Research octane numbers of primary and mixed alcohols from biomass-based syngas

Primary alcohols (ethanol, 1-propanol, 1-butanol, and 1-pentanol) derived from biomass offer a sustainable fuel source that can improve efficiency while reducing carbon dioxide (CO₂) emissions. However, the performance of these primary alcohols in spark-ignited engines is relatively unknown. In this work, the performance of primary alcohols was experimentally determined using the research octane number (RON) and the blending research octane number (BRON). The primary alcohol mixture, or "AlcoMix," consists of 75% ethanol, 11% 1-propanol, 8% 1-butanol, and 6% 1-pentanol and was approved by the U.S. EPA for use in blending with gasoline. This mixture is the probable outcome of the thermochemical conversion of biomass using Fischer-Tropsch chemistry with synthesis gas. The purpose of this research was to determine whether AlcoMix might be a suitable replacement for ethanol in fuel blending as an antiknock blending component for spark-ignited engines. As an indicative measure of knock resistance, the RONs of AlcoMix and ethanol were estimated using a modified, validated method in a CFR engine. The antiknock properties of AlcoMix as a blending component in gasoline were determined by estimating the BRON. The results show that the measured RON of the individual primary alcohols closely match published values. Additionally, the RON and BRON of the primary alcohol mixture nearly match those of ethanol. These results indicate that the primary alcohol mixture produced by thermochemical processes could be used as a substitute for ethanol as a primary fuel or as an antiknock blending component.