Syngas production modified by oxygen vacancies over CeO2-ZrO2-CuO oxygen carrier via chemical looping reforming of methane

Chemical-looping reforming of methane (CLRM) offers an effective approach for the production of syngas. A series of CexZryCu1-x-y (x = 0.6, 0.7, y = 0-0.35) mixed oxides were successfully prepared by sol-gel method, and characterized by means of XRD, H-2-TPR, BET, XPS, Raman and CH4-TPR. The addition of Cu and Zr ions caused the distortion of CeO2 lattice and induced more oxygen vacancies, which promoted the mobility of lattice oxygen in the materials. CexZryCu1-x-y mixed oxides also owned smaller grain size and better thermal stability than pure CeO2-CuO mixed oxides. Among the series of CexZryCu1-x-y mixed oxides, the reducibility of Ce0.6ZrxCu0.4-x and Ce0.7ZrxCu0.3-x samples gradually increased with the Cu content. It was found that the Ce0.7Zr0.2Cu0.1 sample owned the most abundant oxygen vacancies on the surface. The CexZryCu1-x-y mixed oxides with lower Cu content (<= 0.1) produced higher amount of H-2 and CO while smaller CO2. Ce0.7Zr0.2Cu0.1 sample still retained better structural stability and thermal stability after 20 times cycled reaction.