Impact of Adding Bioethanol and Dimethyl Carbonate on Gasoline Properties

Abstract

Bioethanol and dimetyl carbonate (DMC) are considered alternative fuels and additives to the synthesis compounds used now, since bioethanol is a biofuel and dimethyl carbonate (DMC) is non-toxic, biodegradable and can be produced in a cleaner way. In this study, the effect of adding dimethyl carbonate (DMC) and ethanol to gasoline on the volatility was investigated. The volatility was the main goal of this research but also, the effect on the antiknock properties was studied. Mixtures of gasoline with DMC or with bioethanol were prepared in different proportions of additive: 3%, 6% and 9% v/v. Additionally, mixtures with 3% v/v ethanol plus 3% or 6% v/v DMC, and3% DMC plus 6% v/v ethanol were prepared. For the volatility evaluation, the ASTM distillation curve and vapor pressure of these mixtures were determined experimentally in order to predict the performance of the resulting fuels. When adding oxygenated compounds, the increase in vapor pressure was proportional to the additive quantity. Additionally, modifications of the ASTM distillation curves were observed, with these indicating the formation of minimum boiling point azeotropes and the corresponding increase in volatility, with good effect on the ease of ignition in the engine. Based on the experimental results, the vapor lock index VLI, drivability index DI and vapor–liquid ratio temperature T(V/L=20) were calculated to quantify the volatility. The experimental results showed that gasoline mixtures with these oxygenated compounds show a significant increase in antiknock properties. Thus, for mixtures with ethanol, the research octane number (RON) increases by up to 2.2 units and the motor octane number (MON) increases by up to 1.2 units. Gasoline mixtures with DMC have another behavior: RON increased by up to 1.5 units, while the MON value increased by up to 2.5 units. For an initial gasoline with RON = 94.7 and MON 84.7, these increases are important and make the difference by exceeding the RON = 95 limit. Adding dimethyl carbonate to gasoline–ethanol blends improves the sensitivity of the fuel.