物理化学学报 >> 2009, Vol. 25 >> Issue (09): 1791-1798.doi: 10.3866/PKU.WHXB20090829

研究论文 上一篇    下一篇

P(4VP-co-St)/SiO2固载的取代钴卟啉对乙苯的催化氧化性能

王蕊欣, 焦纬洲, 高保娇   

  1. 中北大学化学工程系, 太原 030051
  • 收稿日期:2009-02-10 修回日期:2009-05-09 发布日期:2009-09-03
  • 通讯作者: 高保娇 E-mail:gaobaojiao@126.com

Catalytic Performance of P(4VP-co-St)/SiO2-Supported Co Tetraphenylporphyrins for the Aerobic Oxidation of Phenylethane

WANG Rui-Xin, JIAO Wei-Zhou, GAO Bao-Jiao   

  1. Department of Chemical Engineering, North University of China, Taiyuan 030051, P. R. China
  • Received:2009-02-10 Revised:2009-05-09 Published:2009-09-03
  • Contact: GAO Bao-Jiao E-mail:gaobaojiao@126.com

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摘要：

通过轴向配位法将不同结构的钴卟啉(CoTXPP(X=H, Cl, NO2))分别固载到接枝微粒聚(4-乙烯基吡啶-co-苯乙烯)/SiO2(P(4VP-co-St)/SiO2)上, 室温下分别制备了P(4VP-co-St)/SiO2固载的金属卟啉催化剂CoTPP-P(4VP-co-St)/SiO2, CoTClPP-P(4VP-co-St)/SiO2和CoTNPP-P(4VP-co-St)/SiO2, 利用傅立叶变换红外(FTIR)光谱和电子吸收光谱对其结构及轴配过程进行了表征. 在无溶剂、无助催化剂和还原剂的体系中, 研究对比了其催化分子氧氧化乙苯为苯乙酮的性能, 考察了不同反应条件对苯乙酮产率的影响. 研究发现, 其催化活性随着环外取代基吸电子能力的增强而提高. CoTNPP-P(4VP-co-St)/SiO2的催化活性和选择性最好, 在120 ℃常压下其催化乙苯反应12 h, 苯乙酮收率达到25.53%, 产物α-甲基苄醇的含量则极少. 与普通的催化剂不同, 在催化氧化体系中, CoTNPP-P(4VP-co-St)/SiO2存在最适宜用量, 过量的CoTNPP-P(4VP-co-St)/SiO2反而会使其催化活性降低; P(4VP-co-St)/SiO2表面CoTXPP的固载密度存在一最佳值. 此外, 固载化以后, 催化剂具有较好的重复使用性. 结果表明, 接枝微粒P(4VP-co-St)/SiO2对金属卟啉不仅有明显的保护作用, 而且能提高其稳定性.

关键词: 催化氧化, 聚(4-乙烯基吡啶-co-苯乙烯), 接枝微粒, 轴向配位, 固载金属卟啉, 乙苯

Abstract:

The X-substituted cobalt tetraporphyrins (CoTXPP) (X=H, Cl, NO2) were easily bound to the side chains of the grafting particles poly(4-vinyl-pyridine-co-styrene)/SiO2 (P(4VP-co-St)/SiO2) via an axial coordination reaction to prepare supported catalysts CoTXPP-P(4VP-co-St)/SiO2. Structures of the CoTXPP-P(4VP-co-St)/SiO2 catalysts were characterized with FTIR. The axial coordination reaction between the copolymer P(4VP-co-St) and CoTXPP was studied using electronic absorption spectroscopy. Catalytic performances of the supported catalysts for the oxidation of phenylethane in the absence of any reductant or solvent were investigated and compared in detail. Experimental results show that CoTXPP-P(4VP-co-St)/SiO2 can effectively activate dioxygen and obviously catalyze the oxidation of phenylethane to phenylethanone. The catalytic activities of CoTXPP-P(4VP-co-St)/SiO2 increased as the degree of electron deficiency of the peripheral substituent on the porphyrin ring increased. The catalytic activity of CoTNPP-P(4VP-co-St)/SiO2 was found to be the best. At 120 ℃and under the ordinary pressure of oxygen, the catalyst CoTNPP-P(4VP-co-St)/SiO2 gave excellent results with a 25.53%(x) yield of phenylethanone and very little α-phenylethanol. Additionally, we found that: (1) CoTNPP-P(4VP-co-St)/SiO2 as a biomimetic catalyst had an optimumusage amount, and excess addition would decrease the catalyst's efficiency; (2) the immobilization density of CoTXPP on the surface of P(4VP-co-St)/SiO2 still had a maximum value; (3) the catalyst's activity was stable during six catalytic cycles. All these results indicate that the grafted particles P(4VP-co-St)/SiO2 protect the metalloporphyrins from oxidation and also promote the activation of O2 by the metalloporphyrins.

Key words: Catalytic oxidation, Poly(4-vinyl-pyridine-co-styrene), Grafting particles, Axial coordination, Supported-metalloporphyrin, Phenylethane