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采用Hβ分子筛为催化剂,在液相体系中将桥式双环戊二烯(endo-DCPD)异构为挂式双环戊二烯(exo-DCPD)。无催化剂时双环戊二烯主要发生聚合反应,加入催化剂后生成了大量exoDCPD。在分子筛表面沉积SiO2可提高反应选择性,说明异构反应发生在分子筛孔道内,而外表面主要引发聚合副反应。低n(硅)/n(铝)的分子筛含有大量强度较弱的Lewis酸性位,在异构反应中的活性最高,说明弱酸性位是异构的活性中心。对分子筛焙烧温度考察发现,焙烧温度过低时分子筛的L酸位较少,温度过高时L酸变强而且结晶度急剧下降,500℃焙烧的分子筛异构化性能最佳,证明分子筛异构是孔结构和弱L酸性中心协同作用的结果。
Hβ molecular sieve was used as a catalyst to isomerize bridged dicyclopentadiene (endo-DCPD) to dicyclopentadiene (exo-DCPD) in liquid phase. In the absence of catalyst, dicyclopentadiene mainly polymerizes and a large amount of exoDCPD is formed after addition of catalyst. The deposition of SiO2 on the molecular sieve surface can improve the selectivity of the reaction, indicating that the isomerization reaction takes place in the molecular sieve pores and the outer surface mainly initiates the polymerization side reaction. The low n (Si) / n (Al) molecular sieves contain a large amount of Lewis acid sites with weaker intensity and the highest activity in the isomerization reaction, indicating that the weakly acidic sites are isomeric active sites. The results of the calcination temperature showed that when the calcination temperature is too low, the L acid number of the molecular sieve is small. When the temperature is too high, the L acid becomes strong and the crystallinity decreases sharply. The isomerization behavior of the molecular sieve at 500 ℃ is the best. Is the result of the synergistic effect of pore structure and weak L acid center.