Sn对V2O5/Al2O3催化剂在异丁烷脱氢反应中的影响

Effect of Sn on V2O5/Al2O3 catalyst in dehydrogenation of isobutane

以Al2O3为载体,采用等体积浸渍法制备了负载型高分散氧化钒催化剂(12%V2O5/Al2O3),并选择Sn作为助剂对12%V2O5/Al2O3催化剂的表面性质进行调控,采用XRD、N2等温吸脱附、NH3-TPD、H2-TPR、XPS、TEM和Raman光谱等方法对催化剂进行表征,结合活性评价实验,研究了催化剂表面物种分散状态、酸性和活性物种价态的变化与异丁烷脱氢活性和稳定性之间的关系。表征结果显示,Sn对V2O5/Al2O3表面的酸性和V物种在催化剂表面的分布和价态具有一定的调节作用,当Sn质量分数为1%时,氧化锡在催化剂表面分散均匀,对表面积和孔结构影响较小,同时,表面酸性变化较小,表面低价态的钒物种增多。活性评价结果表明,该催化剂在临氢反应条件下保持了最佳的脱氢活性及稳定性,异丁烷脱氢反应480min后,异丁烷转化率为46.8%,异丁烯收率为39.8%。

The highly dispersed vanadium oxide catalyst(12%V2O5/Al2O3) supported by Al2O3 was prepared by impregnation. The surface properties of 12%V2O5/Al2O3 catalyst were controlled by using Sn as an auxiliary agent. The changes in the dispersion state, acidity, and the valence of active species of the catalyst were studied, and their influences on the dehydrogenation activity and stability of isobutane were discussed. The catalysts were characterized by XRD, N2 adsorption-desorption isotherms, NH3-TPD, H2-TPR, XPS, TEM and Raman spectra. The characterization results showed that Sn could regulate the surface acidity of V2O5/Al2O3 and the distribution and valence state of V species on the surface of the catalyst. When 1%(wt) Sn was added, SnO2 was uniformly dispersed on the surface of the catalyst, and it show little impact on the specific surface area and pore structure. At the same time, the change in surface acidity was small and the vanadium species with low valence increased. The performance evaluation results showed that the catalyst maintained the best reactivity and stability with the presence of hydrogen.After dehydrogenation of isobutane for 480 min, the isobutane conversion was 46.8% and the isobutene yield was 39.8%.