面向异丁烷脱氢介孔γ-Al2O3基催化剂的合成及其高催化性能

摘要

采用溶剂蒸发自组装法调控载体形貌及孔道结构,成功制备了有序介孔氧化铝载体.以铬氧物种为活性组分,碱金属钾为助剂,采用浸渍法制备负载型催化剂,用于异丁烷催化脱氢反应,研究了反应温度、原料流速、催化剂粒径等因素对催化性能的影响.采用X射线粉末衍射、透射电子显微镜、N2物理吸附、氢气程序升温还原及热重等表征方法探讨了载体形貌、孔道结构与催化性能的构效关系,结果表明,低温下有利于控制异丙醇铝的水解和缩合及介孔γ-Al2O3的研制.与常规的y-A12O3相比,所制备的介孔γ-Al2O3的有更大的比表面积和良好的有序性,在600℃、101.325kPa、GHSV=1 000 h-1的条件下,10％(w/w)Cr2O3/γ-Al2O3催化剂性能最佳,异丁烷的转化率达63.1％,异丁烯的选择性达到85.5％.与传统的催化剂相比,介孔 Cr2O3/γ-Al2O3催化剂具有大的比表面积,高度分散的活性组分,优良的催化性能和良好的抗积碳能力.%A thermal stability and ordered mesoporous γ-Al2O3 was synthesized via the improved evaporation induced self-assembly strategy.As the carrier,a series mesoporous Cr2O3/γ-Al2O3 catalysts with various Cr content (1％～15％ (w/w)) had been successfully prepared by impregnation method.The mesoporous γ-Al2O3 and the catalysts were characterized by X-ray diffraction (XRD),transmission electron microscope (TEM),H2 temperature programmed reduction (H2-TPR) and investigated for isobutane catalytic dehydrogenation.The results showed that low temperature process took control of isopropanol aluminum hydrolytic and condensation rate effectively.Mesoporous γ-Al2O3 owns larger surface areas and pore volume and increased channel order.Under given condition (600 ℃,101.325 kPa,GHSV=1 000 h-1),10％Cr2O3/γ-Al2O3 catalyst had the best performance,where the conversion of isobutane reached up to 63.1％ and the selectivity of isobutene reached up to 85.5％.Compared to the conventional catalyst,the mesoporous Cr2O3/γ-Al2O3 catalyst possesses the advantages of larger specific surface area,highly dispersed active components,excellent catalytic property and very strong coking-resistance.