不同改性ZSM-5分子筛负载Ni催化剂的正辛烷芳构化和异构化催化性能

Catalytic Aromatization and Isomerization Performance of Differently Modified ZSM-5 Zeolite-Supported Ni Catalysts for n-Octane

以不同改性的ZSM-5分子筛和无定型SiO_2为载体,采用浸渍法制备了一系列Ni/NaZSM-5和Ni/SiO_2催化剂。在催化加氢脱硫反应条件下,考察了正辛烷在Ni/NaZSM-5、Ni/ZSM-5-P、Ni/ZSM-5-P-Fe和Ni/SiO_2催化下的异构化和芳构化反应性能和产物分布。采用BET、XRD、程序升温氨脱附(NH_3-TPD)、程序升温还原(H_2-TPR)以及吡啶吸附-脱附红外光谱法对催化剂进行表征。结果表明,具有较多的中强酸活性中心和BrΦnsted酸中心的Ni/ZSM-5-P-Fe催化剂具有较高的正辛烷异构化和芳构化催化活性,说明BrΦnsted酸中心能促进正辛烷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正辛烷芳构化及异构化反应效率最高。

The catalysts NiO/SiO2and series of Ni/NaZSM-5 were prepared by spraying nickel on the carriers and were characterized by XRD, XRF, N2adsorption-desorption, NH3-TPD, H2-TPR, and pyridine-FTIR. The performances of NiO/SiO2, NiO/NaZSM-5, NiO/ZSM-5-P and NiO/ZSM-5-P-Fe catalysts in aromatization and isomerization of n-octane and its product distribution were investigated under the condition of catalytic hydrodesulfurization (T=400, p=1.5 MPa, MHSV=5 h-1). The results showed that NiO/ZSM-5-P-Fe exhibited a remarkable enhancement catalytic aromatization and isomerization performance, indicating that the incorporation of metallic active sites and appropriate acid sites into bifunctional catalyst favored the aromatization and isomerization of n-octane compared to a monometallic catalyst, moreover, the presence of iron on NiO/ZSM-5-P-Fe created more medium-strong acid sites while reducing Brønsted acid sites, thus more aromatic products yielded with simultaneously enhancement of n-octane conversion and inhibition of n-octane cracking. © 2016, Science Press. All right reserved.