Heavy oil viscosity reduction at mild temperatures using palladium acetylacetonate

•Palladium acetylacetonate (PdA) reduces heavy oil viscosity at as low as 80 °C.•The viscosity reduction effect is most substantial at 130–250 °C.•PdA releases its ligand to form acetylacetone, which reduces oil viscosity.•PdA intercalates within the asphaltenes at 80–130 °C.•Pd metal forms at higher treatment temperatures, which can catalyze hydrogenation. Metal-ligand compounds (“MLCs”) have been shown to reduce heavy oil viscosity and upgrade oil quality. However, MLCs generally require high treatment temperatures (around 250 °C), which is undesirably energy-intensive. We identified palladium(II) acetylacetonate (“PdA”) as a model MLC that can operate at mild temperatures (