Solketal production from glycerin as a gasoline fuel additive: Synthesis, physical and chemical properties, engine performance and emissions

The driving force of typical urban vehicles is usually produced by spark-ignited internal combustion engines operating with gasoline as fuel. The combustion of gasoline fuel in spark ignition engines leads to air pollution in urban areas and also to the reduction of fossil fuel reserves. Due to the biological structure of the fuel, using ethanol as a blend with gasoline, along with other alternatives to fossil sources, is one of the solutions to decrease gasoline-based air pollution. Even though adding ethanol compounds allows better fuel combustion and reduces pollutants, these compounds lead to an elevated emission of nitrogen oxides into the air when used at higher percentages in blended with fuel. On the contrary, glycerin, a byproduct of the biodiesel production process, acts as a restricting factor in the mass production of biodiesel. Taking these into account, this study proposes a novel blend of biofuels for gasoline fuel by converting glycerin into solketal and then injecting it into ethanol-containing gasoline fuel. The proposed fuel blend provides optimal performance and comes with the least emission of pollutants. The results showed that adding 5%  by volume of solketal to gasoline fuel containing 20% ​​ by volume of ethanol resulted in the best engine performance and lower air pollution compared with the combustion of pure gasoline alone and gasoline fuel containing 20% ​​ethanol. In addition, brake specific fuel consumption with fuel containing 5% solketal at 25, 50 and 75% torques has decreased by five, two and seven tenths of percent, respectively. Also, the addition of 5% solketal, in addition to maintaining the positive effects of adding ethanol in reducing engine exhaust emissions, causes a significant reduction in the emission of nitrogen oxides by about 90%, which is one of the disadvantages of adding ethanol to fuel