ZSM-5分子筛的合成及其在丁烯催化裂解反应中的应用

发布时间：2018-11-18 10:49

【摘要】：采用水热合成法制备了无模板剂ZSM-5分子筛并用正硅酸甲酯(TMOS)对其进行外表面修饰改性,利用XRD、SEM、~(29)Si MAS NMR、~(27)Al MAS NMR、NH_3-TPD、BET和UV-vis DRS对合成分子筛的物相、形貌和酸性等进行了表征,并将其应用于催化丁烯裂解反应。研究表明,经水热合成的无模板剂ZSM-5结晶度较好,与添加模板剂合成的ZSM-5拥有相似的孔道结构和晶体结构以及相近的酸量,但在酸中心分布上有明显差异:孔道内酸中心数量增加且分布更加均匀,孔道交叉处酸中心数量减少;经过外表面修饰改性后,ZSM-5分子筛外表面部分不具备择形性的酸中心被钝化,使其择形选择能力增强。在催化丁烯裂解反应中,用TMOS进行外表面修饰改性的无模板剂ZSM-5分子筛作为催化剂能够有效抑制副反应的发生,丙烯和乙烯的总收率高达58%。
[Abstract]:ZSM-5 molecular sieve without template was prepared by hydrothermal synthesis and modified with methyl orthosilicate (TMOS). XRD,SEM,~ (29) Si MAS NMR,~ (27) Al MAS NMR,NH_3-TPD,) was used to modify the molecular sieve. The phase, morphology and acidity of the synthesized molecular sieve were characterized by BET and UV-vis DRS, and were applied to the catalytic cracking of butene. The results show that ZSM-5 synthesized by hydrothermal method has good crystallinity and has similar pore structure and crystal structure as well as similar acid content to ZSM-5 synthesized by adding template. But there are obvious differences in the distribution of acid centers: the number of acid centers in pore channels increases and the distribution is more uniform, and the number of acid centers at the cross of pores decreases; After modification, the shape selective acid sites of ZSM-5 molecular sieve were not passivated, which enhanced the ability of shape selection. In the catalytic cracking of butene, ZSM-5 molecular sieve without template modified by TMOS can effectively inhibit the occurrence of side reactions. The overall yield of propylene and ethylene is as high as 58%.
【作者单位】：中国石油大学(北京)化学工程学院重质油国家重点实验室;
【分类号】：O643.36

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