关键词: 壳聚糖, 纤维素, 金属卟啉, 环己烷, 氧化

The amino groups or the hydroxyl groups on the chitosan-supported metal tetraphenylporphyrins may play a key role in improving the stability and the catalytic activity of metalloporphyrins. To investigate the different effect produced by two kinds of groups, the situation of metalloporphyrins protected by cellulose from destruction and the cocatalysis of hydroxyl groups, three supported metalloporphyrins were prepared by adsorbing iron, cobalt and manganese porphrin onto chitosan-structure-like cellulose. The amount of metalloporphyrin adsorbed on cellulose was measured by UV-vis spectroscopic technique. The catalysis of the three supported catalysts for aerobic oxidation of cyclohexane was studied in absence of any solvents and reductants, and compared with those of the three chitosan-supported metalloporphyrins accordingly. Under the reaction condition of 418 K and 0.8 MPa air pressure, three cellulose-supported metalloporphyrins were used to perform catalysis for aerobic oxidation of cyclohexane once and exhausted respectively. The selectivity of alcohol and ketone acquired from the three catalysts respectively was lower than those from the corresponding chitosan-supported metalloporphyrins. The results indicate that cellulose has not any protection of them from destruction by oxygen, and the hydroxyl groups in the two kinds of supports have weak cocatalysis of metalloporphyrins for decomposing cyclohexyl hydrogen peroxide into ketone and alcohol. Inversely, chitosan has stronger protection of metalloporphyrins from destruction and the amino groups on it have stronger cocatalysis of metalloporphyrins for decomposing cyclohexyl hydrogen peroxide into products needed. Therefore, the acquired selectivity of alcohol and ketone was higher.

Key words: chitosan, cellulose, metalloporphyrin, cyclohexane, oxidation