Abstract

A copper-containing AlPO₄-5 was synthesised using copper(II) oxide as the copper source and tetraethylammonium hydroxide as the template. The local environment about copper in the as-synthesised, calcined and hydrogen-reduced materials has been studied using XANES and EXAFS. The results for the as-synthesised product show that copper is sited within the AlPO₄-5 framework and that its local environment is a tetragonally distorted Cu(O)₆ octahedron in which the axial bonds are possibly to hydroxy groups. On calcining at 550 °C the environment changes to a non-tetragonally distorted octahedron for which the coordination to the framework is increased by two long bonds to framework oxygens. Copper(II) in CuAPO-5 is reduced by 5% H₂ in He to copper particles of dimensions >40 Å. The catalytic properties of two CuAPO-5 samples (derived from copper(II) oxide and, for comparison, from copper(II) acetate) in the selective catalytic reduction of NO in the presence of NH₃ and O₂ have been investigated, showing maximum conversions of 27% at 440 °C and 53% at 340 °C, respectively.