US2660552A - Combination process for producing lubricating oils - Google Patents

Description

Nov. 24, 1953 F. H. BLANDING COMBINATION PROCESS FOR PRODUCING LUBRICATING OILS Filed Sept. 50, 1950 mzON All m @NW mzoN ZOFJFQQ Patented Nov'Q Z4, 1953 U'Nrrrogs srArEsf Forrest Blandng,"CranfordfNl Jg', assign'oto Standard*I Oil Development Company; "a corpo-1` ratio'nfof Delaware Y.

Thls invention" concerns" a novel -vprocessvfor producing* lubricating 'oils 1 of particularly f high quality.' In accordance with"this inventiongla suitable petroleumfeed'stock-is'-subjected'to ai s catalytic cracking voperation fand-thereafter l-a 5' distillatev boiling in theV lubricating voil 'bolingl range-is separated from 4'thecrackedproductie-J- This 'distillate is 'then dewaxed and fsbj eot'ed to f a solvent extraction operationto provide aparafnic'iubricatingon of remarkaiyhighviscosityf-"l0 indexfu i As i'sk generally knownglan importantcriterion i of a' lubricating' loil` relates fto-= the Y viscosity char-f' 1'" acteristir'zs of the'oil. 4'l'orfliiiany applications temperatures' 'at Which'i-f'a" lubricant mustfbe' ern-F -15 played are f several hundred degrees' i Fahrenheit above *temperatures fexistentfprior to use of the particular mechanism. Consequently, it becomesi l a realproblern to providelubricatingoils 'l'1a`,v-ing":v the -iproper viscosity Lover Y' the' `entire f-operating "20- temperatur'e'range vduetto the* decrease'lin' viscosity'iof alubricatingfoil 'as the@ oil fbecornes l heated yThis oharactristioofi af`1ubricati`n'gf oil Ts is generally identiedas"the`-viscosityiindexilof the foil :malessemiauyl providesfinfrmation as 2.5 to thechange'iniviscosity offthe 'oil overtheftem# perature range'of l'OOlto` 2109 FI -It isap'pa'r'ent that 'for-many applications it'ii'sdesirableto e'mploy'lubri'c'a'ting'oils hav-ing" 'the highest possible 1 viscosity vindex.V 30

In general', threetypesof chemical 'compounds are to be found in the "lubricating oil fraction-fof ,z a crude petrioleurni- "Thesetypesofchelnical coinpounds Vare 'parainicg aromatic, andi naphthenic: 1i hydrocarbons-*It is now? known that'th'e parar'- nic'hydrocarb'ons have by farthefhighestviscosity indices." Thus,vv r'-paraffinic hydrocarbons 'i have viscosity indice's'of abou't'l25fto"`180. 'iNaph- ATf thenie andaromatic' hydrocarbons" have"m`ateriallyrlowerviscosity' indices fand materials Elrioh 4* such"l mixed 'basecrude oils'. In particular, `it has "56 2 been"f ound"that by emplying'soiveitextraction processes,`AL lubricatingfoils maybe fmade more parafiinioby `theselective removal' of aromatic compounds'. *Howeve-the solvents which may be employedv for t"this"general processfwhile being highly selective 5 for fthe "fremoval of condensed ring aromaticconstituents', "are less selective for removing naphtlienic constituents and i `one or two ring aromatic constituents." As a result, lubricating oils obtained by solventfextractiori proc-' essing are characterized'by containing large proportions of naphthenic compounds andfone or two ring aromatic `compounds having'flong side chains, thus lowering the 'potential viscosity index` of the oil. K

In accordancewith thisfinvention, means have now been found for increasing the viscosity index of lbricatingioils by notonlyf's'electively removing aromatic hydrocarbonskbutalso by selectively removing naphthenichydrocarbons? The end re sult'is a paranic lubricating*oilcntainingA only minor proportionsofv naphtlrehic and" aromatic hydrocarbons 'andhavingI viscosity'indices approaching those of paraiinic hydrocarbons or ap-l p'roaohing thevalue-bf 1-25f`o higher;

The7 process by Vvvhiohtlris may bev accomplished depends-upon `a`l combinavtionlof treating steps.' In a'rirststepV of theioperationg a suitablefeed stock'isfsubjeotedito a catalyticra'cking "operation. The catalytic'crackingoperation is effective to substantially eliminate `rnaphthenio hy drocarbons present'in 'the'raw feed stockt There` after, the products of tl'iezcatalytic cracking step may be subjected'to' solvent extraction operations so as to selectivelyV remove the'faromatic 'constituents.

The 'generalnature of this"process may be Weil understood by reference'ito the 'accompanying' drawing referred to inl theffollowing' description of one example by which the requisite' processing 'Y may be conducted;` l l Referring now 'to the` drawing 'illustrating the entirein-tegralprocesstobe employed,numeral"-` I designatesla crude l"petroleum distillation zone. f A crude petroleum'oil such-as a'mixed 'base'crude oil is introduced-to 'distillationv4 zone! through line `2. The distillationoperationis"conducted to permit removal of volatile'fractionsoverhead through line' 3 'andvof' heavier `rboiling products such as gasoline," kerosene` 'and heating" oils through Ysidestreani Withdrawals" 4; 5,1 6 and so on. Thel heavier boiling' fractions having initial' boiling'ra'ngesfof from 800`to'1'1'00'F and higher are vvitl'idravvnas a bottoms'A product throughV- line 1. It is' particularly"contemplated that in the practice of this invention, distillation zone I be of such a nature as to provide a higher boiling fraction boiling in the range of about 70,0 to 1100" F., preferably as obtained by vacuum distillation operations. This fraction is then conducted to a catalytic cracking zone identified by the rectangle 8. The cracking operation to be conducted in zone 8 is of any desired type employing a catalyst such as modified natural or synthetic clay or gel type catalysts. Examples of these are montmorillonite clays, silica-alumina, silica-magnesia composites and other conventional cracking catalysts. The operation may be of a continuous or batch nature employing iixed beds, moving beds, uidized, or suspensoid systems. The heat required for cracking may be supplied as preheat of processed materials and/or as the sensible heat of exothermically regenerated catalyst or in any other conventional manner. The cracking is carried out at temperatures of about 800 to 1000 F. and pressures of about atmospheric to 25 p. s. i. g. or higher in a manner well known. The total cracked products are removed from cracking zone 8 and are conducted to a product fractionator 9. Fractionator 9 is operated to remove lighter fractions of the cracked products through overhead I0, side streams I I, I2 and so on. A bottoms product is obtained from fractionator 9 which may be removed through line I4. In the event the cracking operation conducted in zone 8 was of a iiuidized nature, the material withdrawn through line I4 will contain a small percentage of catalyst particles carried over from zone 8. In this case, it is necessary to pass the product stream of line I4 to a settler I5 or otherwise to permit separation of the liquid hydrocarbon product from the catalyst. Thus, a clariiied hydrocarbon stream is removed from Zone I5 through line I6. This stream is conventionally designated as clarified cycle oil. For the purposes of this invention, the bottoms product of fractionator 9 corresponding to the stream of lines I4 or I6 boils in the range of about 700 to 1100".

As the conduct of the process as described here tofore is generally well known to the art, no further description of this phase of the process is considered necessary. The stream of line I6 derived, as indicated, is then conducted to suitable dewaxing facilities identified by rectangle I'I in the drawing. The operation conducted in zone I'I may be chosen from any of the conventional dewaxing processes of a nature to reduce the wax content of the hydrocarbon fraction treated to any desired extent. In general, it is preferred that a solvent dewaxing operation be employed. For example, the hydrocarbon oil of line I6 may be diltued with about 2 to 4 parts per volume with a solvent such as propane or methyl ethyl ketone. The mixture of hydrocarbon oil and solvent is then heated sufficiently to secure the solution of all wax present. Thereafter, the mixture of oil and solvent is cooled to a temperature oi about F. to 10 F. so as to secure the crystallization of the wax present. The chilled mixture of oil, solvent and wax is then filtered to eliminate this wax, permitting removal from zone I'I through line I8 of a dewaxed hydrocarbon oil.

The dewaxed oil is then passed to a solvent extraction zone I9 wherein the oil is subjected to contact with a solvent exerting a selective solvent action towards aromatic constituents. It should be noted that, as described, the oil is dewaxed prior to solvent extraction. However, if desired, the dewaxing operation may follow til@ solvent extraction operation so that, as will be seen, the raffinate of the solvent extraction operation may be subjected to dewaxing.

As is well known, a variety of solvents may be employed to secure the desired selective removal of aromatic constituents. Thus, for example. sulfur dioxide, phenol, furfural, nitrobenzene and other solvents may be employed. While the contacting of the solvent and oil may be conducted in any desired contacting equipment of a batch or continuous nature, countercurrent treating technique is preferably employed. In such a system, the oil feed of line I8 is introduced to a countercurrent contacting tower I9 at a point near the bottom thereof. Tower I9 is provided with packing, perforated plates or equivalents to secure effective liquid-liquid contacting. A solvent such as phenol is introduced at an upper portion of the tower as through line 20. The oil passes upwardly through the tower while the solvent passes downwardly through the tower, permitting re-` moval from the bottom of the tower of what is known as an extract phase through line 2 I. The extract phase will consist principally of the solvent such as phenol together with the constituents selectively extracted from the oil consisting principally of aromatic hydrocarbons. The n terial withdrawn from the top of tower I9 through line 22 is known as the raiiinate phase and consists principally of the initial oil feed minus the aromatic constituents originally present in the feed, admixed with small proportions of the solvent employed during the contacting. The rafiinate is preferably passed to a iinal distillation zone 23 wherein residual solvent is driven overhead through line 24 while the ilnal lubricating oil product is removed as a bottoms product through line 25.

As described, the process of this invention, preferably necessitates the segregation of a crude petroleum oil into a heavy boiling fraction boiling in the range of about 700-1100 F. This fraction is then subjected to a catalytic cracking operation operative to substantially eliminate naphthenic hydrocarbons from the fraction. The cracked products are then fractionated to provide a clear oil boiling in the range of about 700-` 1100 F. This oil is then subjected to processing effective to selectively remove the aromatic constituents present in the oil. As indicated, this processing preferably entails contacting of the oil with a solvent selective for aromatic hydrocarbons. However, it is within the scope of this invention to employ equivalent operations such as contact with an adsorbent such as silica gel which is also suitable for selectively removing aromatic hydrocarbons. Either before or after the selective removal of the aromatic hydrocar bons, the oil is to be subjected to a dewaxng op eration so as to eliminate a material quantity of the Wax present in the oil.

As a specific example of the operation and utility of this invention, a gas oil was subjected to a uidized catalytic cracking operation. The gas oil boiled in the range of about 650-1100 F. and was derived from a mixture of West Texas and similar types of crude oil. The products of the catalytic cracking operation were fractionated and treated to provide a clariiied oil boiling in the range of '70D-1100D F. rFhis clarified oil was then subjected to contact with a selective solvent consisting of phenol containing 7% of water as a solvent modifier. Contact was carried out in a contacting tower providing 7 extraction stages while injecting 2.8% of water pistoiese 'Pheitbl fetmc-tion of catlytic V`'cycle storie 1 l 165%' cestino foinspirant"fnphami; 218% rzo injection, 7

l Lge Food waxy topped to 700L7 .Dcwaxed topped Yield on feed, vol. percent 100 ln spections:

l Clarified oil from a catalytic cracking operation.

2 By extrapolation from viscosity at 210 F. and 150 F.

Referring to Table I, it will be noted that inspections of the feed and the raffinate obtained from the phenol extraction are given. In addition, data is presented as to the nature of the raiinate after having been dewaxed in a ketone dewaxing operation reducing the raffinate to a pour point of about It is to be understood that as indicated in the table, the raffinate was fractionated so as to secure the fraction boiling in the lubricating oil boiling range of about 700 to 1100 F.

It will be observed that the nal dewaxed raffinate product consisted of a lubricating oil having a viscosity index of 106, indicating that the process as conducted was operative to provide a high viscosity index lubricating oil.

In this example, the initial gas oil, subjected to cracking, had a content of about 26% aromatics, 25% naphthenes, and 49% parainic compounds. After cracking, the clarified oil was found to contain 67% aromatic compounds and 33% non-aromatic compounds, more than 85% of the non-aromatic compounds being parainic in nature. tion of naphthenic compounds achieved by the catalytic cracking. Finally, after the solvent contacting, the ramnate was again analyzed and it was found that the aromatic content had been reduced to about 12%, while the non-aromatic content was 88%. Two points of particular note are to be made from this data. First, the phenol extraction operation provided a yield of nal lubricating oil of about 67% based on the nonaromatic content of the oil subjected to phenol extraction. Secondly, the phenol extraction conducted was not carried out to the extent of conn plete aromatic removal so that by a somewhat more severe extraction operation, greater aromatic removal could have been achieved providing a higher viscosity index product. This was demonstrated by segregating the non-aromatic portion of the raffinate by silica gel treatment, after which it was determined that this portion had a viscosity index of 119.

As a. further example to bring out the advann tages of the process of this invention, the following considerations are presented.

An ordinary high boiling gas oil, boiling in the range of about 700 to 1100 F., may contain about 23% aromatic hydrocarbons, and 20% naphthenic hydrocarbons. Such an oil has a vis cosity index of only about 65 and would not be considered a good feed material to be subjected to processing for the production of high viscosity This shows the substantial elironai *Feed Percent treat 200 300 Yield, vol. percent 100 7 6 67 61 V. I. (undewaxed) 65 95 105 110 Referring to this table, it should be noted that the viscosity indexes given are for the undewaxed phenol treated raffinate. Depending upon the wax content of the treated raiinate, dewaxing would lower the reported viscosity indexes by 10 to 30 units. It is apparent from this data that phenol treating of such a gas oil would not be attractive for the production of high quality lubricating oil. This is particularly true since a phenol treat of about 200% is the maximum percent treat employed in practical commercial operations.

By contrast, however, if the gas oil referred to is subjected to the process of this invention, necessitating the catalytic cracking of this oil and the fractionation of the portion boiling in the range of 700 to 1100 F., the following phenol treating results may be obtained, employing the conditions of the preceding example:

1e l. V. I. (undewaxed) 108 It will be noted from this table that in phenol treating the catalytically cracked gas oil a much higher viscosity index product may be achieved. In this case only a 50 or 60% phenol treat is required to produce a lubricating oil having a viscosity index of contrasted to the 300% treat required in processing the virgin gas oil. In addition to this a somewhat better yield is obtained. In view of the fact that much of the cost of a commercial plant depends upon the extent treat applied, large savings in phenol treatment to achieve a given quality lubricating oil is thus possible.

What is claimed is:

1. The process of producing a lubricating oil comprising the steps of catalytically cracking a gas oil feed stock boiling in the range of about 650 to 1100 F., fractionating an oil fraction from the cracked products boiling in the range of about 700 to 1100 F., and thereafter contacting said fraction with a selective solvent for aromatic compounds to remove aromatic compounds from the said fraction, said process including the step of dewaxing the said fraction after the catalytic cracking step, whereby a high Viscosity index lubricating oil is obtained.

2. The process defined by claim 1 in which the said fraction after treatment with the said selec tive solvent for aromatic compounds is treatedV with silica gel.

3. 'I'he process dened by claim 1 in which the said gas oil contains substantial portions of aromatic, naphthenic, and parainic hydrocarbons.

4. The process for producing a high viscosity index lubricating oil from a gas oil feed stock containing substantial portions of aromatic, naphthenic and paraflinio hydrocarbons and boiling in the range of about 650 to 1100 F., com- 7 prsing the steps of catalytically cracking the said References Cited in theme of this patent gas oil, segregating a clered oil. f rom the said UNITED STATES PATENTS crackmg operatlon having a boiling range of t about '100 to 11oo F., and thereafter connecting Numoef Name Date said clarified oil with about 50 to 400 volume per- 5 025355 Whitely Dec- 31- 1935 cent of phenol, said process including the step 210701383 Tuttle Feb- 9: 1937 of dewexing the alarmed oil, whereby aromatic 2,379,966 Johnson July 10, 1945 hydrocarbons are selectively removed and a high 429,875 God et al- Oct"- 281 1947 viscosity index lubricating oil is obtained. 2,448,489 Hlrschler Aug- 31 1943 FORREST H. BLANDING. 10

Claims (1)

1. THE PROCESS OF PRODUCING A LUBRICATING OIL COMPRISING THE STEPS OF: CATALYTICALLY CRACKING A GAS OIL FEED STOCK BOILING IN THE RANGE OF ABOUT 650* TO 1100* F., FRACTIONATING AN OIL FRACTION FROM THE CRACKED PRODUCTS BOILING IN THE RANGE OF ABOUT 700* TO 1100* F., AND THEREAFTER CONTACTING SAID FRACTION WITH A SELECTIVE SOLVENT FOR AROMATIC COMPOUNDS TO REMOVE AROMATIC COMPOUNDS FROM THE SAID FRACTION, SAID PROCESS INCLUDING THE STEP OF DEWAXING THE SAID FRACTION AFTER THE CATALYTIC CRACKING STEP, WHEREBY A HIGH VISCOSITY INDEX LUBRICATING OIL IS OBTAINED.

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