Basicity and electron donor properties of lanthanum oxide and its mixed oxides with alumina

Abstract

The electron donating properties of La₂O₃ activated at 300, 500 and 800ᵒC and its mixed oxides with alumina are reported from the studies on adsorption of electron acceptors of varying electron affinity on La₂O₃. The electron acceptors with their electron affinity values given in parenthesis are: 7,7,8,8-tetracyanoquinodimethane (2.84 eV), 2,3,5,6-tetrachloro-1,4-benzoquinone (2.40 eV) and <em>p</em>-dinitrobenzene(1.77eV). The basicity of the oxide has been determined by titration with <em>n</em>-butylamine and H_o,max values are reported. The limit of electron transfer from the oxide to the electron acceptor is between 2.40 and 1.77eV. It is observed that La₂O₃ promotes the surface electron properties of alumina without changing its limit of electron transfer.