利用适用于SAPO-34的有机结构导向剂合成SSZ-13分子筛

硅铝分子筛SSZ-13和硅磷铝分子筛SAPO-34已广泛应用于已商业化的催化应用中, 如甲醇制烯烃反应(MTO)和氨气选择性催化还原反应(NH₃-SCR). 目前, 已有多种商业化的有机结构导向剂(OSDA)可用于制备 SAPO-34, 而用于合成SSZ-13的OSDA仍主要依赖经典的N,N,N-三甲基-1-金刚烷基氢氧化铵(TMAdaOH). 因此, 寻找具有较高性价比且可导向合成高硅铝比(SAR)SSZ-13的OSDAs具有重要意义. 本文使用3种可制备SAPO-34的OSDAs二异丙胺(DIPA)、 二丙胺(DPA)、 正丁胺(nBA)]替代部分TMAdaOH, 发现即使不加入晶种也可合成出SSZ-13. 采用粉末X射线衍射(PXRD)和固体核磁共振(ss-NMR)分析方法对制备的SSZ-13进行了系统研究. 结果显示, 所合成的具有可调变SARs的SSZ-13负载Cu之后, 在NH₃-SCR性能上与商业化催化剂相当. 此外, 通过研究DIPA和TMAdaOH合成SSZ-13的晶化机理发现, DIPA的加入可以加快结晶过程、 提高产率并防止非晶相的形成. 本文提出的观点可为寻找更高效和商业化的SSZ-13结构导向剂及合成具有特定性质的SSZ-13提供参考.

Exploring Organic Structure-directing Agents Used for SAPO-34 to Synthesize SSZ-13

The aluminosilicate zeolite SSZ-13 and zeolitic silicoaluminophosphate molecular sieve（SAPO MS） SAPO-34 have been widely used in commercialized catalytic applications， such as the methanol-to-olefins（MTO） process and the selective catalytic reduction of NO_x with NH₃（NH₃-SCR）. Nowadays， a variety of commercialized organic structure-directing agents（OSDAs） have been utilized for preparing SAPO-34， while the OSDAs for synthesizing SSZ-13 still mainly relies on the classical N，N，N-trimethyladamantammonium hydroxide（TMAdaOH）. Therefore， it is of great significance to seek for the suitable OSDAs， which can direct the synthesis of SSZ-13 with higher cost performance and appliable high silicon-to-alumina ratio（SAR）. Herein， three OSDAs used for preparing SAPO-34［diisopropylamine（DIPA）， dipropylamine（DPA） and n-butylamine（nBA）］ were successfully employed for synthesizing SSZ-13 by partial replacing the expensive TMAdaOH with or without the assistance of seeds. Systemic investigation focused on SSZ-13 preparation was explored by powder X-ray diffraction（PXRD） and solid-state nuclear magnetic resonance（ss-NMR） analyses. As a result， the as-synthesized SSZ-13 zeolites possess a tunable range of SARs（11―22） and Cu-SSZ-13 catalysts show excellent NH₃-SCR performance compared with commercialized ones. The crystallization mechanism of SSZ-13 synthesized by DIPA and TMAdaOH were also studied and the addition of DIPA would accelerate the crystallization process， improve the yields， and prevent the formation of amorphous phase. The work presented here might provide new insights for identifying more efficient and commercialized OSDAs for preparing SSZ-13 with tailored properties.