John M. Charlesworth

Influence of temperature on the hydrogenation of Australian Loy-Yang brown coal. 2. Structural analysis of the asphaltene fractions

Abstract A study is made of the asphaltene fractions produced by hydroliquefaction of an Australian Loy-Yang brown coal at temperatures ranging from 300 to 500 °C. A combination of Fourier-Transform 13 C n.m.r. conventional proton n.m.r., i.r. and u.v. spectroscopy is used in conjunction with previously published data to define representative average chemical structures. Results indicate that the asphaltenes increase in aromaticity as the hydrogenation temperature rises, with a rapid change occurring near 450 °C. Furthermore, the asphaltenes formed at the highest hydrogenation temperature of 500 °C appear to consist of dehydrogenated derivatives of species produced at lower temperatures. Most of the saturated carbon atoms in all fractions occur in condensed cyclic structures with very few side-chains or methylene bridges. Because of this, the commonly assumed value of 0.50 for the saturated carbon to hydrogen atomic ratio used in the Brown-Ladner equation may be in error if applied to systems of this type. Below 450 °C the aromatic component of the asphaltenes consists mainly of isolated naphthalenic and mononuclear structures. Below 400 °C a small but significant number of carbon atoms are present in alkyl chains at least 8 carbon atoms long.

Influence of temperature on the hydrogenation of Australian Loy-Yang brown coal. 1. Oxygen removal from coal and product distribution

Abstract A study is made of the composition of the solid, liquid and gaseous fractions produced by hydrogenation of Australian Loy-Yang brown coal at temperatures ranging from 300 to 500 °C. The high oxygen content of the coal (25.5 wt%) is not found to result in a proportionally higher hydrogen consumption when compared to previously published results for a coal with approximately half the oxygen content. Oxygen is found to be removed from the coal mainly as carbon dioxide and water, most probably by decarboxylation and dehydration reactions. At temperatures up to ≈400 °C hydrogen is consumed almost solely by transference from the solvent tetralin to the coal. By this temperature both the maximum degree of conversion and the maximum oil yield are reached. The heavy oil fraction at 400 °C is composed mainly of asphaltenes and preasphaltenes. Above 400 °C hydrogen is consumed from both solvent and gas. A major part of this appears to be involved in the stabilization of decomposition products from the tetralin. The yield of pentane-soluble material is relatively constant up to 450 °C, however, at higher temperatures conversion of asphaltenes and preasphaltenes to pentane-solubles occurs in conjunction with gasification to C1–C3 hydrocarbons. Despite the fact hydrogen consumption and oxygen removal both increase with rising hydrogenation temperature, the H/C atomic ratio for the three heavy oil fractions decreases over the same range.

The glass transition temperature for non-gaussian network polymers

Abstract The influence of crosslinking and copolymerization on the glass transition temperature, Tg, of a range of diepoxide-diamine network polymers is examined. It is established that existing theories relating Tg to the level of crosslinking are inexact above a crosslink concentration of approximately 0.5 mole dm−3. To account for this deviation, the thermodynamic treatment of the glass transition is modified to take into consideration a non-Gaussian spatial distribution of chain segments and the steric restrictions upon movement of segments in the vicinity of junctions. The resulting equation-involving two empirical parameters, and the number of rotatable bonds between junctions—is shown to adequately explain data for the diglycidylethers of bisphenol A and butanediol, crosslinked with benzidine/aniline and 1,8-oc-tanediamine/n-butylamine mixtures. The behavior of networks prepared from α, ω-alkyldiamines containing from 2 to 36 methylene units can be predicted provided it is assumed that

Monitoring the products and kinetics of oil shale pyrolysis using simultaneous nitrogen specific and flame ionization detection

Abstract The use of the thermionic nitrogen specific detector (TSD) and flame ionization detector (FID), in conjunction with gas sampling and capillary column g.c. is described as a means of following the thermal degradation of involatile substances containing organically bound nitrogen. The response of the TSD to a range of nitrogen compounds is shown to be approximately proportional to nitrogen content in most instances. Application of this method to a study of oil shale pyrolysis reveals that nitrogen compounds are evolved more rapidly than hydrocarbons.

Removal of nitrogen compounds from shale oil by adsorption on to acid-treated shale ash

Abstract Basic nitrogen compounds occurring in shale oil can be selectively adsorbed by spent oil shale ash that has first been treated with either a mineral acid, e.g. HCl, or a Lewis acid, e.g. CuCl 2 . For Rundle shale oil a reduction in the basic nitrogen level from 0.55 wt% to less than 0.05 wt%, and total nitrogen from 1.2 wt % to 0.5 wt%, has been achieved using an ash rich in clay minerals and low in carbonates. It has also been shown that pyridine, quinoline and 2,6-dimethylpyridine are all readily adsorbed by ash treated with several common transition metal chlorides. Selection of an appropriate Lewis acid, or mixture of acids should enable adsorption to be optimized when specific impurities are known to be present. Under appropriate conditions most of the reference basic nitrogen compounds can be adsorbed in less than 1 h.