US2163564A - Method of refining mineral oils - Google Patents

Description

June 20, 1939. E. TERRES ET AL 2,163,564

METHOD OF REFINING MINERAL OILS Filed May 23, 1955 2 Sheets-Sheet l ASPHALTENES V MIX/N6 0ND SETTL/NG HSPHALT'F'EEE OIL DISSOLVED IN FLUOEINE SOLVENT.

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June 20, 1939. E. TERRES ET AL 2,163,564

METHOD OF REFINING MINERAL OILS Filed May 23, 1935 2 Sheets-Sheet 2 HZLMQHINE CGNJWININSWSOL VENT ASPHflLT/C WAX Y OIL STOCK HSPHALTENES M/X/NG AN D SETrL/NG ASPHALT- FEEE on.

DISSOL VED IN FLUOE/NE SOLVENTT CHILL/N6 FILTE WA X WAX-FREE OIL DIS8OL VED IN FLUOE/NE SOLVENT? HEATING SETTL/NG DISSOLVED SOLVE/VT PHASE RECOVERY EAF'F/NATE l/NDISSOLl/ED SOLVENT FHA SE RECOVERY EXTRACT 3 vwwwbo w ERNSTTZ-RRES, Ema/45,4 EGEBAETH;

(.JbSEPHMO-S, H /vs RHMSEB Patented June 20, 1939 STATES ATEN'E if.

METHOD OF REFINING MINERAL OILS Ernest Terres, New York, and Erich Saegebarth,

Long Island City, N. Y... and Joseph Moos, Berlin-Mariendorf,

and Hans Rainser, Berlin- Application May 23,

6 Claims.

Our invention relates to the refining of mineral oils by means of solvents and particularly relates to the use of organic and inorganic fluorine compounds in liquid state, which we have discovered to be particularly advantageous for diiferent types of oil refining treatment.

We have found that liquid or liquefied fluorine compounds can be used as solvents or diluents for deasphaltizing and for dewaxing, in the manner that liquid propane is some times used. Also, that under certain circumstances some of these compounds can likewise be used as selective solvents for solvent fractionation of oils, and that these compounds can be used to good effect in conjunction with other solvents which are either selective or non-selective with the fluorine com.- pounds or the oils to be treated.

The fluorine compounds can also be advantageously used in some cases as diluents for oil to be acid treated, as by dissolving the oil in a liquid or liquefied fluorine compound and treating with sulfuric acid to remove unstable constituents of the oil. Various uses of the fluorine compounds will be illustrated in subsequent examples.

The fluorine compounds which we consider as coming within the scope of this invention may be divided into three broad classes, namely:

(1) Aliphatic fluorine compounds, that is, fluorine derivatives of aliphatic hydrocarbons having either straight or branched chains, or both, including both saturated and unsaturated hydrocarbons, in which one or more or all of the hydrogen atoms are substituted by fluorine, and

J which may also contain other substituted halogens such as chlorine and bromine. (2) Aromatic fluorine compounds. (3)Inorganic fluorine compounds. Representative organic fluorine compounds coming within class (1) are as follows:

Pmafilne derioatives.-Mono-, di-, and tri-fluoromethane, and carbon tetrafluoride. Monoto hexa-flucroethanes. Fluorine derivatives of propane, butane and higher parafiines. (The introduction of one or more fluorine atoms into propane may increase its specific qualities for oil 1935, Serial No. 23,136

pentachloromonofluoroethane, symtetrachlorodi fluoroethane, trichlorotrifluoroethane, sym.dichlorotetrafluoroethane, unsym.dichlorotetrafluoroethane, monochloropentafluoroethane, unsyn1.tetrachlorodifluoroethane, unsym.tetrachlorodifluoroethane. Monofluorodibromotrichloroethane, difluorodibromodichloroethane, trifluorodibromomonochloroethane, tetrafluorodibromoethane, sym.difluorodibromodichloroethane. Also, corresponding derivatives of propane and butane.

Representatives of this class for which subsequent examples are given are dichloromonofluoromethane, trichloromonofluoromethane, dichlorodifluoromethane and monobrornodifluoroethane.

Unsaturated aliphatic fluorine dcrivatioea-Dichlorodifiuoroethylene, monochlorotrifluoroethyl ene, trichloromono-fluoroethylene, tetrafluoroethylene, sym.dichlorodifluoroethylene and isomers thereof.

Representative aromatic fluorine compounds coming within class (2) are as follows:

Monofluorobenzol, difluorobenzol, fluorophenols, monofluoronaphthalene and other fluorine and fluorine-halogen derivatives of benzol and its homologues.

Representative inorganic fluorine compounds coming within class (3) are as follows:

Sulfur-containing compounds and other incrgam'c compounds.Sulfuricoxyfluoride, sulfurousoxyfluoride, sulfurylfluoride, thionylfluoride, fluorosulflnic acid, fluorosulfonic acid, disulfur- (ii-fluoride, suliur-difluoride, sulfur-tetrafluoride, and sulfur-hexafluoride. Also corresponding compounds containing selenium or tellurium which do not react with oil.

Uther inorganic compounds.l luorine compounds of nitrogen, antimony, arsenic and tin, such as nitrogentrifluoride, antimony-pentaflm oride, arsenic-pentafluoride and arsenic-trifluoride. Also, compounds of boron such as the addition compound of hydrofluoric acid and metaboric acid having the formula: HBOzHzFz; and compounds of silicon which do not react with oil.

The representatives of class (3) for which subsequent examples are given to indicate their ac ticn are sulfuric-oxyfluoride and sulfur-hexafluoride.

By the expression fluorine-halogen compounds or derivatives as hereinafter used is meant a compound which contains one or more of the other halogens, besides fluorine.

The foregoing fluorine compounds find application, according to our invention, in the following types of refining processes illustrated in the accompanying diagrams:

(A) Deasphaltizing.

Some of the fluorine and fluorine-halogen de rivatives are suitable for deasphaltizing insofar as they dissolve hydrocarbon oils entirely at proper temperatures, whereas asphaltenes are left undissolved. By separating the two layers and recovering the solvent from them, a residual oil can be separated into asphaltines and deasphaltized oil.

(B) Dewaxing.

Some of the fluorine derivatives are suitable as dewaxing agents either alone or in combination with solvents which are soluble in the oil to be dewaxed as well as in the fluorine solvent, for example: benzol, toluol, methylchloride, ethylchloride, carbon bisulphide, ether, esters and others.

(C) Selective solvent extraction.

Some of the mentioned fluorine derivatives may be used for solvent extraction, in which case five different methods of applications may be employed, namely:

(a) One of the mentioned fluorine or fluorinehalogen derivatives may be used alone or in mixtures with others.

(I?) The fluorine or fluorine-halogen derivatives mentioned under (03) may be used in mixture with one or more solvents of the class which is miscible in any proportion with the hydrocarbon oil to be treated and with the fluorine or fluorine-halogen selective solvent. Examples of such solvents are given under the heading (B) dewaxing.

(c) The fluorine or fluorine-halogen derivatives mentioned under (a) may be used in mixture with one or more solvents of the class which is miscible in any proportion in the fluorine or fluorine-halogen selective solvent but which is not miscible or only to a small degree in the hydrocarbon oil to be treated.

Representatives of the latter group of auxiliary solvents are, for example, water or alcohol. These auxiliary solvents serve to decrease the solvent power of the fluorine or fluorine-halogen selective solvent, whereas the group of auxiliary solvents mentioned under (b) tend to increase the solvent power of the selective solvent.

((1) The fluorine and fluorine-halogen compounds mentioned under (a) may also be used for solvent extraction in presence of another selective solvent with which they form two layers under proper conditions. Examples of combinations of solvents having this characteristic are given later.

We have disclosed under (A) above that some fluorine or fluorine-halogen solvents are capable of dissolving hydrocarbons entirely with the exception of asphaltenes. We have found that such fluorine or fluorine-halogen solvents may be used for extraction purposes in combination with a selective solvent which preferably dissolves the undesirable fractions of hydrocarbon oils but which at the same time forms two layers with the fluorine or fluorine-halogen solvent.

(e) For the same purposes as mentioned under 1) we may also employ a solvent for refining purposes which is only selective with respect to the fluorine and fluorine-halogen solvents but not with respect to the hydrocarbon oils, such as propane.

In the accompanying drawings, which show with the aid of explanatory legends several modes of carrying out the invention for purposes of illustration,

Fig. l is a flow diagram illustrating the use of our fluorinated solvents in the successive treatments of an asphaltic waxy oil stock for asphalt removal, wax removal and separation of the oil into a rafflnate fraction and an extract fraction by means of a selective solvent.

It will be understood, if theoil stock to be treated in accordance with the method illustrated by the flow diagram Fig. 1 does not contain asphalt but only wax, that the deasphaltizing step may be by-passed and the solution of oil stock in the fluorine containing solvent may be directly introduced into the dewaxing apparatus, which is indicated in the diagram by the chilling and filtering steps. Likewise, it will be understood, if the oil stock to be treated contains asphalt but no wax, that the dewaxing step may be by-passed and the deasphaltized oil-solvent solution may be directly subjected to extraction with the selective solvent.

In. the extraction step, the deasphaltized and dewaxed solution of oil in fluorine containing solvent may be extracted with a selective solvent alone; or it may be extracted with a mixture of the selective solvent and the fluorine containing solvent, in which latter case part of the fluorine containing solvent flows directly from the supply to the extraction stage as shown in Fig. l, andjoins the selective solvent, prior to entering the mixing and settling step.

In the flow diagram Fig. 2, a method is illustrated in which an asphalting waxy oil stock is freed from asphalt and Wax by means of a fluorinated solvent in the same manner as shown in Fig. 1; and thereafter, the oil solvent solution is heated until separation into two liquid phases takes place, said phases consisting of a dissolved phase, or rafflnate phase, and an undissolved phase, or extract phase. By recovering the solvent from each of said phases the rafilnate and the extract are obtained, respectively.

It has been found that dichloromonofluoromethane and trichloromonofluoromethane div solve mineral oil entirely at temperatures in the neighborhood of or above the pour point of oils which contain wax; also asphaltenes are dissolved entirely. Upon reducing the temperature of the solution containing the waxy lubricating oil distillate dissolved in trichlorornonofluoromethane, the wax crystallized out but a separation of two liquid phases is not obtained at low temperatures.

In the following an example is given for the deWaXing of a Midcontinent overhead cylinder: stock by means of trichlorornonofluoromethane.

Example 1 One volume of a Midcontinent overhead cylinder stock having 10% wax, an A. P. I. gravity of 22.1, a S. U. viscosity of 154 at 210 F. and a pour point of F. was dissolved in 2 volumes of trichloromonofluoromethane, cooled to -50 F. and passed through a filter at this temperature. After removal of the solvent from the filtrate an oil of 26 A. P. I. 182 S. U. viscosity at 219 F. and of a wax content of zero, was obtained. The slack wax showed a melting point of F.

Dichloromonofluoromethane showed the same behavior as outlined for richloromonofluoromethane.

In agitating dichloromonofiuoromethane with certain selective solvents, including chlorophenol, aniline, furfural, nitromethane, furfurylalcohol and others, it has been found that these selective solvents are entirely miscible in dichlorornonofluoromethane and a phase separation does not occur even at temperatures as low as 50 F,

Contrary to this experience trichlorornonorluoromethane gives a phase separation with aniline, nitromethane, furfural, furfurylalcohol and others at low temperature, being only partially soluble therein, whereas it is entirely miscible with chlorophenol, quinoline, benzylalcohol, bromonaphthalene and others.

Dichloromonofiuoromethane and trichloromonofluoro methane can therefore be used auxiliary solvent in combination with selective solvents with which they are entirely miscible. The presence of dichlorornonofiuorometl'iane or trichloromonofluoromethane increases the solvent power of the selective solvent and the treating result can be controlled by the quantity of dichloromonofiuoromethane or trichloromonofluoromethane used.

Trichloromonofiuoromethane may also be used in combination with aniline, nitromethane, i"rfural or furfurylalcohol, in which case the largest amount of trichloromonofluoromethane will serve as diluent and solvent for the rafilnate phase, whereas the extract phase will contain the selective solvent and the oil extract both saturated with the auxiliary solvent trichloromcnofluoromethane,

The action of dichlorodifiuoromethane is quite different from the behavior of trichloromonofiuoromethane or dichloromonofluoromethane in so far as it has no solubility for asphaltenes and its insolubility in selective solvents is more pronounced.

Residual oils may be freed from ashpaltenes by extraction by means of dichlorodifluoromethane. The non-asphaltenic hydrocarbons are dissolved entirely, whereas the asphaltenes form a separate layer and may be segregated in the normal way. This is shown in more detail in the following example.

Example 2 Yield percent 8'? API degrees 21.9 Viscosity at 130 F 664i Viscosity at 210 F 109 Carbon residue 3.0

The yield of asphalt amounted to 13% by volume.

Dichlorodifluoromethane is also suitable for dewaxing purposes, The deasphaltizing and dewaxin processes may also be combined. In such a residual oil, for example, may be treated with the solvent in the neighborhood of 130 F. and t. e asphalt-free solution then cooled to the dewaxing temperature and fitered. If desired, may be the case with oils containing only small quanti 'es of asphaltenes, the separation of oil and wax even be carried out in one operation by d1ssolving the stock in the solvent and cooling it to the dewaxing temperature and filtering it, in

which case the asphaltenes will be separated with the wax.

In. treating mineral oils with dichlorodifluoromethane it is necessary to consider that the temperature range of entire miscibility is limited because this solvent shows a negative temperature coefiicient in regard to the solubility of mineral oils. Upon heating the solution of asphalt-free oil in the solvent, a point can be reached at which separation into two liquid phases occurs. One of the two phases contains the bulk amount or" solvent, having a certain amount of oil in solution. This amount of oil is the smaller, the higher the temperature. The other phase contains the unissolved and separated oil which is, of course, saturated with the solvent. Such phase separation will occur with a heavy cylinder stock at about 212 F. The specific gravity of dichlorodifiuoromethane, which is 1.5 at -36 decreases to 0.83 at 225 F. The position of the two layers may therefore be reversed, depending upon the temperature of the operation and the gravity of the oil.

Example 3 Undissclved Dissolved oil oil Yield, volume "percent" 89. 4 10. 6 A. P. I .degrees 23.6 27. 3 Viscosity at 130 F 1790 Viscosity at 210 F 255 Carbon residue 4.1 1. 2

Dichlorodifluoromethane is not entirely miscible with certain selective solvents, such as quinoline, aniline, dichloroethylether, cresol, phenol, chlorophenol and others. It is therefore possible to use it in combination with the above mentioned solvents in the same manner that propane is used. This procedure is especially advantageous for the treatment of residual oils and is likewise applicable to distillates, as shown by the following examples.

Example 4 One volume of a Midcontinent residual cylinder stock, with properties as shown in the table of the next example, was agitated with four volumes of dichlorodifluoromethane and one vol- Lune of phenol at 104 F. The layers were allowed to settle afterwards and were separated.

The rafiinate layer was treated again with one volume of phenol at the same temperature of 104 F. The layers were again separated and the solvent was removed from the final rafdnate and from the combined extract phases. The properties of the rafinate are shown in the table of the next example.

Example 5 One volume of the same hfidcontinent stock referred to in the preceding example was agitated with. four volumes of dichlorodifluoromethane and one volume of parachlorophenol at le0 F. Upon separation of the layers, the rafiinate phase was treated again with one volume parachlorophenol at 149 13. Upon removal of the solvents from the final rafiinate and the com bined extract phases, the refined oil was ob tained and the properties are shown in the following table:

Original Raflinate, ltafllnai e.

oil Example 4 Example 5 Yield, volume perccnt 1.00 51 A. P. I .dcgrees 20 24. 5 27.5

Visc ity at 130 .l. .797 524 320 Viscosity at 210 F"... 145 98 77 Carbon residue 5. 6 0. 67

Example 5 A dewaxed Midcontinent oil distillate was treated with 3 volumes of dichlorodifiuorometln ane and 1 volume of aniline at 104 F. The layers were allowed to separate and were then i'reed of these solvents. The refined oil was contacted with 16% diatomaceous earth or other filter aid at 450 F. The properties of the finished raffinate are shown in the table the next example.

Example 7 ihe same dewaxed Midcontinent lubricating oi}. distillate was extracted with 2 volumes of dichlorodifiuoromethane and two volumes of parachlorophenol at 113 F. The phases were separated again and the solvents were recovered by distillation. The specifications of the refined oil are shown in the following table:

given in Untreated Rafiinate, Railinate,

stock Example 6 Exampl 7 Yield volume perceut. 100 70 A. P. I d( grees v 23. 2 24. 9 27. 5 Viscosity at F 1287 i 735 Viscosity at 210 F. 91 84. 5 7-1. 8 V. I 75 84 94 Carbon residue 1.9 l. l 0. 42

an equal volume of sulfuricoxyfluoride at room temperature, A separation into two phases occurred.

Example 1'0 A Midcontinent residual oil upon agitation with an equal volume of suliuricoxyfluoride at 87 F. showed a separation into two layers.

Example 11 Equal volumes of chlorphenol and sulfuricoxyfluoride were brought in contact at room temperature and cooled to 32 F. Separation took place at this temperature, whereas above 32 F. chlorophenol was entirely dissolved in sulfuricoxyfiuoride.

Our study of the four fluorine compounds, namely:

Dichloromonofiuoromethane Trichloromonofluoromethane Dichlorodifluoromethane (known as Freon) Sulfuricoxyfiuoride shows a different action of the respective fluorine compounds depending upon the other atoms present in the molecule. Whereas methane, ethane, propane, and other low boiling paraffines, are selective against mineral oils at proper temperatures and against asphaltenes, this behavior is changed by the introduction of chlorine or bromine into the molecule. As known, methylchloride, carbontetrachloride or tribromomethane dissolve mineral oils and asphaltenes entirely. However, the introduction of fluorine into a chlorinated paraffine seems to restore the selectivity, as shown by dichlorodifiuoromethane, and others including monochlorotr-ifiuoroethane, dichlorotrifiuoroethane, dichlorodifluoroethane, dichlorotetrafluoroethane, monochlorotrifiuoromethane, monobromodifiuoroethane, and monochlorodifiuorethane.

Monofiuorine derivatives of chlorinated paraffiines, such as dichloromonofluoromethane and trichloromonofiuoromethane, do not possess the selectivity of dichlorodifluoromethane. It appears, therefore, that more than one fluorine atom. has to be present in these derivatives in order to cause the solvent to be selective.

The introduction of one or more fluorine atoms into propane or other solvent will change its specific qualities for oil refining purposes, such as selectivity, suitability for deasphaltizing and ole-waxing (by decreasing the solubility in the oil) so that it becomes more than a diluent and can be used as a selective solvent. Examples of such fluorinated solvents are the following: trifluoropropane, difluoropropane, monofluoroethane, difiuoroethane, monofluoromethane, difiuoromethane, trifiuoromethane, and carbontetrafluoride.

The use of dichlorodifluoromethane, in accordance with our invention, is described and claimed specifically in our copending application filed of even date herewith.

In the claims the term liquefied means that the substance referred to is used. in a liquid state, whether normally liquid or not, and the expression predominantly fluorine containing means a halogenated derivative of an organic substance containing one or more fluorine atoms in excess of such other halogen atoms as may be contained therein.

We claim the following as our invention:

1. A method of refining a waxy mineral oil stock comprising dissolving the oil in a liquefied organic fluorine compound in which the oil is soluble and at low temperatures the wax is insoluble, chilling the mixture to a low temperature at which the wax separates out, removing the separated wax, and heating the solution in a separate step to a higher temperature to bring about phase separation, and separating the phases.

2. A method of refining a waxy mineral oil comprising dissolving the oil in a fluorine deriva tive of an aromatic hydrocarbon containng no oxygen, chlling the solution to a temperature at which the wax separates out, removing the wax,

and extracting at an elevated temperature with a selective solvent.

3. A method of refining a mineral oil containing asphalt comprising dissolving the oil in a fiuorinated derivative of an aromatic hydrocarbon. containing no oxygen, separating out the undissclved asphalt, chilling the solution to precipitate out wax, and removing the wax.

4. The process of refining a mineral oil comprising dissolving the soluble constituents of the oil in a liquefied predominantly fluorine containing halogenated organic compound, separating the undissolved constituents, treating the solution with a mixture of said compound. and

a solvent selective with respect thereto to extract undesirable constituents of the oil, and separating the phases thereby formed.

5. The process of refining a mineral oil comprising dissolving the soluble constituents of the oil in a liquefied predominantly fluorine containing halogenated organc compound, separating the undissolved constituents, treating the solution with a mixture of said compound and a solvent miscible therewith and selective with respect to the oil to extract undesirable constituents of the oil, and separating the phases thereby formed.

6. The process of refining a mineral oil comprising dissolving the soluble constituents of the oil in a liquefied predominantly fluorine containing halogenated unsaturated hydrocarbon compound, separating the undissolved constituents, treating the solution with a mixture of said compound and a solvent selective with respect thereto to extract undesirable constituents of the oil, and separating the phases thereby formed.

ERNEST TERRES. ERICH SAEGEBARTH. JOSEPH MOOS.

HANS RAMSER.

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