MnO and TiO solid catalysts with low-grade feedstocks for biodiesel production

► Biodiesel was made with manganese oxide (MnO) and titanium oxide (TiO) catalysts. ► MnO and TiO were robust for both transesterification and esterification. ► MnO and TiO handled low quality feedstocks with no pretreatment. ► Using a two-stage process, high quality biodiesel and glycerol were produced.