DE69206314T2 - Hydroconversion process. - Google Patents

Description

This invention relates to the hydroconversion of heavy hydrocarbon oils. More particularly, it relates to a hydrotreating catalyst system that enables operation to provide increased conversion of 538ºC (1000ºF+) feed to lower boiling products.

As is well known to those skilled in the art, oil refinery operators wish to convert high boiling fractions, such as vacuum residue, into lower boiling fractions that are easier to handle and/or market. Examples of the large number of prior art patents directed at this problem are the following:

US-A-4,579,646 discloses a bottoms visbreaking hydroconversion process in which hydrocarbon feedstock is partially coked and the coke in the feedstock is contacted with an oil-soluble metal compound of a Group IV-B, V-B, VII-B or VIII metal to provide a hydroconversion catalyst.

US-A-4,724,069 discloses hydrofining in the presence of a supported catalyst containing a VI-B, VII-B or VIII metal on Alumina, silica or silica-alumina. A naphthenate of Co or Fe is introduced as an additive with the charge oil.

US-A-4,567,156 discloses hydroconversion in the presence of a chromium catalyst prepared by adding a water-soluble aliphatic polyhydroxy compound (such as glycerin) to an aqueous solution of chromic acid, adding a hydrocarbon thereto and heating the mixture in the presence of hydrogen sulfide to give a slurry.

US-A-4,564,441 discloses hydrofining in the presence of a decomposable compound of a metal (Cu, Zn, III-B, IV-B, VI-B, VII-B or VIII) mixed with a hydrocarbon-containing feed; and the mixture is then contacted with a "suitable refractory inorganic material" such as alumina.

US-A-4,557,823 discloses hydrofining in the presence of a decomposable compound of a IV-B metal and a supported catalyst containing a metal from VI-B, VII-B or VIII.

US-A-4,557,824 discloses demetallization in the presence of a decomposable compound of a VI-B, VII-B or VTII metal fed with the charge and a heterogeneous catalyst containing a phosphate of Zr, Co or Fe.

US-A-4,551,230 discloses demetallization in the presence of a decomposable compound of a IV-B, V-B, VI-B, VII-B or VIII metal fed with the feed and a heterogeneous catalyst containing NiAsx on alumina.

US-A-4,430,207 discloses demetallization in the presence of a decomposable compound of a V-B, VI-B, VII-B or VIII metal, which is fed with the feed, and a heterogeneous catalyst containing a phosphate of Zr or Cr.

US-A-4,389,301 discloses hydroprocessing in the presence of added dispersed hydrogenation catalyst (typically ammonium molybdate) and added porous contact particles (typically FCC catalyst fines, alumina or naturally occurring clay).

US-A-4,352,729 discloses hydrotreating in the presence of a molybdenum blue solution in polar organic solvent, which is introduced with the hydrocarbon feed.

US-A-4,338,183 discloses coal liquefaction in the presence of finely divided metal catalyst without a support.

US-A-4,298,454 discloses hydroconversion of a coal-oil mixture in the presence of a thermally decomposable compound of a IV-B, V-B, VI-B, VII-B or VIII metal, preferably Mo.

US-A-4,134,825 discloses hydroconversion of heavy hydrocarbons in the presence of an oil-soluble compound of IV-B, V-B, VI-B, VII-B or VIII metal added to the charge, the compound being converted to a solid, non-colloidal form by heating in the presence of hydrogen.

US-A-4,125,455 discloses hydrotreating in the presence of a fatty acid salt of a VI-B metal, typically molybdenum octoate.

US-A-4,077,867 discloses hydroconversion of coal in the presence of an oil-soluble compound of V-B, VI-B, VII-B or VIII metal plus hydrogen donor solvent.

US-A-4,067,799 discloses hydroconversion in the presence of a metal phthalocyanine plus dispersed iron particles.

US-A-4,066,530 discloses hydroconversion in the presence of (i) an iron component and (ii) a catalytically active further metal component, prepared by dissolving an oil-soluble metal compound in the oil and converting the metal compound in the oil to the corresponding catalytically active metal component.

It is an object of this invention to provide a novel process for hydroconversion, particularly characterized by achieving increased conversion. Other objects will be apparent to those skilled in the art.

According to the present invention there is provided a process for the catalytic hydroconversion of a feed hydrocarbon oil containing from 50-98 weight percent of components boiling above 538°C (1000°F) to convert from 30-90 weight percent thereof to components boiling below 538°C (1000°F), which comprises passing said feed hydrocarbon oil containing from 50-98 weight percent of components boiling above about 538°C (1000°F) into contact with (i) a solid heterogeneous catalyst containing, as a hydrotreating component, a Group IV-B, VB, VI-B, VII-B or VIII metal on a support, and (ii), as an oil-soluble catalyst, a molybdenum compound and a cobalt compound; said batch hydrocarbon oil is maintained in said conversion zone at conversion conditions in the presence of hydrogen and mercaptan until from 30-90 weight percent of said components boiling above 538ºC (1000ºF) are converted to components boiling below 538ºC (1000ºF); and said converted oil is recovered.

The feedstock that can be treated by the process of this invention can include high boiling hydrocarbons, typically those having an initial boiling point (ibp) above about 343°C (650°F). This process is particularly useful for treating feedstock hydrocarbons containing a significant amount of components boiling above about 538°C (1000°F) to convert a substantial portion thereof to components boiling below 538°C (1000°F).

Typical of these streams are heavy crude oil, topped crude oil, vacuum residue, asphaltenes, tars, coal liquids, visbreaker bottoms, etc. An example of such batch streams may be a vacuum residue obtained by blending vacuum residue fractions from Alaska North Slope Crude (59 vol. %), Arabian Medium Crude (5 vol. %), Arabian Heavy Crude (27 vol. %) and Bonny Light Crude (9 vol. %) with the properties listed in Table I: TABLE I PROPERTY Batch API Gravity Composition (wt.%)

Alcor Microcarbon Residue (McR) (%) 19.86

n-C₇-insoluble substances (%) 11.97

Metal content (wppm)

Ni 52

V131

F 9

Cr 0.7

Well 5

It is a characteristic of these batch hydrocarbons that they contain undesirable components such as typically nitrogen (in an amount up to 1 wt%, typically 0.2-0.8 wt%, e.g. about 0.52 wt%), sulfur (in an amount up to 10 wt%, typically 2-6 wt%, e.g. about 3.64 wt%) and metals including Ni, V, Fe, Cr, Na, etc. (in amounts up to 900 wppm, typically 40-400 wppm, e.g. 198 wppm). The undesirable asphaltene content of the batch hydrocarbon can be as high as 22 wt%, typically 8-16 wt%, e.g. 11.97 wt% (analyzed as components insoluble in normal heptane).

The API gravity of the charge may be as low as minus 5, typically minus 5 - plus 35, e.g. about 5.8. The content of components boiling above about 538ºC (1000ºF) may be as high as 100 wt%, typically 50-98+ wt%, e.g. 93.1 wt%. The Alcor MCR Carbon content may be as high as 30 wt%, typically 15-25 wt%, e.g. 19.86 wt%.

In the practice of the process of this invention, the feed hydrocarbon oil may be fed to a hydroconversion process in which conversion to liquid phase occurs at conversion conditions including 371°C-454°C (700°F-850°F), preferably about 399°C-432°C (750°F-810°F), e.g. 426ºC (800ºF), at a hydrogen partial pressure of about 3.5-34.6 MPa (500-5000 psig), preferably about 10.4-17.3 MPa (1500-2500 psig), e.g. 13.9 MPa (2000 psig)

It is a feature of the process of this invention that a catalytically effective amount of an oil-miscible, preferably an oil-soluble, catalyst compound comprising a combination of a molybdenum salt and a cobalt salt is added to the feed hydrocarbon oil (preferably prior to feeding to the hydroconversion).

The salts can typically be:

(i) Metal salts of aliphatic carboxylic acids

Molybdenum stearate

Molybdenum palmitate

Molybdenum myristate

Molybdenum octoate

(ii) Metal salts of naphthenic carboxylic acids

Cobalt naphthenate

Molybdenum naphthenate

(iii) Metal salts of alicyclic carboxylic acids

Molybdenum cyclohexanecarboxylate

(iv) Metal salts of aromatic carboxylic acids

Cobalt benzoate

Cobalt-o-methylbenzoate

Cobalt-m-methylbenzoate

Cobalt phthalate

Molybdenum p-methylbenzoate

(v) Metal salts of sulfonic acids

Molybdenum benzenesulfonate

Cobalt p-toluenesulfonate

(vi) Metal salts of sulfinic acids

Molybdenum benzenesulfinate

(vii) Metal salts of phosphoric acids

Molybdenum phenyl phosphate

(viii) Metal salts of mercaptans

Cobalthexylmercaptide

(ix) Metal salts of phenols

Cobalt phenolate

(x) Metal salts of polyhydroxyaromatic compounds

Molybdenum resorcinate

(xi) Organometallic compounds Molybdenum hexacarbonyl

Cyclopentadienylmolybdenumtricarbonyl

(xiii) Metal salts of organic amines

Cobalt salt of pyrrole

The preferred compounds may be cobalt naphthenate, molybdenum hexacarbonyl, molybdenum naphthenate and molybdenum octoate.

According to the invention, the combined use of molybdenum (e.g. as the naphthenate) and cobalt (e.g. as the naphthenate) provides a positive synergistic accelerating effect on the catalytic desulfurization and demetallization. Typically, cobalt can be used in an amount of 0.2-2 moles, e.g. 0.4 moles per mole of molybdenum can be added.

The metal compounds to be employed are oil-miscible and preferably oil-soluble, i.e. they are soluble in the charge hydrocarbon oil in an amount of at least 0.01 g/100 g, typically 0.025-0.25 g/100 g, e.g. about 0.1 g/100 g or alternatively they are readily dispersible in the charge hydrocarbon oil in an amount of at least these amounts. It is also a feature of these metal compounds that, when activated as set out hereinafter, the activated compounds are also oil-miscible in the hydrocarbon oils with which they come into contact during the practice of the process of this invention.

The activation of the oil-miscible compounds of molybdenum and cobalt according to the practice of the process of this invention can be effected either by pretreatment (prior to hydroconversion) or in situ (during hydroconversion). It is preferred to effect the activation in situ in the presence of the hydrogenation catalyst in order to achieve a highly dispersed catalytic species.

Activation according to the preferred method can be carried out by adding 10-200 wppm, e.g. 30 parts of metal compound to charge hydrocarbon at 15º-149ºC (60ºF-300ºF), e.g. 94ºC (200ºF). The mixture is activated by heating to 204º-446ºC (400ºF-835ºF), typically 2600ºF-370ºC (500ºF-700ºF), e.g. 315ºC (600ºF) at a hydrogen partial pressure of 3.5-34.5 MPa (500-5000 psig), typically 7.0-20.8 MPa (1000-3000 psig), e.g. 13.9 MPa (2000 psig) and at a gaseous mercaptan partial pressure of 0.1-3.5 MPa (5-500 psig), typically 0.15-2.2 MPa (10-300 psig), e.g. 0.4 MPa (50 psig). The total pressure can be 3.5-38.0 MPa (500-5500 psig), typically 7.0-22.8 MPa (1000-3300 psig), eg 14.2 MPa (2050 psig). Typically the gas may contain 40-99 vol.%, typically 90-99 vol.%, eg 98 vol.% hydrogen and 1-10 vol.%, eg 2 vol.% mercaptan such as hydrogen sulphide. The activation time may be 1-12, typically 2-6, eg 3 hrs.

In this embodiment, it will be noted that activation may occur at a temperature lower than the transition temperature.

The mercaptans that may be employed may include hydrogen sulfide, aliphatic mercaptans such as typically methyl mercaptan, lauryl mercaptan, aromatic mercaptans; dimethyl disulfide, carbon disulfide.

These mercaptans obviously decompose during the activation process. It is not clear why this treatment activates the metal compound. It could be possible that the activity is generated as a result of metal sulfides formed during the treatment.

If the sulfur content of the feed hydrocarbon is above about 2 wt.%, it may not be necessary to add a mercaptan during activation, i.e., hydrodesulfurization of the feed may provide sufficient mercaptan to activate (i.e., sulfide) the oil-miscible decomposable catalyst.

In an alternative activation process, the oil-miscible metal compound could be activated in the presence of an oil compatible with the batch oil, i.e. a separate portion of the batch oil or a different oil compatible with the batch oil. In this alternative, the oil-miscible metal compound could be added to the oil in an amount which is considerably greater (e.g. 2-20 times) than is the case when the compound is activated in the presence of the charge stream. After activation (under the same conditions that prevail when activation is carried out in the charge stream), the compatible oil containing the now activated metal could be added to the charge stream in an amount sufficient to provide activated oil-miscible metal compound therein in the desired amount.

In yet another embodiment, activation could be carried out by subjecting the feed hydrocarbon oil containing the oil-miscible metal compound to hydroconversion conditions including a temperature of 370°-462°C (700°F-850°F), preferably about 399°-432°C (750°F-810°F), e.g., 427°C (800°F), at a hydrogen partial pressure of about 3.5-34.5 MPa (500-5000 psig), preferably about 10.4-13.9 MPa (1500-2000 psig), e.g., 13.9 MPa (2000 psig) - in the presence of a mercaptan but in the absence of heterogeneous Hydroconversion catalyst.

In the preferred embodiment, the activation can be carried out during the hydroconversion, i.e. in the presence of the heterogeneous hydroconversion catalyst, hydrogen and mercaptan.

Hydroconversion is carried out in the presence of solid heterogeneous catalyst containing, as a hydrogenation component, a metal of Group IV-B, V-B, VI-B, VII-B or VIII on a support which may typically contain carbon or an oxide of aluminum, silicon, titanium, magnesium or zirconium. Preferably, the catalyst may contain a metal of Group VI-B and VIII - typically nickel and molybdenum.

If the metal is a Group IV-B metal, it can be titanium (Ti), zirconium (Zr) or hafnium (Hf).

If the metal is a Group V-B metal, it can be vanadium (V), niobium (Nb) or tantalum (Ta).

If the metal is a Group VI-B metal, it can be chromium (Cr), molybdenum (Mo) or tungsten (W).

If the metal is a Group VII-B metal, it can be manganese (Mn) or rhenium (Re).

If the metal is a Group VIII metal, it can be a base metal such as iron (Fe), cobalt (Co) or nickel (Ni), or a noble metal such as ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir) or platinum (Pt).

The solid heterogeneous catalyst may also contain, as an accelerator, a metal of Groups I-A, I-B, II-A, II-B or V-A.

If the accelerator is a metal from Group I-A, it may be preferably sodium (Na) or potassium (K).

If the accelerator is a metal from Group I-B, it may preferably be copper (Cu).

If the accelerator is a Group II-A metal, it can be beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) or radium (Ra).

If the accelerator is a Group II-B metal, it can be zinc (Zn), cadmium (Cd) or mercury (Hg).

If the accelerator is a metal from Group V-A, it can be arsenic (As), antimony (Sb) or bismuth (Bi).

The hydrogenation metal can be loaded onto the solid heterogeneous catalyst by immersing the catalyst support in solution (e.g. ammonium heptamolybdate) for 2-24 hours, e.g. 24 hours, followed by drying at 15.5º-149ºC (60ºF-300ºF), e.g. 93ºC (200ºF) for 1-24 hours, e.g. 8 hours, and calcining for 1-24 hours, e.g. 3 hours, at 399º-594ºC (750ºF-1100ºF), e.g. 499ºC (930ºF)

The promoter metal can preferably be loaded onto the solid heterogeneous catalyst by immersing the catalyst support (preferably carrying the calcined hydrogenation metal - although they can be added simultaneously or in any order) in solution (e.g. bismuth nitrate) for 2-24 hours, e.g. 24 hours, followed by drying at 15.5º-149ºC (60ºF-300ºF), e.g. 93ºC (200ºF), for 1-24 hours, e.g. 3 hours, and calcining at 299º-594ºC (570ºF-1100ºF), e.g. 399ºC (750ºF), for 1-12 hours, e.g. 3 hours.

The solid heterogeneous catalyst used in the process of this invention may be characterized by a total pore volume of 0.2-1.2 cc/g, e.g. 0.77 cc/g; a surface area of 50-500 m²/g, e.g. 280 m²/g; and a pore size distribution as follows: Pore diameter Å Volume cc/g

In another embodiment, it may have a pore size distribution as follows: Pore diameter Å Pore volume cc/g typical

The solid heterogeneous catalyst may typically contain 4-30 wt%, e.g. 9.5 wt% Mo, 0-6 wt%, e.g. 3.1 wt% Ni and 0-6 wt%, e.g. 3.1 wt% promoter metal, e.g. bismuth. The LHSV in the hydroconversion reactors may be 1-2, e.g. 0.7. Preferably, the heterogeneous catalyst may be used in the form of extrudates with a diameter of 0.7-6.5 mm, e.g. 1 mm and a length of 0.2-25 mm, e.g. 5 mm.

Hydroconversion can be carried out in a fixed bed, a moving bed, a fluidized bed or preferably an ebullated bed.

It is a feature of the process of this invention that hydroconversion can be carried out in one or more beds. It has been found that the active form of the catalyst forms or accumulates in the first of several reactors; and accordingly, increases in conversion and heteroatom removal activities appear to occur in the first of several reactors.

Effluent from hydroconversion is typically characterized by an increase in the content of liquids boiling below 538ºC (1000ºF). Typically, the Wt% conversion of material boiling above 538ºC (1000ºF) 30%-90%, e.g. 67%, which is typically 5%-25%, e.g. 12%, better than achieved by prior art techniques.

It is a feature of this invention that it enables the achievement of enhanced removal of sulfur (HDS conversion), of nitrogen (HDN conversion) and of metals (HDNi and HDV conversion). Typically, HDS conversion may be 30-90%, e.g. 65%, which is 1%-10%, e.g. 4%, higher than the control runs. Typically, the HDN conversion may be 20%- 60%, e.g. 45%, which is 1%-10%, e.g. 4%, higher than control runs. Typically, the HDNi plus HDV conversion may be 70%-99%, e.g. 90%, which is typically 5%-20%, e.g. 13%, higher than control runs.

The practice of the process of this invention will be apparent to those skilled in the art from the following, wherein, as elsewhere in this specification, all parts are by weight unless otherwise indicated. An asterisk indicates a control example.

EXAMPLE

In this example, which represents the best mode presently known for carrying out the process of this invention, the charge hydrocarbon is a mixture of vacuum residue recovered from Alaskan North Slope (59 vol.%), Arabian Medium (5 vol.%), Arabian Heavy (27 vol.%) and Bonny Light (9 vol.%).

The solid heterogeneous catalyst is a commercially available hydrotreating catalyst (sold by Criterion Catalyst Company as HDS-14438 catalyst) containing 2.83 wt% nickel and 8.75 wt% molybdenum on alumina.

This catalyst is extrudates of 0.8 mm (1/32") diameter and ~ 5 mm long with a surface area of 285.2 m²/g and a total pore volume of 0.78 cc/g. The pore size distribution is: 0.28 cc/g > 250A; 0.21 cc/g > 500A; 0.19 cc/g > 1500A; 0.11 cc/g > 4000A.

In this example, molybdenum naphthenate is added to the hydrocarbon feed in an amount to provide 60 ppm molybdenum metal and cobalt naphthenate to provide 13 ppm cobalt metal. The catalyst is activated in situ during hydroconversion at 418ºC (785ºF) and a hydrogen partial pressure of 13.9 MPa (2000 psig). The hydrogen feed is 1061 Nm3/m3 (6300 SCFB). The feed LHSV is 0.4-1 hr-1.

The results are given in the table below, which shows the 538ºC (1000ºF) conversion, HDS conversion, HDV conversion, HDNi conversion and cyclohexane insolubles - all expressed in wt%.

Comparative tests were conducted in which no molybdenum or cobalt accelerator was used and molybdenum accelerator was used alone. Example cyclohexane

From the table above the following conclusion can be drawn:

(1) Addition of a small amount of cobalt with the molybdenum has a synergistic effect on heteroatom removal (HDS, HDV, HDNi).

(2) The addition of cobalt and molybdenum shows a further decrease in coke content compared to the use of molybdenum alone.

Although this invention has been illustrated by reference to specific embodiments, it will be apparent to those skilled in the art that various bates and modifications may be made which clearly fall within the scope of the appended claims.

Claims (8)

1. A process for catalytically hydroconverting a batch hydrocarbon oil containing 50-98 weight percent of components boiling above 538ºC (1000ºF) to convert from 30-90 weight percent thereof to components boiling below 538ºC (1000ºF), which comprises passing said batch hydrocarbon oil containing from 50-98 weight percent of components boiling above about 538°C (1000°F) into contact with (i) a solid heterogeneous catalyst containing, as a hydrotreating component, a Group IV-B, V-B, VI-B, VII-B or VIII metal on a support, and (ii), as an oil soluble catalyst, a molybdenum compound and a cobalt compound; maintaining said batch hydrocarbon oil in said conversion zone at conversion conditions in the presence of hydrogen and mercaptan until from 30-90 weight percent of said components boiling above 538ºC (1000ºF) are converted to components boiling below 538ºC (1000ºF); and said converted oil is obtained. 2. A process according to claim 1, wherein said oil-soluble catalyst contains molybdenum naphthenate and cobalt naphthenate. 3. A process according to claim 1 or claim 2, wherein said oil-soluble catalyst in the charge hydrocarbon is soluble in an amount of at least 0.01 grams per 100 g of batch hydrocarbon. 4. A process according to any one of claims 1 to 3, wherein said oil-soluble catalyst is activated prior to feeding to said conversion zone. 5. A process according to claim 4, wherein the activation is effected by heating to 204-446°C (400°F-835°F) at 3.5-34.5 MPa (500-5,000 psig) hydrogen partial pressure in the presence of mercaptan or in the presence of an oil miscible with said charge oil. 6. A process according to any one of claims 1 to 5, wherein said oil-soluble catalyst is activated during said conversion. 7. A process according to any one of claims 1 to 6, wherein said heterogeneous catalyst contains (i), as hydrogenation component, a metal of Groups IV-B, V-B, VI-B, VII-B or VIII and (ii), as an accelerator, a metal of Group I-A, I-B, II-A, II-B or V-A. 8. A process according to claim 7, wherein said heterogeneous catalyst contains nickel and molybdenum on alumina.