화학공학소재연구정보센터
Journal of Molecular Catalysis A-Chemical, Vol.153, No.1-2, 93-101, 2000
Catalytic activity of Cu ion-exchanged Na center dot MCM-41 in the liquid-phase oxidation of 2,6-di-tert-butylphenol
The liquid-phase catalytic oxidation of 2,6-di-tert-butylphenol (BOH) was performed under mild reaction conditions using a Cu ion-exchanged Na . MCM-41 (Cu-Na . MCM-41) catalyst. 4,4'-Dihydroxy-3,3',5,5-tetra-tert-butylbiphenyl (H(2)DPQ) and 3,3',5,5'-tetra-tert-butyl-4, 4'-diphenoquinone (DPQ) were obtained as the oxidation products. The addition of an inorganic base such as KOH onto the Cu-Na . MCM-41 catalyst or to the reaction solution was found to cause the increase in the oxidation activity. The oxidation activity of BOH in the presence of KOH in the reaction solution was greater than when using the K added Cu-Na . MCM-41 catalyst. The reaction scheme for the BOH oxidation was proposed, in which scheme the DPQ formation involves both a consecutive pathway via H(2)DPQ intermediate and an oxidative dehydrogenation of a dimer formed by the C-C coupling of the corresponding phenoxy radicals, without H(2)DPQ intermediate. To study the influence of the mesopore of the Na . MCM-41 on the oxidation of BOH, a comparably bulky molecule, Cu ion-exchanged NaZSM-5 (Cu-NaZSM-5) zeolite, whose pens are micro range in size, was attempted as a catalyst for the bulky phenol oxidation. The oxidation activity of the Cu-NaZSM-5 zeolite was found to be considerably lower than that of the Cu-Na . MCM-41 catalyst. The preference of the mesopore environment for the 2, 6-di-tert-butylphenol oxidation against the micropore counterpart was thus confirmed.