Effect of Rare Earth Doping on the Catalytic Activity of Copper‐Containing Hydrotalcites in Phenol Hydroxylation

The copper‐containing hydrotalcites (Cu‐HTLcs) are synthesized under microwave irradiation, the effect of rare earth elements (RE) on the synthesis of Cu‐HTLcs, wherein RE stands for rare earth elements, e.g., La, Y, Sm and Ce, is also investigated in the present work. The hydrotalcite structure of the synthesized samples is verified by XRD and FT‐IR. The results of their catalytic performances in phenol hydroxylation show that the doped rare earth elements can promote the catalytic activity of Cu‐HTLcs, exhibiting a good trend as follows: La>Y>Sm>Ce. XPS results show that the Cu⁺ species are produced after the interaction of La‐Cu‐HTLcs with H₂O₂. Combining with the catalytic test results, we propose a new mechanism about the generation of HO ^. radicals in phenol hydroxylation, it is assumed that HO‐Cu⁺‐OH species are first formed by the reduction of HO‐Cu²⁺‐OH located in hydrotalcites in the presence of H₂O₂, and then react with H₂O₂ to give rise to HO^. radicals.