Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
  • C10G45/58—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins
  • C10G45/60—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins characterised by the catalyst used
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
  • C10G2400/10—Lubricating oil

Definitions

• a method for improving the yield of high viscosity index lube oil obtained by the isomerization of waxes com­prises operating the wax isomerization process at low treat gas rates, rates in the range of 500 to 5000 SCF/bbl, H2, preferably 2000 to 4000 SCF/bbl, H2, most preferably about 2000 to 3000 SCF/bbl, H2. All other isomerization process conditions are maintained in their typical, standard ranges, i.e.
• the wax which is isomerized may come from any of a number of sources. Synthetic waxes from Fischer-Tropsch processes may be used, as may be waxes recovered from the solvent or autorefrigeration dewaxing of conventional hydrocarbon oils, as well as mixtures of these waxes. Waxes from dewaxing conven­tional hydrocarbon oils are commonly called slack waxes and usually contain an appreciable amount of oil. The oil content of these slack waxes can range anywhere from 0 to 45 percent or more, usually 1 to 30 percent oil.
• the waxes are divided into two categories: (1) light paraffinic waxes boiling in the range about 300 to 580°C; and (2) heavy microwaxes having a substan­tial fraction ( ⁇ 50 percent) boiling above 600°C.
• Hydroisomerization is performed over any of the standard hydroisomerization catalysts which contain a hydrogenation metal selected from Group VI and Group VIII mixtures, and Group VIII metals, pre­ferably the Group VIII metals, more preferably the noble Group VIII metals, most preferably platinum.
• Metal loading ranges between 0.1 to 5.0 wt% metal, preferably 0.1 to 1.0 wt% metal most preferably 0.2 to 0.6 wt% metal.
• the hydrogenation metal component is supported on a halogenated refractory inorganic metal oxide support, preferably alumina or silica-alumina, most preferably the transition aluminas, e.g. gamma alumina.
• the halogen is usually chlorine or fluorine or mixture thereof, preferably fluorine, net halogen content in the range 1 to 10 wt%, preferably 2 to 8 wt%.
• the preferred catalyst contains a hydrogena­tion metal component which is a Group VIII metal or mixture thereof, preferably noble Group VIII metal, most preferably platinum on a fluorided alumina or material containing alumina, preferably alumina or material consisting predominantly (i.e.
• XRD X-ray diffraction
• the fluoride content of the catalyst can be determined in a number of ways.
• Fluoride concentration of the sample is determined by ion chromatography analysis of the combustion product solution. Calibration curves are prepared by combusting several concentrations of ethanolic KF standards (in the same manner as the sample) to obtain a 0-10 ppm calibration range. Fluoride concentration of the catalyst is calculated on an ignition-loss-free-basis by comparison of the sample solution response to that of the calibration curve. Ignition loss is determined on a separate sample heated to 800 degrees F for at least 2 hours. Ion chromato­graphic analysis uses standard anion conditions.
• Fluoride distillation with a titrimetric finish. Fluorides are converted into fluorosilicic acid (H2SiF6) by reaction with quartz in phosphoric acid medium, and distilled as such using super heated steam. This is the Willard-­Winter-Tananaev distillation. It should be noted that the use of super heated, dry (rather than wet) steam is crucial in obtaining accurate results. Using a wet steam generator yielded results 10-20% lower. The collected fluorosilicic acid is titrated with standard­ized sodium hydroxide solution. A correction has to be made for the phosphoric acid which is also transferred by the steam. Fluoride data are reported on an igni­tion-loss-free-basis after determination of ignition loss on a sample heated to 400 degrees C for 1 hour.
• a preferred catalyst is a catalyst prepared by a process involving depositing a hydrogenation metal on an alumina or material containing alumina support, cal­cining said metal loaded support typically at between 350 to 500°C, preferably about 450 to 500°C for about 1 to 5 hrs, preferably about 1 to 3 hrs and fluoriding said metal loaded support by using a high pH fluorine source solution to a bulk fluorine level of about 8 wt% or less (e.g., 2 to 8 wt%), preferably about 7 wt% or less, said high pH source solution being at a pH of 3.5 to 4.5 and preferivelyably being a mixture of NH4F and HF followed by rapid drying/heating in a thin bed or rotary kiln to insure thorough even heating in air or oxygen containing atmosphere, or inert atmosphere to a temperature between about 350 to 450°C, in about 3 hours or less, preferably 375 to 400°C and holding, if necessary, at the final temperature for a time sufficient
• a low pH fluorine source solution having a pH of less than 3.5 using aqueous solutions of HF or appropriate mixtures of HF and NH4F to a bulk fluorine level of about 10 wt% or less (e.g., 2 to 10 wt%), preferably about 8 wt% or less followed by drying/heating in a thin bed or rotary kiln to a temperature of about 350 to 450°C, preferably 375 to 425°C in air or oxygen containing atmosphere, or an inert atmosphere and holding at that temperature, if desired, for 1 to 5 hours.
• the alumina or alumina containing support material is preferably in the form of extrudates and are preferably at least about 1/32 inch across the longest cross sectional dimension.
• the catalyst must be held at the final activation temperature for longer than 5 hours, preferably longer than 10 hours and preferably at temperatures of 400 to 450°.
• the above catalysts typically contain from 0.1 to 5.0 wt% metal, preferably 0.1 to 1.0 wt% metal, most preferably 0.2 to 0.6 wt% metal.
• the dried/heated catalyst has a surface nitrogen content of 0.01 or less N/Al by X-ray photo­electron spectroscopy (XPS) preferably 0.007 N/Al (by XPS).
• XPS X-ray photo­electron spectroscopy
• the catalyst following the aforesaid heat­ing, can be charged to the isomerization reactor and brought quickly up to operating conditions.
• the catalyst following the aforesaid heating prepared using the high pH solution technique can be hydrogen activated preferably in pure or plant hydrogen (60-70 vol% H2), at 350 to 400°C, care being taken to employ short activation times, from 1 to 24 hours, preferably 2 to 10 hours being sufficient. Long activation times (in excess of 24 hours) have been found to be detrimental to catalyst performance.
• catalysts made using the low pH solution technique can be activated in pure or plant hydrogen at 350 to 500°C for from 1 to 48 hours or longer.
• a typical activation profile shows a period of 2 hours to go from room temperature to 100°C with the catalyst being held at 100°C for 0 to 2 hours then the temperature is raised from 100 to about 350 over a period of 1 to 3 hours with a hold at the final temper­ature of from 1-4 hours.
• the catalyst can be activated by heating from room temperature to the final temperature of 350-450°C over a period of 2-7 hours with a hold at the final temperature of 0-4 hours.
• activation can be accomplished by going from room temperature to the final temperature of 350-450°C in 1 hour.
• Another preferred catalyst comprises a hydrogenating metal on fluorided alumina or material containing alumina support made by depositing the hydrogenation metal on the support and fluoriding said metal loaded support using acidic fluoride sources such as HF by any convenient technique such as spraying, soaking, incipient wetness, etc. to deposit between 2-10% F preferably 2-8% F.
• acidic fluoride sources such as HF
• the catalyst is dried, typically at 120°C and then crushed to expose inner surfaces, the crushed catalyst is double sieved to remove fines and uncrushed particles.
• This sized catalyst is 1/32 inch or less and typically from 1/64 to 1/32 inch in size across its largest cross-sectional dimension.
• the starting particle or extrudate may be of any physical configuration. Thus particles such as cylinders, trilobes or quadri lobes may be used. Extrudates of any diameter may be utilized and can be anywhere from 1/32 of an inch to many inches in length, the length dimension being set solely by handling considerations. It is preferred that following sizing the particle have a length smaller than the initial extrudate diameter.
• the particle or extrudate is crushed or fractured to expose inner surfaces.
• metal loaded support particle which is already about 1/32 inch in size or smaller and fluoride it as described above using HF.
• the sized material will range in size between about 1/64 to 1/32 inch in size.
• the uncalcined sized catalyst is activated in a hydrogen atmosphere such as pure hydrogen or plant hydrogen containing 60 to 70 vol% H2 by heating to 350 to 500°C, preferably 350 to 450°C for from 1 to 48 hours or longer.
• a hydrogen atmosphere such as pure hydrogen or plant hydrogen containing 60 to 70 vol% H2 by heating to 350 to 500°C, preferably 350 to 450°C for from 1 to 48 hours or longer.
• the hydrogen activation profiles previously described may similarly be employed here.
• This sized catalyst is unexpectedly superior for wax isomerization as compared to the uncrushed particle or extrudate starting material. It has also been discovered that 370+ oil products made using the sized catalyst as compared to the uncrushed or extru­date material starting with wax possessing about 5-10% oil exhibit higher viscosity indexes (VI's) than do 370°C+ oil products made starting with wax possessing 0% oil (on the one hand) and about 20% oil (on the other). Therefore, to produce products having the highest VI one would isomerize wax having from 5-15% oil, preferably 7-10% oil using the "sized" catalyst produced using UF.
• VI's viscosity indexes
• isomerization catalysts are extremely susceptible to deactivation by the presence of heteroatom compounds (i.e. N or S com­pounds) in the wax feed so care must be exercised to remove such heteroatom materials from the wax feed charges.
• heteroatom compounds i.e. N or S com­pounds
• some precautions may not be necessary. In such cases, subjecting such waxes to very mild hydrotreating may be sufficient to insure protection for the isomerization catalyst.
• waxes obtained from natural petroleum sources contain quantities of heteroatom compounds as well as appreciable quantities of oil which contain heteroatom compounds.
• the slack waxes should be hydrotreated to reduce the level of heteroatom compounds to levels commonly accepted in the industry as tolerable for feeds to be exposed to isomerization catalysts. Such levels will typically be a N content of about 1 to 5 ppm and a S content of about 1 to 20 ppm, preferably 2 ppm or less nitrogen and 5 ppm or less sulfur. Similarly, such slack waxes should be deoiled prior to hydrotreating to an oil content in the range of 0 to 35% oil, preferably 5 to 25% oil.
• the hydrotreating step will employ typical hydrotreating catalyst such as Co/Mo or Ni/Mo on alumina under standard, commercially acceptable condi­tions, e.g., temperature of 280 to 400°C, space veloci­ty of 0.1 to 2.0 V/V/hr, pressure of from 500 to 3000 psig H2 and hydrogen gas rates of from 500 to 5000 SCF/bbl.
• typical hydrotreating catalyst such as Co/Mo or Ni/Mo on alumina under standard, commercially acceptable condi­tions, e.g., temperature of 280 to 400°C, space veloci­ty of 0.1 to 2.0 V/V/hr, pressure of from 500 to 3000 psig H2 and hydrogen gas rates of from 500 to 5000 SCF/bbl.
• the isomerization reaction be conducted to a level of conversion such that about 40% or less, preferably 15 to 35%, most preferably 20 to 30%, unconverted wax remains in the fraction of the isomerizate boiling in the lubes boiling range sent to the dewaxing unit.
• the fraction of unconverted wax is calculated as unconverted wax/­(unconverted wax + dewaxed oil) X 100.
• the amount of unconverted was in the 370°C+ oil fraction is taken to be the amount of wax removed or recovered from said oil fraction upon dewaxing.
• the total product from the isomerization unit is fractionated into a lube oil fraction boiling in the 330°C+ range, preferably in the 370°C+ range or even higher.
• This lube oil fraction is solvent dewaxed, preferably using a 20/80 v/v mixture of MEK/MIBK, and unconverted wax is recycled for further isomerization by being fed either to the fresh feed reservoir or directly to the isomerization unit.
• the isomerate is fractionated into a lubes cut and fuels cut, the lubes cut being identified as that fraction boiling in the 330°C+ range, preferably the 370°C+ range or even higher.
• This lube fraction is then dewaxed. Dewaxing is accomplished by techniques which permit the recovery of unconverted wax, since in the process of the present invention this unconverted wax is recycled for further isomerization. It is preferred that this recycled wax by sent to the feed wax reservoir and passed through the hydrotreating unit to remove any quantities of entrained dewaxing solvent, which solvent could be detrimental to the isomerization catalyst.
• a separate stripper can be used to remove entrained dewaxing solvent or other contaminants. Since the unconverted wax is to be recycled, dewaxing procedures which destroy the wax such as catalytic dewaxing are not recommended.
• Solvent dewaxing is utilized and employs typical dewaxing solvents. Solvent dewaxing utilizes typical dewaxing solvents such as C3 to C6 ketones (e.g. methyl ethyl ketone, methyl isobutyl ketone and mixtures thereof), aromatic hydrocarbons (e.g. toluene), mixtures of ketones and aromatics (e.g.
• autorefrigerative sol­vents such a liquified, normally gaseous C2-C4 hydro­carbons such as propane, butane and mixtures thereof, etc. at filter temperatures of -25 to -30°C.
• the preferred solvent to dewax the isomerate under miscible conditions and thereby produce the highest yield of dewaxed oil at a high filter rate is a mixture of MEK/MIBK (20/80) used at a temperature in the range of -25 to -30°C. Pour points lower than -21°C can be achieved using lower filter temperatures and other ratios of said solvent, but a penalty is paid due to operation under immiscible conditions, the penalty being lower filter rates. Further, when dewaxing isomerate made from a microwax, e.g.
• the frac­tion of the isomerate which is dewaxed is the "broad heart cut" identified as the fraction boiling between about 330 and 600°C, preferably about 370 to 580°C.
• the heavy bottoms fraction boiling above about 580°C-­600°C contains appreciable wax and can be recycled for further isomerization by being sent to the isomeriza­tion unit directly, or if any hydrotreating or deoiling is deemed necessary or desirable then the fractionation bottoms may be sent to the fresh feed reservoirs and combined with the wax therein.
• the total liquid product (TLP) from the isomerization unit can be advantageously treated in a second stage at mild conditions using the isomeriza­tion catalyst or simply noble Group VIII on refractory metal oxide catalyst to reduce PNA and other contami­nants in the isomerate and thus yield an oil of im­proved daylight stability.
• the total isomerate is passed over a charge of the isomerization catalyst or over just noble Group VIII on transition alumina.
• Mild conditions are used, e.g. a temperature in the range of about 170 to 270°C, preferably about 180 to 220°C, at pressures of about 300 to 1500 psig H2, preferably 500 to 1000 psig H2, a hydrogen gas rate of about 500 to 10,000 SCF/bbl, preferably 1000 to 5000 SCF/bbl and a flow velocity of about 0.25 to 10 V/V/hr, preferably about 1 to 4 V/V/hr. Higher temperatures than those recited may be employed if pressures in excess of 1500 psi are used, but such high pressures may not be practical.
• the total isomerate can be treated under these mild condition in a separate, dedicated unit or the TLP from the isomerization reactor can be stored in tankage and subsequently passed through the aforemen­tioned isomerization reactor under said mild condi­tions. It has been found to be unnecessary to frac­tionate the first stage product prior to this mild second stage treatment. Subjecting the whole product to this mild second stage treatment produces an oil product which upon subsequent fractionation and dewax­ing yields a base oil exhibiting a high level of daylight stability and oxidation stability. These base oils can be subjected to subsequent hydrotreating under conventional conditions to remove undesirable nitrogen and/or sulfur compounds using conventional catalysts such as KF-840 or HDN-30 (e.g., Co/Mo or Ni/Mo on alumina).
• KF-840 or HDN-30 e.g., Co/Mo or Ni/Mo on alumina.
• the catalyst must contain a hydrogenation/dehydrogenation component (for example, a Group VIII metal such as platinum) and the reaction is carried out in a hydrogen-rich atmos­phere.
• a hydrogenation/dehydrogenation component for example, a Group VIII metal such as platinum
• the volume ratio of hydrogen gas to wax feed (the TREAT GAS RATE) has been shown in the past to affect the reactivity of the wax, but it has not been shown to affect the hydroisomerate product distribution.
• selectivity for 370°C+ oil depends only on the amount of conversion to 370°C ⁇ material and not on any specific process parameter such as temperature, pres­sure or treat gas rate. This observation implied that the distribution of high boiling wax and oil were also independent of parameters such as treat gas rate.
• the increased high boiling oil yield and decreased wax yield mean several things:
• the preferred slack wax conversion level is such that between 25 and 40 wt% unconverted wax remains in that fraction of the isomerate sent to the dewaxing unit.
• the amount of wax present in the stream sent to dewaxing can be controlled by the conversion level.
• hydroisomerization can be carried out to produce more fuels, and a lower overall residual wax yield.
• This leads to destruction of valuable wax and a reduction in the overall oil yield.
• the present invention is a method of minimizing the amount of wax present in the stream to be dewaxed without operating at higher conversion levels and this serves to preserve overall oil yields.
• lower treat gas rates unexpectedly give rise to higher yields of 5.6-5.9 cSt/100°C oil and lower dry wax contents of these oils.
• the slack wax is preferably hydrotreated prior to hydroisomerization to remove nitrogen and sulfur compounds which may be harmful to the hydro­isomerization catalyst.
• Isomerization is carried out between 270 and 400°C, pressures of 500 to 3000 psig (preferably 800 to 1500 psig), and space velocities of 0.1 to 10 V/V/hr, preferably 0.5 to 2 V/V/hr.
• the preferred treat gas rate is between 500 and 5000 SCF/bbl, H2, preferably 2000 to 4000 SCF/bbl, H2, most preferably about 2000 to 3000 SCF/bbl, H2. This range of treat gas rates allows advantage to be taken of the increased reactivity of the slack wax at higher treat gas rates and the increased oil yields and lower dry wax contents which result at lower treat gas rates.
• the isomerate is fractionated to recover the improved yield of oil in the 5.6 to 5.9 cSt @ 100°C viscosity range.
• the hydroisomerate product produced at lower treat gas rates can be isomerized in a second low temperature hydroisomerization to improve day­light stability.
• Catalyst Volume 3600 cc Mode down flow, trickle bed Catalyst Pre-treatment The catalyst was dried at 220°C (4 hours in vacuum, then overnight in a lab oven at atmospheric pressure). The catalyst was charged to the reactor, and heated from ambient to 400°C in flowing H2, pressure 300 psig, as follows: held at 100°C for 24 hours; from 100 to 400°C at 10°C/hour; held at 400°C for 3 hours; reactors cooled to 250°C. Details for the hydroisomerization experiments are given in the Table. Three hydroisomerate products, produced at treat gas rates 2573, 5035 and 9465 SCF H2/B, were assayed.
• Each of the products was topped and the topped material dewaxed, to produce dewaxed oil with approximately 5.85 cST/100°C viscosity.
• Pour points of the dewaxed oils were measured as Westcan auto-­pours, for maximum accuracy.
• the yield of topped material was found not to be the same for the three products.
• the amount of dry wax removed also differed for the three cases.
• Auto-pour is a more sensitive indicator of pour point than is ASTM pour point.
• the data for dewaxing condition A indicates that the oils obtained at 2573 and 9565 SCF/B treat gas rates were dewaxed to lower auto-pour points than the oil obtained at 5035 SCF/B treat gas rate. It is ordinarily under­stood that more wax would have to be removed to reach the lower pour point. However, oil produced at 2573 SCF/B had the least wax of the three cases.
• MIBK methyl isobutyl ketone
• MEK methyl ethyl ketone
• Dewaxings were carried out in a simple batch dewaxing apparatus.
• the waxy oil was heated to total fluidity, diluted with ketone solvent, then cooled with agitation in a cold bath to the required temperature.
• the mixture was filtered using a Buchner filter which was itself cooled by circulating solvent. Solvent was stripped from the wax and oil individually.

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Cited By (15)

Citations (2)

• 1988
  • 1988-12-16 MX MX1423788A patent/MX172104B/es unknown
  • 1988-12-16 ES ES88311985T patent/ES2054834T3/es not_active Expired - Lifetime
  • 1988-12-16 AU AU26964/88A patent/AU612214B2/en not_active Ceased
  • 1988-12-16 EP EP88311985A patent/EP0321304B1/de not_active Expired - Lifetime
  • 1988-12-16 DE DE19883881180 patent/DE3881180T2/de not_active Expired - Fee Related
  • 1988-12-19 JP JP63320305A patent/JPH01308491A/ja active Pending

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