The reduction of zeolite particle size and the development of methods to enhance the basic properties of catalysts are some of the important research fields currently explored. In light of this, this work aimed at evaluating how the combination of crystallite size reduction and ion exchange of micro- and nanocrystalline NaX zeolites with different chain-length linear alkylammonium cations affects their overall properties, Lewis basicity and catalytic activity. Scanning electron microscopy (SEM) analyses showed that micro- and nanocrystalline NaX possessed octahedral and undefined crystalline forms, respectively, both being polycrystalline. ²⁷Al and ²⁹Si MAS-nuclear magnetic resonance (NMR) analyses revealed that nanocrystalline zeolites presented lower long-range organization, forming a less rigid structure with more accessible sites, which is a desirable feature for catalytic applications. These characteristics were confirmed using a range of techniques: nitrogen physisorption, thermogravimetric analysis and catalytic evaluation. Nanocrystalline zeolites exhibited higher exchange degrees than the microcrystalline zeolites, because the smaller crystal sizes and the higher mesoporosity of the former enhance the accessibility to the exchangeable sites and reduce steric hindrance. Catalytic evaluation of the zeolites via Knoevenagel condensation reaction between butyraldehyde and ethyl cyanoacetate confirmed the advantages of both zeolite modification methods Ion-exchanged zeolites presented higher catalytic activity than NaX zeolites. Zeolites with nanometric crystals showed greater conversions, and higher reaction rates than the micrometric. In addition, most of the nanosized catalysts presented higher turnover frequencies at zero reaction time.

降低沸石粒度和开发增强催化剂基本性能的方法是目前正在探索的一些重要研究领域。有鉴于此，这项工作旨在评估微晶尺寸减小以及具有不同链长线性烷基铵阳离子的微晶和纳米晶NaX沸石的离子交换的组合如何影响其整体性能，路易斯碱度和催化活性。扫描电子显微镜（SEM）分析表明，微晶和纳米晶NaX分别具有八面体和不确定的晶型，均为多晶。²⁷ Al和²⁹Si MAS-核磁共振（NMR）分析表明，纳米晶沸石呈现较低的长程组织，形成具有更多可及位置的较低刚性的结构，这是催化应用的理想特征。这些特性已通过一系列技术得到了证实：氮气物理吸附，热重分析和催化评估。纳米晶沸石显示出比微晶沸石更高的交换度，因为前者的较小的晶体尺寸和较高的介孔率提高了对可交换位点的可及性并减少了空间位阻。通过丁醛和氰基乙酸乙酯之间的Knoevenagel缩合反应对沸石进行催化评估，证实了两种沸石改性方法的优势。离子交换沸石比NaX沸石具有更高的催化活性。具有纳米级晶体的沸石显示出比微米级更高的转化率和更高的反应速率。另外，大多数纳米尺寸的催化剂在零反应时间表现出更高的周转频率。