US2345877A - Manufacture of liquid hydrocarbons - Google Patents

Description

Apnl 4, 1944. w. KRox-:NIG' 2,345,877

MANUFACTURE OF LIQUID HYDROGARBONS Filed Feb. 14, 1940 3 Shee'lZS-Sheet 1 VESSEL coocn HEATER .D/.srlL'LAT/QN coLuA/Ar VA e uan COLUMN FIG? -I April 4, 1944. w. KRoENlG MANUFACTURE OF LIQUID HYDROCARBONS 3 sheets-sheet 2 Filed Feb. 14. 1940 i @N mm. n wm mw I QN A UGL vm ,Nl NhN,

an rm aux/m 1 .arge/Fedra April 4, 1944. w. KROENIG 2,345,877

MANUFACTURE OF LIQUID HYDROCARBONS Filed Feb. 14. 1940 5 Sheets-Sheet 3 R51. EASE nessuna VESSEL Hs. -zzz :B5 ZZ www Patented Apr. 4, 1944 4UNITED STATES PATENT OFFICE MANUFACTURE QF LIQUID BYDROCABBONS Walter Kroenig,

Ludwigshafen-on-the-lthine,

Germany, assignor to Standard Catalytic Company, a corporation of Delaware Application February 14, 1940, Serial No. 318,831

Germany January 23, 1939 9 Claims.

of their constituents which boil above 325 C.

under a pressure of 12 milimeters (mercurygauge), for example between 20 and 6,0 per cent thereof, but no more than '75 per cent, are transformed into Diesel oils, lubricating oils, fuel oils or products readily susceptible to' hydrogenation or cracking and which boil above 325 C. under atmospheric pressure; there is no marked increase during this process of those constituents boiling below 325 C. at atmospheric pressure. In practicing this process, the initial materials are heated to temperatures of more than 400 C., preferably from 420 to 470 C., under increased pressure, for example a pressure of up to 150 atmospheres, but preferentially a moderately increased pressure, for example a pressure ofup to about 70 atmospheres, for a period of time which varies accordingto the particular initial material be treated with refining. agents, as for example sulphuric acid or bleaching earths. With a view to obtaining lower boiling motor fuelswthey may also by'themselves or after splitting up into fractions be subjected to cracking or a cracking destructive hydrogenation or also, Awith a view to obtaining lubricating oils, to afmild destructive hydrogenation.

During the heating under pressure it is essential that exactly such heating time is applied as shall cause the cracking eiect"mentioned above. This time is a function of the initial material and of the temperature. Thus, for example, when brown coal low temperature carbonization tar is to be heated to 450 C., 1.5 minutes are needed for the range of from 350 to 450 C.: for a naph.- thenic mineral oil to be heated to 460 C., -l.5 minutes also are needed for the rangeY of `from 350 to 460 C.; for an asphalt-base mineral oil to be heated to 470 C. 3 minutes are needed for the range of from 350 to 470 C. In calculating the duration of stay no consideration is given to the increase in volume of the initial material vdue to the heating.

The advantage of the process according to the present invention resides in the fact that Diesel oils, lubricating oils and fuel oils may, depending on the particular initial material selected, by produced Without destructive hydrogenationor cracking of the products released from pressure, the said oils being superior in quality to those obtained'by subjecting the initial materials di- `used and must be determined by preliminary A rectly to a mild distillation. By this latter method a considerably larger amount of asphalt is formed than by the .method according to the present invention. In this latter case the asphalts and resins contained in the distillate are in a considerably lower molecular state. By subjecting the products released from pressure to a destructive hydrogenation or a cracking treatment, the throughputs and yields may be materially increased and the catalysts are more active than without the pressure heating and release from pressure in the manner defined.

Among suitable initial materials, in addition to those already mentioned, I may ment1on highboiling cracking products, for example of mineral .oils, or heavy oils obtained in the destructive hydrogenation of mineral coals, pitch, cracking residues or brown coals low in parailin wax; specifically I may mention stripper oil, i. e., a

.heavy oil obtained from the escaping vapors in such destructive hydrogenation. 'It is advantageous to add to the initial materials light-boiling substances, for example middle oil, benzine, benzene or its light-boiling homologues whichmay be employed over again in a cycle. Moreover, there may be added products which are obtained during the process itself, as for example hydrocarbons obtained during the release of pressure andv condensation. These additions are not required if the initial material already contains suiiicient quantities of light-boiling constituents. As an alternative, any low-boiling constituents present in the initial material which are rich in hydrogen, as for examplebenzine, may be removed and replaced by low-boiling hydrocarbons poorer in hydrogen, as for example benzene.

In practicing the process the initial materials 'are heated, advantageously in tubes. vto a tem- Y perature of from about-400 to 470 C. under increased pressure, preferably from about 2 to 50 atmospheres. In order to vincrease the speed of substances, as for example brown coal low temperature coke, part of the heated products may be circulated in the tubular system by pumping. Heating may be carried out with the addition of small proportions of gases, as for example hydrogen, water gas, cracking gases, gaseous hydrocarbons, nitrogen, carbon monoxide, carbon dioxide or steam.

The materials so heated are then released from pressure into a vessel, preferably a column, and herein placed under a lower pressure, for example atmospheric or subatmospheric pressure. For this purpose the materials are introduced into the release vessel at a suiiicient distance above the lower discharge opening. The release vessel is kept, at least in the neighbourhood of the point where the heated initial material is admitted, at a temperature which is equal to or but slightly lower, say by about 10 to 50 C. lower, than that of the heated initial material. In the vapour space of the vessel there are advantageously arranged baiile plates, :bell trays or Raschig rings and/or such substances as bauxite, silica gel or active charcoal. By a proper control of the temperature there is thus easily effected a separation into pitchy residues and vaporous products containing heavy oils. The latter leave at the upper end of the vessel, While the former, being liquid at the temperature prevailing in the release vessel, are discharged at the lower end. The temperature, at the point where the vaporous products leave, is only by about 50 to '70 C. lower than at the point where the initial material enters.

After or shortly before releasing the heated e materials from pressure it is advantageous to give them an addition of scavenging gasesVespecially stem, cracking gases, gaseous hydrocarbons, oxides of carbon or nitrogen or hydrogen, the gases being brought approximately to the temperature of the heated materials, or, if the initial materials are very readily decomposed, to a higher temperature; the gases are added in proportions ranging between about 5 and 50 per cent by weight, calculated with reference to the vapours containing heavy oils leaving the release vessel. The scavenging gases may be supplied at the place where the heated' materials are introduced into the release vessel or at the bottom end of the release vessel or at both points simultaneously.

It is of special advantage to practice the pres- .sure heating and the release of pressure under such conditions that the amount of the pitchy residue, which is generally solid at ordinary temperature and fusible, is from about 3 `to 15 per cent and that the heavy oil contained in the vav pours, which boils above 325 C under a pressure of 760 millimeters (mercury gauge), still contains at least 3 per cent of constituents boiling above 325 C. under a pressure of 12 millimeters (mercury gauge). When working in this manner, the vapours leaving always contain resins and asphalts having a lower molecular weight than the asphaltic substances of the initial material and causing no inconvenience in the subsequent treatment.

Before or while the initial material is heated it is of great advantage to add to it adsorption agents in a finely divided state; among substances suitable for this purpose I may mention brown coal low temperature coke, active charcoal, sili- Cates, bauxite and bleaching earths, for example fullers earth, or silica gel, synthetic silicates or similar porous materials or/and metal compounds,

.f especially oxides, sulphides, phosphates or halides of the metals of the second to the eighth group of the periodic system, or organic compounds, preferentially of elements of the fifth to the eighth group of the periodic system. The proportions in which these materials are added vary from 0.1 to 10 per cent.

The vapours containing heavy oils may be treated, if desired after condensation, with adsorption agents of the said kind either in a rigidly arranged or finely distributed condition, preferably at moderate temperatures, or with chemical agents, for example sulphuric acid, o1' subjected to a refining destructive hydrogenation. 'Y

If the products obtained after releasing the pressure-heated materials from pressure be split up into fractions by means of selective solvents, it is advantageous to use solvents having polar groups, as for example phenol, nitrobenzene, furfurol, aniline, phenylhydrazine, dichlordiethylether, keto acids, alcohols or glycol derivatives, but liquid sulphurous acid, liquid ammonia or liquefed hydrocarbons being gaseous at ordinary temperature, or mixtures of both kinds of solvents may also be employed. The fraction rich in hydrogen, if required after having been de y waxed, for example is a good Diesel oil, while the fraction poorer in hydrogen, to which higher boiling constituents richer in hydrogen may still be added, if desired, is` adapted for use as a fuel oil.

Excellent motor fuels and fuel oils are also obtained Iby splitting the very initial materials with selective solvents and subjecting the fractions richer in hydrogen t'o the pressure heating and pressure releasing treatment as above. That fraction which does not leave in the vapour state is withdrawn as a residue poor in hydrogen at the bottom end of the release vessel and used as such, if desired. The vapours escaping from the release vessel are then split up into Diesel oil, heating oil and/or lubricating oil by fractional condensation or by condensation and subsequent distillation. It is of advantage to free these fractions of paraiiin wax. The fraction poor in hydrogen obtained -by splitting up the initial material with selective solvents may be subjected for example to a destructive hydrogenation in the liquid phase, :benzines and Diesel oils or also lubricating oils being thus produced. The said fraction may also be processed together with the pitchy residues poor in hydrogen which result during the release of pressure and, if desired, also together with portions of the heavy oil obtained during the release of pressure, to produce motor fuels.

The process according to the .present invention may also be applied to the products obtained by the so-called low temperature hydrogenation of tars, described for example in the co-pending U. S. application Ser. No. 159,092, nled August 14, 1937. By subjecting the said products to a pressure heating and pressure releasing treatment according to the present invention a product leaving in a vaporous state is obtained from which a pure paraiiin wax may very readily be separated, whereas a small proportion of parailin wax and resin results as a residue. Also a stripper oil obtained by the destructive hydrogenation of mineral oil may have its properties as a fuel oil substantially improved, for example by depressing its pour point, by the process in accordance with the present invention.

The products obtained by the release of presfor example under pressures ranging 'from 5 to 100 atmospheres or higher, advantageously in the presence of catalysts, as for example the porous substances above referred to, provided, if required, With compounds of metals of the second to the eighth group of the periodic system, for

example iron, cobalt, nickel, tungsten, molybdenum, chromium or magnesium, or these metal compounds alone. Synthetically made silicates containing alumina and/or magnesia are especially suitable catalysts. The cracking may be carried out under more rigorous conditions with the production of benzines, or under milder conditions with the production of Diesel oils and benzines, the Diesel oil thus obtained having a specially favourable cetene number. The cracking may also with advantage be carried out with the addition of gaseous hydrocarbons, in which case the presence of hydrogen may have a favourable effect upon the lifetime of the catalyst.' 'I'he cracking may also be carried out in the presence of hydrogen, Without the latter being consumed. The proportions of hydrogen used in this case, however, are smaller than those usual in ordinary destructive hydrogenation. The catalyst may also be passed through the cracking space in equal direction with, or preferably, opposite direction to the vapours togbe cracked.

The vapours containing heavy oils may also, if required after a treatment with adsorbing agents, lbe subjected to a cracking destructive hydrogenation in the presence of appropriate catalysts. Special advantage is gained by adopting for this purpose the. so-called catalytic low temperature hydrogenation under. pressure. For this purpose the vapours are passed along with hydrogen over catalysts having a hydrogenating action, especially over the oxides or, more preferably, the sulphides of the metals of the sixth to eighth group of the periodic system, for example those of tungsten, molybdenum di iron or mixtures thereof, at temperatures of between 270 and 415 C. under a pressure of 50 atmospheres 'f or more, preferably from 200 to 500 atmospheres or more, the temperature being raised in the reaction zone preferably by to 150, especially l50 to 110 C. In this case a .preliminary treatment with hydrogen at temperatures of from about 200 to 250 C.'in the presence of catalysts having a strongly hydrogenating action has proved advantageous. The low temperature hydrogenation may be employed for the manufacture of Diesel oil, lubricating oil and paraflin wax or, after removing the parain wax and while recirculating the lubricating oil, mainly `of Diesel oil or directly of benzine and Diesel oil. The products resulting in the low temperature hydrogenation may also as a whole be converted into benzines with the aid of hydrogenating catalystsarranged on carriers.

The pitchy residues withdrawn at the bottom end of the release vessel may Ibe used, if required in a diluted state, for roadconstruction or as a fuel, or they may be subjected, if desired together with coal, to destructive hydrogenation or low temperature carbonization. They Amay also, if required after removing solids by extraction with pyridine or carbon disulphide, be treated with selective solvents, for example with light-boiling hydrocarbons, such as for instance pentane, heptane, or with liquefied hydrocarbons which are gaseous under ordinary temperature, or with selective solvents for aromatic hydrocarbons, for example liquid sulphurous acid, liquid ammonia or solvents having polar groups.

The accompanying drawings schematically represent several modifications of applicants process. The following examples serve to illustrate how the present invention may be carried out in practice, but the invention is not restricted to the said examples.

Example 1 (see Fig. 1)

i down to 1 atmosphere. Immediately after the said release of pressure 10 per cent by weight of steam (referred to the initial material) heated to 450 C. in a heater 5 are supplied through line I. The mixture ofthe pressure released product and steam then passes into an enlarged vessel 6, at the lower end of which another 15 per ce'nt by weight of steam at 450 C. are added through line 1. In the top end of the vessel 6 in which provision is made to prevent radiation of heat by an insulation 8 three bell trays 9 are arranged in superposition. Within the release vessel the temperature drops from 460 C. at the point I0 where the released product enters to 405 C. at the point II where the vaporous products leave at the top. At the bottom end of the vessel 6 525 per cent (with reference to the crude oil) of apitchy mass melting at 160 C. and containing the iiue dust added are withdrawn through line I2. The fractions leaving in ,a vaporous state at the upper end of the.` vessel which amount to 87 per cent of the crude oil, inclusive of the benzine initially contained. th'erein, are condensed in a cooler I3. 'I'he waste through gas formation amounts to 0.5 per-cent. The condensate contains 27 per cent of constitu-I ents boiling up to 325 C. at atmospheric pressure, whereas only 24 per cent thereof were contained in the initial-material. By this treatment this amount of constituents boiling above 325 C. in vacuo is lessened from to 27 per cent. The condensed in thecooler I3r product is then separated by distillation ina column I4 into 33 pei cent of Diesel oil having a specific gravity oi 0.860 and an' aniline point of 53 C. and a residue of 54 per cent. l The latter is subjected to a distillation in vacuo (6 millimeters (mercury gauge) in a column I5 up to 350 C. (measured in the sump). There are thus obtained 37.4 per cent (referred to crude oil) of a lubricating oil with a specific gravity of 0.936. a viscosity of 6 Engler at 50 C. and a flash point of 220 C. The vacuum residue 'amountsfto 16,6 per cent (referred to crude oil), possessesa specific gravity of 0.966, a viscosity of 11.5 Engler at 99 C. and a flash point of 312 C. l

` Example 2 made aluminum silicate .catalyst at 430 C.. the throughput; being 1 kilogram of oil per hour and per liter of catalyst space.

When passing the initial material once through the cracking zone 29 per cent of benzine are obtained having an octane number of '17. The higher boiling constituents are recycled. The catalyst is reactivated from time to time.

Since the catalyst has its eiiiciency impaired by the addition of water vapor, a gas resulting from the cracking and which contains gaseous hydrocarbone is used instead of the steam introduced into the release vessel, in an amount of 100 cubic meters to each 1000 kilograms of crude oil.

Example 3 (see Fig. 2)

A low temperature carbonization tar from a brown coal of older supplies which has been freed from light oils and contains 7 per cent of asphalt is heated to 450 C. together with 0.5 per cent of brown coal low temperature coke activated with steam in a tubular heater l under a pressure of l atmospheres. The heated material is then released from pressure by a valve 2 into an enlarged vessel 3 protected from loss of heat byan insulation and, immediately upon the said release of pressure, 25 per cent by weight of steam heated to 450 C. in a heater 5 are added through line 6 (percentage with reference to initial material). At the lowereend of the Vessel another 70 per cent by weight of steam at 450 C. are added through line l. At the lower part of the vessel 5 per cent of residue are withdrawn through line 8. There are obtained, besides 0.5 per cent of gaseous hydrocarbons, 94.5 per cent of a distillate containing 4 per cent of asphalt.

This distillate obtained in cooler 0 is collected in a vessel i0 and supplied to the tubular heater i2 and heated therein to 460 C. under a pressure of atmospheres together with 0.5 per cent of brown coal low temperature coke added through line i3. The product is then releasedfrom pressure through valve i4 into an enlarged vessel l5. Into this vessel 10 per cent of steam at 460 C. are introduced through line l 6 at the point where the release of pressure takes place, While another 30 per cent by weight of steam were introduced through line il at its lower end. From the vessel there are withdrawn 4 per cent of residue through line i6; there is formed l per cent of gas. The gases and vapors leave through line i9 and are condensed in a cooler 20. The yield amounts to 95 per cent of a distillate which only contains 0.7 per cent of asphalt.

The initial material contains 45 per cent of constituents boiling up to 325 C. under atmospheric pressure. After the double treatment according to the instant example the proportion of the said constituents has increased to 54 per cent. The constituents boiling above 325 C. in vacuo .which amounted to 27 per cent in the initial oil are reduced to 11 per cent after the double treatment.

The distillate obtained after the second heat treatment is stripped of the water contained therein in vessel 2l and passed under a high pressure produced by pump 22 through heater 24 together with 3 cubic meters of hydrogen to each kilogram of distillate added through line 23. Then the heated mixture is passed over a catalyst of iron sulphide and tungsten sulphide arranged in vessel 25 at a temperature of 322 C. and then over tungsten sulphide in vessel 26 while raising the temperature to from 400 to 450 C. The volumes of the two catalysts are in the ratio of 1:25.

The product obtained, which contains 15 per cent of hydrocarbons boiling up to 200 C. and 65 per cent of hydrocarbons boiling between 200 and 360 C. and constituents of still higher boiling point, is separated into fractions in column 21. The benzine leaving at the upper part of the column is collected in vessel 28. The middle oil is withdrawn throughline 23, whereas the higher boiling constituents. are returned to the highpressure reaction vessel 25 through line 30 and heater 24.

The fraction boiling between 200 and 360 C. is combined with 2 cubic meters of hydrogen to each kilogram of initial material added through line 33 and the mixture is then passed to the hydrogenation vessel 32 by way of heater 3i. In the said hydrogenation vessel the material is passed over bleaching earth provided with tungsten sulphide and pretreated with hydrogen uoride at a temperature of 390 C. and under a pressure ofv 200 atmospheres. By Way of column 34 there is obtained a benzine in vessel 35 having an octane number of 73 (research method).

Example 4 (see Fig. 3)

A low temperature carbonization tar free from light oil containing 7 per cent of asphalt, 45 per cent of constituents boiling up to 325 C. and 27 per cent of constituents boiling above 325 C. in vacuo and 1 per cent of brown coal low temperature coke activated with steam are heated under a pressure of 10 atmospheres with a throughput of 20 kilograms per hour first to 400 C. in a tubular heater i of a capacity of 800 cubic centimeters and then to 460 C. in a tubular heater 2 of a capacity of 1000 cubic centimeters. The reaction material is then cooled down to C. in cooler 5 under the same pressure. A liquid product is thus obtained which contains d per cent of asphalt, 49 per cent of constituents boiling up to 325 C.

under atmospheric pressure and 22 per cent of constituents boiling above 325 C. in vacuo.

This liquid product is then heated to 465 C. in tubular coils i and 5 of the aforesaid capacity (1800 cubic centimeters) together with 0.5 per cent of brown coal low temperature coke activated with steam added through line 6, the throughput being 7 kilograms per hour, and subsequently released from pressure by means of valve 'i into an enlarged Vessel 8 without cooling to a substantial extent. Into this vessel l0 per cent of steam heated to 460 C. in heater 9 are introduced through line i0 at the point Where the release of pressure takes place, while another 30 percent of steam of equal temperature are introduced at the lower end thereof through line il. .At the lower end of the vessel there are withdrawn 7 per cent of residue through line I2. The loss by gas formation amounts to 0.5 per cent. The vaporous products are withdrawn from the top of vessels through line 36 and condensed in cooler 31. The condensate contains 92 per cent'of a distillate containing 0.7 per cent of asphalt, 54 per cent of constituents boiling up to 325 C. under atmospheric pressure and 1l per cent of constituents boiling above 325 C. in vacuo. The last-mentioned distillate is treated as specified in the three last paragraphs of Example 3.

What I claim is:

l. The process for the conversion of a hydrocarbon oil containing asphalt into pitch and a normally liquid hydrocarbon product which comprises heating the initial material to a temperature between about 400 and 470" C. under a pres? sure ranging from 2 to 50 atmospheres at such a rate that the time of heating from about 350 C. to the desired maximum temperature amounts to about 11/2 to 3 minutes; releasing the pressure; passing the heated material upon pressure release into a vessel; introducing a hot scavenging sas into the release zone thereby maintaining the temperature of the material at not substantially lower temperature than said maximum temperature and separating the material into pitch and vaporous products; controlling the total heating time in such a manner as to cause cracking of a substantial part of the constituents boiling above 325?" C. in vacuo tov products boiling between 325 C. under atmospheric pressure and 325 C. in vacuo without substantial increase in constituents boiling below 325 C. under atmospheric pressure; and separately withdrawing the pitch and vaporous products from said vessel.

2. In the process as claimed in claim 1 heating the initial material in the pres/ence of a finely distributed adsorption agent.

3. In the process as claimed in claim 1 introducing a scavenging gas into the release zone at about the point where the heated material enters.

4. The process according to claim 1 which comprises-separating the product which leaves the release zone in a vaporous state, after condensation by distillation in vacuo.

^ 5. The process according to claim 1 which comprises splitting up the product which leaves the release zone in a vaporous state, after condensa- A tion, by means of a selective solvent.

6. The process according to claim 1 which comprises separating the heated material, while being released, into from 3 to 15 per cent of pitch and into products leaving in a vaporous state, which v products in theirheavy oil fraction boiling above 325 C. still contain at least 3 per cent of constituents boi1ingabove325 C. under a. pressure of 12 millimeters (mercury gauge). j

7. A process according to claim 1, which comprises subjecting the product which leaves the release zone in a vaporous state to a catalytic thermal treatment.

8. In the process as claimed in claim 1 heating the Iinitial material under a pressure `ot about 10 atmospheres to the desired maximum temperature. a

9. Intheprocessasclaimedin'claim 1 using steam as a scavenging gas.

waarna icaomc.

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