US2859169A - Heavy oil conversion process - Google Patents

Description

Nbv. 4, 1958 c. B. HERMAN 2,859,169

HEAVY OIL CONVERSION PROCESS Filed Jan. 20, 1955 CASES 1 I31 7 warm I monocal "TAIL GAS HGURE I uses a HYDROGEN I TAIL us 6 1 h P mongggecmg 5s 51 momma rancnoumn 4. mcnomoa 5| CASPHALT 68 J 61 C=Z; n

I253 s2 olwnn um: up \Hm J com 19 5a- REGYCLE) 69 RESIDUAL I cvcLE smc FUEL FIGURE II cuAnLisa HERMAN mvmon Bur (CW ATTORNEY United States Patent Ofifice 2,859,169 Patented Nov. 4, 1958 HEAVY OILCONVERSION PROCESS Application January 20, 1955, Serial No. 483,077

3 Claims. (Cl. 208-59)v The present invention relates to the conversion of heavy hydrocarbons. concerned with a process for producing naphthas of motor firel'quality and gas oils of catalytically cracking quality from'heavy oils such as asphalts and vacuum residua. This'invention proposes a combination heavy oil conversion process comprising the steps of catalysis and hydrogenolysis.

Inib'riefcompass, the present invention comprises a heavy oil conversion process wherein a heavy oil is converted in the presence of a diluent oil. The diluent oil is aromatic-naphthenic in nature, and upon hydrogenation displays good hydrogen donor properties. A mixture of a heavy oiland a diluent oil is subjected to hydrocracking conditions in the presence of a hydrogenation catalyst and in the presence of free hydrogen. The products from the hydrocracking are separated to obtain a fraction containing"th'e diluent oil, now partially hydrogenated, and this fraction-is mixed'with additional amounts of the heavy oil) Thissecond mixture is then thermally treated under hydrogen donor cracking conditions toobtain further conversion of the oil with transfer of. hydrogen from the hydrogenated diluent oilitotheiconversion products.

"succinctly, this invention comprises theessential'steps of hy'drocracking a heavy oil' feed stock While the. feed stock: is dilutedwith ahighly aromatic oil to obtainconversion. products and a hydrogen. donor diluent:

to c'onvertheavy hydrocarbon materials such as petroleum:

residha bydirectly hydrogenating the material using a hydrogenation catalyst. In such a process, conditions are adjusted-toobtain cracking of the hydrocarbon feed with introduction of hydrogen into the fragment molecules formetl 'by the cracking. Thus high boiling, normally valu'eless h'ydrocarbonaceous materials are converted into lowerboiling products having a much higher value. Because this high boiling heavy material is usually extremely deleterious to catalyst and has a high propensity to-deposit' coke on catalyst, care must be used in this type ofcatalytic upgrading process. Despite this operating: drawback of catalyst deterioration, this process is gaining-favor. Not only'are increased amounts of valuuable' products obtained from normally Waste materials, but the products obtained are of high quality. This hydrocracking process substantially desulfurizes the material treated and does not yield any substantial amount of unsaturated orunstable products.

An alternative method of upgrading heavy oils, termed hydrogen donor diluent cracking (HDDC), has also been proposed. in this method the hydrogen is introducedinto' the oil being converted by a hydrogen carrier material in the absence of catalyst. In this HDDC process, a hydrogen donor diluent material, aromatic-naphthenic in nature, is especially prepared by partial hydrogenation The invention is more particularly 111$: hydrogen donor'diluent is thenlusedto convert further amounts ofthe' feed stock in the absence'of a catalyst and.

and is admixed with the oil to be converted. The resulting mixture is then thermally treated such that the oil is cracked and hydrogen is transferred from the donor. diluent to the cracked products. In this manner of. hydrocracking oils, the oil being upgraded is not contacted directly with a hydrogenation catalyst and does not impair catalyst activity by contamination. This proposed HDDC process has disadvantages in that aspecial hy-. drogenation zone is required for preparation of the diluent and that little desulfurization of the oil occurs.

The present invention proposes an integration of the two above-described hydrocracking processes. The inherent disadvantages of each process are greatly minimized through this integration and yet their advantages of being able to upgrade difficult to convert oils are re-' tained. By means of this combination process, heavy oils can be converted to optimum yields of catalytic cracking-quality gas oils and-high quality naphthas or gasolines. Therelative proportion of gas oils and gasolines may be varied as demanded by economic considerations.

In light of the above, it is an object of this invention to propound a combination process for upgrading heavy low valueoils. It is another object of this invention to present to the art a conversion process comprising the steps of hydrocracking an oil diluted with a hydrogen donor precursor in the presence of hydrogenation catalyst to obtain lighter conversion products and ahydrogen donor-diluent; and then using the hydrogen donor diluent, or a mixture of the diluent and some or all of the heavier products from the hydrocracking process, to convert further amounts of the oil in a hydrogen donor diluent cracking. zone.

These and other objects and advantages will become more clear as thisdescription proceeds during which the attached drawings, forming'a part of" this specification, are described indetail. .The drawings are presented' by way of illustration. only. and. the invention is not to b limited thereby.

Figure [of theattached drawing depicts the two-Ste conversionprocess of the present invention wherein the hydrogen donor diluent material is. utilized on a once through basis.

Figurell: of the drawing depicts this two-step process when recycle operation is practiced as to the hydrogen donor diluent material.

Theheavy' oil whichforms the principal charging stock forthe'present' invention is preferably a hydrogen deficient petroleum derived oil such as a heavy crude oil or aresidual fraction therefrom. Particularly preferred is aheavy oil characterized. by an API gravity of -5 to 20, a: Conradscn carbon of 5 to 50 wt. percent and' 'aninitial: boiling point above about 850 to 1100 F. This invention is, however,,capable of enjoying broader applications. Thus heavy oils such as coaltars, shale oils, natural tars and'asphalts, cycle stocks, aromatic extracts, etc. may conveniently be processed. V

Thehydrogen donor diluent precursor used in this invention is composed of predominantly proportions of; aromatic-naphthenic molecules, or partially condensed ring structures, having the ability to readily takeup hya thermal cracking zone relatively unaltered. These structures are, therefore, susceptible to being recovered from reaction mixtures and being regenerated by partial hydrogenation. Some loss of the diluent material will, however, be experienced.

In particular, it has been found that the thermal tars obtained by the thermal cracking of catalytic cycle stocks contain excellent hydrogen donor type molecules. It has also been found, however, that lube oil extracts, virgin gas oils, extracts of catalytic cycle stocks and clarified oils, or the cycle stocks and clarified oils themselves, and cycle oils and heavier products from high temperature, low pressure thermal cracking operations can serve as sources of the donor diluent.

. The catalyst that is used in the first hydrocracking stage of this invention is preferably a sulfur resistant hydrogenation catalyst such as cobalt molybdate, nickel tungsten sulfide and many other catalyst of this nature which are not deactivated by contact with sulfur contaminating materials. The cobalt molybdate catalyst may actually be mixtures of cobalt, molybdenum, and other selected metals. These catalysts can be supported on suitable carriers such as alumina, kieselguhr, charcoal, silica gel, celite, etc. and may have certain compounds added to them to improve their properties. The catalyst is preferably used as a fixed bed composed of catalyst particles of a size in the range of to 80 mesh.

The catalyst may be suitably activated or treated prior to use. With cobalt molybdate supported on alumina this treatment may comprise heating the catalyst to about 1400 F. for a time of about 6 to 48 hours followed with washing with gas oil.

The catalyst may be suitably regenerated by means known by the art. For example, the catalyst can be regenerated by treatment with an oxygen containing gas to turn oif coke-like deposits. Two or more catalytic reactors may be used in this invention to permit continuous operation of the process while allowing regeneration of the catalyst. Alternatively, a fluidized catalyst operation can be used with one vessel for carrying out the reaction and one for catalyst regeneration.

The activity of the catalyst may be increased during use without severe oxidation regeneration treatment by discontinuing the flow of the heavy oil to the catalyst chamber and allowing the diluent to wash over the catalyst to remove, at least in part, some of the carton and metal contaminant deposits.

The operating conditions applicable to the following description of Figure I are conveniently summarized in Table I presented hereinafter.

Referring now to Figure I, the heavy oil to be upgraded, e. g., a vacuum residuum in line 1, is admixed with a hydrogen donor diluent precursor supplied via lines 15 and 2. Certain recycle streams may also be added at this point as will hereinafter appear. The resulting mixture is heated in heater 3, which may be a conventional furnace, to the necessary conversion temperature and then is passed by line 4 to the hydrocracking zone 5. Hydrogen containing gas is admitted tothe contents of line 4 by line 6. Makeup hydrogen may be supplied by line 7. This hydrogen gas may be suitably preheated, if desired. The hydrogen containing gas has preferably a purity of over 70%. After passing through the hydrocracking zone, the mixture is transferred by line 8 to a separator 9 wherein the spent hydrogenation gas is removed. This spent gas is removed by line 10 from the separator and a portion of it may be bled from the process, and the remainder transferred to the hydrocracking zone by line 6.

After this separation, the cracked mixture is transferred by line 11 to a conventional fractionator 12. The cracked mixture may be divided into as many fractions as desired at this point. As shown, however, only material boiling in the naphtha range and lighter, e. g., below 430 F., is removed and transferred by line 13 to further con-- As shown, products boiling in the naphtha range and lighter are removed by line 19 and combined with the l ventional separating and finishing processes.

The remainder of the material in this example is transferred by line 14 to the HDDC unit. It is to be pointed out, however, that a diluent fraction only can be recovered at this point and transferred to the HDDC unit.

The original diluent supplied to the process by line 15.

is selected to be of a boiling range different from that of the residuum. Preferably, the lowest boiling range. of diluent is used that will still sufliciently solubilize with the heavy oil feed. It is preferred to use diluents boiling in the range Within the limits of 400 to 650 F., 211- though diluents of higher boiling range up to about 1,000

F. can readily be used. If a diluent of a 430 to 650 F. boiling range is used, then in order to recover this diluent in fractionator 12, the material transferred by line 14 has a boiling point at least as low as 430 F.

The hydrogen donor material in line 14 which, in this case illustrated, also comprises the heavy bottoms from the hydrocracking zone, is admixed with additional amounts of residuum supplied by line 28. Preferably the; hydrogen donor material and heavy bottoms in line 141 are admixed with /2 to 1 vols. of residuum. In normalx' operation, about 25 to 50% of the heavy oil or residuum feed to the process will be processed in the hydrocracking zone 5 and the remainder will be treated in the HDDC unit 16. Additional recycle streams may be mixed with the feed to the HDDC unit if desired, as will hereinafter appear.

The residium diluted with the hydrogen donor diluent material is then subjected to hydrogen donor diluent Any conventional means may be zone 18. The thermally treated mixture may be separated into several fractions, if desired, at this point.

contents of line 13. Heating oils boiling in the range above naphtha up to about 650 to 700 F. are removed by line 20 as product. These heating oils may conveniently be subjected to further processing such as severe hydrocracking or catalytic cracking to obtain further amounts of naphthas of gasoline quality or used as flux The bottoms from the separation are transferred by line 21 to a conventional vacuum distilla-.

for residual fuels.

tion unit 22 wherein gas oils boiling up to about 950? to 1100 F. are removed by line 23. These gas oils may also be catalytically cracked or can be used as a flux in residual fuels.

The bottoms from this separation are removed by line 24. It is desirable to remove a portion of these bottoms by line 25 to prevent undue buildup of extremely refractory constituents and catalyst contaminants in the i system. Preferably, for the process illustrated, approximately 5 to 50% of these bottoms will be bled from the process when a cut point of 1,000 F.'is used. The remainder of the bottoms is recycled to the hydrocracking zone via line 26 and/or the HDDC zonevia lines 26 and 27. Preferably all of the bottoms are recycled to the HDDC unit 16, as they are not amenable to further.

the selectivity of the hydrocracking step. Conversions in the range of 50 to vol. percent to 1050" F. and

However, this mild conversion greatly promotes catalyst life and 5 lighter products, based on fresh residuum feed, are preferably obtained in the HDDC unit.

These conversion ranges are preferred when it is desired to substantially completely convert the residuum. However, the process may be operated more in the nature of a vis-breaking process so as to'produce' substantial amounts'of residualfuel as demanded by market conditions'. "If a vis-breaking type operation is practiced, then the contents/ ot line 24 will not be recycled. When residual fuel isproduced, a portion of the heating oil in line preferably used to flux the residual oilwith gas oilinline 23 still being charged to catalytic cracking.

For the process as'described with reference to Figure I, the .opera tingconditions are summarized in Table I. Thistable also presents a' specific example of operating conditions. Table II presents the products obtainable from 1 the feed stocks indicated when the process is. o'p'erated'in accordance with example of Table I.

Table I Range Example Hydrocraeking zone;

. Pressure, p. s. i. g to 1,000 400. Temperature, "F 700' to 850.- 780.

Space velocity, v./v./h.r 0.2 to 2; 0.5.

Diluent/heavy oil ratio, vol 3/1 to 1/2 2/1. p p I Diluent boiling range, F wlligitllgl 400 to 430 to 650.

200 to 500 200 (consump- Hydrogenrate, s. c.f./bbl. mixture. on

300 to 1,000. 900 (charge). 1,050"t F.-Conversion, vol. per- 30 to 60 50.

Cata yst Sulfur Resist- Cobalt Moance Hydrolybdate.

genation Q. t Catalyst.

HDDC Zone:

' Pressure; p. s. i. g O-to 1,000."... 400.

. Temperature; T. 700 to 900.. 805.

" Throughput, v.'/v'./hr o 5 1.

Diluent/heavy oil 1 rati vol 1/1 to 1/3 1/2. Diluent boiling range, F 400 to 430 to 650.

1,050 F.(Jonversion, vol. per- 40 to 90 60.

cen

1 Including any recycle streams. 2 1,050 F. conversion is defined as 100 vol. percent fresh heavy 011 feed and diluent less vol. percent; of products boiling above 1,050 F.

Table II Heavy Oil Diluent- Feed Inspections Vacuum Aromatic Residuuln Extracts Elemental Analysis, Wt percent" Carbon 87. 0 89. 7 Hydroge 11. 0 8. 4 Sulfur.-- 2. 0 l. 34 Nitrogen and Oxygen- O. 56 E10 atomic ratio 1. 5 1. l2 Gravity, API 10.0 1.? Oonradson carbon, Wt. percent" 20 6.1) Ash at 800 0., Wt. percent.-- 0. 20 Trace Initial boiling point, F 900 409 Final boiling point, "F 950 Aromatics 85% Yields-Percent on Residuurn and diluent:

Ca-gas, Wt. percent 1.2g 04 Vol. percent 1. a C5430 F. Vol. percent naphtha 11. 4 430650 F., Vol. percent heating oilln t 6501,000 F., Vol. percent gas oil. 48. A 1,000 F+residual fuel 21. 2

With reference to Figure II, a process will be described wherein recycle operation as to the diluent precursor is practiced. The process is illustrated as requiring makeup diluent, but it has been found that with many feed stocks there will be a sufficient amount of aromaticnaphthenes in the feed, or materials that will reduce the aromatic-naphthenes to fully meet the diluent requirements of the process, particularly if the naphtha product is undercut to about 375 F. In some instances, an excess of diluent will be produced. For example, it has been found that a large amount of naphthalene will be produced by the process in some cases.

In this example an asphalt feed is supplied to the process by line 51 and is mixed'with diluent makeup material, from the sources previously indicated, supplied by line 52" and with various recycle streams supplied by line 53. The resulting mixture is then h'eat'edtd reaction temperatures in heater 54' and transferredto' a fixed bedhydrocracking zone 56 by line 55. Hydrogen is mixed with the heated mixture via line 57, makeup hydrogen being supplied to the process by line After being subjected to hydrocracking, the'mixture transferred to separator 60 via line 59 wherein the spent hydrogen gas or tail gas is removed by line 6-1. The mixture is then transferred-from the separator by line 62 to afractionator 63 wherein products boiling below 430 F. are separated and removed by line 64. In this case a diluent fraction boiling in the range of'ab out 430" to 700 Ffis separated and removed by line 65. The remaining bottoms are transferred by line 66 tovacuurii distillation unit 67. The hydrogen donor diluentfraction in line 65 is admixed with additionalamountsof fresli' asphalt supplied by line 68 and transferred to the thermal cracking or I-IDDC unit 69. After being thermally treated, the mixture is passed via line 70 to a' fractionator 71. Again naphthas and light gases are separated and removed by line 72 and mixed with the contents" of line 64 and sent to further conventional processing.

A fraction boiling in the diluent range is separated and transferred by lines 73 and 53 to the hydrocracking" unit. This fraction contains a substantial proportion of the'original diluent precursor introduced into the process because, as previously explained, these molecules are relatively refractory and will pass through the processwithout substantial alteration. However, material not displaying hydrogen donor properties such as parafiins are crac-ked'into the diluent boiling range and it is desir able to remove or bleed from the process a portionof this diluent fraction by line 74 as heating oil product. The makeup diluent supplied to the process by line 52 will make up this loss plus the small loss of diluent caused by cracking of the diluent molecules.

The bottoms from fractionator 71.boiling above about 700 F. are transferred via lines 75 and 66 to a vacuum fractionator 67. The combined bottoms from fractionators 63 and 71 have removed therefrom in the vacuum fractionator gas oils boiling up to about 1000 F. These gas oils are removed from the process via line 76. The bottoms from the Vacuum unit are transferred by lines 77 and 53 to the hydrocracking unit and/or by lines 77 and 78 to the HDDC unit. As previously described, it is desirable to bleed up to about 5 to 50% of this bottoms fraction from the process by line 79 as a residual fuel product. If it is desired to operate the process under milder conversion conditions, a substantial amount of residual fuel product may be withdrawn via line 79 and the bottoms recycle operation eliminated.

Instead of bleeding via line 74 some of the diluent fraction from the process in order to maintain its efiective aromaticity, other means may be used to concentrate the aromatic-naphthenes or aromatic ring structures in this fraction. For example, the contents of line 73 may be subjected to an extraction process such as phenol, furfurol, or sulfur dioxide extraction to concentrate the aromatics therein, and the rafiinate from the extraction process can be withdrawn from the process. Alternatively, the contents of line 73 may be subjected to an aromatization process to increase the aromatic content or can be subjected to mild thermal cracking to remove therefrom paraffins and alkyl groups that do not contribute to the hydrogen donor characteristics of the fractions.

Various modifications of this invention will be readily apparent to those skilled in the art. What is sought to be protected by Letters Patent is succinctly set forth in the following claims.

.What is claimed is:

1. A heavy oil conversion process which comprises forming a mixture of a heavy oil with a diluent oil suitable for being converted to a hydrogen donor diluent and comprising major proportions of aromatic-naphthenes, hydrocracking the mixture in the presence of a hydrogenation catalyst and in the presence of hydrogen under hydrocracking conditions to obtain a 1050 F. conversion in the range of 30 to 60%, separating the cracked mixture to obtain a fraction boiling above 400 F. containing said diluent oil now partially hydrogenated, admixing the fraction so separated with additional amounts of said heavy oil, thermally treating the resulting mixture under hydrogen donor diluent cracking conditions to obtain a 1050 F conversion in the range of 40 to 90%, and separating the thermally treated mixture.

2.. A hydrocarbon conversion process which comprises mixing with a heavy oil /2 to 3 vols of a diluent oil comprising major proportions of aromatic-naphthenes boiling in a range within the limits of 400 and 1000 F. to form a first mixture, adding to said first mixture 300 to 1000 s. c. f. of a free-hydrogen containing gas per vol. of mixture and passing the mixture over a hydro genation catalyst under hydrocracking conditions, said hydrocracking conditions including a temperature in the range of 700 to 850 F., a pressure in the range of to 1000 p. s. i. g., and a space velocity in the range of 0.2 to 2.0 v. /v./hr., whereby a conversion to 1050" F. and lighter material of said first mixture in the range of 30 to 50 vol. percent is obtained and a hydrogen donor diluent is secured, separating from the material so treated a fraction boiling above 400 F. displaying hydrogen donor properties, mixing said fraction with /2 to 1 vols. of additional amounts of said heavy oil to form a second mixture, thermally treating said second mixture under hydrogen donor diluent cracking conditions, said conditions including a temperature in the range of 700 to 900 F., a pressure in the range of .0 to 1000 pt s.i.-g.,1 and a throughput in the range of 0.5 to 5.0 v./v./hr.,,

whereby a conversion to 1050 F. and lighter material of saidsecond mixture in the range of ,50 to 80vol; percent is obtained, and separating the thermally treated mixture to obtain various product fractions. w i

3. A residual oil conversion process which comprises mixing 25 to of a residuum feed with /2to.j3, volumes of an aromatic-naphthenic containing diluent oil suitable for being converted to a hydrogen donor diluent and boiling within the limits of 400 to 100 F., hydro-1 cracking the resulting mixture in the presence of a hydrogenation catalyst and 300 to 1000 s. c. f. of hydrogen per barrel of mixture at a 1050 F.-eonversion in the, range of 30 to and at a pressure below 1000 p. s. i. .g., separating. from the hydrocracked mixture material boiling below about 400 F., mixing the remainder'of said hydroeracked mixture havingan appreciable quantity pr material suitable as a hydrogen donor diluent with the remainder of said residuum feed, thermally treating the second mixture so formed under hydrogen donor diluent. cracking conditions at a 1050 F. conversion the: range of 40 to separating the thermally cracked.

mixture to obtain a fraction boiling in the range of about 430 to 700 F.-, and returning said last named fraction to the hydrocracking zone as said -aromatic-naphthenic Cahn June 18,

Claims (1)

1. A HEAVY OIL CONVERSION PROCESS WHICH COMPRISES FORMING A MIXTURE OF A HEAVY OIL WITH A DILUENT OIL SUITABLE FOR BEING CONVERTED TO A HYDROGEN DONOR DILUENT AND COMPRISING MAJOR PROPORTIONS OF AROMATIC-NAPHTHENES, HYDROCRACKING THE MIXTURE IN THE PRESENCE OF A HYDROGENATION CATALYST AND IN THE PRESENCE OF HYDROGEN UNDER HYDROCRACKING CONDITIONS TO OBTAIN A 1050*F.- CONVERSION IN THE RANGE OF 30 TO 60%, SEPARATING THE CRACKED MIXTURE TO OBTAIN A FRACTION BOILING ABOVE 400*F. CONTAINING SAID DILUENT OIL NOW PARTIALLY HYDROGENATED, ADMIXING THE FRACTION SO SEPARATED WITH ADDITIONAL AMOUNTS OF SAID HEAVY OIL, THERMALLY TREATING THE RESULTING MIXTURE UNDER HYDROGEN DONOR DILUENT CRACKING CONDITIONS TO OBTAIN A 1050*F.- CONVERSION IN THE RANGE OF 40 TO 90%, AND SEPARATING THE THERMALLY TREATED MIXTURE.

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