Finding controllable, low-cost, and scalable ways to generate Ni-based catalysts is the bottleneck for methane dry reforming catalyst design. A new method for generating trimetallic CoxNiyMg100-x-yO solid solution platelets enclosed by (111) facets has been developed from the topotactic pyrolysis of the metastable precursor CoxNiyMg100-x-y(OH)(OCH3) derived from solvothermal synthesis. The catalyst composition and reaction conditions have been modulated to achieve maximum coke resistance and catalyst stability. Long-term stability for 1000 h time on stream at 800 degrees C has been achieved for the optimized Co0.075Ni7.425Mg92.5O catalyst. The role of Co in the catalyst has been disclosed through kinetic measurements and detailed characterization of the spent catalysts. Co is enriched on the Co-Ni alloy surface under reforming conditions and accelerates the gasification of coke intermediates. Co also enhances the chemisorption of oxygen and reduces the activation energy for methane fragmentation, which is the rate-determining step for the overall reaction. (C) 2015 Elsevier Inc. All rights reserved.