US2636841A - Desulfurization of heavy petroleum oils - Google Patents

Description

April 28, 1953 R. I3.A MASON DESULFURIZATION OF HEAVY PETROLEUM OILS Filed NOV. 10, 1950 LLLL Qalph urgess maaonnvennor CLCJCJorneLeS Patented Apr. 28, 1953 DESULFURIZATION OF HEAVY PETROLEUM OILS Ralph Burgess Mason, Baton Rouge, La., assignor to Standard Oil Development Company, a corporation of Delaware Application November 10, 1950, Serial No. 194,969

7 Claims.

The present invention relates to the treatment of sulfur-containing organic materials, in particular sulfur bearing hydrocarbon material, to desulfurize the same. More particularly, the

present invention relates to the desulfurization of of molecules containing sulfur, and so extraction sulfur-containing petroleum fractions, particuof sulfur-containing material is no longer feaslarly heavy fractions as reduced crudes and ible, inasmu-ch as the bulk of the extracted maresidua, terial is in the extract and lost, unless a means The problem of sulfur removal from petroleum is present for removing sulfur from this extract. fractions and crudes is as old as the petroleum in- 10 One satisfactory method for removing sulfur dustry. For most purposes it is undesirable to from products wherein it is present as a ring type have an appreciable amount of sulfur in any pecompound has been by hydrogenation in the prestroleum products. Gasoline should be relatively ence of a so-called sulfactive catalyst. Thus, it sulfur-free to make it compatible with lead, and has been found that certain catalysts, such as decreased sulfur content means increased lead cobalt molybdate, tungsten sulfide, nickel sulsusceptibility. Motor fuels containing sulfur as fide, molybdenum sulde, etc., are good hydrogenmercaptans are undesirable because of odor and ation catalysts and that when these catalyst subgum formation characteristics. Sulfur is objecstances are employed in the hydrogenation of tionable in fuel oils of any kind because it burns petroleum stocks containing sulfur, these catato form SO2 which is obnoxious and corrosive. 20 lysts are not poisoned by sulfur but, on the con- Sulfur occurs in petroleum stocks generally in trary, tend to reduce the sulfur content of the two main forms, as mercaptans and as part of a material being hydrogenated, the sulfur being more or less substituted ring, of which thiophene removed as HzS. However, though this process is the prototype. The former type is generally is quite satisfactory for the hydrogenation, or hyfound in the lower boiling fractions, in the naphdrodesulfurization, of low and medium boiling tha, kerosene, and light gas oil material, whereas petroleum fractions, the process is completely unthe ring-sulfur compounds form the bull:v of the satisfactory for sulfur removal from high boiling sulfur-bearing material of the high boiling pestocks, such as cycle stock, reduced crudes and troleum fractions. Numerous processes for sulresidua. The latter, which are the bottoms prodfur removal from relatively low molecular and uct after the 1050 F. gas oil is taken overhead, lower boiling fractions have been suggested such are notorious carbonizers. When they are passed as doctor sweetening, wherein mercaptans are over a fixed bed of a sulfactive catalyst of the type converted to disuldes, caustic treating, solvent described above in order to remove a portion of f extraction, copper chloride treating, etc., all of the sulfur content by catalytic hydrodesulfurizawhich give a more or less satisfactory decrease tion, carbonization of the catalyst proceeds at in sulfur or inactivation of mercaptans by their once, and in an extremely short time the cataconversion into disulfides. The latter remain in lyst is covered by deposition of carbonaceous mathe treated product, and must be removed if it is terial and is inactivated. Regeneration is expendesired to obtain a sulfur-free product. sive, and since the period of activity is so short,

Sulfur removal from higher boiling fractions, it is economically unfeasible to operate with such however, has been a much more difficult problem a process. and operation. AS pointed Out. here the S111- It is, therefore, an object of the present invenfur is present for the most part, as a part of a tion to provide an improved method of desulfurizring. Such sulfur is, of course, not susceptible to ing Sulfur-bearing organic hydrocarbon matechemical operations which are satisfactory with rial, in particular, desulfurizing high boiling mercaptan sulfur. Also, extraction processes are stocks Such as residua and reduced crudes unsatisfactory, for solvents specific for sulfur A further object of the invention is to provide compounds, such as, for instance, boron fluoride an improved means of refining petroleum fraccomplexes, or liquid hydrogen fluoride-boron fluotions to separate therefrom, sulfur and underde mixtures, vor liquid SO2, no longer are of much lsrable sulfur compounds.

uct, such as a residuum that contains about 3% y of sulfur is estimated to consist almost entirely,

A still further object of the present invention is to provide a cheap method for upgrading heavy stocks such as residua.

A still further object of the present invention is to disclose a novel means of hydrodesulfurizing in the absence of a xed catalyst bed whereby inactivation of catalyst is substantially avoided.

Other objects and advantages of the present invention will become apparent from the following description, read in conjunction with the accompanying drawing describingone embodiment of the present invention.

It has now been found that these objects and advantages may be realized by subjecting sulfurcontaining high boilingT hydrocarbon material, such as reduced crudes and residua, to a'hydrodesulfurization reaction employing, instead `of a fixed catalyst bed, a homogeneous catalyst which is not fouled and inactivatedvby the large quantities of asphaltenes and ash present in such socalled dirty feed stocks, thereby making it possible to dispense with the expensive and easily fouled heterogeneous catalysts, such as molybdenum sulfide, tungsten sulfide, etc.

By a homogeneous catalyst is meant a system wherein -the catalyst is alwayspresenting a fresh surfacefto the reactantai. e.,any system having a self-generating surface. Such a system is mest readily realized, of course, when thecatalyst is completely zniscible in lthe material being treated. Thus, solid reaction products, `formed asa resultof :thecatalytic treatr ent, would exist in a separate phase, and can n activatesuch catalyst by forming a layer or suiace coating, as is the case in yheterogeneous cata-li 1" It .hasnow been found that suitably promoted iron vgroup metal carbonyls, such as NiCOl. Co(CO)f., Fe(CO s,v etc, are particularly useful and desirable as homogeneous catalysts in reducing the vsulfur content of reduced crudos and residua and upgrading such residua. Petroleum residua, which is the term generally applied to the bottoms product after petroleum `stock has been topped and the gas oil removed, i. e., that fraction boiling above 650o F. at atmospheric pressure, are of little value per se, because of their high content of sulfur, ash, and asphaitcnes, and their tendency to coke on heating. in accordance with the present invention, they may readily and economically be vconverted into use ful products such as feed st ci; for catalytic cracking or forbunlrer and marine fuel, none of which uses can tolerate high sulfur content.

In accordance with the present invention, high boiling high molecular weight petroleum frac tions, such as reduced crudos and residua, are treated in a l'iydrogenation zone with hydrogen at pressures from about 50o-5000 p. s. i. g. and at temperatures of about 300900 F., though preferably below 800 F., in the presence of a carbonyl of a metal of the iron group, preferably promoted with a halogen or a hydro-halide promoter. Suitable are chlorine, bromine, iodine, and the corresponding hydro-halides. The catalyst may be present up to 30% of the feed, preferably 5 to 20% by weight, while the promoter may be added in amounts of from 0.5 to 5% by weight of the petroleum feed.

The employment of the promoted carbonyls is particularly advantageous, for not only are the metal carbonyls completely miscible in the feed stock, but also, one may employ for the `hydrogenation, a gas containing substantial amounts of carbon monoxide. Commercial hydrogen .contains small amounts of carbon monoxide, and the cheap and readily available hydrocarbon synthesis gas consisting of l to 2 parts H2 per part CO is particularly suited to this purpose, because not only does the relatively high CO partial pressure tend to keep the metal carbonyl from decomposing, but also, decomposed metal or metal sulnde will be reconverted into the carbonyl in situ.

Metal carbonyl is readily prepared by passing a carbon monoxide-containing gas over or through a solid or liquid dispersion or solution of the metal or metal compound.

The invention Will be best understood when read in conjunction with the accompanying drawing, which is a diagrammatic representation of a preferred embodiment of the invention.

Turning now to the figure wherein is shown diagrammatically a procedure for hydrodesulfurizing and upgrading a heavy residuum, such as YKuwait bottomsyin the presence of a nickel carbonyl catalyst promoted with iodine, the petroleum stock is pumped through lines 2 and 4 into hydrodesulfurization reactor l0, preferably after preheating the stock to make pumping feasible. Nickel carbonyl, prepared in any convenient manner, is passed from storage 3 Via line 5 to reactor l0. Likewise, the halogen promoter, such as iodine, dissolved, if desired, in a small amount of hydrocarbon solvent, introduced into reactor lil via lines 8 and 2.0. The mixture is contacted countercurrently with a hydrogencontaining gas introduced through line l2. The gas may be either commercial hydrogen or one containing substantial quantities of CO, such as l/l Ela/CO hydrocarbon synthesis gas. Hydrogcnator vlo is suitably a packed tower, though other means of obtaining intimate Contact between liquids and gases may be employed.

Within vessel I0 there is maintained a pressure from about 500 to 5000 p. s. i. g., preferably 1500 to 3000 p. s. i. g., depending in part, upon the nature of the material being treated, and temperatures in the range of 300900 F. may be employed, though temperatures under v800 7 F. are preferred since above 800o F., cracking is favored. The essence of desulfurizing ring `type sulfur molecules involves, probably, fracture of the molecule, and thus, some cracking will occur regardless of temperature.

The amount of catalyst is preferably 10 to 20% by weight of the feed, and the promoter is added preferably to the extent of l to 2% by weight of the hydrocarbon feed. Feed rates (liquid), of 0.25 to 4 V./V./hr. may be employed, in conjunction with hydrogeny feed rates of about 500 to 2500 standard cubic feet per barrel. drogen consumption is generally low, inasmuch as it is consumed for the most part, in the conversion of the sulfur to H25.

Product streams containing in suspension, considerable amounts of carbonaceous solids, asphaltenes, ash, nickel sulfide, etc. as well as Ni(C`O)4 and I2. distributed both through the liquid and the solids residue, is withdrawn from reactor l0 through lines 22 and conveyed to settling vessels f2s, wherein sludge and coke, etc., are 4allowed to se tlc. Liquid. product is drawn off through Vlines 2t and passed Via lines 28 and 32 to fractionating equipment Sil equipped with suitable heating means. Overhead 'is recovered dissolved nickel carbonyl and iodine, and these volatilized materials are preferably recycled via lines 30 and i0 to the hydrogenation stage. After the removal of the catalytic constituents, fractionation may proceed at atmospheric .or reduced pressures, and suitable fractions, as

5 6 naphtha, gas oil, heating oil, etc., may be Wthamount of I2 was employed in desulfurizing a drawn and recovered, all in a manner known per 78% Kuwait residuum bottoms fraction.

Hydrodesulfurizing of 78% Kuwait bottoms Run Feed A B C D Catalyst None Ni(CO)4 Ni(CO)4 Ni(CO) c Wt. Percent Catalyst l 20 20 Wt. Percent I2 promoter 0 2 2 Added Gas H2 1/1 P12/CO l/l Hz/CO Hl Pressure, p. i. g 2, 000 2,000 2,000 2, 000 Temperature, F. 750 750 750 750 Sulfur, Wt. Perce 2. 23 2. 2 0.89 0. 44 Desulfurization, Wt. Percent 27. 3 27 71. 0 85. 9

Product Distribution:

Naphtha, 400 F.-

Wt. Percent of product 0 20. 5 7.3 8.4 4. 6 Wt. Percent sulfur 0. 1l O 0. 04 0.05 Gas Oil, 850 F.-

Wt.. Percent orproduct 50. 2 60.8 63. 6 85 9 83.0 Wt. Percent sulfur 1.70 2. 08 l. 6l 0 87 O. 37 Gas Oil Bottoms Wt. Percent of product 49. 8 18 7 29.1 5. 7 12.4 Wt. Percent sulfur 4.41 5 04 4.07 2. 64 1.03

Se, all these fractions having Very low sulfur content. Residue may be withdrawn through line 38 and this may be recovered as such, as when a low sulfur bunker fuel is required, or it may be recycled in part or in toto to the process via line 42.

Returning to reactor IIJ, overhead there is withdrawn through line le a gaseous mixture comprising hydrogen, oxides of carbon, nickel carbonyl, HzS, iodine, hydrocarbon gases and low boiling liquids formed as a result of ring rupture, etc. After cooling (not shown), the overhead product may be passed to a gas-liquid separation Zone I6. Overhead gas stream may be recycled through line I8 to hydrogenator I0 while liquid product, comprising hydrocarbons and probably some dissolved Ni(CO) 4 and I2, may be passed via lines 30 and 32 to the fractionation zone for separation of catalyst and recovery of product.

After withdrawal of the oil product streams from settlers 24, it may be desirable to recover catalyst and promoter from the solid residue. Accordingly, a carbon monoxide-containing gas, which may be synthesis gas, is passed into 24 through lines 44. Suitable conditions for good Ni(CO)4 recovery within settler 2li are temperatures of about 300 F. and pressures of about 2000 p. s. i. g. The volatilized carbonyl and iodine are withdrawn upwardly through lines 46, passed into separator 18, and the excess CO recycled to the settler via line 50. The recovered catalyst and promoter are withdrawn through line 52 and preferably recycled to the catalyst system via lines ft2 and Il, together with the recycle feed. Coke and ash may be withdrawn through lines 54 for further processing.

The above description and exemplary operation admits of numerous Variations obvious to those skilled in the art. Thus, under certain circumstances it may be desirable to pretreat the It will be noted that not only is the sulfur reduction exceptionally high, but also, the product, asa result of the hydrodesulfurizing treatment in accordance with the present invention, has been upgraded into a form readily utilizable as feed to the catalytic cracking process or as a marine fuel, (gas oil bottoms).

While the foregoing description and exemplary operations have served to illustrate specific applications and results of the invention, the latter is not limited thereto, and other modifications which may appear to those skilled in the art are within its scope.

What is claimed is:

1. The process of desulfurizing and upgrading sulfur-containing high boiling petroleum fractions which comprises contacting said fractions in a hydrogenation zone with a hydrogen-containing gas in the presence of an iron group metal carbonyl catalyst and a halogen promoter, maintaining within said zone, a pressure in the range of about 500-5000 p. s. i. g. and a temperature in the range of about 300-900 F. and recovering a product containing substantially less sulfur than said rst-named fraction.

2. The process of claim 1 wherein said temperature is below about 800 F.

3. The process of claim 1 wherein said petroleum fraction is a petroleum residuum.

4. The process of claim 1 wherein said catalyst is nickel carbonyl.

5. The process of claim l wherein said catalytic reaction is promoted with iodine.

6. The process of claim 1 wherein said catalyst and promoter are dissolved in said petroleum fraction.

7. The process of claim 1 wherein said hydrogen-containing gas also contains substantial amounts of carbon monoxide.

RALPH BURGESS MASON.

reduced crude or residua with hydrogen in the References oued in the fue of this patent absence of catalyst prior to the homogenetous de- UNITED STATES PATENTS sulfurizing process; appreciable reduc ion in Number Name D a catalyst and promoter fequlfements my be 809,087 Blackmore Jan. 2te1906 realized. 1,257,829 Evans Feb. 26, 1918 The effectiveness of the halogen promoted 2,516,877 'Horne et al Aug. 1, 1950 metal carbonyl catalyzed hydrosulfurizing of heavy feed stocks is clearly demonstated by the following autoclave data showing results obtained when NiiCOMl promoted with a small OTHER REFERENCES

Claims (1)

1. THE PROCESS OF DESULFURIZING AND UPGRADING SULFUR-CONTAINING HIGH BOILING PETROLEUM FRACTIONS WHICH COMPRISES CONTACTING SAID FRACTIONS IN A HYDROGENATION ZONE WITH A HYDROGEN-CONTAINING GAS IN THE PRESENCE OF AN IRON GROUP METAL CARBONYL CATALYST AND A HALOGEN PROMOTER, MAINTAINING WITHIN SAID ZONE, A PRESSURE IN THE RANGE OF ABOUT 500-5000 P. S. I. G. AND A TEMPERATURE IN THE RANGE OF ABOUT 300*-900* F. AND RECOVERING A PRODUCT CONTAINING SUBSTANTIALLY LESS SULFUR THAN SAID FIRST-NAMED FRACTION.

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