K2SO4-promoted TiO2 for the efficient oxidative coupling of methane

The oxidative coupling of methane (OCM) into C 2−3 hydrocarbons is still limited to a few types of catalysts with low product yield. Herein, we reported our discovery that a K 2 SO 4 -promoted TiO 2 catalyst can effectively catalyze the OCM reactions with a C 2−3 yield of up to 26 %, which is comparable to the classical Mn-NaWO x /SiO 2 catalyst. Besides, this catalyst not only exhibits promising stability for at least 200 h without signs of deactivation under typical OCM conditions but also demonstrates high sulfur-resistance performance, outperforming most reported catalysts. We have evidenced that K + ions are responsible for increasing the surface basicity of rutile TiO 2 , thus benefiting C 2−3 selectivity. The presence of SO 4 2− can prevent the formation of potassium titanates, which catalyze the over-oxidation of CH 4 . The surface lattice oxygen species are confirmed to be the active sites for selective CH 4 activation, while the chemisorbed oxygen species catalyze the combustion of CH 4 to CO 2 .