Catalytic coal hydrogenation

COMBISULF A process for removing sulfur compounds from the gases from combined-cycle power plants with integrated coal gasification. Carbonyl sulfide is removed by catalytic hydrolysis hydrogen sulfide is removed by selective absorbtion in aqueous MEDA and the sulfur is recovered from both processes by a modified Claus unit. Developed by Krupp Koppers and first operated in Spain in 1996. See PRENFLO. 

Hauserman, W.B. (1997). Relating Catalytic Coal or Biomass Gasification Mechanisms to Plant Capital Cost Components, Int. J. Hydrogen Energy, 22, (4). pp. 409-414. 

Catalytic coal liquefaction processes do not specifically use hydrogen donor solvents although coal is introduced into the liquefaction reactor as a slurry in a recycle liquid stream. Catalyst is used as a powder or as granules such as pellets or extrudates. If powdered catalyst is used, it is mixed with the coal/liquid stream entering the reactor. Pelleted catalyst can be used in fixed bed reactors if precautions are taken to avoid plugging with solids or in fluidized bed reactors. In the latter case, the reacting system is actually a three phase fluidized bed, that is, catalyst particles and coal solids, as well as liquid, are fluidized by gas. 

Much of the research pursued by the authors of this paper and by their associates has involved studies of the catalytic hydrogenation of coals in the absence of solvent. The technique has been used to elucidate the mechanisms of catalytic coal liquefaction and to provide simultaneously some insight into the structure of coals. Peter Given was directly instrumental in providing the incentive for this research which has extended since 1983. Previous findings were disseminated through several publications (4-8. In this paper, some of the earlier data have been collated with more recent results (9) to provide an account of the relevance of these studies to the two-component concept. 

The preheated coal slurry (essentially liquefied) is sent to the reactor, where thermal and catalytic cracking, hydrogenation, and hydrocracking take place. These reactions occur rather slowly because fewer reactive bonds are involved in this stage, which produces distillate range small molecules. 

Robert A. Friedel. It would be interesting to carry out the work suggested by Dr. Wender. Type analyses of C naphthenes from a coal hydrogenation product have been reported (2) the types analyzed include ethyl-cyclohexane, propylcyclopentanes, dimethylcyclohexanes, gem-trimethyIcyclo-pentanes, other trimethylcyclopentanes, and methyl-ethylcyclopentanes. Some compounds in these classes could be optically active. Comparable analyses of catalytically reformed petroleum would be of considerable interest in trying to ascertain what optically active components are produced in the reforming. 

On the other hand, coal pyrolysis and coal hydrogenation produce ammonia (a useful by-product), which arises from the more labile nitrogen functional groups, such as amine (-NH2) less reactive nitrogen functions are converted to ammonia by catalytic hydrogenation. 

Processes in which the coal and the catalyst are in intimate contact in the presence of hydrogen gas are often referred to as solid-gas catalytic hydrocarbonization or dry coal hydrogenation. The major features of these processes are (1) rapid heating to temperatures of the order of 450°C-600°C... 

While coal hydrogenation was not a commercial success it was certainly a wartime strategic necessity for Germany and the United Kingdom. It is probable that the introduction of catalytic refinery processes would have been delayed if Standard Oil, Shell, and ICI had not used the coal hydrogenation catalysts for gas oil hydrogenation and developed the other refinery-type processes mentioned previously in Table 2.13. 

Commercially, xylene is obtained by the catalytic reforming of naphthenes in the presence of hydrogen see toluene) or was formerly obtained from coal tar. The material so-produced is suitable for use as a solvent or gasoline ingredient, these uses accounting for a large part of xylene consumption. If xylene is required as a chemical, separation into the iso-... 

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). 

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