Hydroaromatic

Different types of other coal liquefaction processes have been also developed to convert coals to liqnid hydrocarbon fnels. These include high-temperature solvent extraction processes in which no catalyst is added. The solvent is usually a hydroaromatic hydrogen donor, whereas molecnlar hydrogen is added as a secondary source of hydrogen. Similar but catalytic liquefaction processes use zinc chloride and other catalysts, usually under forceful conditions (375-425°C, 100-200 atm). In our own research, superacidic HF-BFo-induced hydroliquefaction of coals, which involves depolymerization-ionic hydrogenation, was found to be highly effective at relatively modest temperatnres (150-170°C). 

Hydrogen can be added to the aromatic stmctures converting them to hydroaromatic rings. The hydrogen addition and removal is generally but not entirely reversible (24). 

A. von Baeyer (Munich) advancement of organic chemistry and the chemical industry through work on organic dyes and hydroaromatic compounds. 

Only a few of the ketones of the fatty series are found as natural constituents of essential oils, the majority of them belonging to the aromatic or hydroaromatic series. The following members of the open-chain series are found in essential oils —... 

Ingledew WM, MEF Tresguerres, JL Canovas (1971) Regulation of the enzymes of the hydroaromatic pathway in Acinetobacter calco-aceticus. J Gen Microbiol 68 273-282. 

Dehydrogenation (the conversion of alicycllc or hydroaromatic compounds into their aromatic counterparts by removal of hydrogen and also, in some cases, of other atoms or groups) finds wide application in the determination of structure of natural products of complex hydroaromatic structure. Dehydrogenation is employed also for the s)mthesis of polycyclic hydrocarbons and their derivatives from the readily accessible synthetic hydroaromatic compounds. A very simple example is the formation of p-methylnaphthalene from a-tetra-lone (which is itself prepared from benzene—see Section IV, 143) ... 

Hydrogen donors are, however, not the only important components of solvents in short contact time reactions. We have shown (4,7,16) that condensed aromatic hydrocarbons also promote coal conversion. Figure 18 shows the results of a series of conversions of West Kentucky 9,14 coal in a variety of process-derived solvents, all of which contained only small amounts of hydroaromatic hydrocarbons. The concentration of di- and polyaromatic ring structures were obtained by a liquid chromatographic technique (4c). It is interesting to note that a number of these process-derived solvents were as effective or were more effective than a synthetic solvent which contained 40% tetralin. The balance between the concentration of H-donors and condensed aromatic hydrocarbons may be an important criterion in adjusting solvent effectiveness at short times. 

SCT-SRC could be further processed at temperatures above that of dissolution to produce a clean solid fuel of reduced sulfur content. Char formation tendency would be lowered by prior removal of mineral matter and undissolved coal. At higher temperatures, desulfurization would proceed rapidly light gas formation might be minimized by keeping the time very short. Hydrogen consumption would be minimized because aromatic-hydroaromatic equilibria favor aromatics as temperatures increase. 

Figure 12. Hydrogen pressure vs. reaction temperature for hydroaromatic-aro-matic equilibrium. Lower hydrogen pressures are needed for producing hydro-aromatics in processing at lower temperatures.

Isomerization and Adduction of Hydroaromatic Systems at Conditions of Coal Liquefaction... 

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