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

Abstract

Abstract BACKGROUND CO 2 reforming of methane, also known as dry reforming of methane, has received significant attention because this technology can convert notorious greenhouse gases (CH 4 /CO 2 ) into useful syngas (H 2 /CO). However, this technology still has not been commercialized, primarily due to the lack of feasible catalysts. RESULTS Based on zirconia (ZrO 2 ) nanoparticles with pure monoclinic (m) or tetragonal (t) crystal phase, three nickel catalysts (Ni/m‐ZrO 2 , Ni/t‐ZrO 2 and Ni/m‐ZrO 2 @Al 2 O 3 ) have been synthesized for CO 2 reforming of methane. The Ni/t‐ZrO 2 catalyst exhibited the lowest reforming activity with CH 4 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‐ZrO 2 catalyst showed much higher initial activity but underwent severe deactivation, during which CH 4 conversion decreased from 56.1% to 33.4% after 300 min of reaction. The nanocomposite Ni/m‐ZrO 2 @Al 2 O 3 catalyst with confinement effect exhibited the best activity and good stability. Specifically, its CH 4 conversion decreased merely from 60.2% to 55.3% after 24 h of reaction. CONCLUSIONS Structural characterizations demonstrate that limited specific surface area and weak metal–support interactions existed on the Ni/t‐ZrO 2 catalyst, which led to large nickel nanoparticles and thus poor reforming activity. Both Ni/m‐ZrO 2 and Ni/m‐ZrO 2 @Al 2 O 3 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‐ZrO 2 @Al 2 O 3 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)