Nickel silicate CHA-type zeolite prepared by interzeolite transformation and its catalytic activity in dry reforming of methane

• Interzeolite transformation of nickelsilicate MWW to CHA (Ni-CHA) using TMAdaOH. • Stabilization of framework Ni species to isolated Ni according to crystallization. • Framework Ni dominantly formed on the external surfaces of CHA structure. • Ni-CHA as a promising DRM catalyst with high CH 4 and CO 2 conversions and stability. We newly synthesized the nickel silicate CHA-type zeolitic material (Ni-CHA) through the interzeolite transformation of the parent nickel silicate MWW-type zeolite (Ni-MWW) using the structure-directing ability of N,N,N-trimethyl-1-adamantammonium hydroxide. With increasing crystallization time under hydrothermal conditions, the parent Ni-MWW was decomposed into an X-ray amorphized nickel silicate, which was then consecutively reassembled into Ni-CHA. Furthermore, as the crystallization progressed, the framework Ni species gradually transformed from intermediate Ni to isolated Ni species, achieving a more thermodynamically stable chemical state. The metallic Ni clusters can be formed by exsolving from the CHA framework during the high-temperature reduction treatment, which were mainly distributed on the external surface. A series of in-situ reduced Ni-CHA- x catalysts obtained after different crystallization times ( x = 0–72 h) were applied to the dry reforming of methane to evaluate their catalytic activity corresponding to the differences in crystallinity and chemical state. As a result, the interzeolite transformed Ni-CHA-72 h catalyst exhibited the highest catalytic performance even compared to the Ni-impregnated commercial SSZ-13.