Seed-assisted grinding synthesis of SAPO-34 catalyst and its prolonged catalytic lifetime in the conversion of methanol to olefins
Seed-assisted grinding synthesis of SAPO-34 catalyst and its prolonged catalytic lifetime in the conversion of methanol to olefins
复制标题
SAPO-34催化剂的种子辅助研磨合成及其在甲醇转化为烯烃中的催化寿命延长
DOI：
10.1007/s11144-019-01655-0
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发表时间：
2019-12-01
影响因子：
1.8
通讯作者：
Zhao, Xinhong
中科院分区：
文献类型：
--
作者：
Lu, Huihui;Duan, Weiting;Zhao, Xinhong
以吗啉为模板剂，采用晶种辅助研磨法合成了纳米级三斜晶系SAPO-34分子筛。优化了硅源、硅浓度、晶化温度和晶化时间等合成条件，得到了相纯度和结晶度均较高的SAPO-34分子筛。特别地，在后续的研究中，利用不同方法预活化的晶种诱导合成纳米SAPO-34分子筛。采用XRD、SEM、N2物理吸附和NH3-TPD等技术对SAPO-34进行了表征。结果表明，机械球磨活化晶种的引入和0.0001 M和0.01 M H_3PO_4的化学刻蚀不仅能有效地将SAPO-3 - 4分子筛的晶粒尺寸从3-4 μm减小到500-800 nm，而且能改善其织构和酸性能。这种纳米尺寸的SAPO-34催化剂在甲醇制烯烃（MTO）反应中表现出显着延长的催化寿命相比，传统的微米尺寸的对应物。类似于无溶剂合成沸石，这种晶种辅助研磨合成方法比传统的水热合成方法更简单、更高效。更重要的是，该方法为制备上级MTO催化剂提供了一条新的途径。
A cost-effective route has been developed for the synthesis of nano-sized triclinic SAPO-34 zeolite via seed-assisted grinding method using lower dosage of morpholine as the sole template. The synthesis conditions including silica source, silica concentration, crystallization temperature and time were refined to obtain SAPO-34 zeolite with high phase purity and crystallinity. Particularly, seed crystals preactivated by different methods were utilized to induce the synthesis of nano-sized SAPO-34 zeolites in the subsequent study. The resultant SAPO-34 samples were characterized by XRD, SEM, N2physisorption and NH3-TPD techniques. It was found that the introduction of seed crystals activated by mechanical milling for 20 min and chemical etching with 0.0001 M and 0.01 M H3PO4can not only effectively reduce the crystal size of SAPO-34 zeolites from 3–4 μm to 500–800 nm level, but also can modify their texture and acid properties. This nano-sized SAPO-34 catalyst exhibits a remarkably prolonged catalytic lifetime in methanol to olefins (MTO) reaction in comparison to the conventional micron-sized counterpart. Analogous to solvent-free synthesis of zeolites, this seed-assisted grinding synthesis method is simpler, more efficient than conventional hydrothermal synthesis. More importantly, this method provides a new avenue for preparing superior MTO catalyst.