A study of smoke formation from wood combustion

Aerosol time of flight mass spectrometry (ATOFMS) was used to analyse the particles emitted during the flaming and smouldering phases of the combustion of samples of hard and soft woods. Eugenol and furfural were also burned and using results from previous work of the authors, they have been shown to be useful proxies for initial wood combustion products. The ratios of elementary carbon to total carbon in the particles were similar for both the woods and for eugenol. The ATOFMS spectra of most of the particles were consistent with the presence of soot precursor constituents along with oxygen containing fragments. Most particle diameters were less than 2.5. μm, with the greatest concentration of <. 0.12. μm

Combustion and pyrolysis reactions of alkylated polycyclic aromatic compounds: The decomposition of 13C methylarenes in relation to diesel engine emissions

The thermal decomposition of methylarenes labelled with 13C in the methyl group was investigated. This was conducted using both a direct injection diesel engine and a pyrolysis flow cell connected to a GC-MS. 2-[13C]methylnaphthalene and 9-[13C]methylphenanthrene were synthesized by means of the Corey-House coupling reaction and their identity and purity confirmed by mass spectrometry and NMR. GC-MS analysis of the aromatic fraction separated from the extract of the exhaust particulate collected from the engine operated with n-hexadecane doped with the labelled methylnaphthalene showed that the 13C was not redistributed among the methyl groups of higher PAH. However, with 9-[13C]methylphenanthrene in the fuel a significant amount was retained in the particulate, even though the principal in-cylinder reaction was dealkylation. Pyrolytic reactions of the 13C-labelled methyl arenes were studied in a micro-pyrolysis-GC-MS-apparatus and confirmed dealkylation as the predominant reaction. The detailed chemical mechanism of the pyrolysis was explained by a scheme involving two alternative radical transfer reactions

Production of mesophase pitch from coal tar and petroleum pitches using supercritical fluid extraction

Supercritical fluid extraction (SFE) is currently being investigated as a possible technique in the production of high quality mesophase pitch from coal tar and petroleum pitches. Mesophase pitch is used to make high technology products, such as carbon fibre. The conventional production of mesophase pitch initially involves the removal of low molecular weight species from coal tar and petroleum pitches. The remaining residue is then transformed into a mesophase pitch through a polymerisation process. The aim of this study involves the extraction of light molecular weight species using SFE. Both petroleum and coal tar pitch contain complex aromatic molecules with an average molecular weight of 200 to 800, whereas mesophase pitch has a molecular weight range of about 1200 to 1300. Toluene, heptane, pentane and methanol were added to CO2 as modifiers at temperatures between 80 and 200°C and at pressures of 200 to 400 atm. The effect of the temperature and pressure on extraction yield was found to be less than that of modifier addition and the results showed that the extraction yields were 19% and 33% from the petroleum and coal tar pitches respectively

A model of peak amplitude enhancement in orthogonal two-dimensional gas chromatography

Increases in peak capacity that are achieved using comprehensive rather than single-column gas chromatography are also often accompanied by significant improvements in minimum detectable amounts. Comprehensive gas chromatography utilizes a zone compression of eluent between primary and secondary chromatography columns, with complete conservation of mass. In this paper, we present a theoretical model of peak amplitude enhancement based on translation of the fractional area under the primary column normal curve to a secondary Gaussian peak. Amplitude enhancement made by peak modulation scales with increasing modulation period and primary column peak width. An exponential relationship between the modulated secondary column peak width and the amplitude enhancement is also observed. The calculated amplitude gains are further corrected for detector current noise generated via flame ionization detection at a range of operating frequencies. An example of trace level atmospheric analysis is used to demonstrate both peak capacity and sensitivity enhancements using the multidimensional technique

Optical properties of SCT extraction residues obtained from Turkish coals

Two Turkish coals of rank high volatile bituminous and sub-bituminous C were subjected to supercritical toluene (SCT) extraction at 400°C and 100 atm. The solid products of SCT extraction were examined with a Leitz MPV microscope since reflectance studies can provide some useful insights into the mechanisms involved through SCT extraction. The disappearance of liptinites is a feature of the optical texture of coals subjected to supercritical toluene. Both residues of coals produced a high reflecting vitroplast. Inetinite macerais of these residues increased and showed an increasing reflectance. No other alterations were observed for the inertinite macerais in SCT extraction residues. © 1995, Elsevier B.V

Optical properties of supercritical toluene extraction residues obtained from Turkish coals

Two Turkish coals of subbituminous C and high-volatile bituminous rank were subjected to supercritical toluene extraction at 400°C and 100 atm. The solid residues were examined microscopically in order to gain useful insight into the mechanisms involved in supercritical toluene extraction. The disappearance of liptinite macerals is a feature of the optical texture of both coals subjected to the extraction process. Residues of the two coals produced high-reflecting vitroplast. The amount of inertinite macerals in the residues increased and showed higher reflectance. No other alterations were observed for the inertinite macerals in the extraction residues

Analytical Methods for Characterizing High-Mass Complex Polydisperse Hydrocarbon Mixtures: An Overview

By attempting to define the principal chemical features and the complete ranges of molecular mass of the heavy ends of coal and petroleum derived liquids, this review aims to facilitate process development for improved utilization of heavy fractions (coal and biomass tars and pitches, petroleum asphaltenes and resids). Historically much heavy petroleum derived material has been used as cheap fuel or simply thrown away. With the rising cash-value of the “bottom of the barrel,” greater emphasis on the detailed chemistry of these materials has become an imperative. This paper reviews analytical techniques used for estimating molecular mass distributions and structural features of complex polydispersed hydrocarbons, with masses above those identifiable by gas-chromatography (or GC-MS). The features of the least soluble – and usually large molecular mass - materials in complex mixtures are not generally observable by examination prior to the fractionation of (i.e. “whole”) complex samples. This has been observed even in cases where the “heavy” fraction accounts for about 50% of the total sample. The major approach reviewed covers the combined use of UV-fluorescence spectroscopy, size exclusion chromatography, mass spectroscopy and NMR-spectroscopy. This is preceded by a description and critical review of useful sample fractionation methods found in the literature.JRC.F.2-Cleaner energ

Analysis of methylated humic acids from fossil fuels by size exclusion chromatography and NMR

Molecular Mass (MM) distributions in humic acids from peat and two lignites have been investigated by high performance size-exclusion chromatography (SEC) after methylation and found to be in the range approximately 300 to more than 5000, with number average NM(Mn) near 800. Values of Mn determined by SEC were in good agreement with those from vapour pressure osmotery. High field 13C NMR spectra of the methylated humic acids are extremely well resolved, and indicate that the samples are significantly different, despite their similar elemental compositions and MM distributions. © 1987

Chemical composition of SCG extracts obtained from coal and maceral concentrates

Five Turkish coals and macerals were subjected to supercritical toluene extraction at 400°C and 100 atm. The extracts were separated into three fractions, namely preasphaltene, asphaltene and oil. Oil fractions were further separated into paraffinic, aromatic and polar sub-fractions. This paper discusses the spectroscopic and chromatographic analysis of these paraffinic, aromatic and polar sub-fractions obtained from the supercritical extraction of whole coals and of their corresponding maceral concentrates