US1997861A - Treatment of hydrocarbon oils - Google Patents

Description

Patented Apr. 16, 1935 UNITED STATES PATENT OFFICE assignors to Universal Oil Products Company, Chicago, 111., a corporation of South Dakota No Drawing. Application September 19, 1931,

Serial No. 563,120

i ll Claim.

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 particularly the invention is directed towards the removal of sulphur from such hydrocarbons.

More specifically, the invention comprises subjecting hydrocarbon oil vapors to treatment with aqueous solutions of oxygenated halogen acids containing salts of metals, treatments being conducted in contact with finely divided metal oxides. oxygenated halogen acids include such acids as hypochlorous acid, chloric acid, bromic acid, iodic acid either alone or in various admixtures and the salts in solution with these acids may be those of such metals as aluminum, zinc, tin, iron, copper, lead, mercury, cobalt, nickel, chromium, manganese, molybdenum and others. The metallic salts are preferably those of other acids than the particular oxyhalogen acid which furnishes the excess acid constituent of the treating solution, such salts as chlorides, sulfates, phosphates, et cetera, beingused as their" solubilites permit. The treating solutions may contain a single salt or combinations of salts and the metal oxides employed as solid contact materials may be those of any of the metalswhose salts are employed in solution alone or in combination, the particular aggregation of materials utilized in any case depending upon the nature of the vapors treated and the treating eflects desired.

In some cases it may be found preferable to space the particles of metallic oxides by support-. ing them on or mixing them with relatively inert materials of a non-metallic nature, such 40 as fullers earth, clays, 'bentonite, bauxite,

crushed flrebrick, pumice stone, etc., this expedient serving to expose more surface and prevent the agglomeration of the oxides into masses too large for efiective action. The function of the oxide mixtures employed may be of a true chemical nature or they may function merely as catalysts.

It is recognized that materials like fullers earth may have an independent refining effect, quite difierent, however, from the action of the oxygenated halogen acids in that fullers'earth and similar materials while having a marked polymerizing influence have substantially no e1- iect in respect to -reduction in sulfur content.

65 Materials like crushed flrebrick serve the princl-' pal purpose of providing large contacting surface and a spreading or spacing effect on the active reagents. The vapor undergoing treatment may be mixed with oxygen-containing gases and steam, the former assisting in the chemical re- 5 actions produced by the solution of oxygenated halogen acids and the latter serving to maintain proper concentrations of the solutions by preventing excessive evaporation of solvent. As examples of oxygen-containing gases, air, oxygen, ozone alone or in combination may be mentioned, ozonized air having been found to be particularly efficacious in some instances.

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, and is also particularly directed towards the desulfurization of hydrocarbons and especially cracked hydrocarbons. 20

The oxygenated halogen acids, the use of which. is comprised in the present invention, have analogous properties to a considerable extent in that they all exert an oxidizing and some polymerizing action upon cracked hydrocarbon vapors 25 whether dissolved alone in water or dissolved along with other salts and alkalies which may have been produced incidentally to the production oi the desiredacid. It is recognized, however, that they differ in degree and to some extent in the nature of the reactions produced. To assist in giving a clear understanding of the nature of the process it will be of advantage to state briefly some of the reactions involved and the products produced when halogens are added to 35 water or aqueous solutions of various alkaline substances.

' When chlorine is added to water, simple solution occurs in the absence of alkaline materials except that chlorine hydrates are formed when temperatures are reduced. When chlorine is passed into aqueous solutions of sodium carbonate of approximately 5 to 10% concentration the primary reaction forms sodium hypochlorite, sodium'chloride and sodium bicarbonate, further addition of chlorine resulting in the decomposition of the bicarbonate to form an equivalent of hypochlorous acid and sodium chloride and evolve carbon dioxide as a gas. To form more highly oxygenated chlorine acids such as chloric or 50 perchloric acid the action of powerful oxidants is essential such as ozone, nitric acid, etc. 'Free hypochlorous acid is produced in a generally similar manner to that described above when an excess of chlorine is passed through caustic soda solutions. The acid is also formed in considerable amounts by the electrolysis of brine solutions usually in stoneware cells divided into small compartments to insure ready and thorough mixing of anodic and cathodicproducts.

Solutions containing free hypochlorous acid and more highly oxygenated acids and as such adaptable to use in the present invention may also be produced by passing chlorine into suspensions of calcium hydrate. Primary reactions result in formation of hypochlorous acid, which further reacts with more chlorine to form chlorine oxide and calcium chlorate. Similar reactions may also be brought about by passing chlorine into aqueous suspensions of carbonates of the alkaline earth metals such as calcium and magnesium The case of bromine is somewhat diflerent than that of chlorine in that the hypothetical hypobromous acid may not be formed when alkaline solutions are saturated with bromine, but rather salts of bromic acid such as sodium bromate.

The latter compound may also be prepared by the electrolysis oi. sodium bromide solutions in any form of apparatus which may be employed in eiectrolyzing soduim chloride solutions to form hypochlorites. I

The saturation of caustic alkalies such as a solution-of potassium hydrate with iodine also tends to form the iodate rather than salts of the hypothetical hypoiodous acid analogous to the hypobromous acid mentioned in the preceding paragraph.

It will be obvious from the preceding descriptive matter as to the various oxygenated halogen acids which may be produced by conducting chlorine, bromine or iodine into aqueous solutions under suitable conditions that reagents or varying strength and eflectiveness for use in treating cracked vapors may be produced particularly when diflerent metallic salts are added to the solution. The method of production of these diiferent reagents is quite general and the products may be used in particular cases to produce controllable results upon a large number of types of cracked vapors of variable" composition. The use of fluorine for producing oxyhalogen acids is excepted because of the violent nature of the reaction between this element and water which results in instantaneous decomposition of the water with the liberation of highly ozonized oxygen, this forming an exception to the general reactions of the other halogens as in many other cases. I

In applying the process of the invention to practice any suitable equipment may be employed which will permit the contacting of the hydrocarbon vapors and the treating reagents employed with the solid contacting or polymerizing materials; for example, a suitable tower or chamber packed with a selected mixture of contact materials may be employed following the i'ractionator of. a cracking system, the reagents being introduced at a suitable point or points along the line of flow of the ascending or descending vapors, thus permitting contact of the mixture of hydrocarbon oil vapors, oxygen-containing gases and stam'with the solution of oxyhalogen acid and metallic salt and the solid contact materials. Similarly, any device which permits the eflicient contacting of the hydrocarbon vapors undergoing treatment with gases, liquids and solids may be employed. The solid contacting materials may sometimes be employed in successive strata of varying composition.

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. In cases involving the use of solutions containing only a small excess of the oxygenated acid the excess of acid may be completely consumed so that subsequent neutralization is not necessary.

Reactions involved in treatments comprised within the scope of the invention are of a complicated nature from a chemical standpoint but the net results are in the direction of reduced unsaturation and sulfur content in the treated.

product. The nature and extent of the reactions with any particular type of hydrocarbon vapors willvary with the amount and nature of the particular oxyhalogen acid and metallic salt solution employed, and also with the amount and type of oxidizing gas mixture and the amount of steam used. It has already been mentioned that the reactivity and treating action of the solutions of oxyhalogen acids and metallic salts which may be used vary in degree and that while they produce similar eflects that they are not precise equivalents. Temperatures and pressures employed in treating operations may vary over a wide range, and it may be advisable in certain instances to use the less reactive acid than the more reactive to control the extent of polymerization desired. Frequently the element of cost enters into consideration as well. By the use of varying mixtures of the oxyhalogen acids and dissolved metallic salts and diflerent oxygen-containing gases, and steam, it has been found possible to produce a wide range of treating effects, all tending toward the selective elimination of unsaturated compounds and reduction in sulfur content. The reactions involved when containing gases and metals both of which also assist the reactions. Whatever fixation of halogen occurs seems to be taken care of by the fact that the addition compounds are higher boiling than the original hydrocarbons from which they were formed and as such are left behind as heavy refluxes during the subsequent fractionation of the treated vapors.

The amounts of reagent used in conductin treatments comprised within the scope of the invention will vary over a wide range depending on the chemical nature of the particular vapors in question, the extent oireflning action desired and the efllciency of the particular reagent solution chosen from the standpoint of economy and availability. The use of hypoohlorous acid has been shown to be of definite commercial value and experimental results thus far obtained indicate that beneficial results are also obtainable by the use of the more highly oxygenated chlothe pressures and temperatures are chosen so that the hydrocarbons are treated substantially in the vapor phase.

As a specific example of a method of treatment comprised within the scope of the invention and the results obtainable therefrom the case of a treatment conducted upon vapors of approximate gasoline boiling point range produced in the cracking of a heavy gas oil distillate produced from California crude may be mentioned. Such vapors may be passed upwardly through a contact mass composed of approximately nine parts of crushed firebrick and one part of a mixture of iron and aluminum oxides, countercurrent to a descending solution containing approximately 3 to 5% free hypochlorous acid. The vapors may be mixed with a small amount of air to assist in oxidizing reactions and steam to the extent of approximately five pounds per barrel of condensed gasoline. The gasoline produced from the vapors without chemical treatment of any kind may have the following properties:

Gravity A. P. I 53.6 Color lemon yellow Gums by copper dish method 580 mgs. Sulfur 0.42%

After treatment with reagents in the amounts and the manner described the condensed gasoline may be found to have the following properties:

Gravity A. P. I.- 53.9 Color plus 30 Color after 4 hrs. exposure to sunlight 26 Gums 22 mgs. Sulfur 0.10%

In another instance a mixture of pressure distillates produced from Mid-Continent and West Texas cracking stocks may be revaporized and treated with substantially the same amounts of reagents that were used in the preceding example. By simple fractionation without chemical treatment such a mixture of distillate may yield a raw gasoline of the following properties:

Gravity A. P. I 54.4 Color light yellow Gums by copper dish method 385 mgs. Sulfur 0.36%

When the vapors are subjected to treatment as described prior to their final fractionation, a finished gasoline of the following properties may be The foregoing specification containing descriptive material and examples of the results obtainable by the use of the process of the invention have been given for illustrative purposes and while they clearly define the invention and indicate its commercial value, it is to be understood that the invention is not limited thereto as a considerable number of other operations are possible without departing from its scope.

We claim as our invention: In the art of refining petroleum distillate,

the step which comprises subjecting petroleum' distillate in heated vaporous condition to the action of an aqueous solution of hypochlorous acid having dissolved therein a salt of copper which is soluble in the solution.

GUSTAV EGLOFF. JACQUE C. MORRELL.