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用TPR,TPO,TPD和脉冲反应等技术以及XRD,EPR和XPS等物理方法对铁铬酸锌尖晶石的表面氧种及其与丁烯-2的反应和吸附性能进行了考察,结果表明该尖晶石表面存在α-,β-和γ-三种氧种。α-氧为表面弱结合氧,主要参与丁烯的深度氧化和使丁烯形成表面滞留物。β-氧为尖晶石结构中与Fe~(3+)配位的表面晶格氧,它参与选择氧化生成丁二烯。γ-氧为α-Fe_2O_3中的晶格氧,在所考察的条件下(270℃)基本上不参与反应。认为在铁铬酸锌的尖晶石相中的铁离子和与它配位的表面晶格氧(即β-氧)构成选择氧化的活性位。在丁烯氧化脱氢反应中通过反应条件的选择来控制表面氧种的类型和它们之间的相对密度,有可能提高活性和选择性
The surface oxygen species of zinc iron chromate and its reaction and adsorption with butene-2 were investigated by means of TPR, TPO, TPD and pulse reaction techniques and XRD, EPR and XPS methods. The results showed that The spinel surface exists α-, β- and γ-three oxygen species. Alpha-oxygen is a surface weakly bound oxygen that is primarily involved in the deep oxidation of butenes and the formation of surface retentate from butenes. The β-oxygen is the surface lattice oxygen coordinated with Fe 3+ in the spinel structure, which is involved in selective oxidation to butadiene. γ-Oxygen is the lattice oxygen in α-Fe_2O_3 and does not substantially participate in the reaction under the conditions investigated (270 ° C). It is believed that the iron ion in the spinel phase of zinc iron chromate and the surface-lattice oxygen (ie, β-oxygen) coordinated thereto form the active site of selective oxidation. It is possible to improve the activity and selectivity by controlling the types of surface oxygen species and their relative densities in the oxidative dehydrogenation of butenes by the choice of reaction conditions