US2063494A - Treatment of hydrocarbon oils - Google Patents

Description

Patented Dec. 8, 1936 UNITED STATES PATENT OFFICE TREATMENT OF HYDROCARBON OILS No Drawing. Application June 19, 1931, Serial No. 545,478. Renewed July 1, 1935 7 Claims.

This invention relates to the treatment of hydrocarbon oils, and refers more particularly to the refining of relatively low boiling hydrocarbon distillates at elevated temperatures, especially those resulting from the conversion of relatively high boiling hydrocarbons at elevated temperatures.

More specifically the invention comprises subjecting hydrocarbon oil vapors to treatment with hydrochloric acid and solutions of mercury salts in the presence of solid contact materials containing solid metallic salts of mercury or other metals, the solid salts employed being preferably either substantially insoluble or of definitely limited solubility, oxygen-containing gases and/or steam being admixed with the oil vapors when desired. The hydrochloric acid may be added as a gas or as an aqueous solution of any desired strength either separately or in solution with the mercury salt or salts thus employed.

As examples of salts of mercury which may be employed in solution according to the process of the invention may be mentioned mercuric chloride, mercuric nitrate and mercury salts of acids of an oxidizing character such as the chlorate. The salts of mercury which are relatively insoluble in acid-free water may be employed in the presence of hydrochloric acid which has the general effect of rendering some of them more soluble.

As examples of salts of metals which may be used as solids may be mentioned such salts as, for example, the chlorides and bromides of copper and mercury, the compounds corresponding to the lower valence in these metals being practically insoluble in water or dilute hydrochloric acid solution. Among other relatively insoluble salts may be mentioned certain phosphates, for example, those of zinc, tin, nickel, cobalt, copper, mercury, calcium, barium, strontium, et cetera. In regard to the use of more soluble salts, conditions of operation may be so maintained that there is present at all times a solid phase of a metallic salt in equilibrium with the salt solution which is employed.

As examples of oxygen-containing gases air, oxygen, ozone, et cetera, alone or in combination may be mentioned, ozonized air having been found to be particularly efficacious in some instances.

In some cases it may be found preferable to space the finely divided solid salts by supporting them on or mixing them with relatively inert materials of a non-metallic nature, such as fullers earth, clays, bentonite, bauxite, crushed firebrick, pumice stone, et cetera, this expedient serving to expose more surface and prevent the ag-' glomeration of the salts into masses too large for efiective action. The function of the salts or mixtures thereof employed may be of a true chemical nature or they may function merely as catalysts.

The usual method of refining cracked distillates is to subject them to treatment with sulfuric acid and alkaline solutions, including plumbite solutions consisting of litharge dissolved in alkaline solutions in various combinations of treatment and subsequently to subject the acid treated product to redistillation usually in the presence of steam. The present invention permits the direct treatment of the hydrocarbon vapors from the cracking process, reducing the cost of reagents and eliminating the redistillation or rerunning operation, although it is within the scope of the invention to revaporize the product in a subsequent operation and subject the vapors to treatment as described.

The invention is more particularly directed to the treatment of vapors of lower boiling cracked distillates though straight run distillates may also be treated within the scope of the invention.

In applying the process of the invention to practice any suitable equipment may be employed which will permit contacting a mixture of hydrocarbon vapors, oxygen-containing gases and/or steam with hydrochloric acid, mercury salt solutions and solid metallic salts, for example, a suitable tower or chamber packed with a selected mixture of solid contact materials may be employed following the fractionator of a cracking system, the liquid and/or gaseous treating reagents being introduced at suitable points along the line of flow of the ascending or descending Vapors, thus permitting proper contact with the solid materials. Similarly, any device which permits the efficient contacting of the hydrocarbon vapors undergoing treatment with liquids, gases and solids may be employed. The solid contacting materials may sometimes be employed in successive strata of varying composition, or masses of uniform or varying composition may be supported in a tower on superimposed plates designed to effect intimate contact.

A convenient method of operation consists in introducing the hydrocarbon vapors to be treated into a point near the bottom of a tower containing contact material supported upon perfo rated plates, hydrochloric acid being added as a solution or as gas at the same point. Minor amounts of air may also be added to the vapor and steam or water necessary to maintain the mercury salt solutions at proper concentrations and prevent crystallization. The particular mercury salt solution to be employed which may be commonly a saturated aqueous solution, may be introduced above the solid contact mass and caused to flow downwardly by gravity countercurrent to the ascending mixture of hydrocarbon oil vapors and hydrochloric acid. In this type of equipment it may be found that treating and fractionation are effected in one step so that subsequent rectification of vapors is not necessary.

It has been found desirable to neutralize the vapors before or after condensation and to'this end the vapors may be treated with ammonia gas or pass counterflow to solutions of alkalis in auxiliary neutralizing equipment, or the condensed vapors may be treated with liquid alkalis such as solutions of caustic soda, ammonia or the like, the traces of reagents and reaction products remaining being washed out with water when found necessary.

The reactions involved in treatments conducted within the scope of the invention have been observed to produce effects comparable with those produced by sulfuric acid of varying strength used after the customary methods of treatment. The amounts of hydrochloric acid used will vary with the character of the vapors treated from a fraction of a percent to as high as 5% by weight of the oil vapors treated in cases where relatively heavy treatments are desired, the amount of mercury salt solution used varying with the type of salt dissolved and the concentration of the solution employed and other factors. The amounts of oxidizing gas and steam used with the hydrochloric acid may also be varied to produce a wide variety of treating effects.

The effects produced upon oil vapors, particularly those produced from the cracking of heavy hydrocarbon oils by the use of oxidizing gases and mercury salts characteristic of the invention are in general those of polymerization or condensation of relatively highly unsaturated hydrocarbons or their derivatives, along with some effect on certain sulfur derivatives either to sweeten or eliminate them. The net result is the controllable elimination of groups of compounds which are readily polymerized under oxidizing conditions to form substances of a gummy or resinous nature which are undesirable in motor fuel, and a substantial reduction in sulfur content.

Various temperatures of treatment may be employed, for example, from 275-600 F., more or less, and the pressures may be subatmospheric, atmospheric or superatmospheric. While the results may vary with the conditions employed, the pressures and temperatures are chosen so that the hydrocarbons are treated substantially in the vapor phase.

As examples of the operation of the process of the invention and of the results obtained, a California cracked distillate of approximately motor fuel boiling range may be vaporized and subjected to treatment with a mixture of hydrochloric acid, oxygen and steam during the passage of the vapors in an upward direction through a stationary contact mass consisting of a mixture of a finely divided zinc oxychloride supported on fullers earth, (the weight of the earth being approximately four times that of the salt) counterfiow to a descending solution of mercuric chloride. The hydrochloric acid may be introduced either as a moderately dilute aqueous solution or as a gas in an amount equivalent to approximately four pounds per barrel with air sufficient to provide the oxygen theoretically required to combine with the hydrogen in the hydrochloric acid. Steam is used at the rate of approximately two pounds per barrel. The untreated product may show a gum content of approximately 650 mgs. per 100 ccs. and have a reddish brown color, with a sulfur content of approximately 0.40%. The treated product after suitable separation from spent reagents, neutralizing with alkalis and washing with water, may show a gum content of approximately 8 mgs. and a color of plus 30 on the Saybolt scale. The sulfur content may be found to be as low as 0.05%.

In the case of a mixed Mid-Continent and West Texas cracked distillate treated in the same manner with approximately the same amount of hydrochloric acid and mercuric chloride solution, the gum content may be reduced from 375 mgs. to 7 and the color raised from a light amber to approximately 30 on the Saybolt scale. The sulfur content may be reduced from 0.4% to approximately 0.1%.

The process of the invention is particularly suitable to the treatment of cracked distillates produced from California oils. In some cases the untreated distillates may contain 675 mgs. of gum and have a dark reddish color while the treated distillates may have a gum content of less than 40 mgs. and a color of 25 to 30 on the Saybolt scale. The sulfur content may be reduced from 0.5% to 0.20%.

The foregoing description and examples have disclosed a process applicable to the treatment of hydrocarbon oil vapors which has a wide applicability and is capable of great variations in the methods of operation and the amounts of reagents employed. Therefore, the specific cases cited are not to be construed in a limiting sense upon the broad scope of the invention, as many other modifications can be used and examples of results therefrom given.

We claim as our invention:

1. A process of refining cracked hydrocarbon distillates, which comprises subjecting said distillate in heated vaporous condition to the action of added hydrochloric acid and an aqueous solution of a relatively stable water soluble salt of mercury in the presence of a solid contact agent containing a relatively stable salt of mercury substantially insoluble in water.

2. A process for refining cracked hydrocarbon distillates which comprises treating the same at a temperature of from 275 F. to 600 F. with added hydrochloric acid in the presence of an aqueous solution of a mercury salt and a metallic salt in solid form.

3. A process for refining cracked hydrocarbon distillates which comprises treating the same at a temperature of from 275 F. to 600 F. with added hydrochloric acid in the presence of an aqueous solution of a mercury salt and a zinc salt in solid form.

4. A process for refining cracked hydrocarbon distillates which comprises treating the same at a temperature of from 275 F. to 600 F. with added hydrochloric acid and a water solution of a mercury salt in the presence of a contact mass containing a zinc salt in solid form.

5. A process for refining cracked hydrocarbon vapors which comprises treating the vapors simultaneously with added hydrochloric acid and a water solution of a mercury salt in the presence of a contact mass containing a metallic salt in solid form.

6. A process for refining cracked hydrocarbon vapors which comprises treating the vapors simultaneously with added hydrochloric acid and a water solution of a mercury salt in the presence of a contact mass containing a mercury salt in solid form.

7. A process for refining cracked hydrocarbon vapors which comprises treating the vapors simultaneously with added hydrochloric acid and a Water solution of a mercury salt in the presence of a contact mass containing a zinc salt in solid form.

GUSTAV EGLOFF. J ACQUE C. MORRELL.