US2004849A - Method of treating hydrocarbons - Google Patents

Description

Patented June 11, 1935 2,004,849 METHOD OF TREATING HYDROCARBONS Max E. Bretschger, Buffalo, N. Y., and Ernest A..

Bosing, Long Beach, Calif., assignors to Bufv -falo Electra-Chemical Company, Inc., Buffalo,

N. Y. v

No Drawing.

Application March 21, 1932,

Serial No. 600,372

5 Claims.

This invention relates to a method of treating hydrocarbon distillates for the refining thereof and removal of deleterious sulfur compounds,

the stabilization of color, and the reduction and stabilization of gums.

Methods of distilling hydrocarbons currently in use produce distillates which contain relatively high proportionsof materials which are generally designated by the oil refiner as unsaturates such as mono and di-olefines, and aromatic derivatives. Certain of these aromatics possess the valuable property of repressing ordecreasing the knocking which is produced under certain operating conditions when a given petroleum distillate is used as fuel in an internal combustion engine. It is highly desirablatherefore, that any refining methods used upon petroleumdistillates should be such that a loss of aromatics contained therein be kept as small as possible.

In addition to the aromatics,- the petroleum distillates also contain sulfur in various chemical combinations. All of these particular sulfur combinations or-derivatives possess certain inherent disadvantages which render petroleum distillates'containing them less valuable than'one in which there is no sulfur, 'or wherein there is contained only a smallquantity of sulfur.

The presence of the unsaturated compounds is detrimental to the quality and marketability of the finished product, as it is generally accepted that these materials give use to poor color stability and to gum formation. Further they are very reactive, and are therefore susceptible to slow'oxidation upon storage with formation of deleterious gums. 1 This action is accelerated by the photochemical action or catalysis of the suns rays. I v

In many of the processes currently usedrfor removal of sulfurfrom hydrocarbon distillates, the valuable aromatic compounds and certain of the mono-olefines. are either destroyed or removed ccincidently with the sulfur. Should the sulfurnot be removed by a special-process and the distillate given the usualacid and alkali wash, v

a small fraction of the sulfurcompoundsare removed during the sulfuric acid treatment, but on steam distillation, the final step in the refining process, the resultant distillate shows the presence of certain residual sulfur compounds by acquiring an off-color and/or an off-odor.

It is well known that certain ofthese sulfur compounds may be removed during sulfuric acid treatment, or maybe removedby preliminary treatment with certain other chemical reagents. However, the chemical reagents react in both cases, not only with'the sulfur, but with a fairly large proportion of the aromatic substances in thedistillate and remove these valuable materials as well.

The present invention provides a method of treatinga given hydrocarbon distillate whereby a selective action is obtained upon the sulfur de' rivatives, producing a maximum removal there-; of, while a minimum reaction and removal of the aromatic compounds is obtained with the consequent minimum removal of such compounds.

The present invention further'comprehends the provision of methods for treating hydrocarbon distillates containing small quantities of aromatic compounds and further provides improvements upon the usual acid treatment of the distillate with sulfuric acid whereby gumformation is reduced to minimal quantities.

Other inventive features will be apparent from the disclosure in the following specification and 7 These various petroleum fractions contain un- 35 desirable impurities and are usually given the well known acid and alkali wash in order to adapt them for use. This treatment consists of an agitation of the impure fractions with sulfuric acid which reacts with or dissolves the various impurities which are then removed 'with' the acid since the latter is not soluble to any great extent in the hydrocarbon. The minute quantity of acid which remains dissolved in the hydrocarbons is then eliminated by agitation with a material capable of neutralizing the acid and which produces a substance either insoluble in the hydrocarbon, or which is soluble in water and which may be removed by a subsequent water wash. In usual standard practice, this step is 50 moved by washing the hydrocarbons with'water, 5

and the final treatment in the refining process consists of a distillation thereof, such distillation generally being by steam.

Where it is desired to entirely eliminate the sulfur compounds, verylarge quantities of sulfuric acid are required, and in such case, more and more of the valuable aromatic derivatives are removed from the hydrocarbons, either com bined with or dissolved in the sulfuric acid together with a large fraction of the unsaturated di-olefines. By our method of treating and refining, we are able 'to reducesubstantially the sulfur content of a hydrocarbon distillate of the type discussed above, and at the same time, de-,

crease the consumption of sulfuric acid. We have found that we are able to produce a hydrocarbon distillate of very high purity, one conone way of working the process, we may add this reagent to the hydrocarbonsjust prior to their entrance to an agitating chamber, such as a turbulence coil. In this method, we use hydrogen peroxide of fairly high concentration, such as 27% hydrogen peroxide or 100 volume hydrogen peroxide, in sufficient quantity to combine with the deleterious sulfur compounds present in the distillate. This mixture is thereafter advantageously treated in the turbulence coil whereby an intimate intermixture of hydrogen peroxide and distillate is secured, and a large contact surface for chemical reaction is provided.

The quantity of hydrogen peroxide necessary to cause the desired chemical reaction will necessarily vary according to the type of distillate treated. For distillates which have been produced from California crudes by a cracking process and which are high in sulfur, larger quantities of hydrogen peroxide must of necessity be used as compared with distillates which are low in sulfur and which are straight runs, produced without cracking from an original crude.

For the treatment of distillates of average sulfur capacity, we have found that a barrel of distillates may be economically and effectively treated by using in the neighborhood of 40 c. c. of 100 volume hydrogen peroxide, effecting a sulfur reduction equivalent to that obtained by using about 35 pounds of sulfuric acid per barrel; that is to say, with a distillate treated with sulfuric acid alone, inorder to effect the same reduction in sulfur compounds, 35 pounds of sulfuric acid would have to be used, over and above that quantity which we find effective in order to obtain a material of comparable purity. After agitating the hydrocarbon-with hydrogen peroxide, sulfuric acid is then added to the mixture of distillate and peroxide and agitated therewith in any suitable manner, such as in a turbulence coil, asmentioned above. When the distillate is high-in aromatic compounds, we find it advantageous to use a comparatively weak, acid mixture such as '50 degree Baum sulfuric acid. During agitation of the sulfuric acid with the hydrogen peroxide and hydrocarbon mixture, any

- wateror hydrogen peroxide, or changed impurity,

immediately thereafter.

for instance, sulfur compounds, are combined with or dissolved in the sulfuric acid which is insoluble in the hydrocarbon and may, therefore, be readily separated therefrom.

We have also found that we may remove sulfur compounds by a modified method of working. In

this particular modification, the required'alnount of sulfuric acid in the form of oleum is added to the hydrocarbon prior to its entrance to the turbulence coil, and the hydrogen peroxide added I The sulfuric acid, which has been thoroughly dispersed throughout the hydrocarbon distillate, dissolves the water solution of the peroxide and the reaction between that reagent and the sulfuric compounds occurs very rapidly, and the product of such reaction is to be found in the sulfuric. acid which may be collected and removed. After an alkali wash, the hydrocarbon is in condition for final distillation and use. By another variation of our method, we may make an acid reagent .by treating sulfuricacid with the hydrogen peroxideand adding the'mixedreagent to the hydrocarbon,.agitating it therewith and finally removing. the acid reagent, together with the excess peroxide andsulfur derivatives which have combined with. or dissolved in sulfuric acid.

As in the first instance outlined above, if it be desirable to retainaromatic compounds in the hydrocarbon,-a somewhat Weak sulfuric acid-"is used; for instance, acid containing less than 80% sulfuric acid, and the hydrogen peroxide added thereto. When the distillate is treated with this chemical reagent, practicallyall' of the aromatics remain in the distillate, while the sulfur derivatives are acted upon and removed. 1 i

l-Iowever, where it is desired to treat with comparatively. strong sulfuric acid, the hydrogen peroxide may be'added to an acid of a specific gravity of 1.84 or to a fuming acid, for instance,

a 103% sulfuric acid. This mixed reagent is immediately added'to the distillate prior ,toits entrance into the agitating chamber 'o'r turbulence coil, and intimate contact of the reagent and dis-' tillate insured by passage throughfsuch coil. As an example of the efficiency and practicability of our process, we may mention that 'we have treated distillates containing 0.26% sulfur which werefoundto contain 0.12% sulfur after treating with our method. We have also. round that there is a reduction in the. mercaptan sulfur content, such 'sulfurcontentfalling from 0.12% to 0.02% after treatment. The significance of such a reduction of mercaptan sulfur content will be readily apparent since it is these undesirable sulfur containing materials which producesour distillates after a final steam distillation, and which require a special doctor treatment in order to transform such sulfur into an innocuous disulphide. Coincident with the sulfur, removal, there is found an improvement in the color of the product, rendering the some more readily marketable, and eliminating the necessity of further treatment for color reduction. i

It will be readily apparent that one advantage of this process is a reduction in the consumption of sulfuric acid required to reduce sulfur contents.- to a definite desired minimum. For instance in the case cited above, a reduction of 0.14% in a sulfur content would have required about 35 pounds of sulfuric acid per barrel. We have been able to effect such a reduction by the use of approximately c. c. of 27% hydrogen peroxide, with economies in operation and improvement of product. It will therefore be apparent that our method effects material economy in process treatment and at the same time, produces a final product of superior quality for use, for example, in internal combustion engines, where excessive sulfur contents are detrimental to the delicate moving parts of the engine, when burned to an acid oxide.

What-is claimed is:-

1. The method of refining liquid hydrocarbon distillates containing aromatic compounds which comprises adding hydrogen peroxide to the distillate, agitating the mixture to enhance chemical reactions occurring therein, agitating sulfuric acid with said mixture of a strength sufiicient to dissolve the oxidized sulfur compounds but insufficient to combinewith the aromatic compounds in the distillate, and separating the acid from the distillate.

2. The step in the refining of liquid hydrocarbon distillates containing aromatic compounds which includes adding to the hydrocarbon a mixture of hydrogen peroxide and sulfuric acid, the concentration of the acid being insufficient to react with the aromatic compounds but sufficient to dissolve the oxidized sulfur compounds, agitating the mixture of distillate, acid andperoxide to insure intimate contact and thereafter separating the acid from the hydrocarbon.

3. The step in the refining of liquid hydrocarbon distillates containing aromatic compounds which includes agitation of the hydrocarbon with hydrogen peroxide in the presence of sulfuric acid insufficient in concentration to combine with the aromatic compounds but sufficient to dissolve the oxidized sulfur compounds. I 4. The step in the refining of hydrocarbondis till-ate which comprises agitation of the hydrocarbon with hydrogen peroxide in the presence of sulfuric acid of a concentration of about 60 Baum in order to dissolve the oxidized sulfur compounds.

5. The steps in refining'of hydrocarbon distillates containing aromatic compounds which sulfuric acid of a concentration sufficient to dis-.

solve the oxidized sulfur compounds.

MAX E. BRETSCHGER. ERNEST A. BOSING.