SAPO-34/SiO_2催化甲醇制烯烃

采用水热法合成了SAPO-34分子筛,并用X射线粉末衍射仪和扫描电子显微镜对SAPO-34分子筛的结构进行了表征,同时探讨了黏合剂种类、甲醇分压、催化剂粒径和硅源等对SAPO-34分子筛催化甲醇制烯烃(MTO)反应性能的影响。实验结果表明,在MTO反应中,三烯(乙烯、丙烯和丁烯)选择性在反应初期存在明显的诱导期;以S iO2为黏合剂合成的SAPO-34/S iO2催化剂不但可缩短MTO反应的诱导期,三烯选择性也较未添加黏合剂或以A l2O3为黏合剂时高1~2个百分点;且当催化剂活性明显下降时,三烯选择性下降的幅度较小。催化剂粒径、甲醇分压及硅源对催化剂的诱导期也有明显的作用。在甲醇分压低于19kPa、催化剂粒径0.25~0.38mm、S iO2为黏合剂、硅酸四乙酯为硅源时,SAPO-34/S iO2催化剂的MTO性能明显提高。

Conversion of Methanol to Olefins over SAPO-34/SiO2 Catalyst

SAPO-34 molecular sieves were synthesized by hydrothermal method and were characterized by means of SEM and XRD.The reactions of methanol to light olefins(MTO) on obtained molecular sieve catalyst were investigated.The effects of binder,silica sources,partial pressure of methanol and particle diameter of catalyst on performance of the catalyst in MTO were studied.There are induction periods in selectivities to light olefins at beginning of MTO.When silica sol is used as binder not only induction periods in selectivities shorten,but also selectivities themselves to light olefins increase by 1%-2%,compared with Al2O3 as binder or without any binder.Performance of catalyst is excellent when the partial pressure of methanol is less than 19 kPa,particle diameter of the catalyst is in range of 0.25-0.38 mm,and silica sol and tetraethyl orthosilicate(TEOS)are used as binder and as silica source correspondingly.