Abstract

Silicalite-1 nanosheets catalyst with a hierarchical architecture was hydrothermally synthesized using [C₁₈H₃₇-N⁺(CH₃)₂-C₆H₁₂-N⁺(CH₃)₂-C₆H₁₃](Br)⁻² as template. It has been studied systematically by investigating the influence of different synthesis parameters and crystallization kinetics under tumbling conditions. Highly crystalline silicalite-1 nanosheets with large external surface was obtained by regulating the crystallization time and the amount of water, template and the alkalinity. It was examined as catalyst for vapor-phase Beckmann rearrangement of cyclohexanone oxime to caprolactam and exhibited an excellent catalytic performance and long catalytic lifetime. This can be attributed to nest silanol groups located on the large external surface of the nanosheets. Furthermore, the high mesoporosity of nanosheets shorten the diffusion path length and reduce coking deposition, which remarkably improve catalyst stability.

摘要

使用[C ₁₈ H ₃₇ -N ⁺（CH ₃）₂ -C ₆ H ₁₂ -N ⁺（CH ₃）₂ -C ₆ H ₁₃ ]（Br）^-2水热合成具有分级结构的Silicalite-1纳米片催化剂作为模板。通过研究翻滚条件下不同合成参数和结晶动力学的影响，对其进行了系统地研究。通过调节结晶时间和水量，模板量和碱度，可以得到具有较大外表面的高度结晶的silicalite-1纳米片。作为环己酮肟的气相贝克曼重排为己内酰胺的催化剂，已进行了检测，并显示出优异的催化性能和较长的催化寿命。这可以归因于位于纳米片大外表面上的嵌套的硅烷醇基团。此外，纳米片的高介孔率缩短了扩散路径的长度并减少了焦化沉积，从而显着提高了催化剂的稳定性。