Development of copper impregnated porous granulates for chemical-looping combustion

Highly porous supports based on clay, alumina and diatomite were developed using extrusion method. By combination of diatomite and clay, a macrostructure was obtained, whereas with alumina composition a mesoporous structure occurred. Composites based on alumina and diatomite result in a systematically tunable macrostructure. Therefore it was possible to increase the total pore volume and achieve a tailored microstructure from the meso- to macropore range. To verify the workability of the developed supports for chemical-looping combustion (CLC), impregnation with 1.5 M copper nitrate trihydrate was performed on selected samples. Presence of mainly CuO and Cu2O phases were obtained in silica based samples (clay, diatomite), whereas CuAl2O4 spinel phase dominated in samples with high alumina content. CLC performance was verified by thermogravimetry using CO + N2 or O2 + N2 gases. The highest performance could be achieved with the γ-alumina–diatomite composite support material.