Effects of iron-based fuel borne catalyst addition on microstructure, element composition and oxidation activity of diesel exhaust particles

Abstract

Metal-based fuel borne catalysts (FBC) have been extensively studied as an effective technology to reduce diesel particles and assist diesel particulate filter (DPF) regeneration. In this study, FBC fuels were prepared with Fe element mass fractions of 0, 100, 200, 300 and 400 mg/kg (marked as Diesel, Fe100, Fe200, Fe300 and Fe400). The effects of FBC additions on fuel economy and emission characteristics were carried out on a common-rail engine. Also, particle size distribution, microstructure, surface functional groups, element content and oxidation properties of exhaust particles were systematically analyzed. Results showed that the brake thermal efficiency was improved with the addition of FBC in diesel fuel, especially at low load, and the NOx and smoke emissions showed a decreasing trend. Compared with Diesel particles, the total mass concentration and the mean particle diameter of Fe300 particles decreased, the overall particle size distribution moved from coarse mode to accumulation mode, however, the total number concentration increased. Fe300 particles had larger layer spacing and microcrystalline curvature, smaller microcrystalline size and lower graphitization. In addition, the relative contents of OH and aliphatic C-H in Fe300 particles were higher than those in Diesel particles. The relative content of C atoms in Fe300 particles decreased, while the relative content of O atoms increased. Temperature-programmed-oxidation experiments indicated that semi-volatile organic components appeared in Fe300 particles, the peak temperature of weight loss rate decreased by 131 °C as compared with Diesel particles, the activation energy was also significantly lower, and therefore the particle oxidation activity was improved.

Diesel particulate filter regeneration mechanism of modern automobile engines and methods of reducing PM emissions: a review

“…According to the experiment, the initial oxidation temperature of soot was decreased by 75.1°C and 107.3°C respectively under the condition of Fe content of 200mg/kg and 400mg/kg. There are two reasons why Fe can catalyze soot oxidation: (1) Fe can hinder the growth of PM during combustion, resulting in the reduction of particle size and the increase of contact area with the catalyst; (2) the addition of Fe makes the particles produce a unique lattice, increases the curvature of the particle micro carbon layer, and makes the particles easier to participate in the oxidation reaction (Liu et al 2020a ). In another study, through the experiment of the oxidation temperature of soot by the mixture of Fe / Ce FBC and perovskite, it was found that the mixture could effectively reduce the oxidation temperature of PM (Lee et al 2010 ).…”

Recent advancement in the application of metal based nanoadditive in diesel/biodiesel fueled compression ignition engine: A comprehensive review on nanofluid preparation and stability, fuel property, combustion, performance, and emission characteristics

“…In fact, OC emission in case of 60 ppm Fe doped fuel was decreased by 65%–85% for the three tested engine loads and accounts for more of the decrease in the total carbon (TC). Liu et al 217 investigated the effect of 300 ppm Fe doped diesel (Fe300) on the chemical composition of exhaust particles. Particles from Fe300 contained more OH and aliphatic CH than that from neat diesel.…”

“…210 Addition of FBCs nano metallic additives to a fuel also results in a decrease in the accumulation mode particles with an increase in the nuclei mode particles. 214,215,217,222 FBCs enhance soot oxidation and total mass concentration of the exhaust particles decreases with the dosing of metallic FBCs. 214,215,217,223,224 However, doping of metallic nanoadditives to fuels leads to an increase in the total particle number (PN) concentration due to formation of self-nucleated metallic NPs.…”

“…214,215,217,222 FBCs enhance soot oxidation and total mass concentration of the exhaust particles decreases with the dosing of metallic FBCs. 214,215,217,223,224 However, doping of metallic nanoadditives to fuels leads to an increase in the total particle number (PN) concentration due to formation of self-nucleated metallic NPs. 33,214,217,218 The number and size of these particles increase with the dosing levels of metallic nanoadditive.…”

Effects of PODE/diesel blends on particulate matter emission and particle oxidation characteristics of a common-rail diesel engine

“…In addition, the disorder degree of soot particles increases and the graphitization degree decreases with an increase in the proportion of ultrafine particles for the blends, which makes the particles easier to be oxidized. Therefore, the energy required in the particle pyrolysis process decreases, and the reaction activation energy decreases [51]. P e a r s o n ' s r -0 .…”