摘要
本文采用PASCA技术研究铂在两种不同γ-Al_2O_3表面上的分散过程和状态。发现铂可与氧化铝表面上的S_k,S_(?)和S_t三类中心作用并生成稳定性和化学活性不同的复合物:PtO_xCI_y-S_k,PtO_xCl_y-S_(?)和PtO_xCl_y-S_t,并测定了o-Ps与这三种不同复合物之间的反应速度常数k。发现还原的催化剂表面上离子态(可溶性)铂含量NI与k值大小成正比。证明了不同氧化铝表面上的中心S(S_k、S(?)和S_t)在电化学性质上可能是不同的。还原过的Pt/Al_2O_3,催化剂是否存在着离子态铂主要取决于氧化铝本身的表面性质。
PASCA(Positron Annihilation Spectroscopy for Chemical Analysis) has been used to study the dispersion process and the state of platinum on the surfaces of two different types of γ-Al_2O_3, The results show that platinum interacts with different surface sites, S_k, S, and S_t, froming'surface interaction complex':PtO_xCl_y-S_k, PtO_xCl_y-S_(?) and PtO_xCl_y-S_t with various stability and chemical activity. The reaction rate constants of o-Ps with these three complexes were also calculated, and it was found that the content of ionic(soluble) platinum(Pt^((?)+)) on surfaces of alumina is associated with the reaction rate constant. The surface sites in these two aluminas were found to be different in chemical and electronic properties. The existence and content of ionic platinum mainly depend upon the surface properties of alumina.
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
1990年第4期289-294,共6页
Journal of Fuel Chemistry and Technology
基金
国务院人事部留学回国人员科技活动基金
中国石油化工总公司资助课题
