US2327155A - Process for treating wax - Google Patents

Description

Patented Aug. 17, 1943 Ralph C. Pollock Long Beach, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Application March 6, 1939,

' Serial No. 260,114

a 5 Claims. (01.196-78) The present invention relates to 'aprocess for producing lubricating oil. The invention also relates to a process for producing wax crystallization modifiers or separation aids and also pour point depressants for lubricating oils. The invention relates particularly to a process'for producing lubricating oils of high viscosity'indexor low viscosity gravity constant from parafiin wax, such as scale and slack wax, in particular oxidized wax. v

I have discovered that valuable lubricating oil of extremely high viscosity index may be produced from parafiin wax by subjecting the paraffin wax to oxidation followed by thermal decom-' position or cracking and separating the lubricating oil contained in the cracked oxidized wax.

In general, the oxidized paraiiin wax from which the valuable lubricating oil may be produced by cracking is prepared by subjecting an unoxidized'parafiin wax to the action of an oxygen containing gas such as air, oxygen oro'zone,

preferably at an elevated temperature. The ,con-' dition and degree of oxidation will vary with the type and oil content of the with temperature of oxidation, with the air rate and whether or not a catalyst is employed. Generally, I prefer to oxidize the paraffin wax for a relatively long period of time, for example '75 hours to 40 Ohours, while maintaining the charge at a relatively low temperature of the order of 280 F. to 350 F.

If desired, the oxidation maybe carried out in the presence of a catalyst. Catalysts which may be employed for this purpose are metal chlorides, such as chloridesoi iron, zinc, tin, aluminurn; metal soap-s, such as 'naphthenates- The degree of oxidation may be determined approximately by measuring the acid and saponification numbers of the oxidized charge. When oxidizing scale wax, forexample, itispreferable to stop the oxidation reaction when the charge shows a. sponiiication number, of approximately 1&0 to 160 and an acid number of approximately 7 reaction contain the valuable lubricating oils oi 40 to 50. The cracking of the oxidized parafiin wax. is preferably carried .out under such controlledconditions as to prevent the production of coke-like'materials in the residue resulting from the cracking distillation. referably, the cracking reaction is carried out at low temperature at not appreciably above 708 F. If desired, the cracking reaction may be carried out in the presence of a catalyst such as aluminum chloride, aluminum oxide, zinc chloride, stannic chloride, etc.

During the cracking of the oxidized paraffin wax, water is formed due to the splitting oil or." hydrogen and oxygen molecules from the oxygenated paraffin wax. Light oils resembling gas oline, gas oil and kerosene arealso produced. The water and light oils thus formed are preferably removed from the cracked paraffin wax by distillation which may be carried out during or subsequent to the cracking reaction. The

cracking also results in the splitting off of light volatile acids; v I

The bottoms thus produced from the-cracking high viscosity index andalso unconverted Wax.

The high viscosity index lubricating oil may be recovered from these cracked bottoms by dissolving them in adiluent and'chilling the mixture to a sufliciently low temperature to crystallize the unconverted wax content and subsequentlyseparating the precipitate of wax and'oth r materials hereinafter discussed as wax modifiers which are insoluble in the solution at the low temperature by knownmethods of filtration, cold settling or centrifuging. --As diluents i 'or this-purpose, I may' employ any of "the known diluent-s in which the oil is soluble'at the low temperature to which the solution is chilled but in which wax is insoluble." l may employ liquefied normally gaseous hydrocarbons such as ethane, ethylene, propane, propylene, butane, butylene or mixtures thereof, like liquid hydrocarbons such as pent'ane, hexane, heptane, octane, nonane or hydrocarbon fractions such as'naphtha, gasoline, kerosene or gas-oil or I may em ploy such diluentsas acetone, methyl ethyl ketone, diethyl ketoneymethyl propyl ketone, ethyl propyl ketone, mixtures of, these ketoncs with benzene, ethyl alcohol, propyl-alcohol, butyl alcohol, cyclohexanone, normally gaseous and nor? mally liquid others, methyl chlorides, 'dichlor ethylene or trichlorethylene or mixtures of these materials with the aforementioned hydrocarbons.

The use of liquefied normally gaseous hydrocarbons, such as liquid propane, is preferred since in addition to having the property of retaining less wax in solution at low temperatures, it may be employed to produce the necessary degree of refrigeration to precipitate the wax from the solution. This is accomplished by reducing the pressure of the mixture and allowing a portion of the liquefied normally gaseous material from the diluent-oxidized wax mixture to vaporize.

The diluted oil subsequent to its separation from the precipitate by filtration, cold settling or centrifuging is, of course, heated to distill off the diluent. If desired, the thus recovered oil may be separately purified by followed by alkali and/or clay treatment on it may be blended with other dewaxed lubricating oils and the blend of oils then purified by alkali or clay treatments. Due to the extremely high Viscosity index of the lubricating oil eecovered from the oxidized wax, this oil maybe used as a blending material for oils of relatively low viscosity index in order to raise the viscosity index of the latter- If desired, a further improvementin viscosity index of the extracted oil may be obtained by subjecting the oil to extraction with selective solvents such as. phenol, turfural and the like. a l

I have further discovered that the cracked bottoms of the. oxidized paraffin wax contain, in addition to the valuable lubricating oil heretofore mentioned certain materials which are quite active in conditioning waxy oils to be dewax'ed' so that the wax may be more readily separated from the oil. When small amounts. of. these materials, for example, 0.5 to 2.01%, are added to lubricating oils to be dewaxed by chilling and filtration, an improvement is obtained with respect to the yield. of dewaxed oil, filter rate or rate of. wax separation and melting point of the separated wax.

The active wax modifier may be-recovered from the cracked oxidized bottoms by mixing the cracked bottoms with a solvent capable ofdissolving oil and wax contained in the cracked bottoms but which will. not dissolvei appreciable quantities of the wax separation aid. For this I purpose, 15 may employ any of the solvents heretoforementioned, preferably the liquefied normally gaseou hydrocarbons, specifically liquid propane. When, for example,,1- volumes. ofliquid propane are commingled with the cracked oxidized bottoms at temperatures preferably aboveroomtemperature and under pressure sufil'cientto main tain the propanein a liquid state; the wax Separation aids precipitate from solution while oil and wax constituentsare dissolvedv by the propane. By allowing the mixture toremain in a quiescent state in a settling. chamber, these wax separation aids settle to the bottom of the settling chamber andv may bejseparated from the solution of propane,.oil and Wax by simple decantationof the solution. The propane, oil and wax solutionmay then be refrigeratedin order to precipitate the wax whichmay thenbe-separated by filtering, settling or centrifuging as previously described.

If desired, the wax separation aids may beprecipitated along with the wax by chilling a: solu tion of diluent such aspropane and thercracked oxidized wax bottoms to a dewaxing temperature and then separating the precipitated. mixture of precipitated wax and. wax separation. aids by filtration, cold settling or centrifuging. The precipitate may then be mixed with asolyent. at a higher temperature. in. order. todissolve the wax from the mixture but toleave the waxseparation aids as an undissolved fraction. By allowing acid treatment 7 the mixture to remain in a quiescent state in a container, the undissolved wax separation aids will settle to the bottom of the container thereby permitting the solution of solvent and wax to be decanted from the settled wax separation aids. As solvents for this purpose, I may use liquid propane or any of the solvents heretofore mentioned at a temperature sufficient to accomplish the desired separation. If desired, the separation may be accomplished by means of a selective solvent capable of dissolving the wax separation aids but not appreciable amounts of Wax, in which case, the mixture of wax, wax separation aids and solvent is permitted to stratify in two distinct layers,

. ire"... a layer. of wax. containing a small amount of the-selective solvent and a layer of solvent in which the waxseparation aids are dissolved. By

separating the two layers, the wax separation aids may be recovered by distilling off the solvent from the layer containing them. As solvents for this purpose, I may use phenol, liquid sulfur d-ioxide, furfu-ral. or any of the solvents ncw known for separatingv oil into paraflinic and nonparaifinic oils.

Ihave also discovered that the cracked oxidized wax, in particular, the bottoms resulting fromthe cracking distillation of the oxidized wax, may be converted into effective wax modifiers, or wax separation aids by a condensation treatment of the cracked fraction alone or in the. presence of aromatic hydrocarbons such as naphthalene, benzol and the like, through the influence of a polymerization catalyst such as aluminumchloride. Such.- a condensation treatment is well known in the condensation of chlorinated aluminous sludge is allowedv to settle and the liquid fraction is withdrawn and distilled. to remove the cleaners naphtha. or kerosene from the liquid fraction which comprises the wax modifier or wax-separation aid; I have-also discovered that. thecracked oxidized bottoms when subjected tothe aforementioned treatment with aluminum chloride may be made to yield a-high percentage of lubricating oil of. high viscosity index. This oil will have a higher viscosity than oil produced from the cracked bottoms withouthaving been. subjected to this treatment.

Instead of subjecting the entire cracked oxidized. wax bottoms tothe condensation treatment, I have found that-an effective wa-xmodifier may be produced by merely subjecting the wax separation aids free from oil and wax heretofore described, to the condensation treatment with aluminum chloride with or without the presence of the aromatic hydrocarbon. Thus, the-cracked oxidized bottoms may be mixed Witha solvent adapted to precipitate the waxseparation aid andto dissolve the oilandwax components. as previously described, and. the solution removed. from theprecipitated wax separation aids. These may then. be subjected to the condensation treatment inthe presence of aluminum chloride and with or without the. aromatic. hydrocarbon.

The cracking. of the oxidized wax may be controlled so asto-produce. a sufiici'ent amount. of wax modifiers andll'ubricating oil of. high. viscosity index. The cracked product afterbeing freed of light oil fractions may then be blended with waxy lubricating oil to bedewaxedin a suificient amount to provide the necessary amount of wax modifier. The mixture is then dewaxed. In this manner, the lubricating oil contained in the cracked products Will -be*-recovered along with the dewaxed oil and thus in general, the viscosity'index of the lubricating oil;

which was subjected to the dewaxing process will be increased due to-the presence-of the lubricating oil recovered from the'cracked material. 1

From the foregoing, it will be seen that it is an object of my invention to oxidize parafiin wax and to subject the oxidized wax to acracking or.

pyrogenic treatment for the purpose of recovering a lubricating oil of high viscosityindex. 1

It is a further object of my invention to recover a wax modifier orwax separation aid from cracked oxidized parafiin wax. Y

Another object of my invention resides in cracking petroleum waxes which have been carefully and sufiiciently oxidized at comparatively low temperatures, with or without the use of catalysts and with limited contact with air or oxygen and then recovering a high viscosity index lubricating oil and/or a wax separation aid from the cracked material.

A further. object of my invention resides in subjecting oxidized waxes to a cracking treatment followed by a condensation treatment with aluminum chloride with or Without thepresence of an aromatic hydrocarbon.

Many-specific objects, features andadvantages of my invention will become apparent to those skilled in the art as the description 01" the invention proceeds in connection with specific examples given below which are not Considered as limiting my invention but merely illustrative of methods of carrying it out.

Example 1 A charge of scale wax having a meltingpoint of 123 F. was heated in a still to a temperature of 250 F. in the presence of 0.5% by weight of nickel naphthenate. Air was then introduced into the charge at a rate of liters per hour for each 500 ml. of the wax and was continued for a period of 360 hourswhile maintaining the above temperature.

The oxidized wax..,upon compleof dewaxed oil was recovered having an A. P." I.

gravity of 28.5 at F., a pour point of about 10 EL, a viscosity of 148.4 seconds Saybolt Universal at F. and 45.2 seconds at 210 F. indicating a viscosity index of about 133.0 and a viscosity gravity constant of 0.825.

Example 2 1% by weight. of the material left in the filter in Example 1, comprising a mixture of wax and wax modifier, was mixed'at 300 F. with a waxy vacuum distilled lubricating oil from Santa Fe Springs crude oil, which had been refined. by a treatment with phenol; The resulting mixture was thenmixedwith approximately 3 volumes of liquid propane under superatmospheric pressure The temperature of the resulting mixture was about 150 F, and the pressure was about 330 lbs. per square, inch. The mixture of waxy lu-l bricating oil, propane and added material was then chilled externally at a rate of approximately 3 F. per minute to approximately -40 F., the refrigeration being accomplished by indirect heat exchange with solid CO2 in a kerosene bath. The

. chilled slurry of propane, lubricating oil, solidified wax and added material was filtered under a pressure of about 30 to 10 lbs. per square inch to efiect the separation of the precipitated'wax and added material from the propane solution of lu- I bricating oil. The filter rate was 9 gallons per square foot of filter surface per hour based on the propane free oil. It will be observed that all determinations of filter rates discussed herein are based on the dewaxed oil after separating the propane therefrom. The filtrate was then distilled to. remove the propane. Approximately 67 by volume of dewax'ed oil was recovered having a pour point of 5 F. The separated wax had a melting point of F.

tion of the run showed an A. P. I. gravity of 230,

a saponification number of 157 and an acid number of 41.

Upon completion of the oxidation run, the charge was placed in a cracking still and heated to about 532 F. This temperature was gradually increased to about 630 F. During this heating period only the lighter unoxidized portionof the wax and the light oil fractions formed by the oxidation reaction were distilled. llo reflux condensation provided during this period. These fractions were recovered separately from the subsequent cracking and distillation treatment. The distillation was continued without a reflux condenser for about another hour at a temperature of 640-690 F. after which an air reflux condenser was provided and the cracking- In a dewaxing'run under similar conditions but without any dewaxing aid the yield of dewaxed oil was 41% by volume and the filter rate 19.5 gallons/sq. ft./hr. The pour point of the oil was 5 and the melting point of, the wax was 136 F.

' Example 3,

of the cracked oxidized bottoms produced in Example 1, prior to the separation of oil therefrom, were mixed with another portion of the phenol rafiinate described in Example 2 and the mixture was dewaxed in accordance with the procedure outlined in Example 2. Approximately 69.8% by volume of dewaxed oil Was obtained having a pour point of 5 F. The filter rate was about 12.3 gallons per square foot per hour. The separated wax had a melting point of approximately 142 F. I r

? Example 4 7 Another portion of the cracked oxidized wax bottoms produced in Example 1 were mixed with 20% by weight of naphthalene and'with 4 /2 volumes of cleanersnaphtha. Approximately 25%,byweight of aluminum chl'oridabased on 'the cracked bottoms, were added and the mixture was maintained for 3 hours at 130 F. to 140 1 After the removal of the aluminous sludge and the cleaners naphtha, the condensation product was considerably harder than the original o: idized wax bottoms.

Approximately 1% by weight of this was used to dewax the S. A. E. 40 phenol raffinate in .ac-' cordance with the procedure of Example 2. Ap

proximately 67.7% by volume of dewaxe'd oil was obtained having a pour point of 5 F. The filter rate was approximately 29.5 gallons per square foot per hour. The separated wax had a melting point of 142 Example 5 Another portion or" the cracked oxidized wax bottoms produced in Example 1 was subjected to a condensation treatment with aluminum chloride inaccordance with the procedure of Ex- Example 6 A charge of scale wax having a melting point of 125 F. was heated in' an aluminum columrito a temperature of 325 F. which was maintained for the period of the oxidation. Air was intro-' duced into the charge at a rate of 10 cubic feet per minute per barrel of the charge for a period of 10 hours. The oxidized wax upon completion of the run showed an A. P. I. gravity of 264, a saponification number of 96.8 and an acid number of 43.8.

The oxidized charge was then placed in a cracking still which was provided with a reflux corr- V V denser and was subjected to cracking fora period of about 13 hours, the temperature'beinggradually increased from about 500F. to 700 F.-during the period of cracking. During the cracking pe-' riod about 10.3% of light oil fractions having an A. P. I. gravity 01 43.3 and about 4.8% or water based on the oxidized wax were distilled from the charge undergoing oxidation. Upon comple' tion of the cracking reaction, the reflux condenser was removed and the cracked oxidized charge was topped at 540 F. to 685 F. Approximately 17.1% based on the oxidized wax of light oil fractions having an A. P.- lZ. gravity of 39.8" were separated from} the cracked bottoms.

The remaining bottoms an- A. P. I. gravity of 28.7. These were separated twoportions. One portion wasmixed with about 7' volumes of propane at 125 F. under pressure sulficien tito maintain the propane ina liquid state and the mixture was allowed to settle. The soluble por tion of the cracked bottoms was 'dec'ant edfrom the precipitated resins and was stripped of propane. Approximately 86.8% of thetrea-ted pen tion was recovered as oil having an A. P. I. gravity of 30.6". The propane soluble portion was then dewaxed in propane inac'cord-ance Withthe dewaxing procedure described mExample 1-. Ap proximately 40.5% based on the bottoms was re covered as a" lubricating oil havingl'arrAP. I.

gravity 25.5", a viscosity of 367.3.secondsSay-r bol-tUniversa'l at F. and 60.'7 seconds at 210 F3, a Viscosity index of 119.1an'd a viscosity gravity constant of .836.- This oil fraction corresponds with an S. A. E. 30 lubricating oil.

The other half of the cracked bottoms wax polymerize-d with aluminum chloride as in Ex ample 4 and were subsequently deresined in liquid propane to produce approximately 83.9% of oil based on the bottoms treated having an A. P. I. gravity of 295. 'Thls oil was then dewaxed as previously described'to produce about 41.7% of an oil having an A. P. I. gravity of 255, a viscosity of 577 seconds at 100 F. and 73.7 seconds at 210 F.,'a viscosity index-of 114.3 and a viscosity gravity constant of .83". This oil fraction corresponds with an S. A. E. 40 lubricating oil.

It will be observed'that the foregoingdescription of my invention is not to be considered as limiting as many variations thereof may be made by those skilled in the art within the scope of the following claims.

I claim: I

'1. A process-for treating Wax which comprises subjecting said-wax to oxidation with an oxidizing agent to produce an oxidized wax, heating oxidized wax to a cracking temperature to crack said oxidized wax, commingli-ng said cracked oxidized wax with a diluent to precipitate resinous materiali'rom said mixture, separating a solution or oil, wax and diluent from said precipitated resinous material, chilling said solution to precipitate wax, separating a solution of oil and diluent from said precipitated- Wax and separating diluent from said solution.

2. A process for treating scale wax which coms subjecting wax to oxidation with an zing agent to produce an oxidized wax and subsequently heating saidoxidized wax to a cracking temperature and cracking said oxidizeo in substantially the liquid phase at said cracking temperature to produce undistilled bottoms containing a lubricating oil fraction of high viscosity index and-recovering a lubricating oil oi high viscosity index by extraction 1e undistilled bottoms produced in the crac i ng step.

3. A process for treating scalewax which comprises subjecting said wax to oxidation with an oxidizing agent to produce an oxidized wax,

'iieating said oxidized wax to a cracking tempera ture cracking said oxidized Wax in substantiallytl ie liquid phase at said cracking tem erature to produce undistilled bottoms containinga lubricating oil fraction of high viscosity index and subjecting such undistilled bottoms to treatnwnt including extraction of a lubricating oil iractiori or high viscosity index and condensation with an aromatic hydrocarbon in the presence" of a polymerization catalyst.

A process for treating scale wax which com pri es subjecting s'aidwax to oxidation with an UXLulZing agent to produce an oxidized wax, heating said oxidized wax to a cracking temperature and. cracking said oxidized wax in substantially tire liquidphase at said cracking temperature to produce undistilieu bottoms containing a lubrieating oil fractionof high viscosity index and subjecting undistilled bottoms from said cracked oxidized wax to condensation with anaromatic nydrocarbon inthe presence of aluminum chloride and recovering a lubricating fraction of high viscosity index by extraction from the" condensed undistil-led bottoms from the cracking step.

5. A process for treating wax which" comprises subjecting said wax to oxidation with an oxidizing agent to produce an oxidized wax heating said oxidized wax to a cracking temperature and cracking said oxidized Wax in substantially the liquid phase at said cracking temperature to produce undistilled bottoms containing a lubrieating oil fraction of high viscosity index and traction from the condensed nndistilled bottoms from the cracking step. r RALPH C. POL-LOCK.