Ethanol-water, a prototypical 'green' solvent mixture, cannot be considered as inert toward supported Pd nanoparticles. We establish severe size dependencies in Pd redox behavior, persistent gradients in Pd phase in a plug-flow situation, and that Pd nanoparticles are contaminated with hydrogen derived from the solvent. † Electronic supplementary information (ESI) available: Catalyst synthesis, operando EXAFS measurements, linear combination analyses, transmission electron microscopy, comparison of 1, 2, and 5 wt% Pd systems. See

Aqueous ethanolic solvents rearrange Pd catalysts facilely toward a common state irrespective of starting Pd dispersion or support material.

A new perspective of the Fujiwara–Moritani reaction is presented, including its kinetic profile and catalyst deactivation studies.