The cobalt-doped sample forms large agglomerates of crystallites already when aged at 65 °C. The porous structure is formed in-between the agglomerates, with an average pore size of 7.3 nm, which increases to 10.5 nm when aged at 80 °C, Figure . The BJH pore volume increases from 0.21 to 0.33 cm 3 g -1 when the aging temperature is increased, indicating that the size and the number of pores are both increasing, Table .