β沸石的微波法制备、表征及醚化性能研究

Microwave Preparation, Characterization and Etherification Performance Study of p - Zeolite

以粗孔硅胶为硅源,偏铝酸钠为铝源,四乙基氢氧化铵为模板剂,在微波辐射条件下,合成β沸石并脱除模板剂。对产物进行XRD、SEM、TEM及NH3-TPD表征分析,讨论凝胶组成和辐射条件对合成β沸石的影响。在固定床反应装置上,考察β沸石催化裂化轻汽油醚化活性。结果表明,在n(Al2O3):n(SiO2)≥0.035、辐射温度≥80℃、晶化时间1h和脱模时间1.5h的条件下,即可获得相对结晶度≥80%的沸石。最佳合成条件为pH≥10、辐射温度140℃、晶化时间1h。与传统方法相比,微波辐射法合成β沸石模板剂用量减少25%,晶化时间缩短36h,脱模时间缩短3.5h以上。微波制备样品的比表面积高于480m2/g,孔体积高于0.300ml/g,其中n(SiO2):n(Al2O3)为29.1的沸石,中强酸酸量占总酸量31.9%,醚化选择性最高为99.8%。

Tetraethyl ammonium hydroxide (organic template) , silica gel ( silica source) and sodium meta-aluminate ( aluminum source) were used to p - zeolite synthesis and template removal in microwave radiation. The as - prepared products were characterized by XRD, SEM, TEM and NH3 - TPD. The effects of the sol composition and the radiation condition on the synthesized p - zeolite were discussed. The etherification test for fluid catalytic cracking of light gasoline was carried out in a fixed - bed reactor. The results showed that the zeolites with 80% relative crystallinity or higher were taked under the following conditions: n (Al2O3) :n (SiO2) ≥0.035, 80 ℃ radiation temperature, 1 h crystal time and 1. 5 h thermal decomposition. The optimum synthesis conditions were pH≥10 , 140 ℃ radiation temperature and 1 h radiation time. The amount of organic template in microwave radiation method was 25% less than that of the traditional way. The crystallizing time and removing template time were shortened 36 h and 3. 5 h. The specific surface area of microwave prepared samples was more than 480 m2 /g, the pore volume of microwave prepared samples were more than 0. 300 ml/g. The p - zeolite with n ( SiO2 ) : n ( Al2O3) = 29. 1 among them had 31. 9% of middling strength acid, the highest selectivity of etherification was 99.8%.