Applied Surface Science, Vol.255, No.7, 4109-4113, 2009
A novel method for immobilization of Co tetraphenylporphyrins on P(4VP-co-St)/SiO2: Efficient catalysts for aerobic oxidation of ethylbenzenes
In this paper, poly(4vinylpyridine-co-styrene) (P(4VP-co-St)) was grafted on silica gel particles in the manner of "grafting from'', and the grafting particle P(4VP-co-St)/SiO2 was gained. The grafting particle P(4VP-co-St)/SiO2 is a novel kind of supports for immobilizing metalloporphyrin catalysts. Then, the immobilization of cobalt tetraphenylporphyrin (CoTPP) on the supports P(4VP-co-St)/SiO2 was carried out via the axial coordination reaction between CoTPP and the pyridine groups of the grafted P(4VP-co-St), resulting in the heterogenised catalysts CoTPP-P(4VP-co-St)/SiO2. The synthesized catalysts were characterized by FTIR and the axial coordination process between CoTPP and the grafted P(4VP-co-St) was confirmed by UV-vis. The effects of various factors on the immobilization reaction of CoTPP were studied in detail. Finally, the catalytic performance of CoTPP-P(4VP-co-St)/SiO2 in the catalytic oxidation process of ethyl benzene was investigated. The experimental results show that the axial coordination reaction is a very easy and novel method for favorably immobilizing CoTPP onto the P(4VP-co-St)/SiO2 surfaces. During the immobilization process of CoTPP on P(4VP-co-St/SiO2, the most bonding amount of CoTPP (0.19g/g) is obtained under the lower temperature (5 degrees C) and the higher concentration of CoTPP(6.0 mg/ml) lasting 4 h. Moreover, the supported catalyst CoTPP-P4VP-co-St)/SiO2 can effectively activate the dioxygen, and obviously catalyze the transform of ethylbenzene into acetophenone. So it exhibits the. ne catalytic activity. (C) 2008 Elsevier B. V. All rights reserved.
Keywords:4-Viniylpyridine;Graft polymerization;SiO2;Cobalt tetraphenylporphyrin;Axial coordination reaction;Immobilization