Exsolved Nickel Nanoparticles Acting as Oxygen Storage Reservoirs and Active Sites for Redox CH4 Conversion

Abstract

The growing demand for H2 and syngas requires the development of new, more efficient processes and materials for their production, especially from CH4 that is a widely available resource. One process that has recently received increased attention is chemical looping CH4 partial oxidation, which, however, poses stringent requirements on material design, including fast oxygen exchange and high storage capacity, high reactivity toward CH4 activation, and resistance to carbon deposition, often only met by composite materials. Here we design a catalytically active material for this process, on the basis of exsolution from a porous titanate. The exsolved Ni particles act as both oxygen storage centers and as active sites for CH4 conversion under redox conditions. We control the extent of exsolution, particle size, and population of Ni particles in order to tune the oxygen capacity, reactivity, and stability of the system and, at the same time, obtain insights into parameters affecting and controlling exsolution.