摘要
采用液相离子交换法制备了不同Ce含量的CeUSY分子筛,并通过Mitchell等体积浸渍法对其进行Ni污染,运用ICP-AES、XRD和N2吸附等温线等方法对其织构性质进行表征,并利用微反应活性评价装置考察了其抗镍性能。结果表明,不同Ce含量改性的USY样品其抗镍效果存在差异,CeUSY分子筛的抗镍效果与Ce含量的关系呈现火山型变化。结合Ni污染前后CeUSY分子筛的H_2-TPR和Py-FTIR表征结果探讨了Ce物种的抗镍机制,证实了Ce物种形态的变化是不同Ce含量的CeUSY分子筛具有不同抗镍效果的重要成因,其中,SOD笼中的Ce(OH)^(2+)在高温条件下可与Ni(OH)^+相互作用,脱去一分子H_2O形成Ce^(3+)-O-Ni^(2+)的稳定结构,阻碍了Ni物种与骨架铝的结合导致CeUSY分子筛中B酸中心的破坏,同时有效抑制了易还原NiO物种的生成。而Ce含量过高使得SOD笼内的Ce物种变成二聚以及三聚物,与Ni(OH)^+作用减弱,使其抗镍性能减弱。
The CeUSY zeolites loaded with Ce were prepared by liquid phase ion exchange method, and the Ni contamination was conducted by Mitchell impregnation method. The texture properties were characterized by inductively coupled plasma atomic emission spectrometry （ICP-AES）, X-ray diffraction （XRD） and N 2 adsorption. Moreover, the nickel tolerance was evaluated by the MAT evaluation device. The results show that CeUSY zeolites with different Ce contents possess a nickel tolerance performance varying in a volcano type with the increase of Ce content. Through the H 2-TPR and Py-FTIR characterization of CeUSY zeolite before and after Ni contamination, it is evident that the change in Ce species morphology is one of the reasons affecting nickel tolerances. It is thought that the interaction between Ce（OH） 2＋ and Ni（OH） ＋ in the SOD cages of the CeUSY zeolite results in a loss of H 2O molecule to form a stable Ce 3＋ -O-Ni 2＋ structure at high temperature, which hinders the combination of Ni species with the framework aluminum to prevent the destruction of the Br nsted acid sites in CeUSY zeolite and effectively inhibits the formation of reducible NiO species. However, with the increase of the content of Ce 3＋ , the part of the introduced Ce would happen to self-assemble in the zeolites as multinuclear hydroxylated species which interacts weakly with Ni 2＋ species compared to mononuclear species and then reduces the nickel tolerance.
作者
孙兆林
惠宇
杨野
秦玉才
张莉
张乐
贾未鸣
祖运
宋丽娟
SUN Zhao-lin;HUI Yu;YANG Ye;QIN Yu-cai;ZHANG Li;ZHANG Le;JIA Wei-ming;ZU Yun;SONG Li-juan(Key Laboratory of Petrochemical Catalytic Science and Technology,Liaoning ShiHua University,Fushun 113001,China;College of Chemistry and Chemical Engineering,China University of Petroleum（East China）,Qingdao 266555,China;Lanzhou Petrochemical Research Center,Petrochemical Research Institute,Petro China Company Limited,Lanzhou 730060,China)
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
2018年第7期856-863,共8页
Journal of Fuel Chemistry and Technology
基金
国家自然科学基金(U1662135
21376114)资助~~
关键词
稀土
落位
形态
USY
抗镍性能
rare earth
location
morphology
USY
nickel tolerance
