Low temperature mechano-catalytic biofuel conversion using liquid metals

Liquid metals are super catalysts that facilitate reactions at low temperatures while also providing new reaction pathways by the incorporation of co-catalysts. Synthesising H₂ and C₂H₄ from renewable resources, with a low carbon footprint, is crucial for environmental sustainability. However, the high temperature requirement and over-reliance on fossil fuels restrict the sustainable production of H₂ and C₂H₄. Here we demonstrate a hybrid catalytic system, which realises the conversion of renewable biofuels into mostly H₂ and C₂H₄ at near room temperature, by employing mechanical energy as the stimulus and liquid metal gallium (Ga) together with nickel (Ni) particles as co-catalysts. During the collision of the suspended nano/micro-sized Ga/Ni co-catalysts, the biofuels, including canola oil and other liquid hydrocarbons, are converted at the interfaces of the catalytic materials. Density functional theory calculations show that C[sbnd]H and C[sbnd]C bond dissociation reactions on the Ga surface proceed under low energy conditions. These biofuels are converted into mainly H₂ and C₂H₄ with CH₄, CO, CO₂, C₂H₂, C₃H₆ and solid carbon as other by-products. With mild heating at ∼ 60 °C and the use of a 20 ml reactor, the process is capable of producing 2.15 cm³ of H₂ and 2.47 cm³ of C₂H₄ per hour with canola oil as the feedstock. Meanwhile, the durability and potential practical applicability of the system are demonstrated with 10 days of continuous operation. This approach offers an alternative for H₂ and C₂H₄ production without involving high reaction temperatures and fossil fuel hydrocarbons.