Multicyclic Hydrocarbon Additives to Reduce Soot Emissions from Diesel Combustion

Abstract

Diesel engines are used worldwide for heavy-duty vehicles, as such engines have high durability and efficiency. Being imperfect, the diesel engine has high emissions of harmful particles into the atmosphere. The demand of such energy has increased, and therefore, the level of pollutants shall also increase. The major emissions that come along with engines are CO, NOX, SOX and soot particles. Soot particles, emitted from diesel engines, have an adverse effect on human health and the environment. Many studies suggest the addition of additives such as oxygenated fuels to diesel to reduce soot emissions. However, it also reduces fuel economy and may produce new pollutants such as aldehydes. Another method to reduce soot could be to increase its reactivity by altering its physicochemical properties (e.g., introducing curvatures in its nanostructures) so that it oxidizes inside the engine or flame. In this direction, two cyclic high-density hydrocarbon fuels, adamantane and pinene are studied as additives for diesel to determine their effect on cetane number, threshold sooting index (TSI), and the physicochemical properties of soot nanoparticles. The addition of up to 6.75 wt% of adamantane in diesel significantly increased the smoke point of diesel from 18 to 29 mm (and threshold sooting index decreased by 44%), indicating a drastic drop in fuel sooting tendency. Adding 10% pinene decreased the TSI by 21% and increased the smoke point from 18 to 21 mm. Adamantane and pinene addition in a small amount to diesel had a minimal impact on the cetane number (less than 1% and 3% decrease in cetane number, respectively). The influence of additive addition to diesel on soot nanostructural characteristics are determined through different characterization approaches including TGA, HRTEM, XRD, EDX, and EELS. The results indicate that these multicyclic additives impose curvatures in the soot nanostructure, create relatively smaller soot fringes, and reduce soot aromatic content, and all of these property variations improve soot reactivity to improve its oxidation in flames or engines and reduce soot emission.

Date of Award	Dec 2021
Original language	American English