晶化条件对HZSM-5分子筛合成收率和性能的影响

Effects of crystallization conditions on the yields and properties of HZSM-5 molecular sieves

考察了SiO2-Al2O3-TPABr-NH3·H20—H2O体系晶化时间、晶化温度和原料用量等对合成HZSM-5性能的影响。当n（SiO2）：n（Al2O3）=100、n（TPABr）：n（SiO2）=0．1、n（NH3）：n（SiO2）=1．5、n（H2O）：n（SiO2）=22和晶种添加质量分数为4％时，180℃静态晶化72h，合成收率与相对结晶度分别为10．1％和99．8％，对应理论收率为11．4％，合成收率与理论收率比为0．89。当投料n（SiO2）：n（A1203）从50增加到400，合成收率与结晶度分别超过8．9％和82．8％，合成收率与理论收率比为0．76—0．89；样品酸量随着n（SiO：）：n（Al2O3）的增加逐渐减小，比表面积为405m2·g-1，合成样品HZSM-5对甲醇制烯烃反应具有良好的酸催化活性。设定反应条件，采用投料n（SiO2）：n（AlO3）=250的样品，甲醇转化率、丙烯选择性和C=2～C=4选择性分别为100％、39．27％和62．01％。

In SiO2-Al2O3-TPABr-NH3 · H2O-H2O system, the effects of hydrothermal crystallization time and temperatures, and raw material amounts on the yields and properties of as-synthesized HZSM-5 molecular sieve were investigated. The results showed that the yield and relative erystallinity of as-synthesized samples were 10. 1% and 99. 8%, respectively, under the condition as follows： n （ SiO2 ） ： n （ Al2O3 ） = 100, n（TPABr）： n（SiO2） =0.1 ,n（NH3） ： n（SiO2） = 1.5,n（H2O） ： n（SiO2） = 22,seed crystal amount 4%, crystallization temperature 180 ℃ and crystallization time 72 h. The corresponding theoretical yield was 11.4%, and the ratio of the yield of as-synthesized samples to the theoretical yield was 0. 89. As n（SiO2）： n（Al2O3） of the raw material enhanced from 50 to 400, the yield and erystallinity of the assynthesized samples remained more than 8.9% and 82.8% ,respectively, and the ratio of as-synthesized sample yield to the theoretical yield was 0.76 - 0.89. The acid amount of the as-synthesized samples decreased gradually with the increase of n （ SiO2 ） ： n （ A1203 ） of the raw material. The as-synthesized HZSM-5 molecular sieve with BET surface area of 405 m2 · g-1 exhibited good acid catalytic activity for methanol-to-olefins reaction. At the set condition, methanol conversion, the selectivity to propylene and C2=-C4= light olefins were 100%, 39.27% and 62.01%, respectively, using HZSM-5 molecular sieve catalyst prepared with the raw material of n （ SiO2 ） ： n （ A12 03 ） = 250.