US2430981A - Method of stabilizing sulfur and sulfur compounds in crude petroleum - Google Patents

Description

Patented Nov. 18, 1.947

LIETHOD OF STABILIZING' AND- SULFUR, COMPQUNDS IN CRUDE PETBO- Charles 0. Hoover, Houston, Tex, assignor to Air Reduction Company, Incorporated; New York,

No Drawing.

This invention relates to the fixation of sulfur in crude petroleum and particularly to a method whereby the difficulty arising from the presence of sulfur and its compounds is avoided. Crude petroleum .often'contains unstable inorganic and organic sulfur compounds, and may also contain 1 elemental sulfur and hydrogen sulfide.- The presence of sulfur, in the forms in which it occurs naturally, often causes serious corrosion of tanks,

pumps and pipe lines. Also in the distillation of such crude petroleum the distillates are contaminated with sulfur as hydrogen sulfide, mercaptans, and disulfides, which as a rule are formed as a result of pyrolysis. These sulfur compounds are evolved as vapors during the distillation, and

may be totally or partially condensed with the distillate. The heat exchange surfaces of the distillation equipment are subject to serious corrosionby the sulfur compounds, particularly by hydrogen sulfide and mercaptans.

Many attemptshave been made to neutralize sulfur compounds in crude petroleum, but up to this time no noteworthy success has been achieved. See Qil and Gas Journal, June 24, 1943,

page 111, for summary of the-problem. As a 25 result, corrosion-of transportation and distillation equipment continues, and the sour distillates obtained from the crude petroleum contain sulfur which must subsequently be removed or modified before the distillates can be used.

It 'is the object of this invention to provide a method for the fixation of sulfur in crude petroleum, whereby the sulfur is converted to ,non-

corrosive forms and gives rise to products which do not contain elemental sulfur, hydrogen sulfide, mercaptans or disulfides. Since the distil lates are obtained free from elemental sulfur, hydrogen sulfide, mercaptans and disulfides, no subsequent treatment for the removal or modl-. fication of these sulfur compounds is necessary.

Other objects and advantages of the invention will be apparent as it isbetter understood by reference to the following specification, in which the preferred embodiments are described.

I have. discovered that the introduction of cuprous naphthenate into the crude oil at ordinary temperatures immediately produces relative- 1y stable and non-corrosive sulfur compounds.

I prefer to introduce cuprous naphthenate into the crude oil assoon as possible after the deliv-' ery of the oil from the oil well. The oil may then be transported or stored with little or no damage. to tanks, pumps, pipelines, etc. It may be distilled in any suitable distillation equipment without the hazard or the corrosion which attends N. Y., a corporation of New York Application February 1, 1945, Serial No. 515,140

OClalma. (Cl. 196-30) the distillation of 011 containing unstabilized sulfur compounds.

Cuprous naphthenate may be prepared in any convenient way as, for example, from cupric I naphthenate by reduction, and may be utilized in any convenient form. Since cuprous naphthenate is easily oxidized, it must be protected from the atmosphere. I prefer to use a solution of cuprous naphthenate in oil and to add the solution to 10 the crude petroleum. The amount ofcuprous naphthenate required will vary depending on the nature of the crude oil to be processed. The

various types of sulfur compounds which may be present in crude oils occur in widely varying ratio. For this reason it is-not always possible to predict the proper dosage from analytical data alone. I prefer to determine the dosage by actual test. As little as 0.1% by weight is often effec-.

tive. One per cent or more may be used, though larger amountsare rarely required.

For example, I have stabilized a Carnie crude by the addition of 0.1% by weight of cuprous naphthenate. Subsequent distillation gave gasoline and kerosene fractions free from hydrogen sulfide, mercaptans and disulfides. In this case,

the amount of cuprous naphthenate added to the crude was equivalent to only a small fraction of the-total sulfur present. Nevertheless the sul- I" fur and sulfur compounds were substantially stabilized. v Without the addition of the cuprous naphthenate to this crude oil, the distillates obtained were contaminated with elemental sulphur, hydrogen sulfide, mercaptans and disul. tides and required further treatment to be made suitable, for commercial use. I have obtained 1 equally good results by treating other crudes. with an appropriate amount of cuprous naphthenate.

In the event thatthe crude 011 contains hydrogen sulfide, the use of cuprous naphthenate is particularly advantageous, since it reacts with the hydrogen sulfide to form cuprous sulfide. Cuprous sulfide does not readily decompose at.

' distillation temperatures to form elemental sulfur, whereas cupric sulfide will decompose under such conditions with the formation of elemental sulfur. The latter readily reacts with hot hydrocarbons to form hydrogen sulfide. Mercaptans and disulfides may also be formed under such conditions and will appear in the distillates unless steps'are taken to ensure their elimination.

For the purposes of this invention the term "stable sulfur compoun is. considered to be a non-corrosive sulfur compound which under the as conditions of distillation of thecrude petroleum,

. 3 does not decompose to give hydrogen sulfide. mercaptans or disulndes in the distillate. 7

While cuprous naphthenate is the preferred reagent in the method, other lower valence copper compounds such as the oleate, linoleate', stear;

ate, resinate, and acetate may be employed in a similar manner with like results. It is essential to avoidthe cupric compounds which donot afford the advantages of the present invention.

The invention as described aifords a simple and economical solution of the problems arising from the presence of sulfur andsulfur compounds in crude petroleum. Various changes may be made in the details of procedure without departing from the invention or sacriflcingthe advantages thereof.

I claim:

1. The method of stabilizing. sulfur and sulfurcompounds in crude petroleum -which comprises adding an oil soluble cuprous compound, in prothe'crude in amount sufllcient to convert the unstable sulfur compounds in the crude into stable sulfur compounds, and thereafter distilling the crude to obtain distillates substantially free from hydrogen sulfide. mercaptans, disulflde's and elemental sulfur. f

4. The-method of stabilizing sulfur and sulfur portion sufficient to convert the unstable sulfur compounds into stable sulfur compounds, to the crude petroleum at prevailing atmospheric temperature. a

5. The method of stabilizing'sulfur and sulfur compoundsin crude petroleum which comprises adding cuprous naphthenate, in proportion of only a fraction of the amount equivalent to the sulfur present in the crude petroleum and sufflcient to convert the unstable sulfur compounds into stable compounds, to the crude petroleum.

6. The method of stabilizing sulfur and sulfur compounds in crude petroleumwhich comprises adding cuprous naphthenate. in Proportion of only a fraction of the amount equivalent to the sulfur present in the crude petroleum and sufflcient to convert the unstable sulfur compounds into stable co'mpounds,-to the crude petroleum,

at the prevailing atmospheric temperature.

" CHARLES o. noovma.

ltEFERENCES crrnn The following references are of record in the flle of this patent:

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