Sandwich Ni-phyllosilicate@doped-ceria for moderate-temperature chemical looping dry reforming of methane

Chemical looping dry reforming of methane (CL-DRM) enables the highly selective oxidation of CH 4 and reduction of CO 2 . We designed sandwich and core-shell structured 5% Ni-SiO 2 @Ce 0.8 M 0.2 O 2-δ (M = Fe, Co, Ni) catalysts for moderate-temperature CL-DRM. Highly dispersed nano Ni particles are anchored on the surface of SiO 2 spheres, and then transition metal oxide-doped CeO 2 is dispersed on the inner core to form a shell layer serving as the oxygen storage role. This trilayer structure provides abundant CeO 2 -Ni interfaces and catalytic sites. Doping of transition metal oxides helps to activate methane for synthesis gas generation at lower temperatures. In the chemical looping cycle, the available OSC (oxygen storage capacity) was enhanced by the introduction of transition metals into ceria and follows the order of Fe-doped (2.92 mmol g −1 ) > Ni-doped (1.69 mmol g −1 ) > Co-doped (0.86 mmol g −1 ) > undoped (0.58 mmol g −1 ) catalysts. The catalyst exhibits high coke resistance and redox reactivity in successive CL-DRM redox cycles at 620 °C. In situ Drifts and Raman of CH 4 /CO 2 temperature programmed desorption over recycled/pre-reduced catalysts show that methane is activated into CH x over highly dispersed nickel nanoparticles at 400 °C and then converted into H 2 and CO by lattice oxygen. Then, oxygen vacancies are refilled, reduced species (Fe 0 and Fe 2+ ) are re-oxidized using CO 2 to produce CO, and deposited carbon from CH 4 POx is also removed via CO 2 gasification. • Sandwich and core-shell structured Ni-phyllosilicate@Ce 0.8 Fe 0.2 O 2-δ with high activity and stability. • Moderate-temperature CL-DRM for CH 4 and CO 2 conversion. • Enhanced oxygen storage capacity and methane activation by transition metal oxide doping.