Generating nanocrystalline SAPO-34 through bead-milling and porogen-assisted recrystallization: Structural evolution and catalytic consequence in dimethyl ether-to-olefin conversion

• Published in: Applied catalysis. A, General Vol. 632; p. 118483
• Main Authors: Zhang, Yunfeng, Ding, Hongxin, Li, Liyuan, Zhu, Kake, Liu, Jichang
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.02.2022; Elsevier Science SA
• Subjects: Bead-milling; Catalytic converters; Conversion; Crystal growth; Crystals; Dimethyl ether; Mass transport; Mechanochemical; Morpholine; Nanocrystals; Nanozeolites; Recrystallization; SAPO-34; Selectivity; Transport properties; Crystal growth; Mechanochemical; Nanozeolites; Bead-milling; SAPO-34
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2022.118483

Mechanochemical bead-milling is a promising post-synthetic way to generate nanocrystalline zeotype materials with promoted catalytic performance. Post-milling recrystallization is often entailed to remedy the damaged framework but leads to crystal growth. Herein, using SAPO-34 (ca. 20 µm) derived from inexpensive morpholine as an example, we showcase that secondary growth can be suppressed by porogen-assisted recrystallization, resulting in formation of tiny crystals (100–200 nm) with better mass transport property. The presence of porogen (polydiallyldimethylammonium chloride) also induced a reduction of acid site density owing to a re-distribution of Si across the crystal, which alleviated zoning of Si at the external surface. The catalytic advantages, with respect to a control sample recrystallized in the absence of porogen, have been experimentally verified in dimethyl ether-to-olefin conversion, exhibiting an exaggerated light olefin selectivity and prolonged catalyst lifetime. This advancement of mechanochemical synthesis opens an avenue to better tailor crystal size for zeotype materials. [Display omitted] •Combined bead-milling and porogen-assisted recrystallization method is developed to generate uniform SAPO-34 nanocrystals.•Secondary growth in the recrystallization process is suppressed by the presence of porogen.•Silicon zoning at the external surface is alleviated after recrystallization.•Enhanced diffusion property and high turnover number in dimethyl ether-to-olefin conversion are achieved.•Exaggerated light olefin selectivity and slowed coking rate are attained.