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合成了具有不同中心原子Keggin阴离子结构的杂多钼酸盐M_3(XMo_(12)O_(40))(M=K~+,NH_4~+,X=P,As)。利用FTIR、TPD、ESR和CV等手段考查了各化合物的氧化还原性质和酸性。比较两种不同中心原子的杂多钼酸盐,其中砷为中心原子的更容易被还原及有较低的酸强度,这类催化剂对异丁醛氧化脱氢活性较低,而对异丁醛氧化为甲基丙烯酸有较高的选择性,中心原子对活性和选择性的影响分别与它们氧化还原电位的升高关联,也与更易给出轿式氧有关。
The heteropoly molybdate M_3 (XMo_ (12) O_ (40)) (M = K ~ +, NH_4 ~ +, X = P, As) with different Keggin anion structures was synthesized. The redox properties and acidity of each compound were investigated by means of FTIR, TPD, ESR and CV. Comparison of two heteropoly-molybdates with different central atoms, in which arsenic as the central atom is easier to be reduced and has a lower acid strength, these catalysts have lower oxidative dehydrogenation activity for isobutyraldehyde, while isobutyraldehyde Oxidation to methacrylic acid has a higher selectivity, the influence of the central atom on activity and selectivity, respectively, associated with their redox potential increases, but also with the more easy to give sedan oxygen.