丙烯氨氧化催化剂物化性能研究──Ⅱ．催化剂失活前后的结构表征

Study on the Physico-Chemical Properties of the Catalyst in Ammoxidation of Propene──II. The Characteristic of the Catalyst before and after Deactivation

采用ＸＲＤ、ＩＲ、Ｍｏｂａｕｅｒ、ＥＳＲ、ＸＰＳ、ＳＥＭ和孔结构分析等分析测试手段，对比研究了新鲜、失活和再生三种丙烯氨氧化催化剂的体相结构和表面性质。结果表明，新鲜催化剂中各元素以Ｆｅ_２（ＭｏＯ_４）_３、α－ＣｏＭｏＯ_４、ＮｉＭｏＯ_４、γ－Ｂｉ_２Ｏ_３·ＭｏＯ_３、α－Ｂｉ_２Ｏ_３．３ＭｏＯ_３、η－ＭｏＯ_３、α－Ｂｉ_２Ｏ_３和β－Ｂｉ_２Ｏ_３形式存在；失活催化剂中，部分Ｆｅ_２（ＭｏＯ_４）_３转变为α－ＦｅＭｏＯ_４和β－ＦｅＭｏＯ_４，部分γ－Ｂｉ_２Ｏ_３·ＭｏＯ_３转变为γ′－Ｂｉ_２Ｏ_３·ＭｏＯ_３和γ″－Ｂｉ_２Ｏ_３·ＭｏＯ_３，部分η－ＭｏＯ_３转变为ＭｏＯ_３；再生催化剂中，γ′－Ｂｉ_２Ｏ_３·ＭｏＯ_３、γ″－Ｂｉ_２Ｏ_３·ＭｏＯ_３ＭｏＯ_３仍存在，但Ｆｅ^（２＋）基本转变为Ｆｅ^（３）；三种催化剂表面都明显存在Ｍｏ、Ｂｉ、Ｓｉ和Ｏ四种元素，且失活催化剂表面存在Ｍｏ、Ｂｉ富集现象；三种催化剂的孔径都集中于中孔范围，其中新鲜催化剂的孔径分布较窄，失活催化剂稍有增加，再生催化剂的孔径分布较宽；失活催化剂颗粒间出现粘连，再生催化剂的颗粒粘连现象有所改善。

Various analytic techniques:X-ray diffraction, IR spectra,Mossbauer spectra,ESR, XPS, pore structure analyses and SEM were employed for comparing the volume structure and surface properties of fresh、deactivated and regenerated catalysts. The results show that the elements are present as Fe_2(MoO_4)_3、α-CoMoO_4、NiMoO_4、γ-Bi_2O_3·MoO3、α-Bi_2O_3·3MoO_3、ηMoO_3、α-Bi_2O_3 and β-Bi_2O_3 in the fresh catalyst(I). While Fe_2(MoO_4)_3 is partly reduced to αFeMoO_4 and β-FeMoO_4,γ-Bi_2O_3. MoO_3 is partly transformed into γ'-Bi_2O_3·MoO_3 and γ-Bi_2O_3 ·MoO_3, and η-MoO_3 is partly transformed into MoO_3 in deactivated catalyst (II). In regenerated catalyst(III),γ'-Bi_2O_3·MoO_3、γ-Bi_2O_3·MoO_3 and MoO_3 are still present, and Fe￣(2+) is mostly transformed into Fe￣(3+). Mo、Bi、Si and O are obviously present on the surfaces of all catalysts, and Mo、Bi are richened on the surface of II. The pores of all catalysts are mostly in middle size, In I、II and III, the pore distribution becomes wider successively. Deactivated catalyst particles have some agglomeration, the particle agglomeration of regenerated catalyst is improved.