镁锌铝尖晶石负载Pt-Sn催化剂对异丁烷脱氢性能的影响

Effect of magnesium-zinc-aluminum spinel support on catalytic performance of Pt-Sn catalysts for isobutane dehydrogenation

采用共沉淀法制备了不同镁锌铝比例的尖晶石载体,并通过等体积浸渍法制备了w(Pt)、w(Sn)均为0.5%的四种催化剂,记为:0.5%Pt-Sn/γ-Al_2O_3、0.5%Pt-Sn/Mg Zn Al4、0.5%Pt-Sn/Mg_2ZnAl_6和0.5%Pt-Sn/MgZn_2Al_6。通过N2物理吸附脱附、X射线衍射(XRD)、NH_3程序升温脱附(NH3-TPD)和电感耦合等离子体发射光谱(ICP)等手段对催化剂进行表征,以异丁烷脱氢反应为对象研究了不同镁锌铝比例的尖晶石载体对催化剂脱氢性能的影响。N_2物理吸附脱附结果表明,相比于γ-Al_2O_3,以镁锌尖晶石为载体的催化剂具有更小的比表面积和更大的孔径,NH3-TPD结果表明镁锌尖晶石载体的酸性较小。评价结果表明0.5%Pt-Sn/MgZnAl_4催化剂表现最佳,其异丁烷的初始转化率达52.09%,稳定后的异丁烯选择性高达98.56%。

The spinel supports with different magnesium-zinc-aluminum ratios were prepared by co-precipitation method. Then the 0.5%Pt-Sn/γ-Al2O3, 0.5%Pt-SrdMgZnAl4, 0.5%Pt-Sn/Mg2ZnAl6 and 0.5%Pt-Sn/MgZn2Al6 catalysts were prepared by incipient wetness impregnation method and characterized by N2 adsorption-desorption, XRD, NH3-TPD and Inductively Coupled Plasma （ICP）. The effects of the spinels supports with different magnesium-zinc-aluminum ratios on the catalytic performance of catalysts in dehydrogenation of isobutane were investigated. The results of N2 adsorption-desorption indicate that the spinel supports provide smaller specific surface area and larger pore size distribution than γ-Al203, and the results of NH3-TPD indicate that the spinel supports exhibit lower acidity than T-Al2O3. The activity test shows that 0.5%Pt-Sn/MgZnAl4 catalyst exhibit the best activity and selectivity with an initial conversion of isobutane of 52.09% and a selectivity to isobutene of 98.56%.