Syngas Production by Chemical Looping Dry Reforming of Methane over Ni‐modified MoO3/ZrO2

Abstract

AbstractWe investigated supported‐MoO3 materials effective for the chemical looping dry reforming of methane (CL–DRM) to decrease the reaction temperature. Ni‐modified molybdenum zirconia (Ni/MoO3/ZrO2) showed CL–DRM activity under isothermal reaction conditions of 650 °C, which was 100–200 °C lower than the previously reported oxide‐based materials. Ni/MoO3/ZrO2 activity strongly depends on the MoO3 loading amount. The optimal loading amount was 9.0 wt.% (Ni/MoO3(9.0)/ZrO2), wherein two‐dimensional polymolybdate species were dominantly formed. Increasing the loading amount to more than 12.0 wt.% resulted in a loss of activity owing to the formation of bulk Zr(MoO4)2 and/or MoO3. In situ Mo K‐edge XANES studies revealed that the surface polymolybdate species serve as oxygen storage sites. The Mo6+ species were reduced to Mo4+ species by CH4 to produce CO and H2. The reduced Mo species reoxidized by CO2 with the concomitant formation of CO. The developed Ni/MoO3(9.0)/ZrO2 was applied to the long‐term CL–DRM under high concentration conditions (20 % CH4 and 20 % CO2) at 650 °C, with two pathways possible for converting CH4 and CO2 to CO and H2 via the redox reaction of the Mo species and coke formation.