Operando investigations of particle size and support effects during the selective CO methanation over oxide supported Ru nanoparticles in idealized and realistic H2 feed gases

Abstract

In addition to the increasing importance in technical applications of the selective CO methanation, it is also an ideal model reaction for testing the catalytic performance of supported Ru catalysts in hydrogenation reactions. The focus of the present work is the molecular scale understanding of the relationship between structure and catalytic performance of supported Ru catalysts, with emphasis on the disentanglement of metal particle size effects from the metal-support interaction for non-reducible (zeolite and Al2O3) and reducible (TiO2) oxide support materials. The findings and mechanistic insights drawn from these studies were obtained using a multi-analytical approach, employing state of the art time on-stream reaction kinetic experiments, as well as time resolved operando diffuse reflectance FTIR and X-ray absorption fine structure (XAFS) spectroscopy. These measurements were supplemented by a detailed elucidation of the composition and structural properties of the catalysts, studied by ex situ characterization techniques, including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), high resolution transmission electron microscope (HR-TEM) imaging, and inductively coupled plasma optical emission spectroscopy (ICP-OES).