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 LaFe_0.8Co_0.15Cu_0.05O₃ 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.