Oxidative coupling of methane using non-stoichiometric lead hydroxyapatite catalyst mixtures

► Mixture catalysts of non-stoichiometric Pb hydroxyapatite were obtained. ► The catalysts were prepared by calcining Pb chloro-hydroxyapatites at 800 °C. ► The OCM activity changed according to the Cl content of precursor apatite. ► Higher C2 selectivity was obtained at a catalyst of higher surface basicity. ► The surface basicity was associated with the average coordination of lattice Pb2+.