US2229278A - Method of treating hydrocarbons - Google Patents

Description

Jan. 2l,` 1941. w. A. CRAIG METHOD OF TEATING HYDROCARBONS Filed June 28, 1958 Csar/V565 w /N 10s/TOR By m5@ ATTORNEYS' Patented Jan. 21, 1941 UNITED STATES METHOD OF TREATING HYDROCARBONS Wallace Alexander Craig, Los Angeles, Calif., as-

signor to Richfield Oil Corporation, Los Angeles, Calif., a corporation of Delaware Application June 28, 1938, Serial No. 216,281

7 Claims.

This invention relates to the manufacture of a motor fuel and more particularly to a process of treating a mixture of a hydrocarbon oil and an aliphatic alcohol whereby the gum forming constituents and other objectionable bodies of the oil are removed and a product obtained which does not require further treatment for sweeten- In carrying out the invention, a mixture of a hydrocarbon oil and an aliphatic alcohol are treated with a maintained solution of a heavy metal salt. I am aware of a prior proposal for the removal of gum forming constituents and other objectionable bodies from hydrocarbons by treatment with heavy metal sal-ts. Such a process is disclosed in the patent to Arthur Lachman, No. 1,790,622, granted January 27, 1931, and Reissue Patent No. 19,879, granted March 3, 1936.

In practicing the prior art process in which hydrocarbon oils are treated with a maintained solution of a heavy metal salt, the gum forming constituents and certain other objectionable bodies in the oil are removed but the treated oil is sour and requires further treatment. Also the product obtains impurities which reduce the effect of tetraethyl lead when the latter is added to such fuel to increase its octane number.

In the present process wherein the hydrocarbon oil is first mixed with an aliphatic alcohol, the necessity of further treatment is avoided. When such mixture is subjected to 'a vapor phase treatment with a maintained solution of a heavy metal salt, the resultant product is no-t only substantially free of gum forming constituents and colored constituents, but it is substantially sweet and therefore does not require further treatment.

While I am unable to state why the substances which account for most of the sourness in cracked gasoline, such as the mercaptans, are removed when a sour hydrocarbon oil is treated as herein described in the presence of alcohol vapors, I have found that the water which is recovered in the present process is alkaline, whereas in the prior art process of treating the hydrocarbon oil alone with a heavy metal salt, the recovered water contains small quantities of acid, such as hydrochloric acid, when the oil is treated with a Zinc chloride solution. It is therefore probable that the alkaline condition of the solution during treatment results in the conversion of the impurities into products that are removed as nonvolatile solids.

As a further feature of the invention I have discovered that if a branched chain alcohol is used, the product obtained is not only free of the gum forming constituents and other objectionable constituents and sweet, but that an increased octane number is obtained. This increase in octane number may possibly be due to the conversion of the branched chain alcohols into branched chain ethers, which are soluble in the hydrocarbon oil, are insoluble in Water and possess excellent anti-knock properties. erably employ a branched chain alcohol having more than two atoms of carbon and less than seven atoms of carbon to the molecule.

'Ihe accompanying drawing is a diagrammatic view of one form of apparatus suitable for use in practicing the process.

In the drawing, the reference numeral I designates a storage tank for the mixture of hydrocarbon oil and alcohol to be treated. The tank is provided with an outlet controlled by a valve 2 and connected to a pump 3 capable of delivering predetermined amounts of liquid. The outlet of the pump is connected to a heater 4 which may be provided with an electric heating coil 5 or other suitable heating means. The heater is in turn connected to a treating `tower 6 which may be provided with suitable heating means, herein shown as a heating coil 1. Suitable packing material 8 is arranged within the tower. A drain pipe 9 is connected to the bottom of the tower and is controlled by a valve I 0. A pipe I I is connected to the tower adjacent the bottom and is controlled by a valve I2. This pipe may be employed for delivering steam to the tower. At the top of the tower a surge chamber I3 is formed. The top of the surge chamber is provided with a feed opening I4 controlled by a valve I5. The heavy metal salt or other treating reagent is charged into the tower through this opening. A pipe I6 is connected to the top of the surge chamber and forms a vapor line which extends into a coil arranged Within a condenser I'I. The lower end of the coil is connected to a discharge pipe 29. The condenser is provided with an inlet I8 and an outlet I9 for water or other cooling fluid.

In practicing the process a suitable quantity of a mixture of an alcohol and a hydrocarbon oil is placed in tank I. The flow of the alcohol-oil mixture is controlled by the valve 2 and the pump 3. The mixture in liquid form is delivered to the heater 4 which is maintained at a desired temperature. It passes from the heater, largely as vapor, and is delivered into the bottom of the treating tower 6. 'Ihe tower is charged with the desired treating reagent with the level of the liquid in the treating tower almost up to the surge chamber I3. The temperature Within the I preftower is controlled by the heating coil 'l or other suitable means. If desired, steam may be introduced into the tower 'l through pipe I2. The alcohol-oil vapors pass up through the tower and are brought into intimate contact with the treating solution by the packing material 8. At the beginning of an operation the vapors within the tower force a portion of the treating solution into the surge chamber but the surge chamber is of such size that no over-flow into the vapor line occurs. Equilibrium is eventually established and the solution trickles down into tower 8 as rapidly as it is lifted into the surge chamber. The treated vapors then pass through the delivery pipe l into the condenser l1 and the cooled material is conveyed to suitable storage pipes' through tank 20.

As a specic example of the operation of the process the treating tower 6 was charged with a solution of zinc chloride in isopropyl alcohol. A mixture of two parts of raw cracked gasoline and one part of isopropyl alcohol was placed in the storage tank I. This mixture was then delivered to the heater 4 and the temperature of the gasoline-alcohol vapors, containing some liquid, entering the treating tower, was maintained at M-190 F. The temperature at the bottom of the tower was 260-270 F., adjacent the center of the tower Z50-265 F., and at the top of the tower 210-2'78 F. The vapors passing through the system and recovered by condensation consisted of water, an oil phase and gas. The gas was assumed to be largely propylene. The water was a solution of unreacted alcohol in water. The oil, after being washed with water several times to remove any dissolved alcohol, was examined to determine its composition. A comparison of the raw cracked gasoline with the recovered treated material is shown below in the table. The tests to which the oil was submitted are the tests prescribed for testing petroleum products.

Table Raw cracked Raw gasoline Reercev cracked fraction cut t eqted gasoline to E. P. of t k' treated stock 0c Gravity, API 50. 8 57. 0 Color, Saybolt Red Yellow 20 Say. color after 4 hrs.

sunlight 16 Mercaptan content, gram mols/ 1000 liters 13. 4 16. G 0 Copper dish gums, Ing/100 ml 279 191 12 Glass dish gums, mg./100 ml 86 l0 ll Sulfur content, percent 0. 74 0. 66 0. 42 Octane number 70+ 72 75- A. S. T. M. distillation:

Initial boiling point, "F 118 120 99 5% 168 160 156 Percent recovered 97.0 98.0 97. 5

The residual solution of zinc chloride removed from the treater at the end of the test was a water solution, the alcohol having been replaced by water. Equally good results would therefore have been obtained if an aqueous solution of Zinc chloride had been used.

The process as conducted and described was carried out with a Zinc chloride solution. Other heavy metal salts can be used in place of Zinc chloride. mean salts of Zinc, copper, cadmium, mercury, iron, chromium, manganese, aluminum, nickel or cobalt. These salts may be the chloride, bromide, sulfate, nitrate or any of the water or alcohol soluble salts of the above named metals of organic acids, such as the sulfonic acid of benzene, toluene or xylene or the sulfo acids derived from the treatment of petroleum oils with sulfuric acid.

While the method described herein is well adapted to carry out my invention, I do not wish to be limited to the conditions herein set forth. Other means of contacting the alcohol-hydrocarbon oil vapor with a maintained solution of a heavy metal salt can be used, such, for example, as a vessel provided with mechanical agitators. While I have described in my example, a method of treating, in vapor phase, a raw cracked gasoline admixed with isopropyl alcohol and contacting the vapors with a maintained solution of zinc chloride, other aliphatic alcohols may be used; also solutions of other heavy metal salts may be employed to effect the desired results. The choice of alcohol and the choice of treating reagent depends upon the type of raw material to be treated and the characteristics that are desired in the nal product. The pressure employed in the above example was atmospheric, but reduced pressure or super-atmospheric pressure can also be employed when needed to obtain the optimum operating conditions.

I claim:

l. The method of producing a motor fuel which comprises vaporizing a mixture of a hydrocarbon oil and a branched chain aliphatic alcohol containing more than two and less than seven carbon atoms in a molecule and contacting the vaporized mixture with a maintained solution of Zinc chloride at a reacting temperature.

2. The method of producing a motor fuel which comprises contacting vapors of a hydrocarbon oil and an aliphatic alcohol containing more than two and less than seven carbon atoms in the molecule with a maintained solution of zinc chloride at a reacting temperature and separating the treated vapors from the solution.

3. In a process of purifying hydrocarbon oils the steps comprising mixing substantially two parts of a hydrocarbon oil and substantially one part of a branched chain aliphatic alcohol containing more than two and less than seven carbon atoms in a molecule and contacting the vaporized mixture with a maintained solution of zinc chloride at a reacting temperature.

4. In a process of purifying hydrocarbon oils the steps comprising mixing substantially two parts raw cracked gasoline and substantially one part isopropyl alcohol, vaporizing the mixture, and contacting the vaporized mixture with a maintained solution of zinc chloride at a reacting temperature.

5. The method of producing a motor fuel which comprises vaporizing a mixture of a hydrocarbon oil and a branched chain aliphatic alcohol containing more than two and less than seven carbon atoms in a molecule, and contacting the vaporized mixture with a maintained solution of a chloride of a heavy metal of the group consisting of zinc, copper, cadmium, mercury, iron, chromium, manganese, aluminum, nickel and cobalt 6. The method of producing a motor fuel which comprises vaporizing a mixture of substantially two parts of a hydrocarbon oil and substantially By the term heavy metal salts Il two parts of raw cracked gasoline and substantially one part of an isopropyl alcohol and contacting the vaporized mixture with a maintained `solution of a chloride of a heavy metal of the group consisting of zinc, copper, cadmium, mercury, iron, chromium, manganese, aluminum, nickel and cobalt.

WALLACE ALEXANDER CRAIG.

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