CATALYSIS OF COPPER-CONTAINING TRANSITION -METAL HYDROTALCITE-LIKE COMPOUNDS IN THE PHENOL HYDROXYLATION WITH HYDROGEN-PEROXIDE

Hydrotalcite-like compounds containing carbonate ion as the interlayer anion were prepared by coprecipitation under low supersaturation cond ition by mixing an aqueous solution of metal nitrates with an aqueous solutions of NaOH and Na2CO3, at room temperature, maintaining pH = 8- 10 with vigorous stirring, Following the mixing, the resulting heavy s lurry was aged at 353 K for 18 h with vigorous stirring, The precipita te was then filtered, washed several times with hot distilled water an d dried in air at 353 K overnight, In this way, CuMI AlCO3-HTLcs and M -I AlCO3-HTLcs were synthesized and characterized by means of XRD and IR, The catalysis of the above mentioned HTLcs were investigated in th e phenol hydroxylation with H2O2. The results indicated that all of th e copper-containing HTLcs had a higher catalytic activity in the react ion, However, those catalysts that did not contain copper had no catal ytic activity in this reaction, This means that copper was the active center in the phenol hydroxylation. Meanwhile, the mechanism was also proposed, which could be used to explain the main reason for higher ac tivity for CuCuAlCO3-HTLcs in the phenol hydroxylation and the effect of Mg2+, Zn2+, Co2+, Ni2+ on activity of CuMI AlCO3-HTLcs.