Effects of Camphor Oil Addition to Diesel on the Nanostructures and Oxidative Reactivity of Combustion-Generated Soot

Abstract

Less viscous and low cetane (LVLC) fuels have emerged as the promising alternative fuels or additives to fossil fuels. Camphor oil is one such potential LVLC fuel currently under consideration. However, it's sooting propensity and subsequent effects on soot nanostructure, when blended with diesel, are not well understood. In this work, the effects of camphor and camphor oil addition to diesel on the sooting propensity, soot oxidative reactivity, and the chemical composition, structural disorders, and the morphology of soot particles are studied using a diffusion flame. The chemical and the microstructural changes in soot are investigated using several experimental techniques such as energy dispersive X-ray spectroscopy, high resolution transmission electron microscopy, Raman and electron energy loss spectroscopy, and powder X-ray diffraction, while the oxidative reactivity is studied using thermogravimetric analysis. The activation energy for O2-induced soot oxidation during the initiation stage shows a significant reduction in its value with the addition of camphor and camphor oil to diesel, which were 220 kJ/mol for diesel soot, 175 kJ/mol for 5% camphor/95% diesel soot, and 150 kJ/mol for 10% camphor oil/90% diesel soot. The blending of camphor and camphor oil with diesel results in soot with smaller fringe length and primary particle diameter, but increases the fringe tortuosity, the degree of crystal disorder, and the amounts of oxygen functionalities and aliphatics in soot. These physico-chemical changes in soot are used to explain the observed trend of oxidative reactivity. This study successfully demonstrates the potential of terpenoid keto compounds with characteristic bicyclic ring structure in improving 2 oxidative reactivity of combustion derived soots as desired in diesel particulate filter technologies.

Designing a Rare DNA-Like Double Helical Microfiber Superstructure via Self-Assembly of In Situ Carbon Fiber-Encapsulated WO3–x Nanorods as an Advanced Supercapacitor Material

“…This has been a standard method used over decades to explain the types of disorders in carbon soot, and more recently, it has been adopted to analyze GO . The corresponding fitted peaks are denoted as D1 = 1353 cm –1 , D2 = 1560 cm –1 , D3 = 1445 cm –1 , D4 = 1150–1250 cm –1 , and G = 1610 cm –1 . The D bands represent the defects and disorder of carbon structure, while the G band represents the graphitic carbon layers .…”

“…34 The corresponding fitted peaks are denoted as D1 = 1353 cm −1 , D2 = 1560 cm −1 , D3 = 1445 cm −1 , D4 = 1150− 1250 cm −1 , and G = 1610 cm −1 . 35 The D bands represent the defects and disorder of carbon structure, while the G band represents the graphitic carbon layers. 36 The ratio of peak intensities (I D1 /I G ) is a good measure of the crystal structure disorder induced due to strong chemical interactions of GO with WO 3−x .…”

Nanostructural Disorder and Reactivity Comparison of Flame Soot and Engine Soot Using Diesel and Jatropha Biodiesel/Diesel Blend as Fuels

“…44,45 Moreover, the difference between the mean primary particle diameters of JE and JF is lower than that of the DE and DF because, during the combustion of diesel with Jatropha biodiesel having fuel-bound oxygen in both the combustion environments, soot oxidation is enhanced, which competes with soot growth to keep the particle size relatively small, as observed in the literature. 14,22,46 Furthermore, a MATLAB code, based on the algorithm reported in ref 47, was utilized to get quantitative information about the fringe length (L a ) and fringe tortuosity index. Each HRTEM image was subjected to negative transformation and grayscale conversion.…”

“…The crystallite length (fringe length), found through HRTEM image analysis, is lower than that found through XRD analysis in Table 2, though the difference is less than some similar studies. 14,34 Aberration correction can be a reason for it, as it significantly reduces the circle of least confusion arising from the spherical aberration of the lens, and thus enhances image quality and resolution and reduces blur. This further improves the image processing in Matlab to provide more accurate estimation of crystal structure parameters.…”

“…Improved engine performance and soot suppression potential have been reported so far by blending diesel with oxygenated biofuels such as bio-alcohols, 10 biodiesels from Jatropha, 11 Karanja, 12 palm oil, 13 and camphor oil. 14 Interestingly, each biofuel, depending on the chemical structure and functional groups such as oxygen content, degree of unsaturation, existence of five-membered cyclic structure, number of aromatic rings, and C/H ratio, significantly influences the soot formation rate and its oxidative reactivity. 15 Along with the fuel properties, soot reactivity is also affected by the presence of chemical functionalities on soot structure found through infrared techniques such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), as reported in ref 16.…”