Preparation, characterization of mixed-valence antimony-tin phosphomolybdic polyoxometalates and application in the cyclohexanone oxidation in the presence of hydrogen peroxide
作者:Fatma-Zohra Maiouf、Abdenour Boumechhour、Siham Benadji、Leila Dermeche、Tassadit Mazari、Christine Lancelot、Chérifa Rabia
DOI:10.5802/crchim.195
日期:——
Résumé In this work, a series of polyoxometalates (POMs), as soluble salts of formula Sn1.5PMo12O40, SbPMo12O40 and H 3-x Sn x1 Sb x2 PMo 12 O 40 (x=2x 1 +3x 2 and x 1 , x 2 = 0–0.75) were synthesized using the cationic exchange method under stoichiometric conditions. They were characterized and tested in the oxidation of cyclohexanone using hydrogen peroxide in the absence of organic solvent, co-catalyst phase transfer compounds or surfactants. UV–Visible and X-ray photoelectron spectroscopic analyses showed a partially reduced state of POM with coexistence of the couples Mo(VI)/Mo(V), Sb(V)/Sb(III) and Sn(IV)/Sn(II), without affecting their structure, results confirmed by FT-IR and Raman spectroscopies. The reversible cyclic voltammetry analysis evidenced the valence change of the Mo species, Mo(VI)/Mo(V). The POMs are found to be active in the cyclohexanone oxidation reaction and among them the most efficient is H 0.75 Sb 0.75 PMo 12 O 40 with 49% of adipic acid yield.
摘要 在这项工作中,我们使用阳离子交换法在化学计量条件下合成了一系列多氧金属酸盐(POMs),其可溶性盐的化学式为Sn1.5PMo12O40、SbPMo12O40和H 3-x Sn x1 Sb x2 PMo 12 O 40(x=2x 1 +3x 2,且x 1 、x 2 = 0–0.75)。在无有机溶剂、共催化剂相转移化合物或表面活性剂的情况下,我们使用过氧化氢对它们进行了表征,并测试了它们在环己酮氧化反应中的表现。紫外可见光和X射线光电子能谱分析表明,POM处于部分还原状态,Mo(VI)/Mo(V)、Sb(V)/Sb(III)和Sn(IV)/Sn(II)共价对共存,但不影响其结构,傅里叶变换红外光谱和拉曼光谱证实了这一结果。可逆循环伏安分析证实了Mo物种的价态变化,即Mo(VI)/Mo(V)。我们发现POM在环己酮氧化反应中很活跃,其中H 0.75 Sb 0.75 PMo 12 O 40的效率最高,可生成49%的己二酸。