Integrated CO2 capture and methanation on Ru/CeO2-MgO combined materials: Morphology effect from CeO2 support

•Ru/CeO2-MgO combined materials for efficient CO2 capture and in situ methanation isothermally.•The Ru/CeO2-MgO with rod and particle CeO2 morphology can vastly improve CO2 conversion.•Ru/CeO2-MgO with rod morphology CeO2 shows stable cycle catalytic performance in integrated CO2 capture and methanation.•The integrated CO2 capture and methanation over Ru/CeO2-MgO is achieved via formates and CO2 dissociation pathways. Integrated CO2 capture and methanation (ICCM) is attracting more attention to promote the reduction of CO2 emission. This work developed and applied a set of combined materials using Ru/CeO2 as catalyst and physically mixed Li, Na, K-doped MgO as adsorbent for the ICCM process. The influences of morphologies of CeO2 (rod, particle, and cube) in combined materials are investigated explicitly in terms of CO2 conversion and CH4 yield. Compared to the CeO2 with cube morphology, the CeO2 with rod and particle morphologies showed better Ru dispersion and more abundant support-metal interaction (SMI). The combined materials with rod and particle morphologies CeO2 (Ru/rod-CeO2-MgO and Ru/particle-CeO2-MgO) show more superior catalytic performance (0.33 and 0.29 mmol/g for CH4 yield and 55.7% and 59.8% for CO2 conversion, respectively) than that with Ru/cube-CeO2-MgO. Furthermore, the Ru/rod-CeO2-MgO shows excellent catalytic stability and reusability during 9 cyclic ICCM evaluations. In situ DRIFTS of Ru/CeO2-MgO revealed that the formates and dissociated CO2 (Ru-CO) might be the critical methanation intermediates in ICCM.