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本文采用K_(T/B)(甲苯对苯的相对吸附系数)值表征Pt原子的电子状态。实验证明:添加MoO_3,La_2O_3,MgO,CeO_的Pt/η-Al_2O_3催化剂的K_(T/B)值比单Pt/η-Al_2O_3的小,这说明上述氧化物表现为电子给予体,缓和了Pt原子的缺电子状态,使其亲电子性变小;添加ZnO,NiO,SnO_2,WO_3,Cr_2O_3的催化剂的K_(T/B)值比单Pt/η-Al_2O_3的大,这说明上述氧化物表现为电子接受体,加剧了Pt原子的缺电子状态,使其亲电子性变大。根据以上结果以及苯加氢反应和环戊烷氢解反应的动力学参数以出结论,氧化物添加剂对Pt原子的电子效应是普遍存在的观象。
In this paper, K_ (T / B) (toluene-benzene relative adsorption coefficient) value of the electronic state of Pt atom. The experimental results show that the K / (T / B) value of Pt / η-Al_2O_3 catalyst with MoO_3, La_2O_3, MgO and CeO_ is smaller than that of Pt / η_Al_2O_3, which indicates that the above oxides behave as electron donors, The electron-deficient state of Pt atom makes it less electrophilic. The K_ (T / B) value of the catalysts doped with ZnO, NiO, SnO_2, WO_3 and Cr_2O_3 is larger than that of Pt_η_Al_2O_3, The performance of the electron acceptor, exacerbated the lack of electronic state of Pt atoms, making it more electrophilic. Based on the above results and the kinetic parameters of benzene hydrogenation and cyclopentane hydrogenolysis, it is concluded that the electron effect of the oxide additive on Pt atoms is a ubiquitous phenomenon.