Surface Restructuring of Hollow Ni@S-1 Promoted the Activation of CH₄ and CO₂ in Chemical Looping

Chemical looping reforming of CH4 coupled with the reduction of CO2 is an effective technology for syngas production and CO2 utilization. This work focuses on the surface restructuring of hollow Ni@S-1, which combines with LaFe0.8Co0.15Cu0.05O3 perovskite oxides to obtain a highly efficient oxygen carrier for chemical looping. Ni-impregnated silicalite-1 was subjected to treatment with tetrapropylammonium hydroxide, resulting in the formation of Ni@S-1 with a hollow structure using the “dissolution-recrystallization” method. Nickel is initially present in the form of nickel phyllosilicate in Ni@S-1. After CH4 oxidation, nickel phyllosilicates are transformed into Ni particles that are encapsulated into S-1, effectively suppressing the sintering of Ni particles. In the CH4 oxidation stage, the syngas yield over the LFCC/15%Ni@S-1 decreases slightly from 8.25 to 7.84 mmol·g–1 during 20 redox cycles, demonstrating better stability and reactivity than that of pure LFCC. After 20 redox cycles, Fe and Co elements migrate from perovskite to Ni@S-1, indicating a stronger interaction between perovskite and Ni@S-1, which may benefit the reactivity.