GB2388844A

GB2388844A - Production of lube bases from waste plastic and Fischer-Tropsch wax

Info

Publication number: GB2388844A
Application number: GB0309105A
Authority: GB
Inventors: Stephen J Miller
Original assignee: Chevron USA Inc
Current assignee: Chevron USA Inc
Priority date: 2002-04-18
Filing date: 2003-04-22
Publication date: 2003-11-26
Anticipated expiration: 2023-04-22
Also published as: GB2388842A; GB2388844B; GB0309105D0; GB2388842B; GB0309108D0

Abstract

The invention provides a process for converting a blend of plastic waste and a Fischer-Tropsch waxy fraction into lube base oils. A Fischer-Tropsch wax 15 is separated into a 1000{F+ fraction and a 1000{F- fraction. The higher boiling fraction 27 is combined with virgin or waste polyolefin 10 and fed to a pyrolysis zone 30 after being heated in a heating unit 20. The pyrolysis effluent is separated into at least a heavy fraction. A light fraction may be processed into a feed for gasoline products. A middle fraction may be hydrotreated and isodewaxed to form diesel, diesel blending and jet fuel, or can be oligomerized, hydrotreated and isodewaxed to form high VI lubricating base oil. The heavy fraction is hydrotreated 40 and isodewaxed 50, and fractionated 60 to yield high VI lubricating base oil. The process can be conducted on a continuous basis. Another aspect of the invention provides a continuous process for converting waste or virgin plastics into lube oils. A further disclosure relates to a process for preparing a lube base oil from a Fischer-Tropsch wax, optionally blended with a waste polyolefin.

Description

PROCESS FOR MAKING LUBRICATING OILS

BACKGROUND OF THE INVENTION

Field of the Invention

1] The present invention relates to a method for transforming waste polymeric materials into useful products and more particularly to an improved process for manufacturing lubricating oils from waste plastics and Fischer-Tropsch waxes. The invention also relates to a process of utilizing waste polymer material to manufacture useful products and more particularly to an improved process for making lubricating base oils from blends of waste plastics and Fischer-Tropsch waxes.

Description of Related Art

2] There is a steadily increasing demand for technology capable of converting discarded and waste plastic materials into useful products. This is due in large measure to public concerns over potential environmental damage caused by the presence of these waste materials. According to a recent report from the EPA Office of Solid Waste, about 62% of all plastic packaging in the United States is composed of polyethylene, the preferred feed for plastics converted to lube oils. Plastics waste is the fastest growing waste product, with about 18 million tons per year in 1995 compared to only four million tons per year in 1970, and this amount is growing by approximately 10% per year.

Transforming plastic waste material and particularly polyethylene into useful products presents a unique opportunity to address a growing environmental problem.

3] Because of environmental concerns, the specifications for fuels, lubricants

and other petroleum products have become more stringent. This in turn has lead to a greater demand for lighter and cleaner petroleum feedstocks with the result that supplies of these feedstocks have been dwindling. In response to this, the production of synthetic lubricating oils from Fischer-Tropsch synthesized hydrocarbons has received increased attention, particularly in view of the relatively large amounts of natural gas reserves and the desire to convert these into more valuable products such as paraffnic lubricating oils.

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Accordingly, it would be advantageous to devise an economical process which converts waste plastic such as polyethylene into high viscosity index (VI) lube oils.

4] Processes are known which convert plastic waste into hydrocarbon oils. For example, U.S. Patent No. 3,845,157 discloses cracking of waste or virgin polyolefins to form gaseous products such as ethylene/olefin copolymers which are further processed to produce synthetic hydrocarbon lubricants. U.S. Patent No. 4,642,401 discloses the production of liquid hydrocarbons by heating pulverized polyolefin waste at temperatures of 150 -500 C and pressures of 20-300 bars. U.S. Patent No. 5,849,964 discloses a process in which waste plastic materials are depolymerized into a volatile phase and a liquid phase. The volatile phase is separated into a gaseous phase and a condensate. The liquid phase, the condensate and the gaseous phase are refined into liquid fuel components using standard refining techniques. U.S. Patent No. 6,143,940 teaches a process of converting waste plastics into high yields of heavy waxes. U.S. Patent No. 6,150,577 discloses a process of converting waste plastics into lubricating oils.

EP0620264 discloses a process for producing lubricating oils from waste or virgin polyolefins by thermally cracking the waste in a fluidized bed to form a waxy product, optionally using a hydrotreatment, then catalytically isomerizing and fractionating to i recover a lubricating oil. I [00051 One drawback to any process which converts plastic waste into useful products is the fact that, as with any recycle feed, the quality and consistency of the starting material is an important factor in obtaining quality end products. Recycled waste plastic not only is quite variable in consistency but its quality varies from one extreme to the over due to the many grades and types of plastics on the market. Another key factor is the importance of having a constant and continuous supply to make the process economical particularly when using off- specification waste obtained from polyolefin

processing plants (so-called "virgin" polyolefin). A process which economically and efficiently converts plastic waste into high VI lube oils while maintaining control over i the quality and quantity of the waste plastic supply and insuring the quality of the end products would be highly desirable.

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( [0006] The present invention provides an economic and efficient process for converting plastic waste into high VI lube oils. The invention also allows the quality of waste plastic pyrolysis feeds and the quality of the end product to be improved.

7] Furthermore, the invention provides an improved process which pyrolyzes plastic waste in combination with Fischer-Tropsch waxy feeds to upgrade the quality of the resultant products.

SUMMARY OF THE INVENTION

First Aspect of the invention [0001] According to a first aspect of the invention, there is provided a process which comprises the steps of blending a wax derived from a Fischer-Tropsch process with a waste andlor virgin polyolefin, passing the combined stream to a heating unit which liquefies the blend and maintains it at a temperature below that at which any significant depolymerization or decomposition would occur, passing the liquefied blend to a pyrolysis reactor maintained at a temperature sufficient to effect depolymerization, passing the effluent from the pyrolysis reactor to a fractionator, recovering at least a heavy liquid fraction, passing the heavy liquid fraction to a catalytic isomerization dewaxing unit (IDA) and recovering a lubricating base oil. A preferred wax derived from a Fischer-Tropsch process for blending with the waste and/or virgin polyolefin includes a 1 000 F+ Fischer-Tropsch wax fraction. If desired, the process can be conducted on a continuous basis.

2] In the first aspect of the present invention, light fractions recovered from the pyrolysis effluent can be further processed and used as a feed for gasoline production.

The light fraction can also be oligomerized to diesel and/or lube. Any middle fraction recovered also can be isomerization dewaxed and fractionated to recover diesel fuel, jet fuel and diesel blending stock. Alternatively, the middle fraction may be passed to a oligomerization reactor, followed by isomerization dewaxing and fractionation to recover high VI lubricating base oil. Any or all of the heavy liquid fraction, the light fraction and/or the middle fraction may be hydrotreated prior to the isomerization dewaxing step.

The hydrotreating step is expected to remove nitrogen, oxygen and sulfurcontaining contaminants, thereby, in certain cases, improving the effectiveness of the isomerization dewaxing process.

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( [0003] In the first aspect of the invention, the heavy liquid fraction obtained from fractionation of the pyrolysis effluent is preferably blended with a heavy liquid fraction from a Fischer-Tropsch process, preferably including both a 1000 F- fraction and/or a 1000 F+ fraction, the blend thereafter subjected to a catalytic isomerization dewaxing, and fractionated to recover a high VI lube oil and a bright stock (i.e. a lubricating oil hydrocarbon in which about 50 wt% boils over 1 000 F).

4] In an embodiment of the process of the first aspect of the invention, the feed to the pyrolysis reactor is a wax derived from a Fischer-Tropsch process. In this embodiment, a process for preparing a lubricating base oil comprises passing a wax derived from a FischerTropsch process to a heating unit maintained at a temperature below the decomposition temperature of the wax; feeding the heated wax to a pyrolysis unit; pyrolyzing the wax to depolymerize at least a portion of the wax and recovering an effluent from the pyrolysis unit; processing the effluent in a separator to form at least a heavy liquid fraction; and, treating the heavy liquid fraction to produce a lubricating base oil. [00081 Among other factors, the process of the first aspect of the present invention is based upon the discovery that waste polyolefin can be economically arid efficiently converted to high quality lubricating base oils by blending the waste with a Fischer Tropsch heavy wax fraction, pyrolyzing the heated blend in a reactor, and subsequently hydrotreating and isomerization dewaxing a fraction obtained from the pyrolysis reactor.

Using a Fischer-Tropsch fraction to supplement the polyolefin waste feed has eliminated the adverse impact on end-product quality caused by variations in the quality and consistency of the waste polyolefin used in the feed. When using virgin polyolefin as the waste polymer in the feed, the addition of a Fischer-Tropsch wax fraction obviates economical problems caused by variations in the cost and supply of polymer from industrial sites. Conducting the process on a continuous basis likewise contributes to economy and efficiency since smaller reactors can be employed and productivity increased. Second Aspect of the Invention [0009] According to a second aspect of Me invention, there is provided a process which includes the steps of: - 4

( [0010] passing a waste and/or virgin polyolefin into a heating unit maintained at a temperature below the decomposition point of the polyolefin to provide a molten feed; [0011] continuously passing the molten feed through a flow-through pyrolysis reactor maintained at a temperature sufficient to depolymerize at least a portion of the polyolefin and at an absolute pressure of at least one bar to produce a pyrolyzed effluent; [0012] passing at least a portion of the effluent from the pyrolysis reactor to a catalytic isomerization dewaxing unit; [0013] fractionating the product from the isomerization dewaxing unit, and [0014] recovering a lubricating oil base stock.

5] In an embodiment of the second aspect of the invention, at least a portion of the pyrolyzed effluent of step (b) may be passed to a hydrotreating unit to remove a significant portion of any nitrogen containing, sulfur-containing and/or oxygenated contaminants. At least a portion of the effluent from the hydrotreating unit may be passed to the catalytic isomerization dewaxing unit.

6] The process of this second aspect of the invention provides several advantages over previously known techniques. The use of a heating unit enables the practitioner to provide a continuous supply of liquified, heated feedstock readily available for pumping to the pyrolysis reactor. Advantageously, the feedstock is blanketed with inert gas thereby minimizing the formation of oxygenated compounds which could cause downstream catalyst deactivation and could lower the quality of the end products.

Continuously passing the polyolefin feed through the pyrolysis reactor allows the practitioner to maintain a low residence time in the reactor which contributes to overall efficiency and economy since a larger volume of feed can be processed. It also enables one to use smaller capacity reactors which likewise provides an. economical benefit.

Although a hydrotreatment is preferred in the process of this aspect of the invention to eliminate virtually all nitrogen, sulfur, and oxygencontaining contaminants, such is not necessary if an inert gas has been used to blanket the feed in the heating unit since it has been observed that lube oil stocks lighter in color are obtained by using an inert gas to minimize formation of oxygenated compounds. The use of an intermediate pore size molecule sieve SAPO in the isomerization dewaxing unit minimizes the cracking associated with other known dewaxing techniques.

BRIEF DESCRIPTION OF THE DRAWINGS

7] Fig. 1 is a schematic flow diagram of one embodiment in accordance with the first aspect of the invention.

8] Fig. 2 is a schematic flow diagram of another embodiment in accordance with the first aspect of the invention which pyrolyzes a blend of a waxy Fischer-Tropsch fraction and waste polymer.

9] Fig. 3 is a schematic flow diagram of one embodiment in accordance with the second aspect of the invention.

0] Fig. 4 is a schematic flow diagram of another embodiment in accordance with the second aspect of the invention which pyrolyzes a blend of a waxy Fischer-Tropsch fraction and waste polymer.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

First Aspect of the Invention [0021] In the Fischer-Tropsch synthesis, a synthetic gas composed mainly of CO and H2, made for example, from natural gas, is converted in the presence of a catalyst into a wide range of gaseous and liquid hydrocarbons and a normally solid paraffinic wax. Catalysts and conditions for performing Fischer-Tropsch reactions are well known to those of skill in the art, and are described, for example, in EP0 921 1 84A1, the contents of which are hereby incorporated by reference in their entirety.

2] The paraffinic wax produced in the Fischer-Tropsch process is a Cs+ product, generally with an initial boiling point in the range of 600 750 F. In practicing the process of the first aspect of the present invention, it is desirable to separate the paraffinic wax into at least two fractions. While the cutpoint between the two fractions depends on the particularly process, a preferred cutpoint is in the range of 950 -1 1 50 F.

The at least two wax fractions which are recovered from the separation are identified herein as a light wax fraction and a heavy wax fraction. The heavy wax fraction will hereinafter be referred to as the Fischer- Tropsch waxy feed. It is the latter which is employed in the first aspect of the present invention for purposes of blending with a - 6

waste or virgin polymer material, preferably polyolefin, and most preferably polyethylene. [0023] The polyolefin material which is blended with the Fischer-Tropsch heavy wax fraction can be a waste recycled product or an off-specification virgin material

obtained from a polyolefin industrial processing plant or a mixture of both. Suitable polyolefins include high density and low density polyethylene, polypropylene, EPDM I elastomers, and the like. Polyethylenes, being the most prevalent waste and virgin plastics, are particularly suitable. The waste plastic can be processed before pyrolyzing to remove metals, paper and other extraneous material. Removing this extraneous material after pyrolyzing will be facilitated by the lower viscosity and lower melting point of the pyrolyzed effluent. The plastic material may be in solid form or admixed with an organic solvent to form a liquid mixture which is employed in preparing the feed to the pyrolysis unit. The polyolefin feed is initially passed to a heating unit normally maintained at a temperature of about 1 50 C-350 C, preferably 200 C-350 C, such that! the feed is maintained below the temperature at which significant decomposition or depolymerization can occur. Normally, less than 5 wt.% of the feed would be thermally depolymerized to 1000 F- material at this temperature. An inert gas such as nitrogen or argon can be used to blanket the feed while in the heater unit to minimize oxidation and prevent the formation of oxygenates which would have an adverse impact on the downstreei-a catalysts and the quality of the end products.

4] At some point before the polyolefin feed is passed to the pyrolysis reactor,! the heavy Fischer-Tropsch wax fraction is blended therewith. The Fischer-Tropsch wax may be added to the polyolefin feed before it enters the heating unit or, less preferably, after the feed leaves the heating unit on its way to the reactor. The Fischer-Tropsch wax and polyolefin waste may be passed to the heating unit in separate streams. The polyolefin/Fischer-Tropsch wax blend should be in a liquefied heated condition before entering the pyrolysis reactor.

5] Pyrolysis conditions employed include temperatures ranging from about 450 C to about 700 C, preferably between about 500 C and about 650 C, at pressures of I less than about 15 bar, preferably in the range of about 1 bar to about 15 bar, and feed rates ranging from about 0.5 to about 5 hr' LHSV. If desired, the polyolefin/Fischer - 7

Tropsch wax blend can be continuously processed using a flow-through pyrolysis reactor as described herein in relation to the second aspect of the present invention. An advantage of a continuous process is the increased throughput in the reactor and the fact that smaller reactors can be employed.

6] The effluent from the pyrolysis unit is then passed to a fractionator.

Preferably, the 1000 F- lighter fraction obtained by distilling the Fischer-Tropsch wax is added to the pyrolysis effluent stream before passing to the fractionator. The effluent stream is fractionated into at least three fractions, a light fraction, a middle fraction and a heavy liquid fraction. The light fraction is further processed using known technology into a feed for gasoline production. The middle fraction can be passed to a hydrotreatment unit which removes nitrogen-containing, sulfur-containing and oxygen-containing contaminants in known manner. The product from the hydrotreating unit is then passed to a catalytic isomerization dewaxing unit (IDW) where the product is processed in known manner. The catalytically isomerized product may further be! hydrofinished to stabilize the product to oxidation and color formation. The finished effluent is then fractionated to form a diesel fuel, a diesel fuel blending stock and/or a jet fuel. Alternatively' the middle fraction can be passed to a oligomerization unit to be processed in a known manner. The effluent from the oligomerization unit can be catalytically isodewaxed in known manner if the pour point of the oligomers is too high (i.e. greater than 0 C), and the product further hyd ofinished. The heavy fraction is preferably passed to a hydrotreatrnent unit, then to an isomerization dewaxing unit, and! furler to a hydrofirushing unit, and the product therefrom fractionated to obtain a high VI lubricating base oil. As used herein, a lubricating base oil or lube base oil refers to a hydrocarbonaceous material boiling generally above about 650 F, with a viscosity at 100 C of at least 2.2 cSt, and a pour point of no more than about 0 C.

7] In a separate embodiment, the pyrolysis effluent stream is fractionated, and a 650 F- fraction and a 650 F+ fraction recovered. In this embodiment, the 650 F fraction may be oligomerized to form additional high VI lubricating base oil. Suitable oligomerization processes are well known in the art. The 650 F+ fraction is processed as I described above, through isomerization dewaxing, with an optional hydrotreatment pretreatment step.

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8] During oligomerization, an olefinic feedstock is contacted with a oligomerization catalyst in a oligomerization zone. Fluid-bed reactors, catalytic distillation reactors, and fixed bed reactors, such as that found in an MTBE or TAME plant, are suitably used as oligomerization reaction zones. Conditions for this reaction in the oligomerization zone are between room temperature and 400 F, preferably between 90 and 275 F, from 0.1 to 3 LHSV, and from O to 500 psi", preferably between 50 and 150 psi". Oligomerization catalysts for can be virtually any acidic material including zeolites, clays, resins, BF3 complexes, HE, H2SO4, AlCl3, ionic liquids (preferably acidic ionic liquids), superacids, etc. The preferred catalyst includes a Group VIII metal on an inorganic oxide support, more preferably a Group VIII metal on a zeolite support. Zeolites are preferred because of their resistance to fouling and ease of regeneration. The most preferred catalyst is nickel on ZSM-5. Catalysts and conditions for the oligomerization of olefins are well known, and disclosed, for example, in U.S. Patent Nos. 4,053,534; 4,482,7S2; 5,105,049 and 5,118, 902, the disclosures of which are!

incorporated herein by reference for all purposes.

9] As set forth above, processing conditions which are employed in the hydrotreatment (HT) unit are those conventionally employed in the art. Typical conditions include temperatures ranging from about 190 C to about 340 C, pressures ranging from about 400-3,000 psi", space velocities (LHSV) from about 0.1 to about 20 hr I, and H2 recycle rates angina from about 400-1 5,000 SCF/bbl. U.S. Patents which disclose suitable hydrotreatment conditions and catalysts used therein include US! 5,378,348; US 4,673,487; and US 4,921,594, the disclosures of which are incorporated

herein by reference.

0] The processing conditions which are employed in the catalytic isomerization dewaxing unit (IDW) likewise are those conventionally employed in the art. Preferably, the catalyst employed contains a intermediate pore size molecular sieve SAPO such as SAPO-11, SAP0-31, SAP0-41 or SM-3. Reference to suitable isomerization dewaxing conditions may be found in U.S. Patent 5,135,638; U.S. Patent 5,246,566; and U.S. Patent 5,282,958, the disclosures all of which are incorporated I

herein in their entirety. Typical reaction conditions in the IDW unit include temperatures ranging from about 200 C to about 475 C, pressures ranging from about 15 psig to about

( 3000 psi", a liquid hourly space velocity (LHSV) ranging from about 0.1 ho' to about 20 hr ', preferably between about 0.2 hr' to about 10 hr' and a hydrogen recycle between about 500 to about 3O,OOO SCF/B, preferably between about 1000 to about 20,000 SCF/B. As is known in the art, isomerization catalytic dewaxing converts e-paraffins into iso- paraffns, thereby reducing the pour point of the resultant oils to form a high VI lube oil at a much higher yield. I [0031] The lubricating base oil which is prepared according to the first aspect of the present invention may be hydrofinished following the catalytic isomerization step.

Hydrofinishing is typically conducted at temperatures ranging from about 190 C. to about 340 C., at pressures from about 400 psig to about 3000 psi", at space velocities (LHSV) from about 0.1 to about 20, and hydrogen recycle rates of from about 400 to about 1500 SCF/bbl. The hydrogenation catalyst employed must be active enough not only to hydrogenate the olefins, diolefins and color bodies within the lube oil fractions, but also to reduce the aromatic content (color bodies). The hydrofinishing step is! beneficial in preparing an acceptably stable lubricating oil. Suitable hydrogenation catalysts include conventional metallic hydrogenation catalysts, particularly the Group VIII metals such as cobalt, nickel, palladium and platinum. The metals are typically associated with carriers such as bauxite, alumina, silica gel, silicaalumina composites, and crystalline alurninosilicate zeolites. Palladium is a particularly preferred Hydrogenation metal. If desired, non-noble Group VIII metals cat be used with molybdates. Metal oxides or sulfides can be used. Suitable catalysts are disclosed in U.S.! Pat. Nos. 3,852, 207; 4,157,294; 3,904,513 and 4,673,487, which are incorporated herein by reference.

2] With reference to Fig. 1, one embodiment of the process of the first aspect of the present invention is illustrated. A Fischer-Tropsch derived feed (15) is fed to a separation unit (25). The heavy wax fraction (27) are forwarded to a heater unit (20), a 65t'-1050 F fraction (28) is passed to hydrotreating and a 650 F- fraction (29) recovered for use as a fuel or fuel blending component. A waste polyolefin feed (15) is passed to the heater (20). The waste polymer/Fischer-Tropsch wax feed blend (21) is forwarded to I a pyrolysis reactor (30). The pyrolysis effluent is then forwarded to a fractionator (35).

A portion of heavier bottoms (36) from the fractionator may be circulated back to the - 10

pyrolysis reactor. A light 390-650 F fraction (37) is drawn off end further processed to produce a fuel, as is 390 F- stream (38). The middle fraction (39) is circulated to a hydrotreating unit (40) and the product passed to an IDW unit (50). At least a portion of heavy portion (36) may also be combined with middle fraction (39) for hydrotreating (40) and isomerization dewaxing in IDW unit (50). The product from the IDW unit is then passed to a fractionator (60) where the various products are drawn off as a diesel fraction (61), and a lube oil fraction (62).

3] Figure 2 discloses a similar process to that exemplified in Figure 1, except for the presence of a oligomerization reactor (80). As shown, the Fischer-Tropsch heavy wax stream (27) and the waste polymer stream (10) are passed to the heater (20) and the heated blend passed to pyrolysis reactor (30). The reactor effluent is passed to fractionator (35). The bottoms (36) from the fractionator may be recirculated to the pyrolysis reactor. The medium (650-1050 F) liquid fraction (39), with at least a portion of 1050 F+ bottoms (36), are admixed with a 650 -1050 F liquid fraction (28) from! separator (25) and the admixture hydrotreated, isodewaxed and fractionated. The lighter 390 -650 F fraction (37) is passed to oligomerization reactor (45) and the effluent therefrom (46) to fractionator (35). A portion of stream (37) may be withdrawn (41) to remove excess unconverted paraffins from the feed to the oligomerization unit.

Alternatively, a 390-650 F fraction may be removed from (46) using a separate fractionator for the oligomerization unit separation not shown).

Second aspect of the Invention [0034] With reference to Fig. 3, the first step in the process of the second aspect if the invention involves feeding a plastic material (10) to a heating unit (20). The feed can be a waste plastic, preferably a polyolefin. Suitable plastic waste includes high density and low density polyethylene, polypropylene, EPDM and the like. Typically, the feed is initially prepared by grinding the waste material to a suitable size, removing extraneous material such as metals, etc., and transporting the solids to the heating unit.

Alternatively, the solids may be dissolved or dispersed in a suitable solvent and the liquid fed to the heater.

5] The feed to the heater may also be composed of virgin plastics, e. g., polyolefins which are scrap materials recovered from polyolefin processing during fabrication or - 11

other manufacturing techniques. Mixtures of polyp mer waste and virgin material may be employed, depending upon available supplies. The quality and quantity of the feed can have an impact on the quality of the end products. Recycled waste plastic is quite variable in consistency and its quality varies widely due to the many grades and types of plastics on the market. it is also important to have a constant and continuous supply to make the process economical. With these factors in mind, it is a preferred embodiment of the invention to admix waste and/or virgin plastic with waxy hydrocarbon fractions obtained from a Fischer-Tropsch process. Reference is made to the disclosure herein

pertaining to the first aspect of the invention for a detailed disclosure of procedures for

converting waste polymer/Fischer-Tropsch wax blends into high VI lube oils.

6] One important aspect of the second aspect of the present invention is the use of a heating unit (20) which functions to melt the plastics feed and maintain the liquefied material at a temperature low enough to avoid cracking or any other thermal decomposition. Suitable temperatures range from about 150 C to about 350 C, preferably about 200 C to about 350 C, such that the feed is maintained below the temperature at which sigrufcant decomposition or depolymerization can occur.

Preferably, an inert gas such as nitrogen or argon blankets the heating unit to avoid any significant oxidation of the feed components. Oxidation could give oxygenated impurities which might lead to catalyst poisoning downstream. Avoiding oxidation also would lead to products which are lighter in color. The heating unit also function s as a "holding" vessel which maintains a constant supply of feed for the flow-through pyrolysis reactor. [0037] The molten feed is then continuously forwarded to a pyrolysis unit (30).

Typically, a flow-through pyrolysis reactor is employed. The temperaturein the reactor normally is maintained between about 450 C and about 700 C, preferably between about 500 C and about 650 C, at pressures of less than about 15 bar, preferably in the range of about I bar to about 15 bar, and feed rates ranging from about 0.5 to about 5 hrt LHSV.

One important advantage of the invention is the fact that the contact time for the molten feed is relatively short, ranging from as low as about 15 minutes to about an hour or more if necessary. This enables the practitioner to use smaller capacity reactors which lowers production costs. Conducting the pyrolysis at atmospheric pressures. Pyrolyzing - 12

! conditions are variable and can easily be adjusted depending upon the time judged desirable to achieve optimum cracking and depolymerization of the feed materials and the type of product desired (e.g., bright stock, neutral oil, etc.). (The feed may be combined with a lower viscosity liquid, e.g. a diesel or a diesel cut from a fractionator in the process, to lower viscosity and make the feed easier to pump, as well as to help bring in heat to melt the plastic.) [0038] Preferably, the pyrolyzed effluent is pumped to a hydrotreating (HT) unit (40) to remove nitrogen, sulfur and any oxygen-containing compounds which could contaminate the products and poison downstream catalysts. Typical hydrotreating conditions which are employed to remove contaminants while avoiding cracking include temperatures ranging from about 190 C to about 340 C, pressures ranging from about 400 psig to about 3000 psi", space velocities (LHSV) in the range of about 0.1 hr ' to about 20 hr-', and hydrogen recycle rates ranging from about 400 to about 15,000 SCF/B.

Hydrotreating catalysts include those conventionally used in hydrotreating units.

Reference is made to the following U.S. patents for a list of suitable catalysts and hydrotreating conditions: Patent Nos. 3,852,207; 4,157,294, 4,921,594; 3,904,513; 4,673,487, the disclosures of which are incorporated herein in their entirety.

9] The pyrolysis effluent, which normally is very waxy, may be pumped directly to an isomerization dewaxing unit (50) (IDW). Since the heavier waxes are difficult to treat in the IDW unit and since the pyrolysis effluent typically contains a broad boiling point range of materials, the effluent may be forwarded to a separation or distillation unit (not shown) . The heavy paraffins are thereupon removed and used directly as hydrocarbon waxes. The lighter olefins (i.e., those boiling below about 650 F) and the gaseous olefins recovered directly from the pyrolysis unit can be forwarded to an oligomerization unit for conversion into lube oil products, normally those boiling in the neutral oil range. Techniques are well known in the art for oligomerizing lower molecular weight alphaolefins into higher molecular weight hydrocarbons which can be converted into useful fuels, lubricants, etc. [0040] During oligomerization, an olefinic feedstock is contacted with a oligomerization catalyst in a oligomerization zone. Fluid-bed reactors, catalytic distillation reactors, and fixed bed reactors, such as that found in an MTBE or TAME - 13

( plant, are suitably used as oligomerization reaction zones. Conditions for this reaction in the oligomerization zone are between room temperature and 400 F, preferably between 90 and 275 F, from 0.1 to 3 LHSV, and from O to 500 psi", preferably between 50 and 150 psi". Oligomerization catalysts for can be virtually any acidic material including zeolites, clays, resins, BF3 complexes, HE, H2S04, AlC13, ionic liquids (preferably acidic ionic liquids), superacids, etc. The preferred catalyst includes a Group VIII metal on an inorganic oxide support, more preferably a Group VIII metal on a zeolite support.

Zeolites are preferred because of their resistance to fouling and ease of regeneration. The most preferred catalyst is nickel on ZSM-5. Catalysts and conditions for the oligomerization of olefins are well known, and disclosed, for example, in U.S. Patent Nos. 4,053,534; 4,482,752, 5,105, 049 and 5,118,902, the disclosures of which are

incorporated herein by reference for all purposes.

1] As indicated above, if a hydrotreating step has been utilized, the product stream therefrom is continuously forwarded to the IDW unit (50). Alternatively, the hydrotreatment effluent may be pumped to a separation unit (not shown) to remove heavy wax materials before sending to the IDW unit. The heavy wax fraction normally boils above 1000 F and is recovered and used as a high grade heavy wax.

2] The IDW unit (50) preferably is operated under the conditions described in U.S. Patent No. 5,135,638, the entire contents of which are incorporated herein.

Preferably, the catalyst employed contains a intermediate pore size molecular sieve such as SAPO-I 1, SAP0-31, SAP0-41 or SM-3. Reference to suitable isomerization dewaxing conditions may also be found in U.S. Patent 5,246,566; and U.S. Patent 5,282,958, the disclosures all of which are incorporated herein in their entirety. Typical

reaction conditions in the IDW unit include temperatures ranging from about 200 C to about 475 C, pressures ranging from about 15 psig to about 3000 psi", a liquid hourly space velocity (LHSV) ranging from about 0.1 hr ' to about 20 hr ', preferably between about 0.2 hr' to about 10 hr' and a hydrogen recycle betvveen about 500 to about 30,000 SCF/B, preferably between about 1000 to about 2O,OOO SCF/B. As is knovvn in the art, isomerization catalytic dewaxing converts e-paraffins into iso- paraffns, thereby reducing the pour point of the resultant oils to form a high VI lube oil at a much higher yield.

- 14

3] At least a portion of the product obtained from the IDW unit is a low pour point lubricating oil stock and can be used as such. Normally, the IDW effluent is forwarded to a distillation unit (60) to separate the effluent into various oil fractions, including a neutral lube oil (62) and a bright stock (63). An amount of diesel (61) is also generally produced. A neutral oil is a refined mineral base oil lubricant with a boiling range above 500 F and below 1000 F. A bright stock is a lubricating oil hydrocarbon in which about 50 wt% boils over 1000 F.

4] A preferred embodiment of the second aspect of the invention as illustrated in Fig. 4 involves blending a heavy wax fraction (27) from a Fischer-Tropsch (Fischer-Tropsch) synthesis with the waste or virgin plastic feed 10. The blending can be done before the feed is sent to the heating unit (20) or the heavy wax fraction can be added to the molten stream being pumped to the pyrolysis unit (30). Typical blends comprise a mixture of 5-95 wt% of a Fischer-Tropsch wax fraction and 95-5 wt% of waste and/or virgin polymer. As shown in Fig. 4, a Fischer-Tropsch waxy feed (15) is forwarded to a separator (25), where a 650 F- fraction (29) recovered for use as a fuel or a fuel blend, and a 650 F-1050 F fraction (28) sent to hydrotreating. The bottoms fraction (27) is circulated to the heater (20) where it is blended with a waste feed (10) The melted stream is continuously pumped to the pyrolysis reactor (30). The pyrolysis effluent is forwarded to fractionator (35). A 390 F- fraction (38) is recovered for use as a fit el or a fuel blending stock. The lighter 390-650 F fraction (37) is sent to an oligomerization reactor (45) and the 650 F.-1050 F. middle fraction (39) forwarded to a hydrotreatment unit (40) and then to an IDW unit (50). At least a portion of heavy fraction (36) is sent to hydrotreatment unit (40) and then to IDW unit (SO). A portion of heavy fraction may optionally be recycled to the pyrolysis reactor (30). Effluent from unit (SO) is processed in fractionator (60) to recover diesel (61), and lube oil (62).

Effluent (46) from oligomerization reactor is separated in fractionator (35). A portion of stream (37) may be withdrawn (41) to remove excess unconverted paraffins from the feed to the oligomerization unit. Alternatively, a 390-650 F fraction may be removed from (46) using a separate fractionator for the oligomerization unit (separation not shown). - 15

5] The invention will now be illustrated by the following examples which are intended to be merely exemplary and in no manner limiting.

Example 1

6] High density polyethylene (HOPE), obtained from Chevron Chemical Company, was mixed 50/50 by weight with a 550-700 F hydrocracked diesel. This was put into a 7.5 gallon stainless steel feed pot with a stirrer, and heated under 10 psi nitrogen to 500 F to melt the plastic and lower the viscosity of the plastic/diesel feed to a point at which it could then be easily pumped. The feed was then pumped upflow, using a gear pump, through a stainless steel reactor containing steel bars to lower the reactor volume to 140 cc. Reactor conditions included a temperature of 975 F, atmospheric pressure, and a residence time of approximately one hour. Products were collected and analyzed.

7] Table I shows the yields and inspections from the pyrolysis run. The yield of 725 F+ product, with an endpoint of about l l DO F, suitable for lubricating base oil, was 51.4 wt% based on plastic in the feed. The liquid bottoms collected from that rurr were then isomerized over a Pt/SAPO-l l catalyst at 500 psi", 600 F, 0.65 LHSV, and 5 MSCFlbbl H2 (followed by a Pd/SiO2-Al2O3 hydrofinishing catalyst at 450 F and 1.3 LHSV) to produce a-37 C pour point 5 4 cSt oil of 156 VI (Table II). The overall 725 F+ yield, based on plastic to the pyrolyzes, was 21.3 wt% [0048]

Example 2

9] Example 1 was repeated, except the plastic was 96 wt% HOPE and 4 wt% waste polyethylene terephthalate. An online stripper separated most of the 600 F-

product from the higher boiling bottoms product. Pyrolysis yields are given in Table III, showing a 725 F+ yield, based on plastic, of 42 4 wt%. Table IV gives yields and inspections for isomerization of the pyrolysis bottoms over the same Pt/SAPO- 11 catalyst as in Example 1, and the same run conditions except for an isomerization temperature of 675 F. This gave a -13 C pour point 4.9 cSt oil of 160 VI. The overall 725 F+ yield, based on plastic to the pyrolyzes, was 25.3 wt%. Since the pyrolysis overhead gas and - 16

( liquid were highly olefinic, oligomerization of these olefins could produce additional low pour point lube base oil.

Example 3

0] A portion of the pyrolysis bottoms made in Example 2 was hydrotreated over a Ni-W/SiO2-Al203 catalyst at 600 F, 1.S LHSV, 1950 psi", and 5 MSCF/bbl H2 to reduce heteroatom content in the feed. At these conditions, cracking of the feed was very low. The hydrotreated feed was then isomerized over the same Pt/SAPO-11 catalyst as in Example I, and the same conditions, except for an isomerization temperature of 670 F and pressure of 1950 psi". This gave a-34 C pour point 3.0 cSt oil of 131 VI (Table V). The overall 725 F+ yield, based on plastic to the pyrolyzes, was 17.2 wt%. It is believed the yield and VI would have been higher had the oil been run to a higher pour point, and distilled to the same viscosity as in Example 2.

Example 4

1] The pyrolysis run of Example 1 was repeated (Table VI) at the same conditions, but this time on a feed composed of a 50/50 mixture by weight of low density polyethylene (LDPE), obtained from Chevron Chemical Company, and a hydrotreated Fischer-Tropsch wax, obtained from Moore & Munger (Table VII). Yields are given in Table VI, showing a 725 F+ yield of 57.5 wt%. The yield for a broader lube feed, 650 F+, was 66.0 wt%. While there was considerable 1000 F+ in the feed to the pyrolyzer, there was little 1000 F+ in the product, which is believed here to be advantageous for low cloud point. he pyrolysis bottoms were then isomerized over the same PtlSAPO-11 catalyst as in Example 1, and at the same conditions, except for an isomerization temperature of 687 F, to give a -22 C pour point 4.4 cSt oil of 154 VI (Table Vm).

The overall 725 F+ yield, based on feed to the pyrolyzes, was 34.8 wt%. For overall 650 F+, the yield was 43.7 wt%. Adding the potential lube from oligomerizing the lighter olefinic product from the pyrolyzer would increase these yields still further. Table VII lists properties of four feed (A = Diesel Diluent: B = Moore & Munger FT Wax: C = - 17

hydrotreated heavy (i.e. bottoms) fraction from pyrolyzed HDPE/PET/Diesel: D = hydrotreated heavy (i.e. bottoms) fraction from pyrolyzed LDPE/FT Wax).

Example 5

2] A portion of the pyrolysis bottoms from Example 4 was hydrotreated over the Ni-W/SiO2-A1203 catalyst as in Example 3. This was then isomerized as in Example 4, except for a isomerization temperature of 640 F. This gave a-15 C pour point 3.8 cSt oil with a 150 VI (Table IX). The overall 725 F+ yield, based on feed to the pyrolyzer, was 31.2 wt%. For overall 650 F+, the yield was 39.7 wt%.

Example 6

3] FT wax was run without plastic. Yields through the pyrolyzer are given in Table X, showing a surprisingly similar product distribution and olefinicity to the run with a 50/50 LDPE/FT wax mix. Again, there was little 1000 F+ in the product, which was mostly in the neutral oil boiling range. Isomerization of the pyrolysis bottoms at 637 OF gave a-14 C pour 3.4 cSt oil of 150 VI (Table Xl). The overall 650 F+ yield was about 37 wt%. Adding the potential lube from oligomerizing the lighter olefinic product from the pyrolyzer would increase the 650 F+ yield to about 52 who. Had all the 650 F- from the pyrolyzer been sent to the oligomerizer, the potential 650 F+ would be about 62 wt%). It's also worth noting that e cloud point for the oil made from FT wax was below 0 C. This would not be expected for isomerization of the starting wax feed, except possibly at very low pour point, and at a substantial yield penalty.

Example 7

4] HDPE beads were admixed with diesel oil to form a 50/50 by weight feed.

The feed was pumped to a heating unit maintained at a temperature of 500 F. The feed was blanketed with nitrogen to minimize oxidation. The heated feed was then continuously pumped upward through a pyrolysis reactor equipped with preheat bars to maintain a reaction temperature of 1025 F and atmospheric pressure. Residence time for - 18

( the feed was 1 hour. The pyrolyzed product was stripped at a temperature of about 550 F with the overhead and bottoms liquids collected separately. The bottoms, which were quite light in color, were forwarded to an IDW unit. Isomerization dewaxing was perfonned under the following conditions: 675 F, 0.5 LHSV, 1950 psi", and 3.6 MSCF/BBL of once-through H2. The product from the IDW unit was fractionated.

Analysis of the yield and composition thereof is set forth in Table XII.

- 19

( Table I

Pyrolysis of 50/50 by Weight Plastic/Diesel at 975 F, Atmospheric Pressure, and 1 Hr Residence Time Plastic = HDPE Yield Wt% C1 05 C2= 0.8

C2 0.6

C3= 1.2

C3 0.5

C4= 0.8

C4 0.5

C4- 4.9

C5-350 OF 9.6

350-650 F 56.0

650-725 OF 3.8

725 OF+ 25.7

725 F+, based on plastic 51.4 Bottoms Wt% of feed 92.0 Gravity, API 42.7 Sulfilr, ppm <1.5 Nitrogen, ppm 1.3 Sim. F)ist., OF, Wt% ST/5 149/302

10/30 390/506

50 572

70/90 692/955

95/EP 1011,'1109

- 20

Table II

Isomerization Dewaxing of Pyrolyzed Product from HDPE/Diesel at 500 psi", 600 F, 0.65 LHSV, and 5 MSCF/bbl H2 Yield. Wt% C3 0.8

C4 2.9

C4- 3.7

C5-350 F 25.3

350-650 F 56.1

650-725 F 3.3

725 F+ 11.6

725 F+, based on 725 F+ to IDW 41.1 Overhead Wt% of Feed 75.9 Sim. Dist., F, Wt% ST/5 73/194

10/30 243/367

50 448

70/90 520/584

95/EP 605/647

Bottoms Wt% of feed 15.4 Pour Point, C -37 Cloud Point, C +9 Viscosity, 40 C, cSt 25.43 100 C, cSt 5.416 VI 156

Sim. Dist., F, Wt% ST/5 621/655

10/30 674/745

50 844

70/90 925/1051

95/EP 1094/1153

Overall Wt% 725 F+, based on plastic 21.3 - 21

( Table III

Pyrolysis of 50/50 by Weight Plastic/Diesel at 975 F, Atmospheric Pressure, and 1 Hr Residence Time Plastic = 96 wt% HDPE/4 wt% PET Yield. Wt% C1 0.2

C2- 05

C2 04 C3= 0.6

C3 0.4

C4= 0.6

C4 0.2

C4- 2.9

C5-350 F 15.6

350-650 F 52.7

650-725 F 7.6

725 F+ 21.2

725 F+, based on plastic 42.4 Overhead Wt% of Feed 56.2 P+ N/Olefins/Aronatics 41.0/56.0/3.0 Sim. Dist., F, Wt% ST/5 106/194

10/30 231/382

50 513

70/90 568/621

95/EP 649/784

Bottoms Wt% of feed 39.5 Gravity, API 40.0 Sulfur, ppm 3.6 Nitrogen, ppm 6.1 Sim. Dist., F, Wt% ST/5 458/525

10/30 555/629

50 732

70/90 821t911 95/EP 944/995

- 22

( Table IV

Isomerization Dewaxing of Pyrolyzed Product from HDPE/PET/Diesel at 500 psi", 675 F, 0.65 LHSV, and 5 MSCF/bbl H2 (Hydrofinish at 450 F and 1.3 LHSV) Yield. Wt% C3 0.5

C4 1.4

C4- 1.9

C5-350 F 7.4

350-650 F 46.3

650-725 F 13.4

725 F+ 31.0

725 F+, based on 725 F+ to IDW 68.9 Overhead Wt% of Feed 56.9 Sim. Dist., F, Wt% ST/5 156/288

10/30 368/538

50 582

70/90 613/650

95/EP 665/694

Bottoms Wt% of feed 38.7 Pour Point, C -13 Cloud Point, C +6 Viscosity, 40 C, cSt 21.63 100 C, cSt 4.920 VI 160

Sim. Dist., F, Wt% ST/5 655/684

10/30 699/752

50 810

70/90 873/958

95/EP 999/1085

Overall Wt% 725 F+, based on plastic 25.3 - 23

( Table V

Isomerization Dewaxing of Hydrotreated Pyrolyzed Product from HDPE/PET at 1950 psi", 670 F, 0.65 LHSV, and 5 MSCF/bbl H2 (Hydrofimsh at 450 F and 1.3 LHSV) Yield. Wt% C1 01 C2 0.2

C3 2.7

C4 6.2

C4- 9.2

C5-350 F 22.3

350-650 F 41.7

650-725 F 6.0

725 F+ 20.8

725 F+, based on 725 F+ to IDW 37.1 Overhead Wt% of Feed 40.3 Sim. Dist., F, Wt% ST/5 72/152

10/30 193/297

50 395

70/90 505/553

95/EP 569/598

Bottoms Wt% of feed 45.0 Po Point, C 34 Cloud Point, C -3 Viscosity, 40 C, cSt 10.86 100 C, cSt 2.967 VI 131

Sim. Dist., F, Wt% ST/5 510/565

10/30 587/642

50 710

70/90 793/899

95/EP 941/1041

Overall Wt% 725 F+, based on plastic 17.2 - 24

Table VI

Pyrolysis of 50/50 by Weight LDPE/FT Wax at 975 F, Atmospheric Pressure, and 1 Hr Residence Time Yield. Wt% C1 0.2

C2= 0.6

C2 04 C3= 0.9

C3 0.7

C4= 0.9

C4 0.4

C4- 4.1

C5-350 F 9.9

350-650 F 20.0

650-725 F 8.5

725 F+ 57.5

Overhead Wt% of Feed 17.1 P+N/Olefins/Aromatics 22.0/76.0/2.0 Sim. Dist., F, Wt% ST/5 114/201

10/30 215/307

50 378

70/90 455/550

95/EP 599/692

Bottoms Wt% of feed 76.0 Gravity, API 40.7 Sulfur, ppm <4 Nitrogen, ppm 7. 9 Sim. Dist., F, Wt% ST/5 460/580

10/30 633/757

50 850

70/90 910/979

95/EP 1002/1051

*- 25

( ID crY Do -

v) oN lo x x x - o vat vat ret c) to v) A] Hi x Hi o -.d - - o - x cry o , - x to ret _ 0\ us ret _ Hi to Hi: I 4 rot mm o m

( Table VIII

Isomerization Dewaxing of Pyrolyzed Product from 50/50 LDPE/FT Wax at 500 psi", 687 F, 0.65 LHSV, and 5 MSCF/bbl H2 (Hydrofinish at 450 F and 1.3 LHSV) Yield. Wt% C3 0.5

C4 0.9

C4- 1.4

C5-350 F 8.7

350-650 F 32.6

650-725 F 11.5

725 F+ 45.8

Overhead Wt% of Feed 34.9 Sim. Dist., F, Wt% ST/5 157/246

10/30 292/430

50 512

70/90 569/611

95/EP 621/641

Bottoms Wt% of feed 60.9 Pour Point, C -22 Cloud Point, C -2 Viscosity, 40 C, cSt 18.70 100 C, cSt 4.416 VI 154

Sim. Dist., F, Wt% ST/5 614/646

10/30 668/745

50 819

70/90 885/961

95/EP 991/1088

Overall Wt% 725 F+, based on feed 34.8 Overall Wt% 650 F+, based on feed 43.7

Table IX

Isomerization Dewaxing of Hydrotreated Pyrolyzed Product hom 50/50 LDPE/FT at 500 psi", 640 F, 0.65 LHSV, and 5 MSCF/bbl H2 (EIydrofinish at 450 F and 1.3 LHSV) Yield. Wt% C2 0.1

C3 0.8

C4 1.7

C4- 2.6

C5-350 F 13.7

350-650 F 31.7

650-725 F 11.0

725 F+ 41.0

Overhead Wt% of Feed 31.9 Sim. Dist., F, Wt% ST/5 81/190

10/30 238/344

50 438

70/90 508/565

95/EP 586/682

Bottoms Wt% of feed 61.6 Pour Point, C - 15 Cloud Point, C -2 Viscosity, 40 C, cSt 15.23 100 C, cSt 3.829 VI 150

Sim. Dist., F, Wt% ST/5 564/601

10/30 623/710

50 798

70/90 878/962

95/EP 995/1067

Overall Wt% 725 F+, based on feed 31.2 Overall Wt% 650 F+, based on feed 39.7

Table X

Pyrolysis of FT Wax at 975 F, Atmospheric Pressure, and 1 Hr Residence Time Yield. Wt% C1 1.0

C2= 0.6

C2 2.4

C3= 0.8

C3 1.8

C4= 1.6

C4 1.3

C4- 9.5

C5-350 F 8.4

350-650 F 21.4

650-725 F 9.6

725 F+ 51.1

Overhead Wt% of Feed 17.6 P+N/Olefins/Aromatics 20.0/79.0/1.0 Sim. Dist., F, Wt% ST/5 130/201

10/30 231/331

50 382

70/90 454/545

95/EP 585/690

Bottoms Wt% of feed 71.8 Gravity, API 41.9 Sulfur, ppm <4 Nitrogen, ppm 2. 2 Sim. Dist., F, Wt% ST/5 454/575

10/30 621/732

50 824

70/90 896/970

95/EP 999/1051

Table XI

Isomerization Dewaxing of Pyrolyzed Product from FT Wax at 500 psi", 637 F, 0.65 LHSV, and 5 MSCF/bbl H2 (Hydrofinish at 450 F and 1.3 LHSV) Yield. Wt% C3 0.5

C4 1.0

C4- 1.5

C5-350 F 10.2

350-650 F 37 4

650-725 F 12.4

725 F+ 38.5

Overhead Wt% of Feed 31.8 Sim. Dist., F, Wt% ST/5 99/196

10/30 243/370

50 463

70/90 525/558

95/EP 568/591

Bottoms Wt% of feed 64.7 Pour Point, 'C -14 Cloud Point, C -1 Viscosity, 40 C, cSt 12.56 100 C, cSt 3.380 VI 150

Sim. Dist., F, Wt% ST/5 553/584

10/30 606/684

50 764

70/90 841/916

95/EP 946/1010

Overall Wt% 725 F+, based on feed 27.6 Overall Wt% 650 F+, based on feed 36.5

f Table XII

Isomerization Dewaxing of Pyrolyzed Product from HDPE/Diesel at 675 F, 1950 psi", 0.5 LHSV, and 3.6 MSCF/bbl H2 (Hydrofinish at 450 F and 1.3 LHSV) C4- 0.5

C5,-180 F 2.3

180-300 F 3.7

300-725 F 73.5

725 F+ 20.00

725 F+ Conversion 27.5 wt.% 725 F+ Overhead Wt% of IDW Feed 74.3 Stl5 175/287 10/30 361/531

50 601

70/90 661/707

95/EP 720/759

725 F+ Bottoms Wt% of IDW Feed 19.4 Wt% of Plastic Feed to Process 26.7 Stl5 686/722 10/30 744/818

50 882

70/90 948/1028

95/EP 1056/1110

Pour Pt. C -9 Cloud Pt. C +14 Viscosity, 40 C, cSt 34.35 100 C, cSt 6. 891 VI 165

( [0056] It is clear from the above that the invention provides an efficient process wherein a waste or virgin polyolefin is heated and continuously processed through a pyrolyzing reactor at low residence times and at atmospheric pressure followed by isomerization dewaxing to produce high yields of lube oil stocks. Shorter residence times mean that smaller reactors can be used. The light olefins from the pyrolysis can be oligomerized to form useful higher molecular weight products. Process conditions in the reactor can be altered to vary the types of products obtained, i.e., neutral oil and/or bright stock. Waxy Fischer-Tropsch products can be blended with the waste polymer feed to the pyrolysis reactor to maintain quality of the feed and quality of the end products. Catalysts and conditions for performing Fischer-Tropsch reactions are well known to those of skill in the art, and are described, for example, in EP 0 921 1 84A1, the contents of which are hereby incorporated by reference in their entirety.

7] While the invention has been described with preferred embodiments, it is to be understood that variations and modifications may be understood that variations and modifications may be resorted to as will be apparent to those skilled in the art. Such variations and modifications are to be considered within the purview and the scope of the claims appended hereto.

Claims

What Is Claimed Is:

1. A process for preparing a lubricating base oil which comprises: (a) combining a waste and/or virgin polyolefin and a wax derived from a Fischer-Tropsch process to form a blend; 5 (b) passing the blend to a heating unit maintained at a temperature of between about 150 C and 350 C; (c) feeding the heated blend to a pyrolysis unit; (d) pyrolyzing the blend to depolyrnerize at least a portion of the blend components and recovering an effluent from the pyrolysis unit; 10 (e) processing the effluent in a separator to form at least a heavy liquid fraction; and, (I) treating the heavy liquid fraction to produce a lubricating base oil.

2. A process according to claim 1, wherein the blend is composed of 5-95 wt. % of Fischer-Tropsch wax and 95-5 wt. % of waste and/or virgin plastic.

15 3. A process according to claim 1, wherein the polyolefin is a polyethylene.

4. A process according to claim 1, wherein the pyrolysis effluent is separated into at least a light fraction, a middle fraction and the heavy liquid fraction.

A process according to claim 1 further comprising processing the heavy liquid fraction in a catalytic isomerization dewaxing unit.

20 6. A process according to claim 1, wherein the catalyst in the ison!erization dewaxing unit contains an intermediate pore size molecular sieve SAPO.

7. A process according to claim 1, which is conducted on a continuous basis.

8. A process according to claim 1, wherein the wax derived from a FischerTropsch process comprises a 1000 F+ waxy fraction.

25 9. process according to claim 8, wherein said 1000 F+ waxy fraction is obtained from the fractionation of a Fischer-Tropsch wax into a 1 000 F+ waxy fraction and a 1000 F- fraction.

10. A process according to claim 9, wherein said 1000 F- fraction is blended with the heavy liquid fraction recovered from the pyrolysis effluent and the blend forwarded 30 to the catalytic isomerization dewaxing unit.

11. A process according to claim 4, wherein said light fraction is further processed into a feed for gasoline production.

f 12. A process according to claim 4, wherein said middle fraction is processed in a hydrotreatment unit, an isomerization dewaxing unit and fractionated to recover fuels. 13. A process according to claim 4, wherein said medium fraction is circulated to a 5 oligomerization reactor and the effluent therefrom processed in a hydrofinishing unit, and fractionated to recover a lubricating base oil 14. A process for preparing a lubricating base oil comprising the steps of: (a) fractionating a solid paraffinic wax obtained from a Fischer-Tropsch synthesis and recovering a 1 000 Ffraction and a 1 000 F+ wax fraction; 10 (b) blending a waste andlor virgin polyethylene and the Fischer- Tropsch 1000 F+ wax fraction wherein the polyethylene and wax fraction are admixed in an amount ranging from about 5-95 wt.% of polyethylene and 95-5 wt.% of the wax fraction; (c) heating the blend in a heating unit maintained at a temperature of about 1 50 C.

15 to about 350 C.; (d) passing the blend to a pyrolysis reactor maintained at a temperature of about 450 C. to about 700 C. and an absolute pressure of at least 1 bar; (e) passing the effluent from the pyrolysis reactor to a separator; (f) recovering at least a middle fraction and a heavy liquid fraction from the 20 separator; (g) admixing the heavy liquid fraction from the separator with the 1 000 F- fraction obtained in step (a) to form a liquid mixture; (h) forwarding the liquid mixture from step (g) to a hydrotreating unit; (i) passing the effluent from the hydrotreating unit to a catalytic isomerization 25 dewaxing unit; (j) passing the effluent from the isomerization dewaxing unit to a fractionator; and (k) recovering a lubricating base oil.

15. A process according to claim 1 4, wherein the pyrolysis reactor is a flow-through unit and the heated blend is continuously circulated lbrough the unit.

30 16. A process according to claim 14, wherein the catalytic isomerization dewaxing unit contains an intermediate pore size molecular sieve catalyst.

( 17. A process according to claim 14, wherein the middle fraction recovered from the pyrolysis effluent is passed to a hydrotreating unit, passed to a catalytic isomerization dewaxing unit, and the effluent from the isomerization dewaxing unit fractionated to recover a diesel fuel, a jet fuel and a diesel blending stock.

5 l8. A process according to claim 14, where the middle fraction recovered from the pyrolysis effluent is passed to a oligomerization reactor, the effluent from the reactor passed to hydrotreating, then passed to a catalytic isomerization dewaxing unit and then fractionated to recover a lubricating base oil.

19. A process for preparing a lubricating base oil which comprises: 10 (a) recovering a heavy wax from a Fischer-Tropsch process; (b) forwarding the wax, optionally blended with a waste andlor virgin polyolefin, to a heating unit maintained at a temperature sufficient to liquify the wax; (c) feeding the heated wax to a pyrolysis unit; (d) pyrolyzing the wax; 15 (e) recovering an effluent from the pyrolysis unit; (f) processing the effluent in a separator to form at least a heavy liquid fraction; and, (g) treating the heavy liquid fraction to produce a lubricating base oil.

20. A process according to claim 19, further comprising processing said heavy liquid 20 fraction in a catalytic isomerization dewaxing unit.

21. A process according to claim 20, wherein the catalyst in the isomerization dewaxing unit contains an intermediate pore size molecular sieve SAPO.

22. A process according to claim 19, which is conducted on a continuous basis.

23. A process according to claim 19, wherein the wax derived from a Fischer-Tropsch 25 process is a 1 000 F+ waxy fraction.

24. A continuous process for converting waste plastic into lube oil stock comprising: (a) passing a waste and/or virgin polyolefin into a heating unit maintained at a temperature between 150 C and 350 C.

(b) continuously passing the molten feed through a flow-through pyrolysis reactor 30 maintained at a temperature sufficient to depolymerize at least a portion of the polyolefin and at an absolute pressure of at least one bar to produce a pyrolyzed effluent;

(c) passing at least a portion of the effluent from the pyrolysis reactor to a catalytic isomerization dewaxing unit; (d) fractionating the product from the isomerization dewaxing unit; and (e) recovering a lubricating oil base stock.

5 25. A process according to claim 24, wherein the lubricating oil base stock comprises a neutral oil andlor a bright stock.

26. A process according to claim 24, wherein the polyolefin is a polyethylene, a polypropylene or an EPDM elastomer.

27. A process according to claim 26, wherein the polyolefin is a high density or low 10 density polyethylene.

28. A process according to claim 24, further comprising passing at least a portion of the pyrolyzed effluent of step (b) to a hydrotreating unit to remove a significant portion of any nitrogen-containing, sulfurcontaining and/or oxygenated contaminants; and passing at least a portion of the effluent from the hydrotreating unit to the catalytic 15 isomerization dewaxing unit of step (c).

29. A process according to claim 24, wherein the catalyst in the isomerization dewaxing unit contains an intermediate pore size molecular sieve SAPO.

30. A process according to claim 24, wherein the healing unit is blanketed with an inert gas. 20 31. A process according to claim 24, wherein the molten feed comprises 5-95 wt% of the polyolefin.

32. A process according to claim 31, wherein the molten feed comprises 955 wt% of a Fischer-Tropsch wax.

33. A process according to claim 24, wherein the feed rate in the pyrolysis reactor 25 ranges from about 0.5 to about 5.0 fur-i LHSV.

34. A process according to claim 24, wherein the temperature in the pyrolysis reactor is in the range of about 450 C to about 700 C.

35. A continuous process for converting waste or virgin plastic into lube oil stock comprising the steps of: 30 (a) passing solid waste and/or virgin polyethylene or a liquid containing said polyethylene into a heating unit maintained at a temperature of about 200 C to about 350 C. and under a blanket of an inert gas to provide a heated feed,

(b) continuously passing the heated polyethylene feed through a pyrolysis flow through reactor maintained at a temperature of about 500 C to about 650 C, a pressure of about 1 bar, and a residence time up to about 1 hour; (c) passing the effluent from the pyrolysis reactor to a separator and recovering at 5 least a heavy fraction; (d) passing at least a portion of the said bottoms fraction to a catalytic isomerization dewaxing unit; (e) passing the product from the isomerization dewaxing unit to a distillation unit; and, recovering a lube oil stock.

10 36. A process of claim 35, wherein the polyethylene contains a high molecular weight fraction which is removed prior to forwarding to the heating unit 37. A process of claim 35, wherein the catalyst in the isomerization dewaxing unit comprises a molecular sieve SAPO.

3 8. A process of claim 3 5, wherein said heated polyethylene feed contains a heavy 15 Fischer-Tropsch wax.

39. A process of claim 35 further comprising passing at least a portion of the heavy fraction of step (c) to a hydrotreating unit and passing the product from the hydrotreating unit to the catalytic isomerization dewaxing unit of step (d).

40. A process according to claim 35, wherein the effluent of the pyrolysis reactor is 20 separated into at least a light fraction, a middle fraction and a heavy fraction.

41. A process according to claim 40, wherein at least a portion of the heavy fraction is circulated back to the pyrolysis reactor.

42. A process according to claim 40, wherein at least a portion of the light fraction is circulated to a oligomerization reactor.

25 43. A process according to claim 40, wherein at least a portion of the middle fraction is circulated to a hydrotreating unit and a catalytic isomerization dewaxing unit.

44. A lubricating base oil made by the process of any one of claims 1 to 23.

45. A lubricating base oil made by the process of any one of claims 24 to 43.

46. A process for preparing a lubricating base oil, substantially as hereinbefore 30 described, with reference to the accompanying drawings.