Size control of SAPO-34 crystals and their catalyst lifetime in the methanol-to-olefin reaction
Size control of SAPO-34 crystals and their catalyst lifetime in the methanol-to-olefin reaction
复制标题
DOI：
10.1016/j.apcata.2009.04.044
复制
发表时间：
2009-06
影响因子：
5.5
通讯作者：
N. Nishiyama;M. Kawaguchi;Y. Hirota;D. Vu;Y. Egashira;K. Ueyama
中科院分区：
文献类型：
--
作者：
N. Nishiyama;M. Kawaguchi;Y. Hirota;D. Vu;Y. Egashira;K. Ueyama
以四乙基氢氧化铵(TEAOH)、吗啉(MOR)、N，N，N‘，N’-四乙乙烷-1，2-二胺(TEEDA)或TEAOH和MOR的混合物为结构导向剂，在水热条件下合成了SAPO-34分子筛。用X射线衍射仪、扫描电子显微镜和场发射扫描电子显微镜研究了SAPO-34的晶体生长。以乙酸乙酯和MOR的混合物为溶剂，水热合成法可以将SAPO34的晶粒度控制在1.5~7μm之间。用TEAOH作SDA时，得到了尺寸为800 nm的SAPO-34小晶体。较小的SAPO-34晶体在甲醇制烯烃反应中表现出较长的催化剂寿命。失活的SAPO-34催化剂结焦量随晶粒度的减小而增加，说明减小SAPO-34的晶粒度可以提高催化剂的活性。
Crystals of SAPO-34 molecular sieves were synthesized under hydrothermal conditions by using tetraethylammonium hydroxide (TEAOH), morpholine (Mor), N,N,N’,N’-tetraethylethane-1,2-diamine (TEEDA), or a mixture of TEAOH and Mor as structure-directing agents (SDA). The crystal growth of SAPO-34 was studied by X-ray diffraction and by scanning electron microscopy and field-emission scanning electron microscopy. The crystal size of SAPO-34 could be controlled between 1.5 and 7μm by hydrothermal synthesis using a mixture of TEAOH and Mor as the SDA. Small SAPO-34 crystals (800nm in size) were formed when TEAOH was used as the SDA. The smaller SAPO-34 crystals showed a longer catalyst lifetime in the methanol-to-olefins reactions. The amount of coke deposited on deactivated SAPO-34 catalyst increased with decreasing crystal size, indicating that the effectiveness of the catalyst could be improved by reducing the crystal size of SAPO-34.