US1940726A - Treatment of hydrocarbon oils - Google Patents

Description

Patented'Dec. 26, 1933 6 UNITED STATES 1,940,726 TREATMENT OF HYDROCARBQN OILS Jacque C. MorrelL'Chicago, 111., assignor to 'Universal Oil Products Company, Chicago, 111., a j corporation of South Dakota No Drawing. ApplicationJanuary 8, 1931 Serial N- 507,519

8 Claims. (Cl. 196 -24) This invention relatesto the treatment of hydrocarbon oils, and refers more particularly to the treatment of the lighter'distillates produced in the cracking of heavy hydrocarbons.

More specifically the invention contemplates the treatmentof cracked distillates with chemical reagents of a particular nature effective in improving the quality of the distillates as regards their adaptability to commercial uses, particularly as fuels for internal combustion engines.

The chemical nature of the lighter hydrocar' bon fractions produced by the cracking of heavy hydrocarbons under elevated temperatures and pressures is very complex. Representatives of practically all hydrocarbon groups have been identified, such groups being, for example, parafiins, olefines, naphthenes, aromatics, terpenes, et cetera. As-charging oils frequently contain-minor amounts of sulfur, oxygen and nitrogen derivatives of hydrocarbons, the cracked products contain these elements in compounds of altered type due to rearrangements and readjustments during the cracking and subsequent reconversion period. The sulphur originally held in combination in the raw charging stocks'appears as hydrogen sulfide and in such sulfur containing hydrocarbon derivatives as mercaptans, sulfides or sulfur ether, thiophenes, et cetera. Frequently, when the raw cracked distillates are treated with acid or alkaline reagents, such as sulfuric acid or caustic soda, further rearrangements occur, producing compounds of a hybrid nature such as the sulfoxy derivatives. It may be stated generally that the presence of sulfur and/or oxygen compounds is undesirable because of their tendency to render the distillates malodorous and unstable in the presence of polymerizing influences so that frequently the oils go off color and develop gummy or resinous substances during storage. The present invention is concerned with improvements in methods for removing or altering the sulfur compounds in cracked distillates so as to render them either less objectionable from a standpoint of odor and instability or of removing them to a degree required by'oommercial requirements.

In one specific embodiment of the invention, cracked hydrocarbon distillates are treated with preferably alkaline alcoholic solutions of sulfides, hydrosulfides and polysulfides of the alkali and/ or akaline earth metals. While the treatment is preferably used as an adjunct to other treatments, in some cases it may constitute the only treatment necessary. Y

The various sulfides, hydrosulfides and polysulfides of the metals of the groups mentioned vary in their solubility in absolute or anhydrous alcohols, such as ethyl or methyl alcohols, the

. solubility usually increasing as the alcohols are alkali. By proper selection of the'base metal, the

particular sulfide thereof, the strength of alcohol and the free alkali concentration, a wide range of reagents may-be prepared applicable to the treatment of cracked distillates.

Treating reagents prepared as mentioned are particularly effective in removing or altering certain types of sulfur derivatives of hydrocarbons,

the apparent mechanism of the reaction being the polymerizing or condensing of the organic sulfur compounds with the metal sulfides which forms either insoluble precipitates or solublehighboiling compounds which remain behind upon distillation of the lighter fractions of the oils treated. In some instances the compounds formed may be soluble in the reagent and in other cases precipitates may appear which are removed by sedimentation or other means.

Reagents of the type comprised in the present invention are particularly efficacious when used following treatment of cracked distillates with sodium plumbite solutions. The use of sodium pluinbite forms primarily mercaptides of lead which are more or less soluble in the oils. The addition of powdered sulfur, such as flowers of sulfur, to oils containing the lead mercaptides 1 5 causes what is known as a break in the treatment which is really the precipitation of the black lead sulfide, the organic residues combining to formcompounds of the type of disulfides. When sufiicient care is not exercised to avoid 1 0 adding excess of sulfur over that necessary to cause the break a portion of the excess remains dissolved in the oil and apparently oxidizes when the oil is exposed to light and air, causing the a better controlled addition of the amount of sulfur requisite to cause precipitation of the lead as sulfide, assures maximum contact due to easier miscibility and apparently removes some of the sulfides, thus lessening the amount of sulfur left in the oils from both standpoints.

In treating oils with reagents characteristic of the invention operations may be conducted in various types of equipment and in a variety of ways, for example, the oil may be treated in a batch agitator by circulating from the bottom of the cone back into the top through distributing means by means of a circulating pump, the reagent being added to the suction side of the pump and being mixed during passage therethrough and through the nozzles or atomizing means on the discharge side. Reagents may be injected at suitable points in the travel of oils through continuous treating equipment, consisting of mixing devices of various types followed by set,- tling and washing chambers. In some instances relatively strong solutions may be added to oils undergoing distillation with fire and/or steam with retention of desirable compounds in the still residues. In other instances treatment under considerably elevated temperatures and pressures may be advisable, in which case apparatus of requisite strength must be employed.

The foregoing description of the invention has disclosed reagents and methods of operation which are comprised within the scope of the proc ess of the invention, but these have been given for illustrative purposes only and are not to b considered in a limiting sense.

As an example of the results obtainable by the operation of the process of the invention, a

cracked distillate containing 0.35% total sulfur in various forms of combination may be treated with 5% by volume of a solution of a potassium polysulfide in 50% ethyl alcohol containing 5% free alkali, treatment being conducted at ordinary temperatures and pressures by circulating from and back to a batch agitator. After suitable supplementary water-washing, it may be found that the sulfur content of the distillate has been reduced to 0.2%. If such a treatment is followed, or in some cases preceded, by supplementary treatment with minimum amounts of 66 B. sulfuric acid, the sulfur content may be found reduced to approximately 0.08%.

I claim as my invention:

1. A step in a process of desulphurizing the condensed overhead product resulting from the cracking of hydrocarbon oil, which comprises subjecting said oil to treatment with an alcoholic solution of a sulfide of an alkali metal.

2. A step in a process of desulphurizing the condensed overhead product resulting from the cracking of hydrocarbon oil, which comprises subjecting said oil to treatment with an alcoholic solution of a sulfide of an alkali metal at substantially atmospheric temperature.

3. A step in a process of desulphurizing the condensed overhead product resulting from the cracking of hydrocarbon oil, which comprises subjecting said oil to treatment with an alcoholic solution of a polysulfide of an alkali metal.

4. A step in a process of desulphurizing the condensed overhead product resulting from the cracking of hydrocarbon oil, which comprises subjecting said oil to treatment with an alcoholic solution of a sulfide of an alkaline earth metal.

5. A step in a process of desulphurizing the condensed overhead product resulting from the cracking of hydrocarbon oil, which comprises subjecting said oil to treatment with an alkaline alcoholic solution of a sulfidev of an alkali metal.

6. A step in a process of desulphurizing the condensed overhead product resulting from the cracking of hydrocarbon oil, which comprises subjecting said oil to treatment with an alkaline alcoholic solution of a polysulfide of an alkali metal.

7. A step in a process of desulphurizing the condensed overhead product resulting from the cracking of hydrocarbon oil, which comprises subjecting said oil to treatment with an alkaline alcoholic solution of a sulfide of an alkaline earth metal.

8. A process for refining hydrocarbon oils con taining mercaptans which comprises treating the oil first with plumbite solution and then with an alcoholic solution of a sulphide of an alkalinous metal.

JACQUE C. MORRELL.