US2232673A - Production of high quality benzine and diesel motor fuels - Google Patents

Description

Feb. 18, 1941. T. w. PFIRRMA-NN PRODUCTION OF HIGH QUALITY BENZINE AND DIESEL MOTOR FUELS Filed Aug. 23, 1958' mir N mUDOOmn.

BY :f-@MA H l5 ATTORNEYS Patented Feb'. 1s, 1941 PATENT OFFICE PRODUCTION oF HIGH QUALITY BENZINE AND DIESEL Moron FUELS y e.; Theodor wilhelm PfirmannQLudwigshafon-onthe-Rhine, Germany Appiioation August 23, 193s',A serialNo. 226,243

In Germany August 30, 1937 1 Claim.

The present invention relates to improvements in the production of high quality benzine and Diesel motor fuels.

vBythe new method ofworking according to this "5"' invention asphaltictars and heavy hydrocarbons can be l'worked up together with a middle oil obtainedby reduction of carbon monoxide with hydrogen (hereinafter referred to as cogasine middle oil) 'in such'manner that the greatest possible yields of readily ignitable Diesel oil on the one hand'and ofnon-knocking benzine on the other hand are'obtained. The method 'of working is basedv on the new observation that cogasine middle oil' notonly precipitates asphalts and high Ino- "f lecular hydrocarbons of a non-parailinic nature,

but also selectively dissolves the hydrocarbons a1- liedtheretofrom the tar, while the heavy hydrocarbons,which are poorer in hydrogen, separate asa second layer beneath the lighter cogasine middle oil solution. By this selective property of the cogasine middle oil, the hydrocarbon-mixture of thetars' is split up into two chemically different 'components so that it is possible to convert the twov fractions thus obtained separately under the most'v favorable conditions for the purpose into benzine and Diesel motor oil by hydrogenation.

The following example describes the new method of working in greater detail:

' BrownA coal producer tar and cogasine middle bilarewell mixed in the ratioof 1:1. About 50 percent ofthe tar separate as a heavy layer havingia specific gravity of more than 1.0 together withjanywater present, while the other half forms thelighter upper., layer dissolved 'in the cogasine middle oil; AThe' tar fraction dissolved in the cogasine middle oil consists for the most part of theI non-aromatic hydrocarbons rich in hydrogen while the heavy tar oil' layer mainly contains the aromatic and asphaltic substances poor in hydrogen. For vexample of the about 43 per cent of acid oils contained in the tar, 80.5 per cent are found in the heavy tar layer and only 19.5 per cent in the cogasine solution; a separation according to molecular weight is also effected because the cogasine solution mainly contains the low molecular weight phenols, while those of higher boiling point are found in the heavy layer.

The cogasine layer is fairly clear and of pale color and may even be directly used as Diesel oil. By a light hydrogenation in the gas phase with rigidly arranged catalysts immune to poisoning by sulphur at from 420 to 440 C., the setting point, stability in storage and color are further improved and at the same time the phenols are hydrogenated to benzene hydrocarbons; the same are diS- (el. '19e-62).

tilled off in the benzine up to 200 C., whereby on the one hand thejready igntability of the Diesel oil is improved and on the other hand a nonknocking benzine is obtained.

' The heavy tar layer is hydrogenated in the liquid 'f phase in the presence of finely divided molybdenum or ltin catalysts at temperatures of from 450 to 500 C. and if desired at higher pressuresthan in the gas phase, and thus converted into benzine and-middle oil, while the heavy oil fraction is returned in known manner. The middle oil obtained is somewhat poorer in hydrogen than the middle oil' occurring in the cogasine layer and yields by further hydrogenation in the gas phase also a non-knocking benzine; it may, however, equally well b e incorporated as Diesel oil with the'Dies'el oil obtained in the first stage because it ignites more readily than the gas oils used atthe present time and furthermore the point of ignition may be adjusted by varying the amount of cogasine middle oil.

The accompanying drawing villustrates schematically the flow of the materials in this example of my process. In th'eabove example there is obtainedr by the hydrogenation in the gas phase from the cogasinetar oil solution, about 8 to 12 per cent of benzine having an octane number of more than 70; the

remainder ishigh quality Diesel motor oil; the Vgasication is very slight. The hydrogenation of the heavy tar residue in the liquid phase yields, with a gasification of from 5 to 10 per cent, from 18 to 30 per cent of benzine depending on the temperature, the octane number of the benzine e being up to 78; the residual distillate oil, from about to 70 per cent of the heavy tar introduced, yields by conversion into benzine in the gas phase an `octane number of between 66 and 70. Thus by mixing the benzinesl obtained from the tar there are` obtained 'from 26 to 40 per cent of benzine with-an octaneE number between 70 and 75, while the remainder, apart from gas, is converted into Diesel motor fuel having a cetene number lying above the average of gas oils. If the middle oil occurring in the liquid phase also be converted into benzine, the amount of Diesel oil is reduced in favor of benzine, the octane number of which then lies at about 70.

If the tar be previously distilled and the distillate worked up together with cogasine middle oil in the gas phase into benzine, benzines having poorer non-knocking properties and an octane number of between about 40 and 48 are obtained; the benzine obtained by hydrogenation of the distillation residue also has an octane number of only from 58 to 66 as compared with from '70 to '18 by the hydrogenation of the heavy tar fraction separated by precipitation. It is true that the middle oil obtained can also be used as Diesel oil, but its readiness to ignite is also about 5 to 10 points below the cetene number of the Diesel oils prepared according to this invention because by the known methods of working a separate working up of aromatics and parafns is impossible.

The process according to this invention is especially suitable for Working up producer tar and low temperature carbonization tar of mineral and brown coals, but may also be used for high temperature tar and suction tar. The yields of benzine and Diesel oil of best quality obviously fluctuate according to the composition of the tars used; thus high temperature tars rich. in aromatics always yield less Diesel oil than for example brown coal producer tars rich in paraflin; in the working up of high temperature tar, however, the yield of Diesel oil is also always higher than when, for example, the tar is first distilled in known manner and the resulting fractions are mixed with cogasine middle oil; the stability in storage of the cogasine solution obtained in the said manner and hydrogenated is also considerably better. A further advantage of the said method of working consists in the better separation of the water from the tars; many tars can only be separated from water by a pressure treatment, whereas by the separation with cogasine middle oil the Water is usually separated between the cogasine middle oil and the heavier layer and can then readily be removed.

The separation of the cogasine middle oil and heavy oil layers may be effected by sedimentation as well as by separating centrifuging. A certain iniluence on the amount and nature of the iinal product to be prepared may be obtained by varying the amount of cogasine middle oil to tar. By using less cogasine middle oil, the fraction of tar oil dissolved is usually less and the heavy layer is increased in size accordingly. Increase in ternperature favors the separation and often displaces the equilibrium in favor of the cogasine layer. The separation of the dust constituents present in most tars can be effected before the precipitation; with some tars it has proved advantageous not to separate the dust, which exists exclusively in the heavy layer, until subsequently, for example by filtration, because the amount to be ltered is then usually only half as great.

In order to render the precipitation complete, a certain amount of cogasine middle oil is always necessary; this may vary between 50 and 150 per cent of the amount of tar used. If it is desired to save cogasine middle oil, it is possible, after precipitation has been effected, to remove a part of the cogasine middle oil used by distillation and to use it again for precipitation; for this purpose nngasine middle oil having a low boiling point of use stationary catalysts.

from about 180 to 220 C. is used because the tar usually contains such constituents only in small amounts. Such a recovery of a cogasine fraction by distillation is also possible in the case of mineral coal low temperature carbonization tar, which tends to decompose during distillation, because the readily decomposable substances are found exclusively in the heavy tar layer.

It is known that hydrocarbons containing bitumen can be converted into benzine together with cogasine; in this case, however, it is impossible to A It has also been proposed to hydrogenate tars of the abovementioned kind by themselves; the hydrogenation products of schtars have also been subsequently mixed with cogasine. Neither of these methods leads to high quality nal products because a separation of the tars into their chemical constituents and the conversion of the separate products in a manner appropriate to their nature is lacking. The hydrogenation process in the presence of cogasine middle oil always proceeds more smoothlyuand better than without the same, and even high boiling oil fractions, when they have been separated from the fractions poor in hydrogen according to this invention, may be hydrogenated Without trouble` with stationary catalysts; this is impos-l sible in the absence of cogasine middle oil.

It has been proposed to split up hydrocarbon mixtures of the above-mentioned kind by means of selective solvents before their further working up. Such a separation is usually attended by high costs, however, because special apparatus are necessary for the separation and the solvents,

usually of a different chemical nature, have to be completely recovered and this is often very expensive. In the present case, however. the solvent is at least partly itself further worked up in the process and is not only a precipitant but also an initial material for the products to be prepared. Moreover it was not hitherto known that hydrocarbon mixtures of the above-mentioned origin could be split up by cogasine middle oil in such manner that benzine on the one hand and Diesel oil on the other hand could be prepared therefrom in a specially high quality by hydrogenation.

What I claim is: i A process for the production by hydrogenatio of high quality benzine and Diesel motor fuels from tars which have been prepared by dry distillation, which consists in splitting up the tar constituents by mixing with middle oils obtained by the reduction of carbon monoxide with hydrogen into two components of different specific gravity, the lighter component being subjected to hydrogenation in the gas phase, together with at least a part of the said middle oils, and the heavier component subjected to hydrogenation in the liquid phase.

THEODOR WILHELM PFIRRMANN.

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