ZSM-22分子筛的形貌控制合成及催化长链正构烷烃制生物航空煤油性能

Morphology Controlled Synthesis of ZSM-22 Molecular Sieves and Their Catalytic Performance on Long-chain Bioalkane to Aviation Kerosene

采用水热或水-溶剂热合成法,通过加入不同添加剂、溶剂和模板剂,合成了短棒状、长针状、花瓣状、粗棒状、椭球状和粗束状等不同晶体或聚集体形貌的ZSM-22分子筛.采用XRD、 SEM、 N_(2)物理吸附、NH_(3)-TPD和Py-IR等方法对不同形貌HZSM-22催化剂的理化性质进行了表征;并以小桐子油加氢脱氧后得到的混合长链正构烷烃为原料,对其加氢裂化/异构化制生物航空煤油性能进行了评价.结果表明,由长度约120 nm的小晶粒聚集而成的椭球状形貌的C-4催化剂具有较大的比表面积和丰富的孔口B酸量.在此基础上,以不同晶体形貌的HZSM-22分子筛为载体,采用等体积浸渍法制备了Pt/ZSM-22催化剂,发现椭球状样品Pt/C-4催化剂具有优异的加氢裂化/异构化性能和稳定性.长链正构生物烷烃转化率达94.21%,生物航空煤油收率高达47.87%,异正比达6.0.

In this paper,ZSM-22 zeolites with different crystal or aggregate morphologies,such as short rods,long needles,petals,thick rods,ellipsoids and coarse bundles,were synthesized through adding different additives,solvents or template agents.HZSM-22 catalysts with different morphologies were characterized by XRD,SEM,N_(2) physical adsorption,NH_(3)-TPD and Py-IR techniques.The performance of HZSM-22 catalysts with different morphologies was evaluated on the hydrocracking and hydroisomerization of long-chain normal bio-paraffins obtained from the hydrodeoxygenated curcas oil to bio-jet fuel.The results showed that the catalyst C-4 with ellipsoid aggregate appearance was assembled by small crystals with a length of about 120 nm,which possesses a large surface area and plenty of B acid sites at the pore mouth of channel.On this basis,Pt/ZSM-22 catalysts were prepared by the equal volume impregnation method using HZSM-22 with different morphologies as support.The Pt/C-4 catalyst presented excellent hydrocracking and isomerization performance and stability.The conversion of long-chain normal bio-paraffins over Pt/C-4 reached 94.21%,and the yield of bio-jet fuel was as high as 47.87%with an iso/n-paraffin ratio of 6.0.