Mo12Bi1.2Fe3Co8K0.4用于异丁烯选择性氧化制甲基丙烯醛

Mo12Bi1.2Fe3Co8K0.4 for selective oxidation of isobutene to methacrolein

摘要:

以(NH4)6Mo7O24·4H2O、Bi(NO3)3·5H2O、Fe(NO3)3·9H2O、Co(NO3)2·6H2O和KNO3为前驱体金属盐，通过共沉淀法制备了一系列MoBiFeCoK混合氧化物催化剂，考察了主金属Mo、Bi，助金属Fe、Co和掺杂金属K的相对含量对催化剂催化异丁烯气相氧化反应的性能，通过SEM、EDX、XRD、NH3-TPD对掺杂K前后的催化剂进行了表征，同时对催化异丁烯气相氧化反应条件进行优化，并测试其100 h的催化稳定性。结果表明，Bi、Fe、Co和K的相对含量对MoBiFeCoK混合氧化物催化剂催化异丁烯气相氧化反应的性能有显著影响，其中Mo12Bi1.2Fe3Co8K0.4表现出最优催化性能；NH3-TPD表征显示，K的掺杂降低了催化剂酸中心量（从Mo12Bi1.2Fe3Co8的15.27 μmol/g降至Mo12Bi1.2Fe3Co8K0.4的5.91 μmol/g），并明显提升主产物甲基丙烯醛（MAL）的选择性；异丁烯气相氧化反应的最佳条件为：以0.66 g的Mo12Bi1.2Fe3Co8K0.4为催化剂，反应温度320 ℃，n(O2)∶n(异丁烯)（氧烯比）＝10∶1，体积空速（GHSV）=2000 h-1的反应条件下，Mo12Bi1.2Fe3Co8K0.4在100 h的催化异丁烯气相氧化反应中表现稳定，异丁烯转化率保持在98.6%，MAL选择性保持在86.4%。

Abstract:

A series of MoBiFeCoK mixed-oxide catalysts were prepared by the co-precipitation method using (NH4)6Mo7O24·4H2O, Bi(NO3)3·5H2O, Fe(NO3)3·9H2O, Co(NO3)2·6H2O , and KNO3 as the precursor metal salts to investigate the relative contents of the main metals Mo and Bi, the co-metals Fe and Co, and the doped K. The performance of the catalysts for the gas-phase oxidation reaction of isobutene was investigated. The relative contents of the main metals Mo and Bi, the co-metals Fe and Co, and the doped metal K were investigated to determine the performance of the catalysts in catalyzing the gas-phase oxidation reaction of isobutene. The catalysts before and after doping with K were characterized by SEM, EDX, XRD, and NH3-TPD, and the catalysts were optimized to catalyze the reaction conditions of the gas-phase oxidation reaction of isobutene and tested for the catalytic stability of the catalysts for 100 h. The results showed that the relative contents of Bi, Fe, Co, and K had a significant effect on the catalytic performance of MoBiFeCoK mixed-oxide catalysts for the gas-phase oxidation reaction of isobutene, with Mo12Bi1.2Fe3Co8K0.4 showing the optimal catalytic performance; the NH3-TPD characterization showed that the doping of K lowered the amount of the acid center of the catalysts (from 15.27 μmol/g of Mo12Bi1.2Fe3Co8 to 5.91 μmol/g of Mo12Bi1.2Fe3Co8K0.4) and significantly enhanced the selectivity of the main product methacrolein (MAL); the optimal conditions for the gas-phase oxidation reaction of isobutene were as follows: 0.66 g of Mo12Bi1.2Fe3Co8K0.4 as catalyst, reaction temperature of 320 ℃, n(O2):n(isobutene) (oxygen-alkene ratio)=10:1, and volume-air velocity (GHSV)=2000 h-1. The catalytic isobutene gas-phase oxidation reaction of Mo12Bi1.2Fe3Co8K0.4 was stable for 100 h, and the isobutene conversion was maintained at 98.6%, and the selectivity of MAL was maintained at 86.4%.