MoO3/Al2O3催化剂中Mo分散的正电子研究

用浸渍法制备了一系列不同Mo含量的MoO₃/Al₂O₃催化剂.测量了这些样品的正电子湮没寿命谱(PALS)与符合多普勒展宽(CDB)谱，以研究其孔洞结构以及Mo分散.正电子寿命测量结果表明,Al₂O₃载体中存在两种不同尺寸的孔洞.掺入MoO₃之后,Mo原子主要进入Al₂O₃的大孔中,使孔洞体积减小.符合多普勒展宽谱结果表明，当MoO 关键词： 3/Al₂O₃催化剂')" href="#">MoO₃/Al₂O₃催化剂 正电子湮没寿命谱 符合多普勒展宽 Mo 分散

Positron annihilation study of Mo dispersion in MoO3/Al2O3 catalysts

A series of MoO3/Al₂O₃ catalysts was prepared by the impregnation method. The positron annihilation lifetime spectra(PALS)and coincidence Doppler broadening (CDB) spectra of the samples were measured to study the pore structure and dispersion of MoO₃. The PALS result shows that there are two types of pores with different size in the Al₂O₃ support. After MoO₃ was loaded in the support, Mo species are mainly dispersed inside the large pores of the support, and thus decrease the volume of the large pores. The CDB spectrum shows significant change while MoO₃ loading is just 3%. This indicates that the Mo species are dispersed into the pores, and cause the change of the electron momentum distribution seen by positrons. As the MoO₃ loading exceeds 18%, the size of the large pores is decreased to the similar size of the small pores, and the positron annihilation parameters show nearly no change with further Mo loading, which indicates saturation of the dispersion of Mo species.