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本工作改进了文献[4]报导的几种原料同时混合、加热煮沸合成的方法采用分步加入原料,控制反应温度、多次重结晶的方法合成了6、7、8个钒原子取代的钼钒磷杂多酸铵;并以铵盐为原料,用离子交换、冷冻分离和真空抽吸相结合的提纯方法制备了未见文献报导的相应的固体杂多酸;H_5[PMo_5V_7O_(37.5)]·xH_2O,H_6[PMo_4V_8O_(37.5)]·xH_2O。通过元素组成分析确定了它们的组成。这些杂多酸在水溶液、非水溶液中的电位滴定表明,杂多阴离子在分解前没有发生自电离、水解等情况,它们在水溶液中是稳定的。酸的碱度分别为5、5、6。通过纸上色谱实验,讨论了杂多酸的分解过程。由热重分析和溶解性实验得到它们的分解温度,本文还讨论了这些化合物的红外、紫外光谱,x光粉末衍射及极谱性质。光谱结果表明,它们可能具有Keggin结构,由导数脉冲极谱得到它们的峰电位。
This work improved the literature [4] reported that several raw materials while mixing, heating and boiling synthesis step by step to join the raw materials, the reaction temperature, multiple recrystallization method synthesized 6,7,8 vanadium atoms substituted molybdenum Vanadium phosphorus heteropoly acid ammonium; and ammonium salt as raw material, with ion exchange, frozen separation and vacuum suction combination of the preparation of the corresponding literature reported solid heteropolyacid; H_5 [PMo_5V_7O_ (37.5)] · XH_2O, H_6 [PMo_4V_8O_ (37.5)] · xH_2O. Their composition is confirmed by elemental composition analysis. Potentiometric titration of these heteropolyacids in aqueous and non-aqueous solutions indicates that the heteropolyanions did not self-ionize, hydrolyze, and the like before decomposition, and they are stable in aqueous solution. The basicity of the acid is 5, 5, 6 respectively. Through the chromatographic experiments on paper, the decomposition of heteropoly acids was discussed. Their decomposition temperatures were obtained by thermogravimetric analysis and solubility experiments. The IR, UV, x-ray powder diffraction and polarographic properties of these compounds were also discussed. The spectroscopic results show that they may have Keggin structures and derive their peak potentials from derivative pulse polarography.