过渡金属Fe、Co、Ni介孔分子筛MCM-41催化剂的制备及其氧化性能
Synthesis of Fe, Co, Ni loaded MCM-41 mesoporous molecular sieves and their catalytic oxidation performance
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摘要: 本研究用直接法和后处理法合成了不同过渡金属(Fe、Co、Ni)负载的介孔分子筛载体材料MCM-41,并利用Al对分子筛进行了改性,制备了Fe/Al复合催化剂,对上述材料进行了表征.研究了这些非均相催化剂对染料活性艳蓝KN-R的催化氧化脱色,分别研究了催化剂制备方法、过渡金属种类及负载量对KN-R脱色效率的影响,并考察了所制得催化剂的稳定性和重复利用性.结果表明,直接法合成的催化剂具有较高的催化性能及较低的金属溶出量,负载铁(Ⅱ)的催化剂对染料的催化降解性能要远高于钴(Ⅱ)和镍(Ⅱ)负载型催化剂,催化氧化活性随金属负载量的提高而显著升高.Al改性进一步提高了催化剂的活性,在pH=2.5,氧化剂H2O2投加剂量为50.0 mmol·L-1,催化剂剂量为4.0 g·L-1的条件下,反应30 min,对初始浓度为250 mg·L-1的KN-R染料的脱色率均可达95%以上,矿化率达60%以上.当Al/Si为0.21,Fe负载量为23.6 mg·g-1时,在10 min内可将250 mg·L-1的KN-R完全脱色.经过3次循环使用后,上述催化剂仍能表现出良好的性能,但进一步循环使用,催化活性下降.
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关键词:
- 催化脱色 /
- 过渡金属负载型催化剂 /
- KN-R染料 /
- 介孔分子筛
Abstract: In this study, direct synthesis and post-treatment methods were developed to prepare a series of heterogeneous catalysts using mesoporous molecular sieves MCM-41 as carrier to load different transition metals (Fe, Co, Ni). Besides, Al was used to improve the structure of MCM-41 and a series of Al/Fe-MCM-41 catalysts were also prepared. The composition, surface morphology and crystalline phase of the catalysts were characterized. Decolorization of an anthraquinone dye, Reactive Brilliant Blue KN-R, by hydrogen peroxide was investigated to evaluate the catalytic activity of these heterogeneous catalysts. The impacts of preparation methods, types and loading amounts of transition metals on decolorization and the stability of the catalysts were investigated. The results showed that the catalysts obtained by direct synthesis had greater catalytic activity and less loss of metals. The Fe(Ⅱ) loaded catalysts had much higher catalytic activity compared to Co(Ⅱ) and Ni(Ⅱ) in dye decolorization. Furthermore, the catalytic activity increased markedly with the loading amount of the transition metals. Under the conditions of 4.0 g·L-1 catalyst, 50.0 mmol·L-1 H2O2, and initial pH 2.5, over 95% of 250 mg·L-1 KN-R were decolorized within 30 min by Fe-MCM-41, and the removal of TOC was greater than 60%. The modification by Al further improved the catalytic activity, and 250 mg·L-1 were completely decolorized within 10 min by Fe/Al composite loaded catalyst when Al/Si ratio was 0.21 and the loading amount of Fe was 23.6 mg·g-1. After 3 times of running, the catalysts maintained good dye decolorization performance, but the catalytic activity decreased in further use. -
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