US1941251A - Treatment of hydrocarbon oils - Google Patents

Description

Dec. 26, 1933. R. F. DAVIS 1,941,251

TREAE'MENT OF HYDROCARBON OILS I v Filed June 1, 1931 FIG. I BINARY SYSTEM- SO -SN MELLOR-VOLJO, PAGE 22 REES C.

TEMPERATURE DEG 25 50 75 I00 PER CENT STANNIC CHLORIDE FIG. 2 RY. SYSTEM- so -s- 8R4 LLOR- VOL. 10, PAGE 223 TEMPERATURE DEGREES c. (1

0 25 so 75 I00 PER CENT STANNIC BROMIDE INVENTOR RICHARD F. DAVIS ATTORN Patented Dec. 26, 1933 UNITED STATES PATENT OFFICE TREATMENT OF HYDROCARBON OILS Application June 1, 1931. Serial No. 541,210 4 Claims. (01. 19637) This invention relates to the treatment of hydrocarbon oils, and refers more particularly to the treatment of the distillates produced in the refining of petroleum, though liquid hydrocarbons from other sources may also be treated.

More specifically the invention contemplates the provision of a process adaptable to refining hydrocarbon oil mixtures to reduce the percentage of such objectionable constituents as highly unsaturated hydrocarbons, asphaltic suspensoids, sulphur, nitrogen and oxygen derivatives and to reduce the percentage of aromatic or ring hydrocarbons when such reduction is desirable, The invention further contemplates the use of a method of treatment whereby these groups of compounds may be controllably removed from the oils in question, and recovered in approximately the same condition in which they existed in the original mixture.

Hydrocarbon oil mixtures from difierent sources are characterized by extreme variability depending upon the nature of the original raw material from which they are produced such as, for example, petroleum from various localities, coals of difierent types, shale deposits, etc. The nature of distillates produced by the secondary pyrolysis of hydrocarbon fractions is frequently more complex than the original oils that were decomposed by heat and to bring them to a degree of refinement and stability required by commercial considerations is frequently a long drawn and expensive process. Various methods of chemical treatment are commonly resorted to, the most generally used being treatment with the relatively cheap and readily available sulfuric acid and also with such treating reagents as caustic soda, plumbite solutions, various adsorbent earths, metallic oxides, etcetera, the treatment employed in any specific case being chosen to reduce the undesirable constituents of the hydrocarbon oil mixtures to a point determined by the cost of treatment and the quality required. The present invention provides a method of treatment of wide applicability and in the majority of instances offers decided advantages over other treatments which might be employed to efiect similar results. i

In one specific embodiment the invention comprises the treatment of liquid hydrocarbon oil mixtures with solutions of certain metallic halides in liquid sulfur dioxide, the particular metallic compound used and the concentration of the same in the solution being varied to meet the requirements of specific cases.

A number of halides of the heavy metals are Compound M.P.F. B.Pt.F.

Stanmc chloride. SnCh 27 237 Stannic bromide, S11E11. 86 398 Aluminium chloride, A1013" *374 361 Ferric chloride, FeCls 568 Titanium tetrachloride, 'liCl 13 278 Mercuric chloride, HgClz. 540 580 Zinc chloride, ZnClz 689 r .5 7

\ 2.5 Atmospheres pressure.

The compounds shown in the table are uniformly characterized by a tendency to induce polymerization and condensation reactions between unsaturated hydrocarbons typical of hydrocarbon oil mixtures. The degree of and effectiveness along this line will vary to a large extent with the character of the particular salt employed. While the solubility of these compounds in liquid sulfur dioxide may be quite variable it has been found that sufficient amounts of the salts can be dissolved to assist in producing treating effects under quite a wide range of temperature and pressure. The appended curves, taken from A Comprehensive Treatise on Inorganic and Theoretical Chemistry by J. W. Mellor, -vol. 10, page 223, indicate that for stannic chloride and stannic bromide large concentrations of these salts in liquid sulfur dioxide may be employed in treatments at atmospheric temperatures and at temperatures considerably below atmospheric. In the case of titanium tetrachloride 55.8% may be dissolved in liquid sulfur dioxide at the critical solution temperature of 11.9 C. Similarly, it 100 has been found that other metallic halides have sufficient solubility to permit their use as polymerizing materials in conjunction with liquid sulfur dioxide treatment.

The process of the invention may be applied to 105 the treatment of hydrocarbon oils in several ways, the simplest being the so-called batch treatment in which the solution of metallic halide is added to the oil contained in a cone-bottomed agitator, contact being secured by circulation of the re- 110 agent by outside pumps or by the use of mechanical agitating devices. In this type of apparatus suflicient agitation may sometimes be obtained by controllably releasing pressure upon the system so that a limited ebullition of the solvent occurs, the rising bubbles of vapor serving to carry portions of the remaining liquid into contact with the oil.

The reagents may also be utilized in continuous treating plants consisting of alternate mixing and settling devices followed by neutralizing and washing elements.

The process may also be conducted in arrangements of apparatus designed to permit counterflow treatment which has been found to increase the efiiciency of many treating processes.

The reactions produced upon hydrocarbon mixtures by the use of reagents disclosed in the present invention are generally two-fold consisting of a combination of the treating and polymerizing effect of the dissolved metallic halides upon unsaturates and other easily polymerized compounds present in the oils and the solvent effect of the liquid sulphur dioxide upon the original groups of hydrocarbons and their derivatives and the polymerized or condensed products formed as a result of the action of the metallic halides. By suitably varying the proportions of solvent and solute the extent of either effect may be controlled in any manner desired, so that on the one hand the reaction may be predominantly that of polymerization of unsaturates and on the other hand predominantly a solution effect of the general character already well-known in the case of liquid sulfur dioxide.

There may also be formed at times substances of complex and rather indeterminate composition which are formed of sulfur dioxide, metallic halide and hydrocarbon compounds, these aggregates appearing as a third layer or precipitate after some treatments.

While the principal effect of the halides is to produce high molecular weight aggregates from the polymerization of unsaturated compounds there may at times occur a degree of desulfurization as is particularly the case in treatments with solutions of mercuric chloride which latter compound unites directly with mercaptans to form products of varying solubility depending upon the molecular weight of the sulfur derivatives involved. The effect of aluminum chloride may, on the other hand, be primarily one of condensation without specially marked elfect upon the sulfur content.

It is to be observed that the process of the invention possesses the feature of permitting polymerizing effects to occur at relatively low temperatures and in the absence of water. When such salts as ferric chloride and zinc chloride are used in aqueous solution, usually at superatmospheric temperatures polymerizing effects are obtained but difiiculties arise in the disposal of the polymers due to their insolubility in the treating solution, whereas the use of these compounds dissolved in liquid sulfur dioxide permits the removal of such polymers by solution.

The following example will indicate the results obtainable in one treatment conducted within the scope of the invention. A cracked distillate produced from the pyrolysis of heavy topped crude and containing by volume of 400 end point gasoline may be treated at slightly elevated temperatures and pressures with 2% by volume of a mixture of 60% stannic chloride and 40% liquid sulfur dioxide, treatment being conducted by circulation in a closed agitator. After separation of the sludge the supernatant oil may be neutralized, washed with water and redistilled" with steam, the gasoline produced having a color of 28 on the Saybolt scale which remains above 25 after the four-hour sunlight test and a maximum of 25 mgs. of gum by the copper dish test. The same distillate when treated with 66 B. sulfuric acid by ordinary methods at the rate of 10 pounds per barrel may produce a gasoline when the treated distillate is redistilled with a color of only 22 Saybolt which drops to 18 on four hours exposure to sunlight and the gum content may be as high as 50 mgs.

As another example of the adaptability of the process, a California lubricating oil distillate may be treated with 20% by volume of liquid sulfur dioxide containing 5 to 10% by weight of titanium chloride, treatment being conducted countercurrent at ordinary temperatures in apparatus adapted to withstanding the pressure necessary for preventing volatilization of the sulfur dioxide. In such a case the titanium chloride may cause a coalescence of the asphaltic and gummy material in the raw lubricating distillate which alters the relative solubilities of the sulfur dioxide in the oil and the oil in the sulfur dioxide so that a more selective and clean-cut separation is effected, the treated oil needing only such final treatments as caustic washing or contact treatment with finely divided clays to produce a finished lubricating oil or a stock which may be redistilled under vacuum to produce cuts of varying viscosity. Sulfuric acid treatment of such heavy lubricating distillates is frequently hampered by the viscosity of the oil which makes thorough contact difficult, and oxidation effects produced by the acid upon the oil resulting in loss of acid by reduction and the formation of stiff and tarry sludges which are difiicult" to separate.

The foregoing description and examples will sufiice to show that the invention comprises the process of general applicability to the treatment of hydrocarbon oils from various sources, but the cases cited are illustrative merely and should not be construed in a limiting sense upon the broad scope of the invention, since many other types of treatments are possible than the ones specifically disclosed.

I claim as my invention:

1. In the refining of the condensed overhead products resulting from the heat treatment of hydrocarbon oil, the improvement which comprises subjecting said products in liquid condition to the action of liquid sulphur dioxide containing dissolved therein a metallic halide which is soluble in the liquid sulphur dioxide.

2. A process of refining the distillates resulting from the cracking of hydrocarbon oil. which comprises subjecting said distillate in liquid condition to the action of liquid sulphur dioxide containing dissolved therein a metallic halide which is soluble in the liquid sulphur dioxide.

3. A process of refining the distillates resulting from the cracking of hydrocarbon oil, which comprises subjecting said distillate in liquid condition to the action of liquid sulphur dioxide containing dissolved therein stannic chloride.

4. A process of refining the distillates resulting from the cracking of hydrocarbon oil. which comprises subjecting said distillate in liquid condition to the action of liquid sulphur dioxide containing dissolved therein mercuric chloride.

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