Bridging Bioethanol and Diesel Engines: Real-World Performance of a Higher-Alcohol Derived from Catalytic Conversion of Bioethanol

Abstract

This work assesses the real-world performance and emission characteristics of a compression-ignition (CI) engine fuelled with a blend of conventional diesel and a bioethanol-derived higher-alcohol fuel (Catalyxx C4+), evaluated under the World Harmonized Light-Duty Vehicle Test Cycle (WLTC). Both cold- and hot-start conditions were analysed, corresponding to coolant temperatures of 20 °C and 70 °C, respectively, in order to capture representative operating scenarios ranging from short-distance urban driving to extended real-world use. Catalyxx C4+ is a renewable drop-in biofuel produced via the thermocatalytic conversion of bioethanol and consists of a mixture of linear and branched higher alcohols spanning C4 to C8. A fuel blend containing 20% Catalyxx C4+ by volume (80% diesel) demonstrated substantial emission benefits relative to neat diesel. Under cold-start operation, particle number (PN), particle mass (PM), and CO emissions were reduced by 61.6%, 77.8%, and 39.3%, respectively. Even greater reductions were observed under hot-start conditions, with decreases of 64.0% in PN, 78.5% in PM, and 66.9% in CO emissions. These results highlight the strong potential of bioethanol-derived higher-alcohol drop-in fuels to significantly mitigate pollutant emissions in CI engines. Furthermore, they emphasize the importance of evaluating sustainable alternative fuels under test conditions that closely reflect real-world vehicle operation, encompassing both low-temperature engine start-up and fully warmed, long-distance driving scenarios.