US1988793A - Process for the production of lubricating oil - Google Patents

Description

Patented Jan. 22, 1935 UNITED STATES PROCESS FOR THE PRODUCTION OF LUBRICATING OIL Robert E. Haylett, Long Beach, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a. corporation of California No Drawing. Application October 22, 1932, Serial No. 639,154

8 Claims. (Cl. 196-13) This invention relates to a process for the production of lubricating oil. More specifically, it relates to a process for the production of lubricating oil from petroleum by the use of solvents.

. 5 The lubricating oil components of many crude oils are highly complex in character'and consist of a mixture of hydrocarbons having widely different characteristics. Those hydrocarbons present which exhibit a minimum change in viscosity with l a change in temperature, i. e., have a low viscosity temperature susceptibility are considered to be most valuable as lubricants forintemal combustion engines whereas those hydrocarbons present which exhibit the maximum change in viscosity 15 with a change in temperature, i. e., have a high viscosity temperature susceptibility, are considered to be the least valuable. Lubricants which exhibit a low temperature viscosity susceptibilityare often referred to as the 'paraflinic oils whereas those which exhibit a high temperature viscosity-are referred to as non-paraflinic oils. I

At the present time the method most commonly used for separating the lubricating oil fractions of petroleum into paraflinic and non-paraflinic oils consists in treating these fractions withliquid sulphur dioxide. For example, a lubricating oil distillate containing paraflinic and non paraflinic oil is extracted at a temperature ranging from about 0 F. to 10 F. with liquid sulphur dioxide. The liquid sulphur dioxide dissolves the non-paramnic fractions present in the oil and due to the relatively high specific gravity'of the sulphur dioxide solution of non-parafflnic oil as compared to the liquid sulphur dioxide insoluble oil present in the distillate it is possible to obtain a separation, a

gravity separation, of the paraflinic oil from the non ep'araiiinic fractions dissolved in liquid sulphur dioxide. Upon settlement the paramnic oil obtained, referred to as the rafflnate, forms an up- I 40 per layer which may be decanted away and distilled for the removal of any remaining sulphur dioxide present after which the oil may be further treated with acid, alkali and clay to produce a finished lubricant. The lower layer formed after settlements contains the major portion of the nonparafiinic oil dissolved in liquid sulphur dioxide.-

This solution maybe withdrawn from the extraction vessel and distilled to recover the sulphur dioxide and the non-paraflinic oil which is often referred to as extract.

Extracts produced from petroleum hydrocarbon mixtures by the use of liquid sulphur dioxide at relatively low temperatures are usually highly non-paraiiinic in character. Complete separation of the non-parafiinic fractions from the rafl'inate oil cannot be obtained because the liquid sulphur dioxide apparently exhibitsa tendency to leave a certain amount of the non-parafilnic components in the rafiinate phase. This is especially true where theextraction has been carried out at temperatures between F. and 20 F. At these temperatures the solvent power 01' the liquid sulphur dioxide towards the oils present which are seminon-paraffinic is materially lessened. Consequently, these components are forced into rafll- 10 nate phase and as a result the temperature viscosity susceptibility of this oil is increased. By proper selection of temperature this same effect maybe produced by most solvents which exhibit any appreciable solvent power for the non-paraffinic fractions in ahydrocarbon mixture. Thus by proper selection of temperature solvents such as aniline, nitrobenzene, furfural or selenium oxychloride will separate a highly non-paramnic extract and a rafiinate which is more or less contaminated with non-paraffinic fractions.

Dichlorethyl ether (B B) is another solvent which is usedto separate hydrocarbon oils into parafiinic and non-paraffinic fractions. The usual method of employing this solvent is to mix it with the oil to be treated, heat the oil to a temperature sufiiciently-high to obtain complete miscibility between the oil and the ether, cool the solution to a temperature somewhat below the point of complete miscibility and separate the oil which '30 is insoluble at this somewhat lowered temperature from the dichlorethyl ether and dissolved oil. Due to the relatively greater specific gravity of the oil dissolved in the ether over the undissolved oil portion the ether solution of oil forms a lower layer or phase in the extraction vessel and the ether insoluble oil forms a lower layer or phase. These layers may then be separated by simple decantation methods and then distilled. to separate the oils from their dichlorethyl ether contents. The temperature at which the oil to be extracted becomes completely miscible with the dichlorethyl ether, of course, will vary but generally this temperature is within the range of 100 F. to 175 F. After complete miscibility of the ether and the oil the temperature of the oil-ether solution is lowered at least 40 F. where the paraflinic oil separates from the non-parafiinic oil dissolved in the ether, The paraflinic oil forms the upper layer and the non-paraflinic oil dissolved in the dichlorethyl ether forms the lower layer. These layers are separated, as has been described, by simple decantation and then distilled to separate the dichlorethyl ether from the oils.

'Raffinates produced from hydrocarbon mixtures by the use of B B dichlorethyl ether at relatively high temperatures are highly paraffinic in nature but the extracts so produced usually contain appreciable amounts of oil which have temperature viscosity susceptibility characteristics intermediate between the most paraflinic oils and the least parafiinic oils. Thus it appears that while dichlorethyl ether is capable at relatively high temperatures of separating raflinates from hydrocarbon mixtures which are highly paraflinic in character there is apt to be a considerable loss of a portion of the parafiinic fractions in the extract phase. Furthermore raflinates may be produced from hydrocarbon mixtures similar to those separated by B B dichlorethyl ether at relatively high temperatures by extracting the hydrocarbon mixture with selective solvents such as aniline, nitrobenzene, furfural, methyl cellosolve, cellulose acetate, cresylic acid, phenol or phenyl acetate near the critical solution temperature of the oil and the solvent. At this temperature only the most paraffinic fractions present in the hydrocarbon mixture remain undissolved.

It therefore appears to be highly desirable to extract hydrocarbon mixtures containing paraifinic and non-parafiinic hydro-carbons with a solvent capable of forming a highly non-paraflinic fraction and then re-extracting the raflinate so produced with a solvent capable of producing a highly parafiinic fraction. By extracting the hydrocarbon mixture with a solvent capable of removing the highly non-parafiinic fractions those components are removed from the hydrocarbon mixture which lessen the effectiveness of the solvent employed to separate the highly paraffinic fractions. Thus, if the oil is first extracted with a solvent of the liquid sulphur dioxide type and then the raffinate so produced is re-extracted with a solvent of the B B dichlorethyl ether type, a second raflinate is produced which is highly paraffinic in character. The liquid sulphur dioxide removes from the oil at relatively low temperatures those fractions which are highly non-parafiinic in character and which tend to lessen the effectiveness of the dichlorethyl ether to separate a highly paramnic raffinate from the oil remaining undissolved from the sulphur di. oxide extraction.

It is, therefore, an object of my invention to extract hydrocarbon mixtures into paraflinic and non-paraffinic fractions by means of a plurality of solvents.

It is another object of my invention to extract hydrocarbon mixtures with a solvent capable of forming a highly non-parafiinic fraction and a parafiinic fraction and thereafter to re-extract the paraflinic fraction so produced with another solvent capable of separating therefrom a highly paraffinic fraction.

It is a further object of my invention to separate hydrocarbon mixtures with liquid sulphur dioxide into a raflinate and an extract and thereafter re-extract the raflinate with B B dichlorethyl ether.

It is still another object of my invention to separate hydrocarbon mixtures into an extract and a railinate with a solvent at one temperature and then re-extract the raflinate with another solvent at a different temperature.

My process is applicable to lubricating oil distillates, petroleum residues or hydrocarbon mixtures containing lubricating oil hydrocarbons. Providing a hydrocarbon mixturecontaining asphalt is employed as raw stock to be treated I may first extract such residue with a solvent capable of dissolving the oil but which leaves the asphalt remaining after ,the extraction as an undissolved residue. The solvent may then be distilled away from the oil after which the oil may be separated into its parafiinic and nonparaflinic fractions by the process which I have previously described. Solvents which I may employ to separate the asphalt from the oil are naphtha, gasoline and liquefied normally gaseous hydrocarbons, such as ethane, propane, butane or pentane or mixtures thereof. The liquefied normally gaseous hydrocarbons which I may em-. ploy are liquids at ordinary temperature if maintained under pressure. In separating the asphalt from the oil with these hydrocarbons I commingle the asphaltic oil with the liquefied normally gaseous hydrocarbon at a temperature of 50-75 F. and under sufiicient pressure to maintain the light liquid hydrocarbon solvent in the liquid state.

Usually three volumes of the light liquid hydrocarbon solvent to one part of the asphaltic oil will cause satisfactory separation of the asphalt, however, I may use a greater or less proportion of solvent. After separation of the solvent solution of oil from the undissolved asphalt the solvent is distilled away from the oil and the latter is then separated into its parafiinic and non-parafiinic components by such solvents as liquid sulphur dioxide and B B dichlorethyl ether.

As an example of the preferred method of carrying out my process, a lubricating oil fraction derived from a Mid-Continent or Western crude oil is commingled under pressure and at a temperature of approximately -15 F. with liquid sulphur dioxide, the commingled mass is then allowed to settle until there is formed an upper layer containing the paraflinic oil and a lower layer containing the highly non-parafllnic oil. These fractions are distilled to remove their content of sulphur dioxide after which the parafiinic fraction is mixed with B B dichlorethyl ether in the proportion of three parts of the ether to one part of oil. This mixture is heated to a temperature sufficiently high to obtain complete miscibility between the oil and ether after which the solution is cooled to a temperature approximately 40 F. below the point of complete miscibility. At this temperature there separates from solution an oil which is very highly paramnic in character. This highly paraflinic fraction has a lower specific gravity than the non-paraflinic oil dissolved inthe dichlorethyl ether. Upon settling the highly paraifinic oil forms an upper layer and the dichlorethyl ether solution of nonparafiinic oil forms a lower layer. These layers are separated by simple decantation. The dichlorethyl ether is then separated from the highly parafilnic oil and the non-parafiinic oil by distillation. The highly paraflinic fraction may then be further treated, if desired, with acid, alkali and/or clay to obtain any further refining necessary to produce a finished oil. Usually when acid treatment is employed subsequent to extraction with dichlorethyl ether I find that the oil is sufficiently purified by treatment with 5-10 pounds of 93% sulphuric acid per barrel of oil.

The temperatures which I'may employ during extraction depends upon the type of products desired. When the initial extraction is carried out with a solvent such as liquid sulphur dioxide the temperature employed governs, to a great extent, the characteristics of the extract and rafiinate so produced.- In general the lower the temperature employed during extraction the more non-paraflinic will be the extract produced and the more contaminated will be the raflinate with non-parafiinc constituents. As the effectiveness of the B B dichlorethyl ether to separate a highly paraflinic fraction from the sulphur dioxide raflinate depends somewhat upon the degree of contamination of the sulphur dioxide rafllnate with non-parafllnic fractions, it is important that the temperature selected for the initial extraction with liquid sulphur dioxide be within the range wherein the raffinate will contain a minimum amount of the non-paraflinic fractions.

Furthermore the temperature which I may employ during the extraction of the sulphur dioxide raffinate with B B dichlorethyl ether will govern to some extent the degree of parafllnicity of the raifinate fraction. As the temperature employed for extraction of the sulphur dioxide raffinate with B B dichlorethyl ether approaches the point of complete miscibility a raffinate is produced which exhibits a maximum degree of parainnicity but the yield or raflinate is correspondingly low as only the most parafllnic fractions will remain insoluble in the dichlorethyl ether at this temperature.

Thus extraction of the hydrocarbon mixture at a low temperature with sulphur dioxide produces an extract which is highly non-parafllnic and a raffinate which is more or less contaminated with non-paraflinic oil fractions. If the rafiinate fraction produced by extracting the hydrocarbon mixture at low temperature with sulphur dioxide is re-extracted at a relatively high temperature with B B dichlorethyl ether, i. e., within a few degrees of the temperature of complete miscibility, it is possible-to obtain an oil fraction insoluble in the B B dichlorethyl ether= which is highly parailinic in character.

As a modification of my process I may first extract the hydrocarbon mixture with a solvent of the B B dichlorethyl ether type and then re-extract the extract so produced with a solvent of the sulphur dioxide type. The B B dichlorethyl ether is capable of producing a rafllnate fraction which is relatively free from non-paraffinic constituents but the extracts produced by extraction with B B dichlorethyl ether are usually contaminated with paraflinic oil fractions. This is especially true where the temperatures during extraction have been maintained at a relatively high temperature. High temperature extraction with B B dichlorethyl ether tends to force parafiinic fractions into the extract phase. By extracting a hydrocarbon mixture containing paraflinic and non-paraflinc fractions at a relatively high temperature with B B dichlorethyl ether a highly paraflinic raflinate can be produced and then by re-extracting the extract from the B B dichlorethyl ether extraction with liquid sulphur dioxide at a relatively low temperature, an extract can be obtained which is highly nonparaflinic in character. At the same time the extraction of the B B dichlorethyl ether extract at the low temperature with liquid sulphur dioxide produces a raflinate fraction which has characteristics intermediate between paraflinic and non-paraflinic oils. This fraction is useful as a second grade lubricant and can be employed for purposes where the temperature viscosity susceptibility of the oil is not an essential characteristic.

In general the temperatures employed during extraction with B B dichlorethyl ether are within 40 F. of the temperature of complete miscibility and the temperatures employed in extraction with liquid sulphur dioxide are at least 15 F. or lower. I do not propose to bind myself within these limits, however, as it may be desirable in many cases to carry out the extraction with B B dichlorethyl ether at a temperature of more than 40F. below the point of complete miscibility and to extract with liquid sulphur dioxide at temperatures above l5 F.

The foregoing'example is merely descriptive of one method of carrying out my process and is not to be taken as limiting the invention which I claim. I

I claim:

1. A process for the production of lubricating oil from a hydrocarbon oil mixture which comprises extracting said oil with a solvent of the liquid sulphur dioxide type into a rafiinate and an extract and subsequently extracting said raflinate into a plurality of fractions with a solvent of the B B dichlorethyl ether type.

2. A process for the production of lubricating oil from a hydrocarbon oil mixture which comprises extracting said oil with asolvent of 'the B B" dichlorethyl ether type into a rafllnate and an extract and subsequently extracting said extract into fractions with a solvent of the liquid sulphur dioxide type.

3. A process for the production of lubricating oil from a hydrocarbon oil mixture which comprises extracting said oil with a solvent of the sulphur dioxide type into a rafiinate fraction and fractions dissolved in said solvent of the sulphur dioxide type, re-extracting said railinate fraction with a solvent of the B B dichlorethyl ether type into a second raflinate fraction and fractions dissolved in said solvent of the B B dichlorethyl ether type and subsequently separating said solvents from said fractions.

4. A process for the production of lubricating oil from a hydrocarbon oil mixture which comprises extracting said oil at a relatively high temperature with a solvent of the B B dichlorethyl ether type into a railinate and an extract and subsequently extracting said extract into a pluvralitybf fractions at a relatively low temperature with a solvent of the liquid sulphur dioxide type.

,5. A process for the production of lubricating oil from a hydrocarbon oil mixture which comprises extracting said oil at a relatively low temperature with a solvent of the liquid sulphur dioxide type into a raflinate and an extract and subsequently extracting said raflinate into a plurality of fractions at a relatively high temperature with a solvent of the B B dichlorethyl ether type.

6. A process for the production of lubricating oil from a hydrocarbon oil mixture which'comprises extracting said oil with liquid sulphur dioxide into an extract and a railinate and subsequently extracting said raflinate into a plurality of fractions with dichlorethyl ether.

7. A process for the production of lubricating oil from a hydrocarbon oil mixture which comprises extracting said oil at low temperatures with liquid sulphur dioxide into an extract and a rafllnate and subsequently extracting said railinate into a plurality of fractions with dichlor- I high temperatures'in'to a plurality of fractions with B B dichlorethyl ether.

ROBERT E. HAYLETI.