面向异丁烷脱氢介孔γ-Al_2O_3基催化剂的合成及其高催化性能

Synthesis and Catalytic Performance of Mesoporous γ-Al_2O_3 Catalyst for Isobutane Dehydrogenation

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、N_2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-Al_2O_3的研制。与常规的γ-Al_2O_3相比,所制备的介孔γ-Al_2O_3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)Cr_2O_3/γ-Al_2O_3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Cr_2O_3/γ-Al_2O_3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.