Difference of acid characters and catalytic cracking performance between ZSM-5 zeolites synthesized with various templates

doi:10.11949/j.issn.0438-1157.20160397

Abstract

Abstract:

ZSM-5 zeolites with similar crystal size and Si/Al ratio were synthesized in the presence of n-butylamine (NBA), tetrapropyl ammonium (TPA⁺) and no template (NT), respectively. The samples were characterized by XRD, TEM, NH₃-TPD, N₂ sorption analysis and applied to n-hexane cracking to investigate the difference of their acid characters, cracking selectivity and lifetime. The results showed that the samples had different acid properties and acid distribution in spite of similar Si/Al. Under the same initial conversion, the samples exhibited different product distribution. ZSM-5 using NBA and TPA⁺ showed higher selectivity of ethylene and propylene than ZSM-5 without template. However, the latter had much longer stable period than the former two and its conversion could stay above 96% for 1200 min.

Key words: template, ZSM-5, acid property, catalytic cracking, lifetime

摘要：

分别以正丁胺、四丙基溴化铵为模板及无模板条件下制备了3种晶粒尺寸及硅铝比相近的ZSM-5分子筛，通过X射线衍射（XRD）、扫描电镜（SEM）、氨气程序升温脱附（NH₃-TPD）、N₂吸附/脱附对分子筛进行了表征，将其应用于正己烷裂解反应考察其性能差异。结果表明，实验控制三者ZSM-5样品具有相似的硅铝比，却仍显示出不同的酸性质及酸分布；在相同初始转化率下，不同模板制备的ZSM-5具有不同的产物选择性，正丁胺和四丙基溴化铵为模板制备的ZSM-5分子筛的双烯选择性高于无模板制备的ZSM-5分子筛，但无模板制备的ZSM-5分子筛表现出更高的裂解稳定性，转化率可在1200 min内保持在96%以上，远远高于其他模板制备的ZSM-5分子筛。

关键词: 模板剂, ZSM-5, 酸性质, 催化裂解, 寿命

CLC Number:

O643.32

MA Tong, GENG Zubao, LI Bing, ZHAO Qi, GONG Yanjun. Difference of acid characters and catalytic cracking performance between ZSM-5 zeolites synthesized with various templates[J]. CIESC Journal, 2016, 67(8): 3374-3379.

马通, 耿祖豹, 李冰, 赵琦, 巩雁军. 不同模板制备ZSM-5分子筛的酸性特征及催化裂解性能差异[J]. 化工学报, 2016, 67(8): 3374-3379.

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