Effect of working conditions on oxidation activity and surface functional group of particulate matter emitted from China Ⅵ GDI engine

Abstract

Gasoline particulate filter (GPF) is one of the most important means to solve particle emissions of gasoline direct injection (GDI) engines in the present and the future. In order to provide a theoretical guidance for the regeneration control and improvement of GPF, this paper analyzes the oxidation activity and surface functional group of particulate matter (PM) emitted from a China VI GDI engine at different working conditions, and the oxidation characteristics of ultrafine particles. The results show that ultrafine particles account for most PM emitted from the GDI engine, and the ratio of ultrafine particulates is affected by working conditions. The activation energy of PM changes in the range of 110 ∼ 180 kJ/mol under different working conditions. With the increase of engine load, the oxidation activity of PM decreases, which is manifested by the increase in characteristic temperatures of the oxidation activity. As the increase of engine speed, the oxidation activity increases. The activation energy of ultrafine particles is in the range of 88.0 ∼ 111.4 kJ/mol, and its oxidation activity is not significantly related to the particle diameter. The content of CO and C–H functional groups change obviously under different working conditions. IC-H/IC=C and IC=O/IC=C are in the range of 1.14 ∼ 1.8 and 1.25 ∼ 2.17. The oxidation activity of PM is positively correlated with the content of C–H functional groups.