Physicochemical properties and oxidative reactivity of combustion-generated soot from diesel blended with bicyclic hydrocarbon additives

  • Moataz K. Abdrabou

Student thesis: Master's Thesis

Abstract

Diesel fuel is readily used in internal combustion engines as the most common source of energy for heavy-duty transportation vehicles. This dependence on diesel engines results in the release of huge amounts of pollutants in the atmosphere. The pollutant of the highest concern in the current time is the particulate matter (PM). The diesel engine emission of particulate matter, i.e. soot particles, is of serious environmental concern as they are carcinogenic and remain suspended in the air for a prolonged time causing adverse effects on human health and the environment. Therefore, a lot of research attention is now being devoted towards investigating the soot nanostructure and its oxidative reactivity to reduce soot formation and emission without compromising on the fuel efficiency. One way to achieve this is by altering the nanostructure of the soot particles by introducing fringe curvature in its structure and enhancing the oxidative reactivity of the soot particles. The curvature and the disorder of soot nanostructure can be initiated by the introduction of the less stable 5-membered rings into the more stable 6-membered, planar graphitic-like structure of the soot. Therefore, this study investigates the effect of the addition of norbornane, a saturated, 5-membered bicyclic hydrocarbon additive to diesel on the physicochemical properties, sooting propensity, chemical composition, structural disorders and oxidative reactivity of combustion generated soot. Detailed physio-chemical analysis revealed that the threshold sooting index (TSI) of the blend is reduced to 29.5 at an optimum blending percentage of 10% norbornane -90% diesel (NBD10) as compared to the TSI of 37.0 for pure diesel. Detailed soot nano-structural analysis using XRD, Raman, HRTEM and EDX revealed that the addition of an unsaturated 5-membered bicyclic additive such as norbornane resulted in increased soot nano-structural disorder, smaller polycyclic aromatic hydrocarbons (PAH) size, increased fringe curvature and significantly greater aliphatic/aromatic content in the soot as compared to an unsaturated 5-membered bicyclic additives such as dicyclopentadiene (DCPD). The oxidative reactivity studies confirmed that the soot produced from norbornane is easily oxidized in air, since it requires a lower initial activation energy (90 kJ/mol) compared to DCPD (120 kJ/mol) and pure diesel soot (170 kJ/mol). These results suggest that norbornane, a saturated 5-membered bicyclic compound which is readily available as a by-product of the polymer industry and in distillation cuts of crude oil refineries can serve as a potential fuel additive for designing advanced blended fuels.
Date of AwardJun 2020
Original languageAmerican English

Keywords

  • Diesel
  • 5-Membered bicyclic
  • Soot
  • Oxidative Reactivity
  • PM Emissions.

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