A nanoscale Ni/ZrO2 catalyst coated with Al2O3 for carbon dioxide reforming of methane

Abstract

AbstractBACKGROUNDCO2 reforming of methane, also known as dry reforming of methane, has received significant attention because this technology can convert notorious greenhouse gases (CH4/CO2) into useful syngas (H2/CO). However, this technology still has not been commercialized, primarily due to the lack of feasible catalysts.RESULTSBased on zirconia (ZrO2) nanoparticles with pure monoclinic (m) or tetragonal (t) crystal phase, three nickel catalysts (Ni/m‐ZrO2, Ni/t‐ZrO2 and Ni/m‐ZrO2@Al2O3) have been synthesized for CO2 reforming of methane. The Ni/t‐ZrO2 catalyst exhibited the lowest reforming activity with CH4 conversion of 15.5% at 700 °C under 1 atm with a gas hourly space velocity of 96 000 mL (h gcat)−1. The Ni/m‐ZrO2 catalyst showed much higher initial activity but underwent severe deactivation, during which CH4 conversion decreased from 56.1% to 33.4% after 300 min of reaction. The nanocomposite Ni/m‐ZrO2@Al2O3 catalyst with confinement effect exhibited the best activity and good stability. Specifically, its CH4 conversion decreased merely from 60.2% to 55.3% after 24 h of reaction.CONCLUSIONSStructural characterizations demonstrate that limited specific surface area and weak metal–support interactions existed on the Ni/t‐ZrO2 catalyst, which led to large nickel nanoparticles and thus poor reforming activity. Both Ni/m‐ZrO2 and Ni/m‐ZrO2@Al2O3 catalysts had high specific surface area and very small nickel nanoparticles, which may rationalize the high reforming activity. The improved stability of the Ni/m‐ZrO2@Al2O3 catalyst was mainly related to the alleviated carbon deposition resulting from enriched surface basicity and strengthened metal–support interactions. © 2020 Society of Chemical Industry (SCI)