US2833697A - Desulfurization of crude oils by catalytic high-pressure hydrogenation - Google Patents

Description

y 6, 1958 w OETTINGER 2,833,697

DESULFURIZATIOMOF CRUDE OILS BY CATALYTIC HIGH-PRESSURE HYDROGENATION Filed Oct. 19, 1954 23' INVENTOR."

Y. W LLI 021T GER r I ATT YS DESULFURIZATION F CRUDE OILS BY CATA- LYTIC HIGH-PRESSURE HYDROGENATION Willi Oetlinger, Ludwigshafen (Rhine), Germany, assignor to Badische Anilin- & Soda-Fabrik Aktiengesellschaft, Ludwigshafen (Rhine), Germany Application October 19, 1954, Serial No. 463,213 Claims priority, application Germany October 23, 1953 6 Claims. (Cl. 196-24) This invention relates to a new and improved method of desulfurizing crude oils by catalytic high-pressure hydrogenation.

. It has been known in the art to desulfurize crude oils or their fractions by refining high-pressure hydrogenation in the presence of catalysts.

I have now found and developed a new technique for desulfurizing crude oils in which less hydrogen is required than in the refining hydrogenation processes known in the art. In the process according to my invention at least one low boiling fraction is expelled from the crude oil by distillation, the residue is subjected to refining high-pressure hydrogenation with hydrogen at a pressure of at least 200 to 1000 atmospheres and at a temperature of 350 C. to 490 C. in the presence of catalysts, the resultant reaction mixture is cooled to temperatures below 100 C. substantially at the reaction pressure, the gas and liquid fraction are separated from each other, the gas is returned in a cycle, the pressure on the liquid product is reduced by at least 50 atmospheres, but kept above atmospheric pressure, and the gas containing hydrogen thus set free is used for the refining high-pressure hydrogenationof at least one of the fractions separated by the distillation of the crude oil. Y I 'In' a preferred embodiment my invention provides distilling off from the crude oil a gasoline and a diesel oil fraction and then passing the residue over fixed-bed catalysts together with hydrogen in a conventional manner. Catalysts useful for this purpose in particular are the metals of the 6th group of the periodic system, as for example molybdenum, tungsten, uranium and chromium, as well as those of the iron and platinum group, in particular nickel, cobalt, platinum, palladium and ruthenium as well'as rhenium; Copper, zinc, cadmium, tin, lead,- titanium and manganese are also suitable. These metals are preferably used in the form of their compounds, as for example oxides, sulfides, thiosulfates, carbonates, halides, cyanides, phosphorus compounds, nitrates, borates, silicates, aluminates or the salts of organic acids, preferably those of low molecular weight. Mixtures are preferred and there may be used for example at least two of the abovementioned metals which are situated in a horizontal series of the periodic system. Of the said metals there may be used those with the atomic numbers 74 to 82 with at least one metal with the atomic number 20 to 30 or 40 to 50 or at least one metal'with the atomic number 20 to 30 with at least one metal with the atomic number 40 to 50 or at least two metals within the said three groups of atomic numbers together. It is also possible to use at least one metal of the 6th group or vanadium together with iron, nickel, lead, cadmium, titanium, manganese or with'at least two of these metals. Mixtures of atleast one metal of the iron group with copper, zinc, cadmium, tin, lead, titanium, silver, gold, manganese, platinum, palladium or at least two of these metals are also suitable. In all cases, the compounds of the said metals arepreferred.

It is also possible to use at least one heavy metal of 2,833,697 Patented May 6, 1958 ICC 2 the 1st group together with zinc, cadmium, titanium, tin, lead, bismuth, manganese or at least twoof these elements. These metals are advantageously used as chro mates, vanadates, manganates or molybdates.

In mixtures it is preferable to use a larger amount of one component than of another, for example the metal of the 6th group in a larger amount than that of the 8th group.

At least one representative of the rare earths, in particular thorium oxide, can also be added to the said mixtures. Small amounts of alkali can alsobe added.

The catalysts can be applied to carriers, such as lignite coke, active carbon, bleaching earths, alumina or synthetic silicates. These can be pretreated-with acids or hydrogen halides. The silicates of the said metals, in particular those of the 8th group, which should not contain more than 10% of aluminum or magnesium, have also proved suitable. They are preferably not contained in the silicates. These silicates may additionally be provided with the same or advantageously another metal of the said groups, advantageously the 5th and 6th groups, by impregnation by means of solutions of the said compounds of these metals, in particular their. salts. It is advantageous to use compounds of metals of the 6th group together with those of the iron or platinum group, the latter generally being used in smaller amounts than the former. I

The refining high-pressure hydrogenation of the residue is generally carried out at a pressure of 200 to 1000 atmospheres, in particular 250 to 500 atmospheres, and at 350 C. to 490 C., preferably at 460 C. When working in the liquid phase, finely divided catalysts should be used. Combined with the reaction chamber is a hot separator. There may also be used a plurality of separators in whichthe liquid fractions are condensed and from which they are withdrawn. The gas leaving the last separator is returned. The hydrogenating gas may be pure hydrogen or also watergas, coke oven gas, illuminating gas,cracking waste gas, low temperature carbonization gas or other hydrogen-containing gases.

The pressure of the liquid reaction product is then reduced, for example, to 20 to atmospheres, the lower limit being preferably the pressure at which the refining hydrogenation of the fractions distilled off from the crude oil is carried out. The gas disengaged by the'reduction of pressure, which contains hydrogen, and may be freed from hydrogen sulfide, is led together with the distillate, for example, the diesel oil and/or the gasoline, at a temperature of, preferably, 300 C. to 430 C. and under a pressure of 20 to 200 atmospheres, preferably 20 to 150 atmospheres, over one of the above-mentioned catalysts. The amount of hydrogen is advantageously 0.1 to 1 cubic metre, usually 0.2 to 0.7 cubicmetre, per kilogram of oil fraction. The unspent hydrogen is returned, if desired, to this stageafter removal of hydrogen sulfide.

The source of hydrogen may also be hydrogen which has been obtained in the reforming of the gasoline which has been obtained by distillation from the crude oil. For the reforming of the said gasoline, this, or only part of a fraction thereof, in particular the heavy gasoline fraction, is led at temperatures of about 430 C. to 570 C. over catalysts. Suitable catalysts are for example active alumina, synthetic silicates, acid-treated bleaching earths,

traneous hydrogen. When hydrogen has formedin sufficient quantity, it is returned. In the reforming, 0.3 to 4 cubic metres of hydrogen-containing gas per kilogram of gasoline fraction or more is led in a cycle. The excess gas is then used for the refining high-pressure hydrogenation of the oil residue- If this hydrogen should not be iquite sufficient, there may be added during the reforming of the gasoline, gasoline from another source so that the formation of hydrogen is increased.

Hydrogen-containing gas from a reforming process of a gasoline from a'source other than from the gasoline fraction of the crude oil can also be used for the refining hydrogenation.

In order to prolong the service life of the catalysts for the refining high-pressure hydrogenation of the distillation residue, the crude oil,or preferably only the residue, is led together with hydrogen'at temperatures of 300 C. to 450 C. through a reaction chamber which is provided with substances having large surfaces. These may be porous or non-porous; for example Raschigri'ngs or other shaped filler bodies of ceramic substances or metals may be used. Bleaching earths, alumina, synthetically-made silicates are also suitable. It is of special advantage when the free reaction space between the said pieced or shaped bodies amounts to at least 40%, advantageously50 to 70%, of the total reaction chamber. Those substances are therefore especially suitable which constitute large structures with hollow spaces, as for example relatively large and thin-walled Raschig rings. Infthis reaction chamber, the crude oil or residue is freed from ash. The initial material purified in this way is then heated to about reaction temperature, but this is not necessary if the pretreatment has been carried out at a suitably'high temperature. The residence time in the reaction chamber during this pretreatment is chosen so that no appreciable change in the initial material occurs. If stoppages occur in the dc-ashing vessel, another vessel of the sameconstruction is substituted while the first is being cleaned.

The amount of hydrogen added together with that led in circulation amounts to 0.1 to 2 cubic metres .per .kilogram of initial material. i

The accompanying drawing is a diagrammatic representation of one form of application suitable for the practice of the invention.

The following examples will further illustrate this invention but the invention is not limited thereto.

I Example 1 1000 kilograms of Kuwait crudeoil are heated in a heater 1 in an apparatus as shown diagrammatically in the accompanying drawing and separated in a distillation column 2 into 195 kg. of gasoline with 0.07% of sulfur, 240 kg. of diesel oil with 0.86% of sulfur and 565 kg. of residue with 4.0% of sulfur.

The 565 kg. of residue are withdrawn from the bottom of the column 2 through a pipe 3, compressed to 300 atmospheres by means of a pump 4, mixed at 5 with hy: drogen introduced at 6 and at 7 with returned waste gas and fed into a preheater 8. 1.5 cubic metres of fresh and circulated hydrogen are used and the reactants are led at 300 atmospheres and 410 C. through a first reaction chamber 9 which is filled with clay Raschig rings. The free space between and within the rings amounts to 65% of the total reaction chamber. The ash contained in the residue is thus separated. When the chamber 9 has become extensively filled with ash, the valves 10 and 11, which have hitherto been open, are closed and the closed valves 12 and 33 are opened. The reactants are thus supplied to the reserve reaction chamber 14. After some time, the chamber 9, which has in themeantime been cleaned, can be returned to service. The ash-free product passes with the gas over an intermediate heater 15, in which the reactants are heated to 425 G, into a reaction chamber 16 which is filled with fixed-bed catalyst. The catalyst consists of nickel silicate provided with 10% of M00 T he loading of the catalyst amounts to 1.5 kg. of residue per litre of catalyst per hour. After cooling the reaction product in the cooler 17 at about the same pressure to about 35 C., the hydrogen-containing gas is separated in the vessel 18 and returned in cir-. The liquid fraction is culation through the pipe 19. relieved of pressure down to 60 atmospheres through a valve 20 and led into a vessel 21. The liquid fraction thus'withdrawn is relieved of pressure down to at'mos-.

pheric pressure through a valve 22. The reaction product, which is withdrawn at 23, contains only 1.4% of sulfur.

The gas set free by reducing the pressure from 300 to 60 atmospheres containing of hydrogen is led from vessel 21 through pipe 24 together with the diesel oil from pipe 25 distilledolf from the crude 'oil, heated up in a preheater 26 and led at 380 C. and 60 atmospheres into a reaction vessel 27 which is filled with nickel silicate provided with 10% of tungsten sulfide. The throughput of diesel oil amounts to 2 kilograms per litre of catalyst per hour. The gas containing hydrogen is returned in circulation from the separating vessel 28 by a pipe 29. The product of this stage is a diesel oil with 0.05% of sulfur. This is withdrawn at 30.

The gasoline distilled off from the crude oil may, if desired, be refined with the diesel oil.

If it is desired to desulfurize the diesel oil in the usual way together with the residue at 300 atmospheres, 20% more fresh hydrogen would be needed. Furthermore by the present process, i. e. with separate working up ofthe residue and oil fractions, the compression energy for the said amount of hydrogen is saved.

Example 2 Iraq crude oil is separated by distillation into 8% light gasoline, 18% heavy gasoline, 32% middle oil with 0.7% of sulfur and 42% of residue with 3.6% of sulfur. The heavy gasoline, together with 1.5 cubic metres of hydrogen led' in circulation, is led with a catalyst loading of 0.5 kg. of oil per litre of catalyst per hour at a total pressure of 25 atmospheres over a catalyst consisting of active alumina containing 0.1% platinum at 505 C.

This catalyst is prepared as follows:

An aluminum nitrate solution, the concentration of which corresponds to an Al O -contcnt of 8%, and a 15% ammonia solution are fed simultaneously into a vessel heated to 95 C. so that the mixed solutions in the vessel have a pH value of 7. The solution while still hot is introduced together with the precipitate formed into a filter press and the filter cake is Washed forj3 to 4 hours with hot water at 70 C. to 80 C. The alumina hydrate thus obtained is then soaked with a solution of platinum chloride, dried, shaped and heated to about 440 C.

The gas with about of hydrogen formed by reason of the dehydrogenation which occurs is withdrawn from the gas circulation and compressed to 325 atmospheres. Together with the distillation residue, also compressed to 325 atmospheres, this gas is heated to 410 C. and led through a chamber which is filled with Raschig rings in such a way that the free space in and between the Raschig rings amounts to 60% of the total reaction chamber. The ash contained in the distillation residue thus separates therein without appreciable change in the initial material. The oil which is now free from ash is cooled together with the gas to 395 C. and then passes into the actual reaction chamber which contains as catalyst the above-described alumina provided with cobalt molybdatein an amount of 9% (calculated as metal). The throughput, with reference to the space occupied by the catalyst, amounts to 1.5 kilograms of oil 'perlitre of the top and returned to circulation. The ratio of gas to distillation residue is 1.6 cubic metres per kilogram of distillation residue.

From the bottom of the separator, the oil is withdrawn and released to 65 atmospheres in a second separator. From this separator a gas containing about 65% hydrogen is withdrawn at the top. The oil from the second separator is completely relieved of pressure and supplied to a distillation. in the distillation there are obtained, with reference to the total crude oil, 0.8%

of a heavy gasoline which is supplied together with the 10% of heavy gasoline from the crude oil to the abovementioned reforming hydrogenation, and also 3.5% of middle oil and 36.7% of heavy oil with 1.4% of sulfur. The hydrogen-containing gas withdrawn from the top of the second separator is heated together with the middle oil from the crude oil to 355 C. and led at a total pressure of 65 atmospheres over a catalyst consisting of nickel silicate with 10% of M The catalyst loading amounts to 2 kilograms of oil per litre of catalyst per hour. The gas leaving the reaction chamber is returned in circulation. The ratio of gas to oil is 0.25 cubic metre of gas per kilogram of oil. The middle oil thus obtained contains 0.1% of sulfur.

The invention is hereby claimed as follows:

1. In a process for desulfurizing crude oils by catalytic high-pressure hydrogenation, the steps which comprise (1) expelling from the crude oil by distillation at least one fraction, (2) subjecting the residue to catalytic refining high-pressure hydrogenation with hydrogen at about 200 to 1000 atmospheres and 350 C. to 490 C., (3) cooling the resultant reaction mixture at about the reaction pressure to a temperature below 100 C., (4) separating the gas and liquid fractions formed in step 3 from each other, (5) returning the gas recovered from step (4) to step (2),. (6) reducing the pressure of said liquid fraction recovered from step 4 to a pressure at least 50 atmospheres lower but above atmospheric pressure to liberate a quantity of hydrogen-containing gas, and (7) refining by catalytic high-pressure hydrogenation with gas liberated from step 6) at least one of the fractions separated by the distillation of the crude oil in step 1).

2. A process as claimed in claim 1 wherein the crude oil residue from step (1) is led at temperatures of 300 C. to 500 C. over substances having a large surface before the refining hydrogenation of step (2).

3. A process as claimed in claim 1 wherein in step (6) the liquid fraction of the crude oil residue recovered from step 4 isrelieved of pressure to about the pressure at which the refining high-pressure hydrogenation of the distillate fraction is carried out in step (7).

4. A process as claimed in claim 1 wherein the liquid fraction of the crude oil residue recovered from step 4 is relieved of pressure in step (6) to a pressure between 20 and 150 atmospheres.

5. A process as claimed in claim 1 wherein a hydrogen-containing gas obtained by the reforming of gasoline is used for the refining high-pressure hydrogenation of the crude oil residue in step (2).

6. A process for desulfurizing a crude oil which comprises separating from the crude oil by distillation a gasoline fraction and a middle fraction, reforming at least a part of the gasoline fraction, subjecting at least part of the resulting waste gas together with the crude oil residue at a pressure of 200 to 1000 atmospheres and a temperature of 350 C. to 490 C. to catalytic refining high-pressure hydrogenation, cooling the resultant reaction mixture at about the reaction pressure to a temperature below C. to form a gaseous fraction and a liquid fraction, separating the gaseous fraction from the liquid fraction, returning said gaseous fraction to said catalytic refining hydrogenation of said residue, reducing the pressure of said liquid fraction to a pressure of 20 to atmospheres and using the hydrogen-containing gas thus liberted for refining high-pressure hydrogenation of said middle fraction.

References Cited in the file of this patent 0 UNITED STATES PATENTS 1,983,241 Pier et al. Dec. 4, 1934 2,431,920 Cole Dec. 2, 1947 2,516,877 Home et al. Aug. 1, 1950 2,567,252 Strang Sept. 11, 1951 2,587,987 Franklin Mar. 4, 1952 2,671,754 De Rosset et al Mar. 9, 1954 2,672,433 Porter et a1. Mar. 16, 1954 2,691,623 Hartly Oct. 12, 1954 2,726,193 Docksey et a1 Dec. 6, 1955 FOREIGN PATENTS 501,920 Belgium Mar. 31, 1951 1,024,551 France Jan. 10, 1953 1,056,387 France Oct. 21, 1953

Claims (1)

1. IN A PROCESS FOR DESULFURIZING CRUDE OILS BY CATALYTIC HIGH-PRESSURE HYDROGENATION, THE STEPS WHICH COMPRISE (1) EXPELLING FROM THE CRUDE OIL BY DISTILLATION AT LEAST ONE FRACTION, (2) SUBJECTING THE RESIDUE TO CATALYTIC REFINING HIGH-PRESSURE HYDROGENATION WITH HYDROGEN AT ABOUT 200 TO 1000 ATMOSPHERES AND 350*C. TO 490*C., (3) COOLING THE RESULTANT REACTION MIXTURE AT ABOUT THE REACTION PRESSURE TO A TEMPERATURE BELOW 100*C., (4) SEPARATING THE GAS AND LIQUID FRACTIONS FORMED IN STEP 3 FROM EACH OTHER, (5) RETURNING THE GAS RECOVERED FROM STEP (4) TO STEP (2), (6) REDUCING THE PRESSURE OF SAID LIQUID FRACTION RECOVERED FROM STEP 4 TO A PRESSURE AT LEAST 50 ATMOSPHERES LOWER BUT ABOVE ATMOSPHERIC PRESSURE

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