US2035607A - Process of purifying and refining hydrocarbon oils - Google Patents

Description

March 31, 1636.

A. LAcHMAN PROCESS OF PURIFYING tND REFINING HYDROCARBON OILS Filed -July 26, 1929 2 Sheets-Sheet 1 .mi a

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INVENTOR BY #Pff/a@ iff/MM ATTORNEY March 31, 1936. A. I Acl-uvlAN` 2,035,507

PROCESS OF PURIFYING' AND REFINING HYDROCRBON OILS 2 Sheets-Sheet 2 www A BNN. mmm

w y IIIIII A @N w .MM n mw Y m\..\\.\\\ K KMS mm m www@ ML fffcN wmml mm@ wm (nur: mk wwu@ 9m mm Patented Mar. 3l, 1936 'rares ATi orties PROCESS OF PURIFYING AND REFINING HYDROCARBON OILS Application July 2,6, 1929, Serial N0. 381,?05

19 Claims.

This invention relates to an improved process of purifying and refining hydrocarbon oils obtained by distillation or cracking of mineral oils such as lubricating oil stocks, lamp oil distillates, gasoline or naphtha stocks, or distillates derived from shale oil, and more specically refers to the treatment of gasoline or naphtha stock produced by cracking crude pretroleum oils or distillates derived from relatively high sulphur bearing mineral oils, in which hydrogen sulphide, mercaptans and other sulphur bearing compounds, as well as varying percentages of oxygenated hydrocarbons and unstable hydrocarbons (such as diolenes and acetylenes) may be present or formed during said distillation or cracking operation.

Reference is made to United States Patent No. 1,809,170, granted June 9, 1931 to Arthur Lachman, Serial No. 361,513, led May 8, 1929 for Process of refining hydrocarbon oils, which discloses a vapor phase method or process for purifying and refining mineral oil products With a water solution of certain metallic salts, or mixtures of the same, such as zinc, copper, cadmium, mercury iron, chromium, manganese,` aluminum, nickel or cobalt water soluble salts which may be the chloride, bromide, iodide, sulphate, sulphite, nitrate and also any of the water soluble salts of the above named metals of organic acids, such as the sulphonic acids of benzol, toluol and xylol, or the sulphonic acids derived from the treatment of petroleum oil with sulphuric acid, it being observed that the enumerated metals may be classed as heavy metals and it being understood further that the Word heavy as used in the term salt of a heavy metal (which latter phrase is embodied in the claims to comprehend the materials capable of use in my process) is to be understood as including those metals which forni soluble salt solutions capable of being maintained in solution at the temperatures and pressures at which the hereinbefore-described process may be practiced.

For the purpose of simplifying the description of my invention, reference will be made mainly to gasoline stock. Crude gasoline stocks obtained by distillation or cracking petroleum oils, consists of a mixture of saturated and unsaturated hydrocarbons together with sulphur compounds, nitrogen bases and other substances of an undened nature. These latter substances are readily oxidizable at ordinary temperature and, are usually responsible for the change` of color which takes places when refined gasoline is stored. These oxidizable substances are removed with difficulty when gasoline stocksr are treated by the methods known in the art.

By well-known methods, crude gasoline stocks obtained by distillation of crude petroleum oil or by cracking a higher boiling petroleum oil, are customarily treated with approximately from 1 per cent to as high as 8 per cent or higher by weight, sulphuric acid, the quantity of sulphuric acid depending upon the nature of the gasoline stock to be treated and the degree of relinement desired. This acid treatment usually consists in commingling the gasoline stock with the required amount of sulphuric acid necessary to obtain the desired extraction, either by the wel1-known batch or continuous treatment, after which the products ofk the acid reaction are permitted to settle and are then withdrawn from the treated gasoline stock. The acid treated gaso-` line stock is then neutralized by washing with a water solution of an alkali and finally with water. This treatment removes most of the impurities, but subsequent treatments are usually necessary to deodorize and remove or convert corrosive sulphur compounds into noncorrosive bodies. For this purpose, a water solution of sodium plumbite or sodium hypochlorite is usually employed to render the gasoline stock sweet to the doctor test. In these treatments, particularly where hypochlorite of soda is employed, chlorinated hydrocarbons may be formed to a small extent which may be converted into corrosive compounds during a subsequent distillation.

The general objections to a treatment of this character, are as follows: (1) Gasoline purified by this method frequently becomes discolored when stored for a period of time; (2) considerable quantities of sulphuric acid are required, which are diflicult to recover; (3) as high as 10 per cent of the valuable unstable hydrocarbons contained in the gasoline. stock may be lost and (4) the treatment must frequently be followed by a sweetening process, such as that heretofore described.

Now, I have discovered that the sulphuric acid normally used to treat crude gasoline stocks may be reduced to a great extent, and in many cases may be entirely eliminated by the employment of a water solution of certain metallic salts, or mixtures of the saine which may be zinc, copper, cadmium, mercury, iron,` chromium, manganese, aluminum,` nickel or cobalt water soluble salts, such as the chloride, bromide, iodide, sulphate, sulphite, nitrate, nitrite, and also any of' the water soluble salts of the above named metals of organic acids, such as the sulphonic acids of benzol, toluol and Xylol, or the sulphonic acid salts derived from the treatment of petroleum oils with sulphuric acid.

The process described briefly consists in passing the hydrocarbon oil product, such as gasoline stock, in a liquid phase, commingled with a substantially concentrated water solution of any of the above named salts or mixtures thereof, through a heating coil under a pressure sufficient to prevent any substantial vaporization therein, at temperatures of approximately 300 to 600 degrees F., and then immediately releasing the pressure and separating by distillation the purified hydrocarbon oil pro-duct from the water solution of the metallic salt or salts, the extracted impurities and products of polymerization or condensation, or as shown in Figure II the gasoline stock and water solution of metallic salt or salts may be first separately heated and then commingled under a pressure.

The hydrocarbon oil stock to be treated by my invention may or may not have had a preliminary treatment with sulphuric acid, or other agents to partlypurify the same, or may be first partly purified by my invention and the purification completed by methods known in the art such as treatment with caustic alkali, sulphuric acid, etc. In the case of gasoline stocks produced by cracking high sulphur bearing crude petroleum oil or residuums, it may be advantageous to treat such gasoline stocks with sulphuric acid or sulphuric anhydride at low temperatures, ranging from approximately 0 to 30 degrees F. before the treatment with a concentrated water solution of any of the aforesaid Water soluble metallic salts at the elevated temperatures and pressures heretofore stated and this treatment may also be followed by treatment with an alkaline water solution of sodium, potassium, or calcium hydroxide, or the carbonates of sodium or potassium.

Although a solution of less concentration may be employed which may range from 50 or less to approximately 85 per cent, the strength of the Awater solution of the metallic salt or mixtures of salts employed is preferably a substantially concentrated solution, and the temperature employed for the treatment is preferably approximately 300 to 600 degrees F.,-this Vtemperature depending upon the vaporizing temperature .of the oil under treatment.

One of the principal objects of this invention is to accomplish a purification of gasoline or naphtha stocks produced by thermo molecular decomposition of high boiling petroleum oils, by a treatment with a substantially concentrated water solution of a metal salt under a pressure sufficient to prevent any substantial vaporization thereof and at a temperature of approximatelyV 300 to 600 degrees F., followed by a distillation and fractionation operation to separate the products of reaction and higher boiling polymerized products from the purified gasoline or naphtha stocks.

Another object of the invention is to provide a continuous, rapid and economical process for purifying gasoline stocks produced by the thermo decomposition of higher boiling petroleum oils, by treating the same under super-atmospheric pressure sucient to maintain a liquid phase, with a substantially concentrated watersolution of a metallic salt at temperatures of approximately 300 to 600 degrees F., to polymerize substantially all the unstable hydrocarbons contained therein and at the same time remove Various other objects and advantages of the present invention will be apparent from the description of the preferred form or example of the process embodying the invention. For this purpose, reference is made to the accompanying drawings in which there is illustrated two forms of apparatus in which the invention may be performed.

Figure I represents one form of an apparatus for carrying out the invention in which the petroleum oil product to be treated is first commingled with the water solution of a metallic salt and thereafter heated to a reaction temperature by causing the same to pass through a heating coil under pressure.

Figure II represents another form of apparatus in which the petroleum oil product and the water solution of a metallic salt are separately heated to a reaction temperature and are thereafter commingled by means of a jet mixer.

In- Figure I, 3 represents generally a tank for holding a supply of gasoline or other petroleum oil stock to be processed. Pipe I, controlled by valve 2, connects the gasoline stock tank 3 near the top to a source of supply not shown. Pipe 4, controlled by valve 5, connects the gasoline stock tank 3 to the inlet side of pump 6. Pipe 4U, controlled by valve 4I connects pipe 4 to a fractionating tower not shown. Pipe I connects pump 6 to jet mixer 8. I3 represents generally a tank for holding a concentrated water solution of a metallic salt such as zinc chloride, zinc bromide, zinc iodide, etc., or any of the other metal salts heretofore enumerated. Pipe I4, controlled by Valve I5, connects tank I3 near the top to a source of supply not shown. Pipe I I, controlled by valve I2, connects tank I3 near the bottom to the inlet side of pump I. Pipe 9 connects the discharge side of pump I0 to jet mixer 8. Pipe |6 connects the jet mixer 8 to heater coil 38. The heater coil 38 is stationed in the furnace I'I. 'I'he furnace is provided with a burner I8 which leads to a supply of fuel not shown. Pipe 39, controlled by pressure release valve I9, connects the heater coil 38 to distillation tower 20. The distillation tower 26 is provided with bubble trays 2 I. Pipe 22, controlled by valve 23, connects the distillation tower 2! near the bottom to a source of water supply not shown. Pipe 25 controlled by valve 24, connects distillation tower 23 at the bottom to tank 26. Pipe 28 controlled by valve 21, connects the tank 26 to a storage not shown. The pipe 29 connects distillation tower 20 at the top to condenser coil 3|. Condenser coil 3| is stationed in the condenser box 30 and is provided with a Water inlet pipe 32 and a water outlet pipe 3'I. The pipe 32 leads to a source of water supply not shown and the water outlet pipe 3l leads to a waste receiver not shown. Pipe 33 connects condenser coil 3| to treated gasoline tank 34. Pipe 36, controlled by valve 35, connects the treated gasoline tank near the bottom to a storage not shown.

In Figure II, 3 represents generally a tank for holding a supply of gasoline or other petroleum oil stock to be processed. Pipe I, controlled by valve 2, connects the gasoline stock tank 3 near the top to a source of supply not shown. Pipe 4, controlled by valve 5, connects the gasoline stock tank 3 to the inlet side of pump 6. Pipe 40, controlled by Valve 4I, connects pipe 4 to a fractionating tower not shown. Pipe 'I connects pump 6 to heater coil 38. Heater coil 33 is stationed in a furnace Il. Furnace I 'I is provided with a burner I8 which leads to a fuel supply not shown. I3 represents generally a tank for holding a concentrated water solution of a metallic salt such as zinc chloride, Zinc bromide, zinc iodide, etc., or any of the other metallic salts heretofore enumerated. Pipe I ll, controlled by valve l5, connects tank i3 near the top to a source of supply not shown. Pipe II controlled by valve I2, connects tank I3 near the bottom tothe inlet side of pump Ill. Pipe 9 connects the discharge side of pump i Il to heater coil 44. Heater coil dll is stationed in furnace 42. Furnace 42 is provided with a burner i3 which leads to a fuel supply not shown. Pipe 45 connects heater coil 44 to jet mixer 8. Pipe 39 connects heater coil 38 to jet mixer 8. Pipe I 3 connects jet mixer 8 to reac-V tion chamber 4B. Pipe All controlled by pressure release valve IS, connects reaction chamber 4E to distillation tower 2li. Distillation tower 2B is provided with bubble trays 2I. Pipe 22, controlled by valve 23, connects distillation tower 2e to a source of water supply not shown. Pipe 25, controlled by valve 2d, connects the bottom of distillation tower 2! to tank 2S. Pipe 2B, controlled by valve 2l, connects tank 26 to a storage not shown. Pipe 29 connects distillation tower 28 at the top to condenser coil 3 I. Condenser coil 3I is situated in the condenser box 30, and is provided with a water inlet pipe 32 and a water outlet pipe 3l. The pipe 32 leads to a source of water supply not shown and the water outlet pipe 3l leads to a waste receiver not shown. Pipe 33 connects the condenser box 3i) to treated gasoline tank 34. Pipe 38, controlled by valve 35, connects the treated gasoline tank 34 near the bottom to a storage no-t shown.

The process as carried out in the apparatus described in Figure I, is as follows:

Tank 3 is lled with the petroleum oil product to be treated by operation of valve 2. Petroleum oil distillate, such as gasoline stock contained in tank 3, is permitted to ow through pipe Ll and into the inlet side of pump 6, the rate of ilow being governed by operation of valve 5. Pump 6 continuously discharges the gasoline stock under a pressure of approximately to 1000 pounds gauge, into jet mixer 8, wherein the gasoline stock is continuously commingled with the necessary quantity of a substantially concentrated water solution of a metallic salt such as zinc chloride from the supply tank I 3.

The water solution of metallic salt contained in the supply tank I3 is permitted to flow through pipe II and into the inlet side of pump I3 which discharges the same under a pressure ranging from approximately 100 to 1000 pounds gauge through pipe 9 and into said jet mixer 8, the rate of flow being governed by operation of valve I2.

The quantity of water solution of metallic salt may range from as low as l per cent to as high as l0 per cent or higher, by volume, depending upon the stock to be treated. For example, if a crude gasoline stock contains a high percentage of impurities to be extracted as high as l0 per cent by Volume or more of a concentrated water Ysolution of any of the aforesaid metallic salts or mixtures of the same may be employed. The pressure maintained on the system by means of pumps 3 and I e is so regulated that the commingled mixture of the water solution of metallic salt or salts and gasoline stock under treatment passing through heater coil 38 will be maintained in a substantially liquid phase, such pressure depending upon the boiling point of the gasoline stock and the temperature employed. From jet mixer 8, the gasoline stock, commingled with the water solution of the metallic salt or salts passes through heater coil 38, pipe 39 and pressure release valve IS, where the pressure is reduced to atmospheric or approximately atmospheric, and then passes into distillation tower 23. The commingled mixture passing through heater coil 38 is heated to the reaction temperature. Preferably a temperature ranging from approximately 300 to 400 degrees F. is suitable to employ in treating ordinary gasoline stocks. However, with some grades oi petroleum oil distillates, as high as ,600 degrees F. or a little higher, may be employed.

In distillation tower 2i), the puried gasoline stock at a temperature ranging from approximately 300 to 400 degrees F., together with a portion of the water content of the salt solution, are vapcrized and separated from the products of the reaction and the metallic salt or salts employed. The purified gasoline stock, mixed with "5' water vapor, passes out of distillation tower 23, through pipe 29, into condenser coil 3i, stationed in the condenser box 3e, wherein the said puried gasoline stock and water vapor are condensed to a liquid, passing through pipe 33 and into the treated gasoline tank 311. A cooling fluid such as water is employed to condense the gasoline vapors passing through condenser coil 3l coming from a source not shown through pipe 32 and passing out of condenser box 3e through i which separate in the bottom of distillation tower r;

253 are intermittently or continuously drawn into 35 through pipe 25, the ilow being controlled by valve 24, water being continuously or intermittently introduced into the lower section of dis tillation tower 2li, through pipe 22, controlled by valve E3, in quantities sufficient to replace the vaporized water from the metallic salt water solution so as to maintain the used metallic salts or compounds and products of the reaction in a fluid condition.

From tank 26 the excess water solution of metallic salt or salts and products of the reaction are conducted to a storage not shown through pipe controlled by valve 2l, and the metallic salts or compounds are separated from the reaction products and purified for re-use.

As illustrated in Figures I and II, if it is desired to treat a gasoline stock coming directly from a fractionating tower, or other distillation apparatus, in a vapor or semi-vapor state, valve 5 is closed and valve @El is opened, which permits the gasoline stock coming from a source not shown, in a vapor or semi-vapor state, to flow through the pipe et] and into the inlet side of pump 6, wherein the gasoline stock is completely condensed to a liquid by the applied pressure maintained on the system and the introduction of the cool water solution of a metallic salt or salts in Figure I and by the application of pressure in Figure II.

The process as carried out in the apparatus described in Figure II is substantially the same as the process heretofore described for Figure I, except that` the petroleum oil or gasoline stock to be treated and the water solution of a metallic salt or salts are rst separately heated to the reaction temperature by heating coils 38 and 44 at a pressure sufficient to prevent any substantial vaporization therein, after which the heated gasoline stools and heated water solution of a metallic salt or salts as heretofore enumerated are commingled in jet mixer 8 and pass through pipe IG, reaction chamber 66, pipe 4T, pressure release valve l and into distillation tower 2i).

While the process herein described is well adapted for carrying out the objects of the present invention, it is to be understood that various modifications and changes may be made without departing from the invention, such for example, as the use of centrifugal or other mechanical mixers, or the employment of any of the well-known contact towers wherein a water solution of a metallic salt or mixtures of metallic salts, either organic or inorganic, heretofore enumerated, may be commingled with or brought into contact with a petroleum oil at a pressure sufcient to prevent substantial vaporization at the reacting temperature, and the invention includes all such modications and changes as come within the scope of the appended claims.

What I claim is:

1. A process of purifying petroleum oil products, comprising, commingling a petroleum oil product with a substantially concentrated water solution of a zinc salt, passing the commingled mixture through a heating coil and heating the mixture to a reaction temperature under pressure sufficient to prevent substantial vaporization, releasing the pressure and separating by vaporization, fractionation and condensation a purified petroleum oil product from products of reaction and excess treating agent.

2. A process of purifying petroleum oil products, comprising, commingling a petroleum oil product with a substantially concentrated water solution of a zinc salt, passing the commingled mixture through a heating coil and heating the mixture to a temperature of approximately 300 to 60) degrees F. under pressure sufficient to prevent substantial vaporization, releasing the pressure and separating by Vaporization, fractionation and condensation a purified petroleum oil product from products of reaction and excess treating agent.

3. A continuous process for purifying gasoline stocks, comprising, continuously commingling gasoline stock with a substantially concentrated water solution of a Zinc salt, continuously passing the commingled mixture through a heating element and heating the mixture to a temperature of approximately SUO to 600 degrees F., under a pressure sufhcient to prevent substantial vaporization, releasing the pressure and separating by vaporization, fractionation and condensation a puried gasoline stock from products of reaction and excess treating agent.

4. A process of removing gum forming constituents from cracked gasoline stock, comprising, commingling a cracked gasoline stock with a water solution of aV zinc salt and heating the commingled mixture to a temperature of approximately 300 to 600 degrees F., under a pressure sufficient to prevent substantial vaporization, while passing through a. heating'. coil, for a perod of time suicient to cause the unstable hydrocarbons contained in the cracked gasoline stock to polymerize with the formation of gums, then reducing the pressure to approximately atmospheric and separating by vaporization, fractionation and condensation a purified gasoline stock from products vof reaction, polymerization and excess treating agent.

5. A continuous process for purifying gasoline stocks derived by thermo-decomposition of higher boiling petroleum oils, comprising, continuously commingling gasoline stock with a water solution of zinc sulphate, continuously passing the commingled mixture through a heating coil and heating the commingled gasoline stock and water solution of Zinc sulphate to a temperature of approximately 360 to 400 degrees F., under a pressure sufficient to prevent substantial vaporization, continuously releasing the pressure after the commingled mixture of gasoline stock and water solution vof zinc sulphate has passed through said heating coil, continuously passing the treated gasoline stock, products of reaction and excess treating agent into a vaporizing tower, continuously vaporizing, fractionating and separating a purified gasoline stock and water vapor from' higher boiling reaction products and excess treating agent.

6. A continuous process of purifying gasoline stocks derived by the thermo molecular decomposition of higher boiling petroleum oils, cornprising, continuously commingling gasoline stock with a water solution of a zinc salt, continuously passing the commingled mixture through a heating coil and heating the commingled gasoline stock and Vwater solution of zinc salt to a temperature of approximately 300 to 400 degrees F., under a pressure suflicient to prevent substantial vaporization, continuously releasing the pressure and continuously passing the heated mixture of gasoline stock, water solution of zinc salt and products of reaction into a vaporizing tower, continuously Vaporizing and separating by Vaporization, fractionation and condensation a puried gasoline stock mixed with water from higher boiling products of reaction and excess treating agent, continuously introducing water into the vaporizing tower in quantities suicient to replace the water of vaporization, continuously withdrawing products of reaction and introduced water containing excess treating agent, substantially as described.

7. A process of purifying gasoline stock, comprising, contacting gasoline stock with a water solution of a zinc salt while passing through a heating coil, under a pressure suicient to prevent any substantial vaporization, and heating the mixed gasoline stock and water solution of Zinc salt to a temperature of approximately 300 to 400 degrees F., releasing the pressure after the gasoline stock Inixed with the water solution of Zinc salt has passed through the heating coil, and separating by vaporization, fractionation and condensation a purified gasoline stock from higher boiling products of reaction and excess treating agent.

8. A process of purifying petroleum oil, cornprising, commingling the petroleum oil with a water solution of zinc salt, passing the commingled mixture through a heating coil and heating the commingled mixture to a reaction temperature, under a pressure suicient to prevent substantial vaporization, releasing the pressure and passing the treated petroleum oil, products of reaction and water solution of Zinc salt into a vaporizing tower, maintaining the zinc salt in a fluid condition by addition of water, vaporizing, fractionating and separating a puried petroleum oil, mixed with water vapor, from higher boiling reaction products and excess treating agent.

9. A process of purifying petroleum oil products, comprising, commingling a petroleum oil product with a substantially concentrated Water solution of a zinc salt, passing the commingled mixture through a heating coil and heating the mixture to a temperature of approximately 400 degrees F. under pressure sufcient to prevent substantial vaporization, releasing the pressure and separating by vaporization, fractionation and condensation a purified petroleum oil product from products of reaction and excess treating agent.

10. A continuous process for purifying gasoline stocks, comprising, continuously commingling gasoline stock with a substantially concentrated water solution of a zinc salt, continuously passing the commingled mixture through a heating element and heating the mixture to a temperature of approximately 400 degrees F., under a pressure sufficient to prevent substantial vaporization, releasing the pressure and separating by vaporization, fractionation and condensation a purified gasoline stock from products of reaction and excess treating agent.

11. A process of purifying gasoline stock, comprising, contacting gasoline stock with a Water solution of a zinc salt while passing through a heating coil, under a pressure suiiicient to prevent any substantial vaporization, and heating the mixed gasoline stock and water solution of zinc salt to atemperature of approximately 400 degrees F., releasing the pressure after the gasoline stock mixed with the water solution of zinc salt has passed through the heating coil, and separating by vaporization, fractionation and condensation a purified gasoline stock from higher boiling products of reaction and excess treating agent.

12. A process of purifying petroleum oil products, comprising, commingling a petroleum oil product with a water solution of a salt of a heavy metal, passing the commingled mixture through a heating coil and heating the mixture to a reaction temperature under pressure sufcient to prevent substantial Vaporization, releasing the pressure and separating by vaporization, fractionation and condensation a puried petroleum oil product from products of reaction and excess treating agent.

13. A process of purifying gasoline stock, comprising, contacting gasoline stock with a water solution of a salt of a heavy metal While passing through a heating coil, under a pressure suflicient to prevent any substantial vaporization, the gasoline sto-ck and Water solution of the metal salt being heated to a temperature of approximately 400 F., releasing the pressure after the gasoline stock mixed with the water solution has passed through the heating coil, and separating by vaporization, fractionation and condensation a puried gasoline stock from higher boiling products of reaction and excess treating agent.

14. A process of purifying a petroleum oil product comprising heating said product and a substantially concentrated solution of the salt of a heavy metal under a pressure suflicient to prevent substantial vaporization and at a reaction temperature and-after the same have been commingled under said premura-reducing the pressure and separating by vaporization, fractionation and condensation a purified oil product from products of reaction and the excess treating agent.

15. 'Ihe process of purifying petroleum oil products comprising passing the oil through a heating zone and maintaining the oil under pressure suicient to prevent substantial vaporization while heating the oil to a temperature somewhere between 300 to 600 F., forcing into the stream of oil a substantially concentrated water solution of a heavy metal salt, maintaining pressure on the mixture of oil and Water solution of the salt after they are mixed, reducing the pressure and passing the mixture to a collecting Zone, and fractionating the purified oil.

16. A process of purifying a petroleum oil product which comprises causing said product to vaporize from a heated commingled mixture of the product and a water solution of a zinc salt by reducing the pressure on said heated mixture.

17 A process of purifying a petroleum oil product which comprises causing said product to vaporize from a heated commingled mixture of the product and a water solution of an iron salt by reducing the pressure on said heated mixture.

18. A process of purifying a petroleum oil product which comp-rises causing said product to vaporize from a heated commingled mixture of the product and a water solution of a cadmium salt by reducing the pressure on said heated mixture.

19. The method of purifying a hydrocarbon initially available in a vapor or semi-vapor phase which comprises condensing said hydrocarbon by imposition of pressure thereupon and by commingling a cool aqueous solution of a salt of a heavy metal therewith, maintaining a pressure thereupon While the mixture is heated to prevent substantial vaporization thereof, and nally reducing the pressure to vaporize said mixture.

ARTHUR LACHMAN.

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