Selective oxidation of methane to CO on Ni@BOx via reaction-induced vapor migration of boron-containing species onto Ni

Dynamic migration of support-derived species and subsequent encapsulation of supported metal nanoparticles (NPs) are the well-known features of the Strong Metal-Support Interaction (SMSI) effect. Here, we report occurrence of the classical SMSI state in physical mixture of Ni NPs and porous hexagonal boron nitride powder (Ni|pBN) during methane oxidation reaction at 600 ℃, in which Ni NPs are encapsulated by BOx overlayers derived from the pBN component. The SMSI state can switch the methane oxidation selectivity from CO2 on the fresh Ni|pBN catalyst to CO on the used catalyst. The encapsulation of Ni NPs by BOx overlayers has also been observed in Ni/Al2O3 catalyst which is physically mixed with pBN. Comprehensive characterizations confirm that the SMSI state is induced by vapor migration of boron-containing species e.g. BOxHy from pBN to metal surfaces, in which both high reaction temperature and water product play an important role.