Due to their tunable acidity, shape selectivity, and excellent stability, zeolites are of great importance as solid acid materials in industrial catalysis. Tuning the properties of the acid sites in zeolites allows for the rational design and fabrication of catalysts for target reactions. Dimethyl ether (DME) carbonylation, a critical chain-growth reaction for C1 resource utilization, is selectively catalyzed by the Brønsted acid sites within the eight-membered rings (8-MRs) of mordenite (MOR). It is anticipated that strengthening the Brønsted acidity—particularly in 8-MRs—will improve the catalytic performance of MOR. In this work, density functional theory (DFT) calculations are first employed and the results used to design a modified MOR with stannum (Sn) and to predict the corresponding changes in acidity. Guided by the theoretical studies, a series of Sn-modified MOR are synthesized via a defect-engineering and subsequent heteroatom-substitution strategy. After partial desilication, isolated tetrahedral Sn species in an open configuration are successfully synthesized for the first time, within which tetrahedrally coordinated Al sites are preserved. An acidic characterization is used to confirm that the acidity of the Brønsted acid sites is enhanced by the introduction of the Sn species; as a result, the sample exhibits excellent activity in DME carbonylation reaction. Kinetic and DFT studies reveal that this strengthened acidity facilitates the adsorption of DME and reduces the activation barriers of DME dissociation and acetyl formation, accounting for the improved activity. The work demonstrates mechanistic insights into the promoting effects of strong acidity on DME carbonylation and offers a promising strategy to precisely control the acidic strength of zeolites.

中文翻译：

---

通过工程开放锡位点设计用于二甲醚羰基化的酸性增强的丝光沸石催化剂

由于其酸性可调、形状选择性和优异的稳定性，沸石作为工业催化中的固体酸材料具有重要意义。调节沸石中酸性位点的性质可以合理设计和制造目标反应的催化剂。二甲醚 (DME) 羰基化是 C1 资源利用的关键链增长反应，由丝光沸石 (MOR) 八元环 (8-MR) 内的布朗斯台德酸位点选择性催化。预计增强 Brønsted 酸度（尤其是 8-MR 中的酸度）将提高 MOR 的催化性能。在这项工作中，首先采用密度泛函理论 (DFT) 计算，并将结果用于设计含锡 (Sn) 的改良 MOR 并预测酸度的相应变化。在理论研究的指导下，通过缺陷工程和随后的杂原子取代策略合成了一系列 Sn 修饰的 MOR。部分脱硅后，首次成功合成了开放构型的孤立四面体锡物质，其中保留了四面体配位的铝位点。酸性表征用于确认布朗斯台德酸性位点的酸性通过引入锡物质而增强；结果，样品在DME羰基化反应中表现出优异的活性。动力学和 DFT 研究表明，这种增强的酸性有利于 DME 的吸附，并减少了 DME 解离和乙酰基形成的活化屏障，从而提高了活性。这项工作展示了强酸性对 DME 羰基化促进作用的机制见解，并提供了精确控制沸石酸性强度的有前途的策略。