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利用浸渍法制备不同载体的钒基催化剂(V/β,V/γ-Al_2O_3),并考察该催化剂在丙烷氧化脱氢制丙烯反应中的活性.利用X射线衍射(XRD)、紫外-可见漫反射(UV-Vis DRS)、N_2吸附-脱附(BET)和原位红外光谱对催化剂进行表征.结果表明,β分子筛和γ-Al_2O_3具有大的比表面积,孔径分布窄,使V能够以高分散、孤立态的V物种存在.原位红外光谱结果表明,丙烯在8V/β-分子筛(8V/γ-Al_2O_3)和8V4Mg/β-分子筛(8V4Mg/γ-Al_2O_3)催化剂上吸附后,C—H键上的H与催化剂活性中心的晶格氧发生了作用形成H—O键,随着温度升高出现C—O键,C—O键将进一步氧化生成COx,且8V4Mg/β-分子筛(8V4Mg/γ-Al_2O_3)催化剂上出现C—O键的温度比8V/β-分子筛(8V/γ-Al_2O_3)催化剂上高,说明Mg有利于丙烯的选择性.500℃反应时,8V4Mg/β分子筛具有很好的催化活性,丙烯的选择性达71.9%,丙烷的转化率达16.7%.
The vanadium-based catalysts (V / β, V / γ-Al 2 O 3) with different supports were prepared by impregnation method and the activity of the catalyst in the reaction of propylene to dehydrogenation to propene was investigated. XRD, UV- UV-Vis DRS, N 2 adsorption-desorption (BET) and in-situ infrared spectroscopy were used to characterize the catalysts. The results showed that β zeolite and γ-Al 2 O 3 have large specific surface area and narrow pore size distribution, Dispersed and isolated V. The in situ FTIR spectra showed that after adsorption of propylene on 8V / γ-Al 2 O 3 and 8V 4 Mg / γ-Al 2 O 3 catalysts, the C- H on the H bond interacts with the lattice oxygen in the active site of the catalyst to form an H-O bond. As the temperature increases, a C-O bond is formed, and the C-O bond is further oxidized to form COx, and the 8V4Mg / 8V4Mg / γ-Al_2O_3) catalyst was higher than that of the 8V / β-zeolite (8V / γ-Al_2O_3) catalyst, indicating that Mg favors the selectivity of propylene. With good catalytic activity, propylene selectivity of 71.9%, propane conversion rate of 16.7%.