晶化时间对高岭土微球上ZSM-5沸石的原位合成及其催化性能的影响

 采用XRD、SEM、FT-IR和N₂吸附等技术研究了晶化时间对高岭土微球上合成ZSM-5沸石的影响。并以大庆VGO为原料， 在重油微反装置上考察了晶化时间对高岭土微球原位合成ZSM-5沸石催化性能的影响。结果表明，晶化时间不超过24h时,只有ZSM-5沸石类似，NaP和MOR沸石的相对结晶度也是随晶化时间的增加而先增加后下降。不同晶化时间制得的样品均以B酸为主, L酸量较少, 有利于催化裂化反应进行。晶化时间为48小时的样品可以作为增产丙烯助剂, 在催化剂中添加5%(质量分数)时, 丙烯收率可从7.12%提高到9.46%。

EFFECT OF CRYSTALLIZATION TIME ON IN-SITU SYNTHESIS AND CATALYTIC PROPERTIES OF ZSM-5 ZEOLITE ON KAOLIN MICROSPHERES

XRD, SEM, FT-IR and N2 adsorption were used to characterize the effect of crystallization time on in-situ synthesis of ZSM-5 zeolite on kaolin microsphere. The results indicate that pure ZSM-5 zeolite is obtained before 24h and MOR and NaP zeolite appears at 36 h. The change trends of relative crystallinity of two zeolites are similar to that of ZSM-5 zeolite. The SEM results show that the crystallization of ZSM-5 is a continual process and ZSM-5 crystals with perfect shapes are achieved at 48h. The acidity of composite materials with different crystallization time represents mainly B acid modality which is in favor of Fluid Catalytic Cracking reaction, containing only a few L acids. The effect of crystallization time on the catalytic performances of composite materials was investigated on the micro fixed-bed reactor unit using Da qing VGO as feedstock. The composite materials obtained at 48h bear good catalytic performance for heavy oil-to-light olefin.