Insights into the Influence of CeO 2 Crystal Facet on CO 2 Hydrogenation to Methanol over Pd/CeO 2 Catalysts

作者：Feng Jiang, Shanshan Wang, Bing Liu, Jie Liu, Li Wang, Yang Xiao, Yuebing Xu, Xiaohao Liu · 发表于：ACS Catalysis · 年份：2020 · DOI：10.1021/acscatal.0c03324 · 被引用次数：909 · 研究领域：Catalytic Processes in Materials Science、Catalysts for Methane Reforming、Carbon dioxide utilization in catalysis

CeO 2 is an excellent potential material for CO 2 hydrogenation attributed to the highly tunable properties including metal–support interaction and abundant oxygen vacancy. In this work, four CeO 2 supports with structurally well-defined different shapes and crystal facets are hydrothermally prepared, and their effects on the composition of Pd species and oxygen vacancy over Pd/CeO 2 catalysts have been intensively investigated in the reduction of CO 2 to methanol. The 2Pd/CeO 2 -R (rods) shows the highest concentration and number of oxygen vacancies, where the (110) facet with high surface oxygen mobility and low oxygen vacancy formation energy is exposed over the CeO 2 -R surface. The oxygen mobility at the interface of (111) and (100) facets mainly observed on 2Pd/CeO 2 -P (polyhedrons) is higher than the single (111) and (100) facets mainly observed on 2Pd/CeO 2 -O (octahedrons) and 2Pd/CeO 2 -C (cubs), respectively. The presence of Pd highly promotes the formation of oxygen vacancies by providing dissociated H atoms to facilitate the removal of surface O in ceria support under a H 2 atmosphere. Both the Pd x Ce 1– x O δ solid solution dominated on CeO 2 -R and the PdO species dominated on CeO 2 -O are reduced to metallic Pd after reduction with 6–10 nm average particle size. As revealed by density functional theory (DFT) calculations, in contrast to the single Pd 0 atom on CeO 2 and the thermodynamically most unstable Pd x Ce 1− x O δ solid solution, the Pd 0 nanoparticl...