摘要
应用IR,XPS,TPR,NO和CO2吸附及脉冲微反等技术研究了氟硅酸铵处理前后γ-Al2O3及负载NiW催化剂的表面性质,探讨了其改性机理和它对催化剂活性相的影响.结果表明,经氟硅酸铵处理后,γ-Al2O3表面的不饱和四面体空位及其四配位Al3+上的强碱性羟基均明显减少,改变了γ-Al2O3表面的酸碱性和Ni2+在γ-Al2O3表面的分布,使NiO倾向分布于γ-Al2O3的八面体空位.过量的氟硅酸铵处理将明显破坏γ-Al2O3表面的碱性羟基,导致WO3和NiO的分散度下降,使改性后催化剂的噻吩加氢脱硫性能降低.
The surface properties of γ Al 2O 3 and NiW/Al 2O 3 samples before and after fluorination with (NH 4) 2SiF 6 have been studied by using IR, XRD, XPS and adsorption of NO and CO 2. Their activity for HDS of thiophene has been measured with pulse micro reaction system. The mechanism of fluorination and its influence on the active phase of the catalyst have also been discussed. The results show that the tetrahedral vacancies of γ Al 2O 3, which contain more net positive charge as well as its strongest basic OH groups cordinated to tetrahedral Al 3+ , decrease when γ Al 2O 3 is fluorinated with (NH 4) 2SiF 6. It causes the Ni species on NiW F/Al 2O 3 to prefer to occupy the octahedral vacancies of γ Al 2O 3. However, when γ Al 2O 3 is fluorinated excessively with (NH 4) 2SiF 6, its basic OH groups are replaced largely by F -, which reduces the dispersity of WO 3 and NiO. This disadvantage would cover up the advantage of fluorination for the distribution of Ni species and cut down HDS activity of fluorinated catalyst.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
1997年第4期279-283,共5页
基金
抚顺石油化工研究院资助
关键词
氟化
氟硅酸铵
镍
钨
负载型
催化剂
加氢
炼油
Alumina, Fluorination, Ammonium fluorosilicate, Nickel, Tungsten, Supported catalyst, Hydrodesulfurization