Low temperature mechano-catalytic biofuel conversion using liquid metals

Abstract

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 CH and CC 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.