Methods and systems for manufacturing lubrication oils

Abstract

Disclosed are methods and systems for manufacturing lubrication oils. In one embodiment, a method for manufacturing a lubrication oil includes the steps of receiving into an activated carbon guard bed unit an unconverted oil (UCO) feedstock, the UCO feedstock comprising polynuclear aromatic (PNA) compounds and contacting the UCO feedstock with activated carbon within the activated carbon guard bed unit to remove at least a portion of the PNA compounds, thereby forming a treated UCO feedstock.

Claims

1. A method for manufacturing a lubrication oil, the method comprising the steps of: hydrocracking a gas oil feedstock to provide a hydrocracked unconverted oil (UCO); receiving into an activated carbon guard bed unit said UCO feedstock, the UCO feedstock comprising polynuclear aromatic (PNA) compounds; and contacting the UCO feedstock with activated carbon within the activated carbon guard bed unit to remove at least a portion of the PNA compounds, thereby forming a treated UCO feedstock; and catalytically dewaxing the treated UCO feedstock directly following the contacting step.

2. The method of claim 1, wherein dewaxing comprises contacting the treated UCO feedstock with a dewaxing catalyst.

3. The method of claim 1, further comprising hydrofinishing the treated UCO feedstock.

4. The method of claim 3, wherein hydrofinishing comprises contacting the treated UCO feedstock with an amorphous or crystalline metal oxide hydrofinishing catalyst.

5. The method of claim 1, wherein contacting the UCO feedstock with activated carbon comprises contacting the UCO feedstock with activated carbon in a lead guard bed of a lead/lag guard bed unit, and wherein the UCO feedstock is not contacted with a lag guard bed of the lead/lag guard be unit.

6. The method of claim 1, further comprising providing the UCO feedstock.

7. The method of claim 6, wherein providing the UCO feedstock comprises providing a UCO feedstock having a normal boiling point of at least 600 F. (316 C.).

8. The method of claim 1, wherein removing at least a portion of the PNA compounds comprises removing at least a portion of the PNA compounds having five or more aromatic rings.

9. A method for manufacturing a lubrication oil, the method comprising the steps of: providing a UCO feedstock having a normal boiling point of at least 600 F. (316 C.) and selected from the group consisting of: gas oils and vacuum gas oils (VGO), hydrocracked gas oils and vacuum gas oils, deasphalted oils, slack waxes, foots oils, coker tower bottoms, reduced crude, vacuum tower bottoms, deasphalted vacuum residues, FCC tower bottoms and cycle oils and raffinates from a solvent extraction process, the UCO feedstock comprising polynuclear aromatic (PNA) compounds; receiving into an activated carbon guard bed unit the unconverted oil (UCO) feedstock; contacting the UCO feedstock with activated carbon within the activated carbon guard bed unit to remove at least a portion of the PNA compounds, thereby forming a treated UCO feedstock, wherein removing at least a portion of the PNA compounds comprises removing at least a portion of the PNA compounds having five or more aromatic rings, and wherein contacting the UCO feedstock with activated carbon comprises contacting the UCO feedstock with activated carbon in a lead guard bed of a lead/lag guard bed unit, and wherein the UCO feedstock is not contacted with a lag guard bed of the lead/lag guard be unit; dewaxing the treated UCO feedstock directly following the contacting step by contacting the treated UCO feedstock with a dewaxing catalyst; and hydrofinishing the treated UCO feedstock by contacting the treated UCO feedstock with an amorphous or crystalline metal oxide hydrofinishing catalyst.

10. A method for manufacturing a lubrication oil, the method comprising the steps of: receiving into an activated carbon guard bed unit an unconverted oil (UCO) feedstock, the UCO feedstock comprising polynuclear aromatic (PNA) compounds; and contacting the UCO feedstock with activated carbon within the activated carbon guard bed unit to remove at least a portion of the PNA compounds, thereby forming a treated UCO feedstock; catalytically dewaxing the treated UCO feedstock directly following the contacting step; and hydrofinishing the treated UCO feedstock.

11. The method of claim 10, wherein dewaxing comprises contacting the treated UCO feedstock with a dewaxing catalyst.

12. The method of claim 10, wherein hydrofinishing comprises contacting the treated UCO feedstock with an amorphous or crystalline metal oxide hydrofinishing catalyst.

13. The method of claim 10, wherein contacting the UCO feedstock with activated carbon comprises contacting the UCO feedstock with activated carbon in a lead guard bed of a lead/lag guard bed unit, and wherein the UCO feedstock is not contacted with a lag guard bed of the lead/lag guard be unit.

14. The method of claim 10, further comprising providing the UCO feedstock by hydrocracking gas oil.

15. The method of claim 10, further providing the UCO feedstock comprising a normal boiling point of at least 600 F. (316 C.).

16. The method of claim 15, wherein providing the UCO feedstock comprises providing a UCO feedstock selected from the group consisting of: gas oils and vacuum gas oils (VGO), hydrocracked gas oils and vacuum gas oils, deasphalted oils, slack waxes, foots oils, coker tower bottoms, reduced crude, vacuum tower bottoms, deasphalted vacuum residues, FCC tower bottoms and cycle oils and raffinates from a solvent extraction process.

17. The method of claim 10, wherein removing at least a portion of the PNA compounds comprises removing at least a portion of the PNA compounds having five or more aromatic rings.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The present embodiments will hereinafter be described in conjunction with the following drawing FIGURE, wherein like numerals denote like elements, and wherein:

(2) FIG. 1 is a process flow diagram illustrating a method implemented on a lubrication oil manufacturing system in accordance with various embodiments of the present disclosure.

DETAILED DESCRIPTION

(3) The following detailed description is merely exemplary in nature and is not intended to limit the application and uses of the embodiments described. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.

(4) The present disclosure generally provides methods and systems for manufacturing lubrication oils. The embodiments described herein employ the use of activate carbon beds to remove or reduce the presence of polynuclear aromatic compounds (PNAs). As used herein, activated carbon is suitable for absorb polar multi-ring species such as PNAs. The effluent unconverted oil (UCO) from the carbon bed is low in PNAs and would allow the product to meet desired specifications upon processing in downstream lubrication oil manufacturing units, without premature deactivation of down stream catalytic processes.

(5) Feedstocks suitable for use herein may be one or a combination of refinery streams having a normal boiling point of at least 600 F. (316 C.), although the process is also useful with oils that have initial boiling points as low as 435 F. (224 C.), and are generally referred to herein as unconverted oils (UCO). By having a normal boiling point of at least 600 F. (316 C.) is meant that 10% by volume of the feedstock has a boiling point at atmospheric pressure of at least 600 F. (316 C.). While higher boiling lube oil feedstocks can be processed in accordance with the present disclosure, the preferred feedstock will have a boiling range such that at least 85% by volume of the feedstock boils at 1250 F. (677 C.), and more preferably at most 1100 F. (593 C.). Such feedstocks, particularly vacuum gas oils, will contain from 35 wt. % to 70 wt. % aromatics, at least 40% of them being 2-ring and higher aromatics. Representative feedstocks that can be treated using the present process include gas oils and vacuum gas oils (VGO), hydrocracked gas oils and vacuum gas oils, deasphalted oils, slack waxes, foots oils, coker tower bottoms, reduced crude, vacuum tower bottoms, deasphalted vacuum residues, FCC tower bottoms and cycle oils and raffinates from a solvent extraction process. The nitrogen, sulfur and saturate contents of these feeds will vary depending on a number of factors. The preferred feedstocks for the present disclosure will have an entrained oil viscosity index of greater than 30. In a more preferred embodiment, the entrained oil in the feedstock will have a viscosity index in the range of 80-160.

(6) FIG. 1 is a process flow diagram illustrating a method implemented on a lubrication oil manufacturing system 100 in accordance with various embodiments of the present disclosure. As shown therein, a lube oil feedstock is conducted via line 101 to an activated carbon guard bed unit 105. Activated carbon is well known in the art and may be derived from various sources including petroleum coke, coal, wood, and shells, such as coconut shells, using carbonization and/or activation process steps. Activation may be accomplished, e.g. by thermal treatment under an atmosphere of CO.sub.2, H.sub.2O, and mixtures thereof, by chemical treating steps, and combinations thereof. Suitable activated carbon is commercially available and may be obtained for example from Calgon Activated Corp. of Compton, Calif., USA.

(7) The lube oil feedstock stream to be treated is contacted with activated carbon at contacting conditions to remove one or more polynuclear aromatic compounds and produce a treated lube oil feedstock stream. For example, the PNA compounds that are removed using the activated carbon are those containing, for example, five, six, or more aromatic rings. The polynuclear aromatic compounds may be removed from the lube oil feedstock stream by various mechanisms such as adsorption, reaction, and reactive adsorption with the adsorbent. The treated lube oil feedstock stream has a lower polynuclear aromatic compound content relative to the polynuclear aromatic compound content of the untreated lube oil feedstock stream. The contacting conditions include a temperature of at least about 50 C., for example from about 100 C. to about 300 C.

(8) The activated carbon guard bed unit 105 may be configured in a lead/lag configuration including a first guard bed 105A and a second guard bed 105B. As illustrated, the guard bed unit 105 is configured for closed loop product regeneration. The first and second guard beds 105A and 105B are configured as a swing bed arrangement in which one of the first and second guard beds 105A and 105B is in a contacting mode and the other of the first and second guard beds 105A and 105B is in a regenerative or offline mode. In particular, when a first plurality of valves are in an opened position and a second plurality of valves are in a closed position, the first guard bed 105A is in the contacting mode and the second guard bed 105B is in the regenerative or offline mode. Alternatively, when the first plurality of valves are in the closed position and the second plurality of valves are in the opened position, the first guard bed 105A is in the regenerative or offline mode and the second guard bed 105B is in the contacting mode.

(9) As illustrated, the first guard bed 105A in the contacting mode receives the untreated lube oil feedstock stream 101 and is operating at contacting conditions, as noted above. In the regenerative mode, the second guard bed 105B, which was previously in the contacting mode, contains spent activated carbon, and does not receive the untreated lube oil feedstock stream 101. During this time, the second guard bed may be regenerated by using a suitable regeneration process, or the spent activated carbon may be substituted for fresh activated carbon. The treated lube oil feedstock continues downstream via line 102.

(10) With the PNA compounds removed or reduced in concentration from the feedstock stream 101, the treated lube oil feedstock may be passed to catalytic dewaxing unit 110. Make-up hydrogen-containing treat gas can be introduced via line 111 when needed. Catalytic dewaxing can be performed by exposing the feedstock to a dewaxing catalyst under effective (catalytic) dewaxing conditions. Effective dewaxing conditions can include a temperature of at least 500 F. (260 C.), or at least 550 F. (288 C.), or at least 600 F. (316 C.), or at least 650 F. (343 C.). Alternatively, the temperature can be 750 F. (399 C.) or less, or 700 F. (371 C.) or less, or 650 F. (343 C.) or less. The pressure can be at least 200 psig (1.4 MPa), or at least 400 psig (2.8 MPa), or at least 750 psig (5.2 MPa), or at least 1000 psig (6.9 MPa). Alternatively, the pressure can be 2500 psig (17.2 MPa) or less, or 1200 psig (8.2 MPa) or less, or 1000 psig (6.9 MPa) or less, or 800 psig (5.5 MPa) or less. The liquid hourly space velocity (LHSV) over the dewaxing catalyst can be at least 0.1 hr.sup.1, or at least 0.2 hr.sup.1, or at least 0.5 hr.sup.1, or at least 1.0 hr.sup.1, or at least 1.5 hr.sup.1. Alternatively, the LHSV can be 10.0 hr.sup.1 or less, or 5.0 hr.sup.1 or less, or 3.0 hr.sup.1 or less, or 2.0 hr.sup.1 or less.

(11) Catalytic dewaxing involves the removal and/or isomerization of long chain, paraffinic (wax) molecules from feeds. Catalytic dewaxing can be accomplished by selective cracking or by hydroisomerizing these linear molecules. Hydrodewaxing catalysts can be selected from molecular sieves such as crystalline aluminosilicates (zeolites) or silico-aluminophosphates (SAPOs). In an embodiment, the molecular sieve can be a 1-D or 3-D molecular sieve. In another embodiment, the molecular sieve can be a 10-member ring 1-D molecular sieve. Examples of molecular sieves which have shown dewaxing activity in the literature can include ZSM-48, ZSM-22, ZSM-23, ZSM-35, Beta, USY, ZSM-5, and combinations thereof. In an embodiment, the molecular sieve can be ZSM-22, ZSM-23, ZSM-35, ZSM-48, or a combination thereof. In still another embodiment, the molecular sieve can be ZSM-48, ZSM-23, ZSM-5, or a combination thereof. In yet another embodiment, the molecular sieve can be ZSM-48, ZSM-23, or a combination thereof. Optionally, the dewaxing catalyst can include a binder for the molecular sieve, such as alumina, titania, silica, silica-alumina, zirconia, or a combination thereof.

(12) One feature of molecular sieves that can impact the activity of the molecular sieve is the ratio of silica to alumina in the molecular sieve. In an embodiment, the molecular sieve can have a silica to alumina ratio of 200 to 1 or less, or 120 to 1 or less, or 100 to 1 or less, or 90 to 1 or less, or 75 to 1 or less. In an embodiment, the molecular sieve can have a silica to alumina ratio of at least 30 to 1, or at least 50 to 1, or at least 65 to 1.

(13) The dewaxing catalyst can also include a metal hydrogenation component, such as a Group VIII metal. Suitable Group VIII metals can include Pt, Pd, Ni, or a combination thereof. The dewaxing catalyst can include at least 0.1 wt % of a Group VIII metal, or at least 0.3 wt %, or at least 0.5 wt %, or at least 1.0 wt %, or at least 2.5 wt %, or at least 5.0 wt %. Alternatively, the dewaxing catalyst can include 10.0 wt % or less of a Group VIII metal, or 5.0 wt % or less, or 2.5 wt % or less, or 1.5 wt % or less, or 1.0 wt % or less. In some embodiments, the dewaxing catalyst can also include at least one Group VIB metal, such as W or Mo. Such Group VIB metals are typically used in conjunction with at least one Group VIII metal, such as Ni or Co. An example of such an embodiment is a dewaxing catalyst that includes Ni and W, Mo, or a combination of W and Mo. In such an embodiment, the dewaxing catalyst can include at least 0.5 wt % of a Group VIB metal, or at least 1.0 wt %, or at least 2.5 wt %, or at least 5.0 wt %. Alternatively, the dewaxing catalyst can include 20.0 wt % or less of a Group VIB metal, or 15.0 wt % or less, or 10.0 wt % or less, or 5.0 wt % or less, or 1.0 wt % or less. In an embodiment, the dewaxing catalyst can include Pt, Pd, or a combination thereof. In another embodiment, the dewaxing catalyst can include Co and Mo, Ni and W, Ni and Mo, or Ni, W, and Mo.

(14) With continued reference to FIG. 1, the effluent from catalytic dewaxing unit is sent to hydrofinishing unit 115 via line 103. The hydrofinishing step following dewaxing offers further opportunity to improve product quality without significantly affecting its pour point. Hydrofinishing is a mild, relatively cold hydrotreating process, that employs a catalyst, hydrogen and mild reaction conditions to remove trace amounts of heteroatom compounds, aromatics and olefins, to improve primarily oxidation stability and color. Hydrofinishing reaction conditions include temperatures from 300 F. to 675 F. (149 C. to 357 C.), preferably from 300 F. to 600 F. (149 C. to 315 C.), a total pressure of from 400 to 3000 psig (2859 to 20786 kPa), a liquid hourly space velocity ranging from 0.1 to 5 LHSV (hr.sup.1), preferably 0.5 to 3 hr.sup.1. The hydrotreating catalyst will comprise a support component and one or more catalytic metal components. The one or more metals are selected from Group VIB (Mo, W, Cr) and Group VIII (Ni, Co and the noble metals Pt and Pd). The metal or metals may be present from as little as 0.1 wt % for noble metals, to as high as 30 wt % of the catalyst composition for non-noble metals. Preferred support materials are low in acid and include, for example, amorphous or crystalline metal oxides such as alumina, silica, silica alumina and ultra large pore crystalline materials known as mesoporous crystalline materials, of which MCM-41 is a preferred support component. Unsupported base metal (non-noble metal) catalysts are also applicable as hydrofinishing catalysts.

(15) The effluent stream from hydrofinishing unit 115 is passed via line 104 to a separation unit 120, wherein a gaseous effluent stream 121 is separated from the resulting liquid phase lube oil base stock. The gaseous effluent stream 121, a portion of which will be unreacted hydrogen-containing treat gas can be recycled via line 121A to dewaxing unit 110, for example. The resulting lube oil base stock, which will meet Group II or Group III base oil requirements, is collected via line 130, and sent downstream for collection or further processing, if desired.

(16) Accordingly, embodiments of the present disclosure provide methods and systems for manufacturing lubrication oils. The embodiments described herein employ the use of activate carbon beds to remove or reduce the presence of polynuclear aromatic compounds (PNAs). As used herein, activated carbon is suitable for absorb polar multi-ring species such as PNAs. The effluent unconverted oil (UCO) from the carbon bed is low in PNAs and would allow the product to meet desired specifications upon processing in downstream lubrication oil manufacturing units, without premature deactivation of down stream catalytic processes.

(17) While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the application in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing one or more embodiments, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope, as set forth in the appended claims.