Synergistic Effects of Fuel Components on Aromatics Formation in Combustion: A Review

Abstract

Aromatics, especially polycyclic aromatic hydrocarbons (PAHs), are important combustion pollutants known to be carcinogenic and mutagenic and are also precursors of soot and, consequently, combustion-generated particulate matters that can significantly threaten environmental security and human health. In engine combustion, the multi-component and broad-source feature of transportation fuels makes synergistic effects commonly exist and greatly enhances the formation of aromatics and soot. Understanding the synergistic effects of different fuel components on aromatic formation facilitates concrete guidance for controlling soot emissions. This review focuses specifically on the synergistic effects of aromatics formation, including benzene, indene, naphthalene, and larger PAHs, in combustion among hydrocarbon blends and hydrocarbons blended with oxygenated fuels. Progresses in experimental measurements, theoretical calculations of critical reactions, and kinetic modeling are reviewed in detail. Special attention is paid to blends of aromatics and linear fuels, which show pronounced synergistic effects in PAH formation. Furthermore, some prospects for future research on synergistic effects in aromatic formation are provided.