US2063518A - Treatment of hydrocarbon oils - Google Patents

Description

Patented Dec. 8, 1936 UNITED STATES 2,063,518 TREATMENT or HYDROCARBON oms Jacque C. Morrell and Gustav Egloff, Chicago,

Ill., assignors, by mesne assignments, to Universal Oil Products Company, Chicago, 111., a

' corporation of Delaware No Drawing. Application June 19, 1931, Serial No. 545,477. Renewed July 1, 1935 4 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 zinc salts in the presence of solid contact materials containing solid metallic salts of zinc and 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 of any desired strength either separately or in solution with the zinc salt or salts thus employed.

As examples of salts of zinc which may be employed in solution according to the process of the invention may be mentioned zinc chloride, zinc bromide, zinc iodide, zinc sulfate, zinc nitrate and certain salts of zinc with acids of an oxidizing type such as, for example, the chlorate, iodate, permanganate, et cetera, the salts given being examples of those which are markedly soluble in water. The solubility of these more soluble salts as well as some of the less soluble such as the sulfite, phosphate, arsenate, et cetera, are influenced by the presence of hydrochloric acid used according to the process of the invention generally in the direction of increased solubility.

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 maybe mentioned certain phosphates, for example, those of zinc, tin, nickel, cobalt, copper, mercury, calcium, barium, strontium, etc. 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 airhaving 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, bentonitabauxite, crushed firebrick, pumice stone, etc., this expedient serving to expose more surface and prevent the agglomeration of the salts into masses too large for effective action. The function of the salts or mixtures thereof employed may be of a true chemical nature or they may function merely as a catalysts. v

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, zinc 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 intimatecontact.

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 a perforated plate, 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 zinc salt solutions at proper concentrations and prevent crystalization. The particular zinc salt solution to be employed which may be commonly a saturated aqueous solution, may be introduced above the solid contact mass and caused to fiow 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 zinc 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 zinc 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 sub-atmospheric, 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 cuprous chloride supported on fullers earth, (the weight of the earth being approximately four times that of the salt) counterfiow to a descending substantially saturated solution of zinc 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 475 mgs. per ccs. and have a reddish brown color, with a sulfur content of approximately 0.38%. The treated product after suitable separation from spent reagents, neutralizing with alkalis and washing with water, may show a gum content of approximately 20 mgs. and a color of plus 30 on the Saybolt scale. The sulfur content may be found to be as low as 0.15%.

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 zinc chloride solution, using mercurous chloride in place of cuprous chloride, the gum content may be reduced from 350 mgs. to 10 and the color raised from a light amber to approximately 30 on the Saybolt scale. The sulfur content may be reduced from 0.35% to approximately 0.20%.

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 650 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 0.55% 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 for refining hydrocarbon vapors which comprises treating the same with added aqueous hydrogen chloride in the presence of a relatively stable water soluble zinc salt in aqueous solution and a relatively stable zinc salt in amount above that which will dissolve in the aqueous hydrogen chloride and the aqueous solution whereby to maintain a solid phase of the last named salt.

2. The process as defined in claim 1 further characterized in that said water soluble salt comprises zinc chloride.

3. A process for refining cracked hydrocarbon distillates which comprises treating the distillate at a temperature between 275 F. and 600 F. with added aqueous hydrogen chloride in the presence of zinc salt in aqueous solution and in solid form.

4. A process for refining cracked hydrocarbon distillates which comprises treating the distillates at a temperature between 275 F. and 600 F. with added aqueous hydrogen chloride and an aqueous zinc chloride solution in the presence of a solid zinc salt which is substantially insoluble in the aqueous hydrogen chloride and said aqueous solution.

JACQUE C. MORRELL. GUSTAV EGLOFF.