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研究了以重质氧化镁载体浸渍偏钒酸铵水溶液制备的５－８２ＶＭｇＯ系列催化剂在５００℃下的丙烷氧化脱氢反应，该系列催化剂的活性和选择性比柠檬酸盐法制备的纯钒酸镁和文献报道的相应催化剂好，ＸＲＤ表征结果表明，该系列催化剂有正钒酸镁Ｍｇ_３Ｖ_２Ｏ_８和焦钒酸镁α－Ｍｇ_２Ｖ_２Ｏ_７两相共存。为了研究正焦钒酸镁之间可能存在的双相协同催化作用，以柠檬酸盐法制备了三个纯的钒酸镁相和Ｍｇ_３Ｖ_２Ｏ_８／α－Ｍｇ_２Ｖ_２Ｏ_７摩尔比分别为３／１、１／１和１／３的双相催化剂，该法通过控制溶液中Ｍｇ／Ｖ摩尔比可以容易地制得所要的钒酸镁。还以机械混合Ｍｇ_３Ｖ_２Ｏ_８和α－Ｍｇ_２Ｖ_２Ｏ_７制得相应的双相催化剂。上述催化剂性能评价结果表明，ＶＭｇＯ二元催化剂的活性相为Ｍｇ／Ｖ＝３／２、２／２和１／２的钒酸镁；在相同丙烷转化率下，丙烯选择性顺序为：α－Ｍｇ_２Ｖ_２Ｏ_７＞Ｍｇ_３Ｖ_２Ｏ_８＞β－ＭｇＶ_２Ｏ_６；且相应的双相催化剂的丙烯选择性均高于纯的Ｍｇ_３Ｖ_２Ｏ_８和α－Ｍｇ_２Ｖ_２Ｏ_７．这些结果表明丙烷氧化脱氢ＶＭｇＯ催化剂可能存在着双相协同催化作用。
We studied the oxidative dehydrogenation of propane with 5-82VMgO series catalyst prepared by impregnating the solution of ammonium metavanadate with heavy magnesia carrier at 500 ℃. The activity and selectivity of this series of catalysts were better than that of pure vanadate prepared by citrate method Magnesium and the corresponding catalysts reported in the literature are good, XRD characterization results show that this series of catalysts with magnesium orthovanadate Mg_3V_2O_8 and magnesium pyrophosphate Mg2V_2O_7 coexist. In order to study the possible bi-phase synergistic catalysis between Mg-orthovanadates, three pure magnesium vanadate phases and three molar ratios of Mg_3V_2O_8 / α-Mg_2V_2O_7 And 1/3 of the biphasic catalyst. This method makes it easy to prepare the desired magnesium vanadate by controlling the Mg / V molar ratio in the solution. The corresponding binary catalysts were also prepared by mechanical mixing of Mg_3V_2O_8 and α-Mg_2V_2O_7. The results of the catalyst performance evaluation showed that the active phase of the VMgO binary catalyst was magnesium vanadate with Mg / V = 3/2, 2/2 and 1/2; and the propylene selectivity at the same propane conversion was α- Mg_2V_2O_7> Mg_3V_2O_8> β-MgV_2O_6; and the corresponding propylene biphasic catalysts have higher propylene selectivity than pure Mg_3V_2O_8 and α-Mg_2V_2O_7. These results indicate that biphasic synergistic catalysis may exist for the oxidative dehydrogenation of propane to VMgO.