The synthesis of nanosized ZSM-5 zeolites with high crystallinity and suitable acidity is very significant for their great potential in various catalytic applications. Herein, a series of zeolite ZSM-5 crystals with different particle sizes and SiO₂/Al₂O₃ ratios (10–30) were synthesized by a temperature-varying two-step crystallization method in a concentrated gel system containing L-lysine and/or polyvinylpyrrolidone (PVP) additives. By optimizing the addition amounts of the two additives, the crystal size of the ZSM-5 zeolite could be reduced to less than 100 nm. Meanwhile, relatively high crystallinity and framework Al incorporation rates could be achieved, resulting in the generation of high-quality ZSM-5 nanocrystals. The nanosized H-form ZSM-5 zeolite with a SiO₂/Al₂O₃ ratio of 20 showed enhanced catalytic efficiency and stability for the alkylation of 2-methylnaphthalene (2-MN) with methanol to produce an important intermediate, 2,6-dimethylnaphthalene (2,6-DMN). A relatively high and steady yield of 2,6-DMN (above 7.2%) could be achieved during 20 h time-on-stream at 400 °C. The smaller crystal size, higher crystallinity and framework Al content could provide more accessible Brønsted acid sites in the 10-membered ring channel of the ZSM-5 nanocrystals, which are the main active sites responsible for the shape-selectivity of the targeted product of 2,6-DMN. As a result, the formation of other side products like 1-MN and poly-MN could be effectively inhibited, thus leading to an improved 2,6-DMN yield and coke resistance over the nanosized ZSM-5 catalyst.

中文翻译：

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非离子聚合物和氨基酸辅助合成ZSM-5纳米晶及其在2-甲基萘烷基化反应中的催化应用

合成具有高结晶度和合适酸度的纳米ZSM-5沸石因其在各种催化应用中的巨大潜力而​​具有非常重要的意义。本文采用变温两步_结晶法在_含有L-赖氨酸和/或聚乙烯吡咯烷酮（PVP）添加剂。通过优化两种添加剂的添加量，ZSM-5沸石的晶体尺寸可以减小到100 nm以下。同时，可以获得相对较高的结晶度和骨架Al掺入率，从而产生高质量的ZSM-5纳米晶体。 SiO ₂ /Al ₂ O ₃比为20的纳米H型ZSM-5沸石在2-甲基萘(2-MN)与甲醇的烷基化生产重要中间体2,6的过程中表现出增强的催化效率和稳定性。 -二甲基萘（2,6-DMN）。在 400 °C 下运行 20 小时期间，可以实现相对较高且稳定的 2,6-DMN 收率（高于 7.2%）。较小的晶体尺寸、较高的结晶度和骨架Al含量可以在ZSM-5纳米晶体的10元环通道中提供更容易接近的布朗斯台德酸位点，这是负责2的目标产物的形状选择性的主要活性位点。 ,6-DMN。结果，可以有效抑制1-MN和聚MN等其他副产物的形成，从而与纳米ZSM-5催化剂相比，提高2,6-DMN产率和抗焦炭性。