TEAOH-TMABr-Al2O3-SiO2-H2O体系中小晶粒offretite沸石的合成研究

不加无机强碱，在纯有机胺体系中合成了小晶粒offretite沸石，并采用XRD、SEM、FT-IR以及苯与丙烯烷基化制异丙苯探针反应对典型样品进行了结构性能表征。结果表明，采用四乙基氢氧化铵TEAOH与四甲基溴化铵TMABr为双模板剂时，TEAOH的量对合成产物影响很大，而TMABr的量增大容易导致生成Beta沸石。所合成的offretite沸石在苯与丙烯烷基化制异丙苯反应中活性和选择性较高。

Synthesis of small size crystalline offretite in TEAOH-TMABr-Al2O3-SiO2-H2O system

The traditional route for the synthesis of zeolites is in the system of M2O-Al2O3-SiO2-H2O or M2O-organic template-Al2O3-SiO2-H2O (M2O: Na2O, K2O or Li2O), in which inorganic alkali is necessary. Recent advances in zeolite synthesis have centered on high silica zeolite systems or have employed exotic templates. However, low Si/Al ratio zeolites are particularly attractive because they can offer high acid site density for catalytic applications and greater ion-exchange capacity in addition to compositional diversity for separation processes. Blackwell reported their discovery of two new zeolite materials UZM-4 and UZM-5, synthesized at low Si/Al ratio by using the combination of two of the most common organic templates, tetramethylammonium and tetraethylammonium ions. This exploits a new approach for novel zeolites synthesis. Offretite was first described by Gonnard and has relatively large pores of 0.67 nm running in the c-direction. It has been synthesized by several methods, such as in the system containing tetramethylammonium (TMA), Na+, K+ or p-dioxane and alkaline cations as well. Offretite synthesized by using only the combination of two organic templates (TEAOH, TMABr) has not yet to be reported. In this paper, small crystalline offretite was synthesized in a TEAOH/TMABr mixed template system at a typical synthesis composition of 12TEAOH∶ TMABr∶Al2O3∶13.5SiO2∶240H2O, and at crystallization temperature of 423 K within 7 days. The samples were characterized by XRD, SEM and IR. The catalytic properties of offretite were investigated in the alkylation of benzene with propene. These results showed that the dosage of TEAOH directly affects the crystalline phase and size of the product. Compared with TMABr, TEAOH played a more important role in the crystallization. With increasing the dosage of TMABr, zeolite Beta is obtained. The catalytic properties of H-offretite are superior in benzene alkylation reaction.