Synthesis of copper-substituted aluminophosphate molecular sieves (CuAPO-11) and their catalytic behavior for phenol hydroxylation Original Research Article

Cu-substituted aluminophosphate molecular sieves (CuAPO-11) containing different amounts of copper were synthesized by static hydrothermal crystallization and characterized using XRD, ICP-AES, N2-adsorption, SEM and DR UV–Vis techniques. Experimental data show that the Cu limitation in the synthesis gel used for CuAPO-11 is 0.20 in the form of CuO/Al2O3 molar ratio. A new Cu-containing crystal phase (denoted as CuAlPO) with a different structure from CuAPO-11 can be formed if the CuO/Al2O3 molar ratio in the gel is beyond the value of 0.20. To evaluate the catalytic oxidation properties of CuAPO-11 and CuAlPO, we carried out the phenol hydroxylation reaction using aqueous hydrogen peroxide (30 wt.% aqueous H2O2) as an oxidant; an excellent transformation of phenol into dihydroxybenzenes (catechol and hydroquinone) was achieved under benign reaction conditions.