense of the acid site in a zeolite framework.Conditions of a step for template molecule removal affected strongly the concentration of very strong acid site in HZSM-5. Treatment with ammonia with water at ca 373 K was also studied as a procedure to affect the solid acidity, and a similarity of acid sites created by both methods was identified. From the quantitative measurements of acid sites, it was found that the very strong acid site consisted of two Al cations. Catalytic activity for octane cracking was enhanced by the presence of very strong acid site.Strong Bronsted acid site with a narrow distribution of acid strength and large amount, which was active for alkane cracking, was formed by Na_2H_2-ethylenediaminetetraacetic acid treatment of ultra stable Y zeolite.