US2886521A - Process for the sweetening of petroleum products - Google Patents

Description

Un d States tm PROCESS FOR THE SWEETENING OF PETROLEUM PRODUCTS Andr Gislon, Paris, and Joseph Quiquerez and Jean Daniel Maurin, Gonfreville LOrcher, France, assignors to Compagnie Francaise de Raifiuage, Societe Anonyme, Paris, France No Drawing. Application February 18, 1954 Serial No. 411,256

Claims priority, application France December 12, 1953 19 Claims. Cl. 208-197) The two first-mentioned applicants have established previously that the air oxidation of 'mercaptans which are usually contained in petroleum products-Le. the sweetening of these products-is catalyzed by organic chelate compounds having metallic constituents-and, in particular, by cobalt chelates of Schifi bases resulting from the condensation of salicylic aldehyde with a diamine.

Depending on the different methods in which the process may be carried out, the chelates may be introduced in the fully prepared state in the petroleum prodact to be treated, or they may be formed in situ; the dia-mine which produces the Schiff base may be aliphatic, cyclic, aromatic or hydro-aromatic. The chelate can be used in the presence of a solvent such as an alcohol, a ketone, a phenol, a fatty acid, etc., or in the form of an aqueous alcohol dispersion. In a continuous process the product may be put in contact with an excess of chelate in such a dispersion, which is recycled after separation. Or, again, one could add the chelate solution to the prod: nct to be treated in a minimum quantity just suflicient so that the product then becomes slowly sweet in the course of storage. The oxygen dissolved in the products to be treated is often sufficient to permit the oxidation without it being necessary to provide for air blowing.

The present invention consists of operating the oxidation of mercaptans according to these techniques, which are the object of U.S. Patent No. 2,659,691 and US. patent applications Serial Numbers 340,918 and 385,274 filed respectively on March 6, 1953 (now US. Patent No. 2,823,173, granted February 11, 1958) and October 9, 1953, in the joint names of Andr Gislon and Joseph Quiquerez, in the presence of a salt of lead;

The improvement which the addition of a lead salt makes possible the attainment of considerable economy "ice 2 in the presence of an aqueous alkaline solution, the function of which is essentially to neutralise the acid liberated by the formation of the chelate.

It is not however absolutely essential that the stoichio; metric quantity of soda necessary for this neutralisation only, should be employed and there may be, particularly in the case of continuous reactions, an excess of soda with respect to the quantity of acid liberated at any given moment.

, Or. again, the. petroleum product to which. the chelate has been added-either added as such or produced in sitll: by successive. additions of the Schilf base and the cobalt saltrnay be brought, if, desired, in the presence oi-a chelate solvent, into contact with an alkaline sQlutiOIt, containing a lead salt, that is to say, finally. with an I alkaline solution of plumbite.

In a further alternative method, the petroleum product containing a lead salt may he treated with an aqueous alcoholic dispersion of chelate, which may have been produced in situv in the aqueous alcoholic medium by addition of the Sohiii base and a lead salt in a solution of a dispersion agent.

The. following examples, which are not limitative, indi cate various methods of carrying out the process and the advantages that result from it.

(a) Of 0.30 gram per liter ofcreso containing 10%; of lead in the form of cresolate Obtainedby diStOI iIF-LEv litharge in cresol. V

(b) Of 0.30 gram per liter of cresol containing 10% of cobalt chelate 0f disalicylal propylene diimine-LZ.

in the amount of chelate used and facilitates the sweetening of the petroleum products.

The process in accordance with the present invention may be applied in the form of various alternatives which differ either in the conditions under which the lead salt is added to the petroleum product or to the chelated compound, either by the process of obtaining this latter, or by a particularassociation of these two factors.

The principal methods of carrying the invention into effect are described below, but these indications are not to be construed as limitations of the invention.

The lead salt may be chosen from amongst those which are soluble in the hydrocarbons: organic salt, phenolate, mercaptide, etc.

' The lead salt may be added to the hydrocarbon to be treated together with the chelate in the presence of a solvent of the latter as circumstances may require.

There may be added to the petroleum product, at the same time as the lead salt, the Schiif base and the cobalt salt which are intended to. produce in situ the chelate compound.

(c) Of 0.50 gram per liter of cresol containing 10%. of the above chelate.

(d) Of 0.20 gram per liter of cresol containing 10% of the above chelate.

(e) Of.0.30 gram per liter of cresol containing 6.6% of the above chelate and 6.6% of lead.

. (f) .0f 0.30 gram per liter of cresol containing 6.6%, of the above chelate and.10% of'lead.

All these gasolines are put in storage and those containing chelate show a progressive reduction of their mercaptan content concurrent with the formation of a precipi tate of. oxides of cobalt and/or of lead whichis readily separated by filtration, leaving a, gasolinesubstantially free of such metallic compounds.

Table 1 shows the development of the mercaptans after 24 hours in the various experiments as well as the stability of the gasolines obtained by the different treatments in comparison to the untreated (test h) and inhibited gasoline (test g).

Table 1 Reagents, 'g./l. Content of Sass Quantity 'oisulpbu'r Stability Tests oxidized Inducby 1 g. of tion Chelate Cresol Lead Initial After chelate Period 24 Hrs. (Grams) (a) v 0 0. 30 0. 03 0. 024 0. 022 (b) 0.03 0.30 0 0.02 1 0.003 (C) 0. 05 0. 50 0 0. 024 0. 000 (d) 0. 02 0. 20 0 0. 025 0. 010 (e) -0. 02 0. 30 0. 02 0. 024 0.000 0.02 0.30 0.03 0.025 0.000 (9) 0 0. 30 0 0. 024 0. 024 (It) 0 0 0 0. 024 0. 024

1 The period of induction has been calculated in accordance with the I norm A.S.T.M. No. D525-49.

. 3 One notes that lead alone is practically without effect,

that the chelate alone results in an absolute sweetening only if a sufficient amount isiused, on the order of 0.05

gram per liter in the-examples studied, while the corn-:

hination chelate-lead resultsin a sweetening with a comsumption of chelate of 0.02 gram per liter, that is, a saving of 60% as compared with the treatment without lead.

One also will note from the examples of Table 1 that the process improves the inhibition of the gasoline.

EXAMPLE 2 One treats in the same manner as in Example 1, either an Iraq kerosene having a boiling range of 196 to 257" C. and a specific gravity of 0.795 or an Iraq gas oil boiling between 192 and 371 C. and'having'a specific gravity of 0.838 with 0.30 gram per liter of crcsol containing 10% bis disalicylal ethylene diimino di'cobalt and 10% of lead in the form of cresolate.

- Table 2 shows the advantage of the use of lead which results in sweetening with an increased activity of the After sweetening the products are decolored by 1 part per thousand of active earth or by a wash with 20%- sulfuric acid. The products are substantially free of said metallic compounds.

EXAMPLE 3 (a) To a straight run Iraq gasoline with a boiling range of 40 to 160 C. and a specific gravity of 0.720, is added 3.0 cm. per liter of methanol containing grams per liter of salicylal propylene diimino-cobalt.

(b) To a sample of the same gasoline is added of its volume of the same gasoline washed by the plumbite process; thus one obtains a gasoline of which ,4 of the niercaptans are combined in the form of lead mercaptide. To this gasoline is added 3.0 cm. per liter of methanol containing 10 grams per liter of cobalt chelate.

(c) 'To a sample of the same gasoline is added 0.014 gram per liter of lead in the form of naphthenate, then 3.0 cm. per liter of methanol containing 10 grams per liter of cobalt chelate.-

The products are left in storage for 24 hours, are filtered over sand and one finds that absolute sweetening has been obtained only in the case of the gasolines treated with the cobalt chelate in the presence of lead.

This example relates to the case where the cobalt chelate is formed in situ.

To a straight run gasoline of Mid-East origin with a boiling range of 40 to 200 C. and a specific gravity of 0.728 and which does not contain any free sulfur, is added in parallel experiments:

(a) Of 0.015 gram per liter of disalicylal propylene diimine-l,2 and 0.0032 gram per liter of cobalt in the form of naphthenate.

(b) 0f 0.015 gram per liter of disalicylal propylen diimine-l,2; 0.0032 gram per liter of cobalt (naphthenate) and 0.0047 gram per liter of lead in the form of mercaptide.

(c) 0f 0.015 gram per liter of disalicylal propylene diiminc-1,2; 0.0032 gram per liter of cobalt (naphthenate) and 0.028 gram per liter of lead in the form of naphthenate.

After 24 hours one filters and determines the mercaptan content. The results shown in Table 4 underline the on the cobalt salt.

Table 4 Reagents (grams per liter) Snsn. Percent Sulphur oxidized per 1 gram salicylal Cobalt After 01 chelate Lead dlimlne uaphthe- Initial 24 Hrs. (grams) nate EXAMPLE 5 j The same gasoline as in Example 4 is treated by the same reagents as in Example 4, but in the presence of 25 cm. per liter of 10% caustic soda. The results obtained for the quantities of reagents used are summarized in Table 5.

' Table 5 Reagents (grams per litre) Base, Percent Sulphur oxidized per gram salicylal Cobalt NaOH After of chelate Lead diirnine naph- 10% Initial 24 Hrs. (Grams) the late cmfi/l.

EXAMPLE 6 In a continuous operation one brings a gasoline--with a boiling range of 40 to 200 C. and a specific gravity of 0.730-in which successively are injected 7.5 grams per cubic meter of disalicylal propylene diimine-1,2 and 1.6 grams per cubic meter of cobalt in the form of acetyl acetonate, in contact in a mixer with A of its volume of 10% caustic soda in which are dissolved 3.5 grams per liter of litharge, while air is injected simultaneously.

The aqueous phase is separated in a settler and'irecycled to the 'mixer.

Onehas thus treated 70 liters of gasoline containing 0.025% by weight of sulfur in the form of mercaptan with 100 cm. of caustic soda containing the plumbite.

The gasoline obtained had a copper number of 3.

EXAMPLE 7 An aqueous dispersion of cobalt chelate of disalicylal propylene diimine 1,2 is prepared by adding stoichiometric quantities of caustic, of disalicylal propylene diimine 1,2 and of cobalt nitrate to a mixture of 90% by volume of water and 10% by volume of a commercial solution of a wetting agent known as Teepol. In this manner a stable aqueous dispersion containing 1% of chelate is obtained.

One liter of straight run Iraq gasoline having a final boiling point of 200 C. and a specific gravity of 0.720, containing 0.025 by weight of sulfur in the form of mercaptan is agitated for 3 minutes with 3 cm. of the above mentioned dispersion of 1% chelate and is left to settle.

After 24 hours the mercaptan content has dropped to 0.012% S A parallel experiment conducted with the same quan- EXAMPLE 8 One has prepared an aqueous alcohol solution of cobalt chelate derived from disalicylal propylene diimine 1,2 containing 6 grams per liter of chelate and 100 cm. per liter of methanol.

(1) For every 250 cm. of this solution one treats continuously in the presence of air 70 liters of the same gasoline as in Example 7. After treatment one has obtained a gasoline contaning 0.007% S In this experiment 1 gram of chelate has oxidized 5.4 grams of een- (2) For every 250 cm. of the aqueous alcohol chelate solution mentioned above one has treated 70 liters of the same gasoline to which previously 0.03 gram per liter of lead in the form of cresolate has been added.

One has obtained in a continuous process 100 liters of gasoline with a content of 0.000% of S and in this experiment one gram of chelate has oxidized 12 grams Of 8353;.

All the examples given above rely on the addition of a lead salt to the products in reaction. However, it falls also within the scope of the invention to employ, for the sweetening treatments considered, an equipment which includes parts or members made of lead. The applicants have, in elfect, established that, in certain conditions of operation involved in carrying the process of sweetening into effect, and to which the invention applies, these parts or members of lead may result in the formation of a lead salt which then plays the same part as if it has been added, in that form, to the products in reaction.

We claim:

1. Process for the sweetening of petroleum products by oxidation of the mercaptans in the simultaneous presence of a salt of lead and of a chelate of cobalt of a Schifi base resulting from the condensation of an aromatic hydroxy aldehyde with a diamine.

2. Process according to claim 1 in which the said aromatic hydroxy aldehyde is salicylic aldehyde.

3. Process according to claim 1 in which the chelate compound is introduced in the petroleum product to be treated in the form of a solution in a solvent miscible in the petroleum product together with a salt of lead soluble in the hydrocarbons.

4. Process according to claim 1 in which the salt of lead is soluble in the hydrocarbons.

- 5. Process according to claim 2"in'whi'cl1" the'che'l ate compound is introduced in the petroleum'product tob'e treated in the form of a solution in a solvent miscible in the petroleum product together with a salt of lead soluble in the hydrocarbons.

6. Process according to claim 2 in which the chelate is formed in situ by addition to the petroleum product of a cobalt salt soluble in the hydrocarbons and of a Schiff base resulting from the condensation of an aromatic hydroxy aldehyde with a diamine.

7. Process according to claim 2 in which the petroleum product to which previously a cobalt salt of a Schiff base and a lead salt have been added is brought into contact with an alkaline solution.

8. Process according to claim 2 in which the petroleum product to which previously a cobalt salt of a Schifi base has been added, is brought into contact with an alkaline solution containing a mineral salt of lead.

9. Process according to claim 2 in which the petroleum product to which a lead salt has previously been added is treated with an aqueous dispersion of a chelate of cobalt.

10. Process according to claim 2 in which the petroleum product to which a lead salt has previously been added is treated with an aqueous dispersion of a chelate of cobalt, prepared by the addition of a cobalt salt and of a Schifi base to an aqueous solution of a surface active agent.

11. Process according to claim 2 in which the petroleum product to which previously has been added a lead salt is treated with an aqueous alcohol dispersion of a cobalt chelate.

12. A composition for the sweetening of petroleum products which comprises a mixed solution of a lead salt and cobalt chelate of a Schitf base resulting from the condensation of an aromatic hydroxy aldehyde with a diamine.

13. A composition for the sweetening of petroleum products which comprises a mixed solution of a cobalt chelate compound of a Schifi base resulting from the condensation of an aromatic hydroxy aldehyde with a diamine and a lead salt soluble in the hydrocarbons.

14. A composition for the sweetening of petroleum products which comprises a mixed solution of a cobalt chelate compound of a Schifi" base resulting from the condensation of an aromatic hydroxy aldehyde with a diamine and a lead salt in a solvent which is miscible with the hydrocarbons and which is selected from the class consisting of alcohols, ketones, phenols and fatty acids.

15. A composition for the sweetening of petroleum products, comprised of a solution, in cresol, of cresolate of lead and of chelate of cobalt of a disalicylal-diimine.

16. For the sweetening of petroleum products, two solutions utilized conjointly and constituted, one by a solution of a Schifi base resulting from the condensation of an aromatic hydroxy aldehyde on a diamine, the other by a mixed solution of two salts, one of cobalt, the other of lead, both salts being soluble in the hydrocarbons.

17. For the sweetening of petroleum products, two solutions utilized conjointly and constituted, the one by a solution of a Schiif base resulting from the condensation of an aromatic hydroxy aldehyde on a diamine, the said solution being rendered alkaline by a stoichiometric quantity of an alkaline hydroxide with two molecules of alkali per molecule of disalicylal-diimine, the other solution being a mixed solution of two salts, one of cobalt, the other of lead, both salts being soluble in the hydrocarbons.

18. For the sweetening of petroleum products, two solutions utilized conjointly and constituted, the one by an alcoholic solution of disalicylal-diimine and alkaline alcoholate, with two molecules of alkali per molecule of dialicylal-diimine, the other by a mixed solution of two salts, the one of cobalt, the other of lead, both salts being soluble in the hydrocarbons.

19. The process of sweetening petroleum products which comprises efiecting the oxidation of mercaptans in said products in the presence of a free oxygen containing gas, an organicchelate compound comprised of the reaction product of an imino-phenol and a cobalt salt and 5 a lead salt.

References Cited in the file of this patent UNITED STATES PATENTS Borgstrom Jan. 5, 1932 Morrell Apr. 18, 1933 Paulsen Apr. 8, 1942 Gholson Dec. 1, 1942 Moulthrop Sept. 8, 1953

Claims (1)

1. PROCESS FOR SWEETENING OF PETROLEUM PRODUCTS BY OXIDATION OF THE MERCAPTANS IN THE SIMULTANEOUS PRESENCE OF A SALT OF LEAD AND OF A CHELATE OF COBALT OF A SCHIFF BASE RESULTING FROM THE CONDENSATION OF AN AROMATIC HYDROXY ALDEHYDE WITH A DIAMINE.