不同改性ZSM-5分子筛负载Ni催化剂上1-庚烯芳构化和异构化性能研究

STUDY OF AROMATIZATION AND ISOMERIZATION OF 1-HEPTENE OVER DIFFERENT MODIFIED ZSM-5 ZEOLITE-SUPPORTED Ni CATALYSTS

以磷改性ZSM-5分子筛(ZSM-5-P)、磷和铁改性ZSM-5分子筛(ZSM-5-P-Fe)、未改性NaZSM-5分子筛和无定形SiO_2为载体,通过浸渍法制备了Ni/ZSM-5-P,Ni/ZSM-5-P-Fe,Ni/NaZSM-5,Ni/SiO_2催化剂,采用N2吸附-脱附、X射线衍射、NH3-TPD、H_2-TPR以及吡啶吸附-脱附红外光谱等手段对催化剂进行表征,并在催化加氢脱硫反应条件下,考察了1-庚烯在上述催化剂作用下的芳构化和异构化反应性能。结果表明:Ni/ZSM-5-P-Fe和Ni/ZSM-5-P比Ni/NaZSM-5具有更高的催化反应活性,其异构化产品、芳烃及气体收率明显增加;Ni/ZSM-5-P-Fe具有较多的中强酸活性中心和B酸中心,在该催化剂作用下1-庚烯具有较高的异构化和芳构化反应性能,说明B酸中心能较好地促进1-庚烯异构化和芳构化反应的进行,在一定强度的酸中心和金属中心协同作用下1-庚烯芳构化及异构化反应效率最高。

The aromatization and isomerization performance of 1-heptene over Ni/SiO2, Ni/NaZSM-5, Ni/ZSM-5-P and Ni/ZSM-5-P-Fe was investigated at the conditions of catalytic hydrodesulfurization （T=673 K, P=1.5 MPa, WHSV=5 h 1）. The catalysts were prepared by loading nickel on the carri- ers by spraying method and were characterized by XRD, XRF, N2 adsorption-desorption and NH3-TPD, H2 TPR, and pyridine-FTIR techniques. The product distributions show that Ni/ZSM-5 P-Fe and Ni/ZSM-5-P exhibit a remarkable enhancement of aromatization and isomerization of 1-heptene compared with that of Ni/ZSM-5, resulting in increased yields of isomerized product, aromatics, and dry gas. The performance of Ni/ZSM-5-P-Fe is even better because it has more mid-strong acid center and Bronsted acid, indicating that the Bronsted acid promotes the aromatization and isomerization of 1-heptene. It is concluded that the synergetic effect of metallic active sites and appropriate acid sites on the bifunctional catalysts is in favor of the aromatization and isomerization of 1-heptene.