US1881927A - Alfred pott and hans bboche - Google Patents

Description

PROCESS FOR HYDROGENATING SOLID CARBONACEOUS MATERIAL, PARTICULARLY SOLID FUELS SUCH AS COAL Filed July 9, 1928 Get. 11, 1932. POTT ET AL 1,881,927

Patented Oct. 11, 1932 UNITED STATES PATENT OFFICE.

ALFRED POTT AND HANS BROCHE, OF ESSEN-RUHR, GERMANY PROCESS FOR HYDROGENATING SOLID GARBONACEOUS MATERIAL, IPABTIEULARLY SOLID FUELS SUCH AS COAL Application filed July 9, 1928, Serial No.

This invention relates to a process for hydrogenating solid carbonaceous material, more particularly solid fuels, such as pit coal, lignite, peat and the like,and is based on 5 the following discovery.

For the purpose of oiling or benzinizing,

or in general of adding hydrogen to solid carbonaceous material, more particularly to fuels, such as pit coal, lignite, peat and the a like, ithas hitherto been customary to proceed by providing the carbonaceous material with as large as possible a surface area for attack by the hydrogen with which it was to be brought to react, as for instance by dis- 5 integrating or pulverizing it and then causing it to react directly with hydrogen at a suitably raised pressure and a high temperav ture. Thus a sort of distillation of the carbonaceous material was carried out with simultaneous employment of hydrogen under conditions which permitted not only the distilling out of carbon compounds but also the decomposition thereof (cracking) and subsequent combination with the hydrogen. The carbonaceous material was in this case pre pared with or without paste oil, the former being for the purpose of forming the pulverulent material into a paste which could be conveyed by pumping, as well as for the purpose of precluding injurious local heating. The paste oil was generally added in quantities amounting to from to per cent. of the carbonaceous material to be treated.

According to this discovery such a process does not present economical possibilities of obtaining the maximum yield of liquid hydrocarbons from the carbonaceous material, particularly in the case of caking coals. The temperatures at which the hydrogenation is 40 preferably effected are above 400 C. and are accordingly so high that the. coal, and. the valuable constituents distilled from the coal, must decompose. Such a decomposition cannot take place, according to experience, without the formation of coke. This coke however either cannot be hydrogenated at all or is at least considerably more difficult to hydrogenate than the original valuable constituents of the coal.

" If therefore the coils are treated, as is at 291,475, and in Germany July 12, 1927.

present usual, in their original condition, with or without paste oil, with hydrogen under pressure, at the rather high temperatures that are most suitable for the hydrogenating cracking, the conversion of the coal into the reactive form, as required for the attainment of a maximum yield of oil, does not occur, but cracking immediately occurs instead, with a more or less extensive formation of coke. The hydrogenation result therefore always remains below that which is obtained, in the case of cracking hydrogenation of th opened or disintegrated coal.

Now the present invention consists in abandoning the unitary process hitherto adopted for the direct conversion of the car bonaceous material, preferably after disintegration, with or without the addition of paste oil, into liquid hydrocarbons, and of sub-'- dividing the process into at least two stages,

which are carried out separately under the different conditions which are most suitable for each stage. isolating valuable reactive parts of the carbonaceous material from the latter to a farreaching extent and converting them into a form in which they have an increased capability of reacting with hydrogen at a suitable temperature and pressure.

For this purpose the first stage is carried out in such a way and its result is so guided that the valuable carbon constituents are obtained in an isolated form under conditions in which decomposition is precluded. The

-portions so obtained are now cracked in a second stage and the addition of hydrogen The first stage consists in no I then carried out at a suitable pressure and temperature. The cracking of carbon compounds and the addition of hydrogen to the cracked products can advantageously be carried out in a single stage of the process.

Since in the first stage constituents that are valuable for the hydrogenation are obtained from the carbonaceous material separately in an isolated con d1t1on, and moreover are 1n a more reactive state, the first stage may be designated. as opening the coal for the subsequent refining. The second stage is characterized as cracking and hydrogenation or hydrog nating cracking.

. out as cheaply as possible both as regards apparatus and operation and that furthermore as large a portion as possible of the coal material isob'tained as a crude product for the subsequent refining reaction itself, such as benzinizing for example, and is obtained in the form which is particularly suitable for such refining processes. In order to attain this result the inventors employ a treatment of the solid fuelswith liquids, the boiling point ofwhich is not low but is above about 100 C., at quite definite temperatures, without employing hydrogen, in closed vessels, under the pressure which corresponds to the vapour pressure of the liquid at the temperature adopted in each particular instance. By this treatment the coal material is opened to a far-reaching extent; and a thorough physical and chemical change takes place in the structure of the coal substance. The latter expresses itself for example in the fact that in the case of caking pit coals 70 per cent. and more of the pure coal become completely soluble in organic solvents such as benzene, tetraline and the like. After expulsion of the solvent the opened coal already constitutes a material which differs fundamentally in appearance from the initial substance. It is pitch-like, lustrous, melts in the warm, and has in the case assumed a drip point of about C. for example. For refining reactions such for example as cracking under hydrogen pressure, this opened product shows itself to be incomparably more suitable than the original untreated coal. Hence according to the present invention as contrasted with all the known processes, the solid fuels are treated with suitable liquids boiling above 100 C. under such conditions that a maximum of the coal sub-' stance is opened without decomposition and converted into a form which is particularly suitable for further reactions. In this process the opened substance is completely taken up by the liquid in question, and, if it is considered desirable, can be easily separated from the ash and any unopened portions.

The temperatures that are to be employed in the treatment of the solid fuelswith the liquids in question, such for example as tetraline, tar fractions, oils and so forth, are very different for the various sorts of coal and must be ascertained by experiment. In general they are immediately below or at the temperatures at which the coal in question begins to decompose under normal conditions. In any case the inventors have ascortained that just at those temperatures the opening force of the liquids in question is particularly great.

Now it is exceedingly importantto ob- Since the opening force of the solvents at higher temperatures is greater than at low temperatures the possibility of working even at higher temperatures without causing de-' composition is a great advantage. If for example caking gas-flame coal with a comparatively high decomposition point is opened by the process described at increasing temperatures in four separate extractions, for instance at 320, 350, 380 and 400 (1, onethird of the time is sufficient for the com-- pletest obtainable opening as in continuous working at 320 C. The liquids with which the opening is being effected are preferably allowed to work in a circuit in the individual temperaturestages and to come continually.

into contact with fresh quantities of coal, so that they become richer with the opened products. At certain intervals the liquids are then combined for the purpose of separating out the opened products taken up.

It has furthermore been ascertained in certain cases that the portions which are cracked above the so-called decomposition temperatures of the initial coal or of the residual coal, after their opening in a dissolved condition, can without detriment be heated to higher temperatures. If therefore it is desired 'to attain the highest possible technical and economical effect the'opening must be carried out in the shortest possible time but a maximum amount of the coal must be opened and it must be obtained in a condition which is particularly'suitable for the refining reaction. A shortening of the time required for the opening can be obtained by carrying the final temperatures of one openingphase somewhat beyond the decomposition temperatures of the-residual coals finally obtained. In the case of such an appropriate method of working, yields of extract are obtained amounting to more than 70 per cent. of the pure coal, which can be hydrogenated in a remarkable manner and above all substantially more easily than the initial coal in its original condition.

The final temperature at which the opening is ultimately carried out is different for each kind of solid fuel and should be so clcctel that only trifling gas crackings occur with a considerable shortening of the opening time. Thus on the one hand there should not be, a formation of coke, on the other hand the yield should not be so diminished or immore phases with permanent or temporary employment of the temperatures somewhat higher than the decomposition temperatures.

It is also possible to begin with the higher temperature or to begin first near the decomposition temperature (oreven below the latter), and then to effect a rise in the phase in question (temperature interval of the corresponding extraction) or during the process carried out at once.

The speed of the opening may however also be accelerated, in addition to or instead of by the means stated, by employing specially suitable liquids for the opening of the solid fuels. Besides tetraline, which comes primarily into consideration and besides other tar fractions and oils boiling above 100 C. and other bydrocarbons, phenol comes into consideration, such as is obtained more particularly from tar distilled at a low temperature or even from other tars. Phenol has a very high solubility, but enters into reaction with the coal material to a certain extent. This is shown by the fact that extracts obtained by treating with tetraline are practically completely soluble in benzene, while the extracts obtained with phenol are insoluble in benzene to about I; per cent. and even in tetraline are only soluble to about 60 per cent. The phenol extracts are fusible. According to existing experimental results up to per cent. and more of the pure coal can be opened by a treatment of only a few hours with phenols.

Such extracts obtained by means of phenol admit of being hydrogenated and benzinized particularly easily. Even inert caking pit coals can be opened with phenols or phenol fractions in an exceedingly efl'ective manner, and thereupon hydrogenated to petrol for example. Obviously phenols or phenol fractions may be employed not only alone but inixed'with other solvents, such as tetraline,

oils and the like. Tar fractions with a sufficient percentage of phenol can also be employed. v

In all these cases the fuel is accordingly dissolved and enters" at least partially into reaction with the solvent, without the reactive capacity of the portions so opened, particularly their capacity for being hydrogenated, being perceptibly or substantially impaired.

The solvent employed though 'fundamentally constituting a liquid may however be added insolid form and pass over'into the molten condition at the treatment-temperature employed or may even already-pass over at an earlier pointinto the liquid condition.

It is further possible to employ a; single solvent for each individual temperature stage, or else a suitable mixture of solvents. Moreover the same solvent may be employed for the whole of the opening contemplated in the heat, or else different solvents may be' employed in the different temperature stages.

Furthermore the invention is not entirely limited to the fact that temperature treatments differing from one another are carried out, but also applies to a single treatment at the same temperature.

If it is a question of the treatment in a single working stage with rising temperature, here again the solvents may remain the same or else may be suitably changed during the operation. a

The accompanying drawing is a diagrammatic illustration of apparatus which may be used in carrying out our invention.

As illustrated in the drawing, the coal or other solid bituminous material is supplied from a bin or hopper 1 and the solvent is supplied from a tank 2. The'solid material and solvent are delivered to amixer 3 from which the mixture is discharged, preferably by a screw conveyor 4, into an autoclave 5. in which the extraction takes place substantially in the absence of hydrogen and at the temperature and pressure herein described. The temperature within the autoclave 5 preterably increases from the point where the mixture enters to the point where it is discharged from the autoclave, so that the mixture during its progress through the autoclave is treated at gradually increasing tem peratures according to the increasing decomposition temperature of the successive resiues.

Upon leaving the autoclave 5, the mixture is delivered to a centrifugal machine 6 from which the extracts are delivered to a still 8 and the insoluble residue to a ho per 7. Withinthe machine 6, all of the solu le part of the mixture is taken up by introducing additional solvent through the pipe 12.

Within the still 8, the solvent is distilled and passesinto the cooler 9 wherein it is condensed and from which it is returned by a pump 13 through the pipe 14: to the tank 2. The extracts from the still 8, while still warm andin the fluid state, are led into a tank 10 and thence by a screw conveyer or equivalent means into an autoclave 11, in which destructive hydrogenation takes place in the manner herein described.

Since the heat treatment takes place in closed vessels, the pressure in the latter is I primarily given by the vapour pressure of the solvent atthe temperature in question. Any changes of temperature obtained by other means are however not hereby precluded. In all these cases there is the important advantage of being able to work in a...

single stage and carrying out the entire opening very quickly, the initial coal being heated I tion temperature of the. initial coal or a' ove .p

the latter, and kept at this temperature until the portions that decompose above this temperature in the original condition are opened and can now be exposed without damage to even higher temperatures, whereupon the temperature is raised and the same procedure continued until the desired far-reaching or possible opening has been attained.

In a whole series of experiments ithas been found that with a correct selection of liquids and temperatures, yields of li uid or fusible coal constituents are obtaine without de composition, of a quantity and character such as have hitherto not been produced with other processes.

Example 500 grammes of powdered or suitably disintegrated gas-flame coal are treated for a few hours with about 1000 cubic centimetres of tetraline, in four extractions at 320, 350, 380 and 400 C. for example, or in a single operation with a. rise of temperature from 320 to 400 0., the said rise being gradual or inaccurately adjusted steps. The coal is thus thoroughly opened and completely changed, without decompositions being observed. More than about 70 per cent. of the pure coal is passed into solution, and can easily be separatedfrom the ash and the undissolved part. The opened products, after expulsion of the solvent, constitute a pitchlike lustrous mass, which melts when heated, and has a drip point of about 100 C. Upon coking there remains behind a residue of less than 25 per cent.

The extracts obtained during the primary opening of the carbonaceous material in the first stage can now be caused to react with hydrogen in a second stage, after more or less complete removal of the solvent, at a suitably raised temperature and pressure.

If for example it is a question of convert ing the opened portions of the fuel to the utmost possible extent into petrol, not only is a maximum possible absorption of hydrogen by the opened portions to be hydrogenated essential, but also the cracking thereof into readily boiling products with complete or far-reaching avoidance of separation of gas and formation of coke, that is to say, as far as possible without the occurrence of residues, or particularly of residues to be hydrogenated. If for example, for the addition of hydrogen at a raised pressure and temperature to the opened portions of the fuel, catalysts are employed which act mainly in promoting the hydrogenating reaction, such as molybdio acid and similarly acting catalysts, although the absorption of hydrogen is assisted, the yield of petrol is only inconsiderably raised, in comparison with processes which do not work with such hydrogenation catalysts. If, however, even in the resence of such "icatalysts, the temperature 1s raised for the purpose of compelling the cracking of the substances to be hydrogenated into their readily boiling constituents. it is found by experience that incrustations and formations of coke occur, which prevent even such a special raising of .the temperature from being connected with such a rise controllable pressures and temperatures, and

therefore in an economical manner, and a remarkable yield of the final product is obtained, more particularly of petrol.

- v Cracking or cracking and hydrogenating' catalysts known in themselves may be employed. It has however been found that in particular the chlorine compounds of the heavy metals, such for example as iron, tin, cobalt, nickel, manganese, chromium and the like, and also those of manganese are particularly effective. The chlorine compounds of the lower valency stages of theseelements are preferably used.

The chlorine compounds ofmagnesium also however constitute remarkably suitable catalysts for the oiling and benzinizing process, as do also the other halides.

In particular it has been ascertained that the cracking action of the halogen compounds increases with the increasing atomic weight thereof. Thus for'example the fluorine compounds of the heavy metals and of magnesium are less effective, whereas the bromine compounds are at least equally effective and apparently even more so, than the corresponding chlorine compounds.

In the course of the extensive experiments carried out by the present inventors, cuprolls chloride has been found to be particularly effective, and substantially exceeds in efi'ectiveness even the other chlorine compounds,

particularly in the benzinizing of fuels or coal extracts. The yield of petrolv when em-. Eloying chlorine compounds as catalysts has een raised to a multi le of those obtained in the hydrogenation 0 opened fuel constituents in the absence of catalysts or even with hydrogenation effect is small, it is also possible to add known hydrogenation catalysts, for the purpose of accelerating the hydrogening the fuel extracts.

Finally it is however also possible to employ mixed catalysts. As such mixed catalysts there come into consideration on the one hand the fluorides, chlorides, and bromides of the hea metals and of magnesium, preferably in t eir lower valency stages, and on the other hand the oxides of the metals of the sixth to eighth groups in the periodic s stem. These mixed catalysts are prepare in a known manner b meltin or smterin together the indivi ual constituents in de ite proportions. As examples there may be mentioned :Cr O,, CuCl; M00 CuCl; M00 ZnCl and so forth. It is also possible to prepare these mixed'catalysts from the oxides or mixed oxides of the said metals,"

mixtures of these substances being subjected in succession to-a reduction and artial halogenation. For example an e ective mixed catalyst consisting of chromium oxide and copper chloride is obtained by first precipitatin the oxides of hydroxides of the said meta s together from an aqueous solution and then treating them at a raised temperature with hydrogen and then with chlorine. I

The second stage however must not also be carried out in one o eration. It has in fact' been found prefera le to 'hydrogenate the coal extracts first at moderate temperatures and with the emplo ment of predominantly hydrogenating cata ysts, that is to say, as

gently as possible and to convert th'em'mto oils of more or less high boiling points, that is, to oil them, and onl then to ring these pre-hydrogenated pro ucts up to the hi h cracking temperatures which are requisite or benzinizin with simultaneous employment of energetically acting cracking catalysts. With this method of working the formation of incrustations is prevented practically completely and the extract is most thoroughly converted into petrol. In both phases the natural tension may sufiice or in the first stage hydro en of moderate pressure may be em-. ploye and 'in the second stage hydrogen of raised or even of very high premure. 'The preliminary hydrogenation product, which constitutes the oiled but not yet benzinized extract, onl contains a small percentage of solid parti c es, which are usual y distributed very finely in the oil. Of a formation of solid coke-like crusts adhering to the walls there is no longer anything tobe observed.

The pre-hydrogenated viscous extract oil admits then of being extensively converted into petrol, even without any appreciable formati on of incrustations.

According to this form of the invention the coal substance is treated from the commencement in an exceedingly gentle manner, being first thoroughly opened and made accessible to-hydrogenation, but furthermore the portions that are less suitable for hydrogenation and are liable to fdrm coke and incrustations are separated, and finally the opened portions of the coal are treated with hydrogen at meas-' ured temperatures. Only then are the extractively obtained and gentlytpre-hydro n-- ated portions of the coal benzinized. T ere is accordingly effected in the coursepf the process a gradual transition of the hard, readily cokable and decomposable coal substance into a pitch-like or asphalt-like product (coal extract), which is then converted by gentle hydrogen treatment into a heavy oil pre-hydrogenation product oiled ex--- tract It is the oiled extract which is first subjected to the actual complete benzinizing, with the result that the formation of coked residues and incrustations from the sub stances introduced to the hydrogenation is reduced in the course of the process a hith-v erto unobtain'able minimum.

Now what has been stated with regard. to

the benzinizing of the hitherto unknown coal extracts also applies to all the other derivative distillation products and conversion products of the coal, which are already known. As hereinbefore shown, in the benzinizing of tars of any kind, such for example as the hightemperature and low-temperature tars, of oils, (pitch and the like, the crust formation is dec1 edly a disturbing factor and hampers the technical and economical carrying out of such processes to an excessive de as.

The step-wise hydro enation of t e coal extracts, oils, tars, pitc es and the like ma be carried out in separate a pliances, whic are heated to or otherwise ept at'diiferent temperatures and charged with different catalysts. It is however also possible to work in a single aggregate; in this case. one part of the apparatus is heated to moderate temperatures and charged withthe known hydrogem ation catalysts generally employed in tech- V.

,nologv, such as metals, metallic-oxides, acid anhy rides, or even suitable mixed'catalysts. The otherpart of the apparatus is brought to .the requisite high cracln'ng temperatures,

the material to be hydrogenated, but also come into contact with the oil vapours in the vapour chamber. a Since according to the invention on the one hand the isolating and preparation of the valuable coal constituents are efiected at temperatures and pressures at which these portions are quite gently treat ed and on the other hand the cracking and hydrogenation or hydrogenating cracking may be carried.

out at-pressures and temperatures which are most advantageous for these reactions.- the remarkable economy and hlgh yleld (up to 7 per cent. and higher) of the process according to the invention is evident.

The object of the invention may furthermore be .assisted by subjecting the coal constituents that reactv with hydrogen, or the unsaturated hydrocarbon compounds, in a form that still contains a small percentage of a solvent or of the extracting medium, to the reaction with hydrogen at a suitably raised pressure and temperature. In this form of theintermediate product primarily obtained may be found one cause or the cause of its increased reactivity, which in conjunction with the gentle obtaining of the intermediate product is a condition of the astonishing high yield.

A further advantage of the invention consists in the fact that it is also suitable for the treatment of caking fuels. The invention can be carried out in comparatively small pieces of apparatus, of which those for the carrying out 'of the first stage of the process do not have to stand serious pressures orthc attack by hydrogen. The solvents employed are wholly or to a considerable extent recovered and can be introduced into the cycle of the process again.

For the hydrogenation itself under certain conditions even hydrogenous gases with less than 80 per cent. of hydrogen, such for example as illuminating gas or coke-oven gas with only from 50 to 55 per cent. of hydrogen, can be successfully employed as hydrogenating gases. Since these gases are available in practically any quantities they may be freely employed in excess to any desired extent.

. The gases, before being supplied for such other uses as have hitherto been customary,

are led through the hydrogenating apparatus,

in which certain'quantities of hydrogen are withdrawn from them. It is quite possible, by regulating the velocity of flow, always to conduct the process in such a way that the partial pressure of the hydrogen does not fall below a definite limit; which is advantageous for the velocity of the hydrogenating reaction. Furthermore the present high state 'of high-pressure technology enables the entire process to be accomplished if desired at a correspondingly higher pressure than when working with pure hydrogen.

The possibility of employing hydrogenous gases, such as coke-oven gas, lighting gas and water gas, directly as hydrogenating media brings with it quite remarkable and surprising advantages. Since the high cost connected with the production of high-percentage hydro n ar e not present, the hydrogen is availa 1e for the price appropriate to its calorific value. By the removal of the hydrogen the residual gas experiences a considerable improvement in calorific value. The latter is still further raised, for Instance when coke-oven gas is employed for the hydrogenation of coal, by the fact that the hydrogen of low calorific value is replaced by the gaseous hydrogenation products of higher calorific value. Thus it is possible to obtain in a remarkably e'fiective manner from coke-oven gas a rich gas which is highly suitable for the purposes of distant gas supply, and also to extract the hydrogen which is of little value for distant transport but is the most valuable raw material for hydrogenation reactions.

What we claim is 1. A process for the hydrogenation of solid bituminous material, comprising a first stage in which said material, in the absence of any substantial amount of free hydrogen, is subj ected to the action of solvent media capable of dissolving hydrocarbons and having a boiling point above 100 (3., whereby an ex.- tract is obtained, the extraction being effected successively at temperatures which increase gradually, the increasing temperature being chosen as high as is possible without decomposing the constituents of the material being treated, the pressure during the first stage being substantially the same as the vapor pressures of the solvent media at the respective temperatures, this treatment being continued until at least 50% of the material is extracted, there being left an undissolved carbonaceous residue, whereupon, in a subse-' quent stage, the extract is hydrogenated by subjecting the same to a pressure above 20 atmospheres and a temperature above-approximately 300 C. drogen.

2. A. process according to claim 1, in which the residual material remaining undissolvd is introduced into another solvent.

3.- A process according to claim 1, in which the treatment of the material is effected in different temperature phases, the solvent media working in circuits in the individual temperature phases and coming into contact with fresh'quantities of the material being treated, the solvent media in the. different circuits being combined after the extraction has taken place, for the purposeof further working.

4. A process according to claim 1, in which the extraction of the material is effected b treatment with suitable solvents at gradua ly increasing temperatures in one continuous operation, the temperatures being increased in the presence of hy-.

to the same extent as the extraction of the 7 nations of the heavy tar-fractions, oils and phenols is used-as a solvent, the initial material and the residual material. in the solvent being treated at a temperature between 100 C. and 410C.

7. A process according to claim 1, in,which the extracts are first pro-hydrogenated in the presence of a catalyst from the class consisting of finely divided metal, metal-oxide which may be reduced only with difliculty, and acid anhydride of the sixth, seventh and eighth groups of the periodic system.

8. A process according to claim 1, iil which the extracts are first pre-hydrogenated in the presence of a catalyst from the class consisting of finely divided metal, metal-oxide which may be reduced only with difliculty,

andacid anhydride of the sixth, seventh and eighth groups of the periodic system, and in which the subsequent cracking hydrogenation takes place in the presence of a catalyst from the class consisting of halogen combimetals, magnesium, copper and manganese.

In testimony whereof we have signed our names to this specification. I

ALFRED POTT. HANS BROCHE.

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