层柱人工水热合成皂石的制备与表征

摘要

利用具有理想皂石结构的人工水热合成蒙皂石为层原料,通过与羟基聚合铝离子([Al13O4(OH)24(H2O)12]7+)交换反应合成得到了一种层柱粘土.实验对于该铝柱皂石进行了粉末XRD,FT-IR和TG-DTA表征.氮气吸附实验说明其高温活化(773 K,2 h)产物具有很高的BET比表面(360 m2·g-1).相对于层柱蒙脱土,层柱皂石显示了更高的催化裂解性能和热稳定性.层柱皂石的异丙苯裂解转化率达到了65%;而层柱蒙脱土的转化率只有4%.这说明层材料的四面体取代对于层柱粘土Bronsted酸位的形成具有重要的决定作用.氨程序升温脱附实验发现铝柱皂石在350～650℃区间具有较强的氨脱附量,表明层柱皂石具有层柱蒙脱土所没有的强酸中心.%Alumina pillared clay was synthesized by a cationic exchange reaction with [Al13O4(OH)24(H2O)12]7+ (referred to as Al13) using synthetic smectite with ideal saponite structure as parent material. The obtained pillared saponite was characterized by X-ray powder diffraction, FT-IR and TG-DTA. The pillared materials showed a very high the alumina pillared montmorillonite, the pillared saponite exhibited higher cracking activity and better thermal stability. The cumene conversion was ca. 65% over the pillared saponite by the impulse reaction, while it was only ～4% for the pillared montmorillonite, indicating that the substitutions in the tetrahedral sheets played an important role in the development of Bronsted acidity of the catalyst. By temperature programmed desorption of ammonia (TPDA), pillared saponite showed high strong acidity in the temperature range 350～650℃.