采用浸渍法制备了不同V2O5担载量的V2O5/MO-Al2O3(M = Mg, Ca, Sr, Ba)催化剂,钒物种的前驱体为偏钒酸铵.对制备的催化剂进行了一系列表征,并对催化剂上正丁烷选择性氧化脱氢制取丁烯进行了反应研究.表征结果(包括比表面积、X射线衍射、傅里叶红外光谱、氢气程序升温还原和拉曼光谱)显示,不同碱土金属元素掺杂的催化剂显示不同的钒价态信息和催化性能.其中掺杂Ca, Sr, Ba的催化剂,正钒酸盐相很难被还原,因此催化剂的氧化还原循环难以建立,导致以上三种催化剂在正丁烷氧化脱氢反应中活性较低.然而, Mg掺杂的催化剂却显示出较高的催化活性和选择性.实验结果表明：在Mg掺杂的载体上担载5% V2O5的催化剂上600°C时可获得高达30.3%的正丁烷转化率和64.3%的烯烃总选择性.这与V2O5担载量为5%时,在获得高度分散的钒氧化合物物种时可使MgO晶相稳定存在密切相关.%V2O5/MO-Al2O3(M = Mg, Ca, Sr, Ba) catalysts with different V2O5loading were prepared by impreg-nation with ammonium metavanadate as the V precursor and characterized and tested for the se-lectively oxidative dehydrogenation ofn-butane to butenes. Characterization by BET, XRD, FTIR, H2-TPR and Raman spectra showed that the catalysts doped with different alkaline earth metals had different structure and catalytic activity. The catalysts doped with Ca, Sr or Ba had the orthovana-date phase that was difficult to reduce, so their redox cycles could not be established and they ex-hibited low activity. The catalysts doped with Mg showed high catalytic activity and selectivity. The catalyst with 5% V2O5 loading exhibited the highestn-butane conversion (30.3%) and total butene selectivity (64.3%) at 600 °C. This was due to the well dispersed VOx species and the existence of the MgO crystalline phase, which were both present at a V2O5 loading of 5%.
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