Combining Time-Resolved Hard X-ray Diffraction and Diffuse Reflectance Infrared Spectroscopy To Illuminate CO Dissociation and Transient Carbon Storage by Supported Pd Nanoparticles during CO/NO Cycling

摘要

A novel combination of time-resolved hard X-ray diffraction (HXRD) with diffuse reflectance infrared spectroscopy (DRIFTS) and mass spectrometry (MS) that takes advantage of the intrinsic properties of very high energy X-rays has been developed for use in studying gas-solid interactions. The method has allowed us to specify how Al_2O_3-supported Pd nanoparticles (～3 nm diameter) actively participate in prototypical de-NO_x chemistry. We show that unresolved issues in the behavior of this system observed using time-resolved extended X-ray absorption fine structure (EXAFS) during CO/NO cycling are due to the dissociation of adsorbed CO species and transient storage of atomic carbon within the Pd nanoparticles, forming PdC_x.