Investigation of Cu- and Fe-Doped CsH3PMo11VO40 Heteropoly Compounds for the Selective Oxidation of Methacrolein to Methacrylic Acid

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• 作者：Heng Zhang ; Ruiyi Yan ; Li Yang ; Yanyan Diao ; Lei Wang ; Suojiang Zhang
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2013
• 出版时间：March 27, 2013
• 年：2013
• 卷：52
• 期：12
• 页码：4484-4490
• 全文大小：376K
• 年卷期：v.52,no.12(March 27, 2013)
• ISSN：1520-5045

文摘

Selective oxidation of methacrolein to methacrylic acid was carried out over Cu- and Fe-doped acidic cesium salts of molybdovanadophosphoric acids. The influences of preparation conditions on the structure and catalytic properties of the catalysts were investigated. Results showed that the addition method of NH₄⁺ in the precursors greatly affected the structure of the calcined catalysts. When MoO₃, V₂O₅, and H₃PO₄ were used to prepare the parent heteropoly acid, which further reacted with the mixed metal nitrates to form the Keggin-type precursor, the addition of ammonia promoted the formation of single-phase cubic secondary structure of the precursor. After being calcined at 360 掳C for 12 h, ammonium ions totally decomposed, and vanadium ions were partially expelled from the primary Keggin units. The catalytically less active MoO₃ phase, observed in the sample calcined in air, did not exist in the sample calcined in N₂. When NH₄VO₃ was used to replace V₂O₅ and ammonia to prepare the precursor, the ammonium exhibited higher thermal stability, and the calcination atmosphere had almost no effect on the phase composition of the calcined catalysts. It is also found that Cu and Fe as counterions can improve the redox property and thereby enhance the performance of the catalyst.