Brown coal hydrogenation coals

Figure 17 shows the product yields of indirect brown coal hydrogenation with tetralin as a function of stratification and texture (lithotype... 

Tars can be hydrogenated to produce Hquid fuels. High hydrogen and low asphaltene, ie, benzene-soluble and pentane-iasoluble, contents are desirable. The central German brown coals are attractive for this reason. The tars from the eastern part of Germany require much lower pressures and less hydrogen per unit of product than do brown coals near Cologne, which can require pressures up to 71 MPa (700 atm) (see Petroleum). 

Figure 6. Dependence of maximum tar yields and corresponding total volatile matter yields during flash pyrolysis on atomic hydrogen-to-carbon ratio for some Australian and V.S.A. coals (O, 9), black coals (X), brown coals (A), Pittsburgh No. 8 (USA.) ( ), Montana lignite (USA).

Further detailed studies in this area are obviously needed to resolve the chemistry involved. Such pyrolysis studies supplemented by hydrogenation experiments with acid-form and salt-form brown coals offer promise of resolving the precise role of pyrolysis in the hydrogenation of these coals and of how the ash-forming cations participate in the hydrogenation reactions. 

The first part of this paper has shown that Australian black and brown coals differ significantly in a number of respects from coals of similar ranks from North America and elsewhere in the northern hemisphere. The rest of the paper than proceeded to indicate the progress being made to determine how the characteristics of Australian coals influence their conversion to volatile and liquid products during pyrolysis and hydrogenation. 

Calculation of hydrogen transferred to the coal fractions, g/lOOg of dry brown coal... 

Hooper, R.J., "The Dissolution of a Victorian Brown Coal in a Hydrogen-Donor Solvent", PhD Thesis, University of Melbourne, Australia, April 1978... 

Thus we have conducted work on the structural parameters of coal hydrogenation products using the method of Brown-Ladner (1), and from the results obtained we have developed correlations of the reaction. Based on the above, the outline of the reaction mechanisms have been previously discussed and our results have been reported (2, 3J. ... 

The cost of hydrogenating coal was high, 190 marks per ton, or the equivalent of 24 cents per gallon. (24) This was more than double the price of imported gasoline, but for Germany, with only a limited supply of natural petroleum, no alternative remained during the War other than the construction of synthetic petroleum plants. In this way Germany utilized her naturally abundant supplies of bituminous and brown coal. 

Methanol can also be produced from syngas with hydrogen and carbon monoxide in a 2 1 ratio. Coal-derived methanol typically has low sulfur and other impurities. Syngas from coal can be reformed by reacting with water to produce hydrogen. Ammonium sulfate from coal tar by pyrolysis can be converted to ammonia. The humus substances can be recovered from brown coal by alkali extraction. 

Figure 1 Space-time-yield (volume/volume reactor/100 hours) of gasoline and middle oil for brown and bituminous coals as a function of composition of starting coal. Data from continuous coal hydrogenation facilities operating in Germany during the 1930 s.

The coal-oil-catalyst paste and an excess of hydrogen (300 to 500 cubic meters per ton of brown coal paste, 500 to 1000 cubic meters per ton of bituminous coal paste) are pumped at 250 to 300 atmospheres pressure through a heat exchanger and a gas-fired preheater into the reactors. The reactants enter the first of three or four converters at about 430° C. (806° F.) and are rapidly heated to 470° to 490° C. (878° to 915° F.) by the exothermic heat of the hydrogenation reaction. The temperature in the reactors is kept in the range 470° to 490° C. (878° to 915° F.) by injection of about 1000 cubic meters of cold hydrogen per ton of coal paste. 

Hydrogenation of bituminous coal was found more difficult than that of brown coal, chiefly because the primary products of hydrogenation of bituminous coal have a higher percentage of asphaltenes (material soluble in benzene but insoluble in w-hexane). The slower rate of destructive hydrogenation of asphaltenes is reflected in the much lower throughput of bituminous coal per unit volume of reactor. 

Solvent-Refined Coal Process. In the 1920s the anthracene oil fraction recovered from pyrolysis, or coking, of coal was utilized to extract 35—40% of bituminous coals at low pressures for the purpose of manufacturing low cost newspaper inks (113). Tetralin was found to have higher solvent power for coals, and the I. G. Farben Pott-Broche process (114) was developed, wherein a mixture of cresol and tetralin was used to dissolve ca 75% of brown coals at 13.8 MPa (2000 psi) and 427°C. The extract was filtered, and the filtrate vacuum distilled. The overhead was distilled a second time at atmospheric pressure to separate solvent, which was recycled to extraction, and a heavier liquid, which was sent to hydrogenation. The bottoms product from vacuum distillation, or solvent-extracted coal, was carbonized to produce electrode carbon. Filter cake from the filters was coked in rotary kilns for tar and oil recovery. A variety of liquid products were obtained from the solvent extraction-hydrogenation system (113). A similar process was employed in Japan during Wodd War II to produce electrode coke, asphalt (qv), and carbonized fuel briquettes (115). 

Fischer-Tropsch unit - (MOLYBDENUMAND COMPOUNDS] (Vol 16) -use offluidi2ation [FLUIDIZATION] (Vol 11) -use of hydrogen [HYDROGEN] (Vol 13) -lignite for [LIGNITE AND BROWN COAL] (Vol 15)... 

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