US3485747A - Preparation of kerosene type petroleum hydrocarbon solvents substantially free from objectionable odors - Google Patents

Description

3,485,747 PREPARATIDN F KERQSENE TYPE PETROLEUM HYDROCARBON SOLVENTS SUBSTAN'HALLY FREE FRUM OBJECTIONABLE ODD-RS Joseph Phillips, Petrolia, Pa., assignor to Witco Chemical Company, Inc, New York, N.Y., a corporation of Delaware No Drawing. Filed July 14, 1967, Ser. No. 653,325 Int. Cl. C10g 29/20 US. Cl. 208289 Claims ABSTRACT OF THE DISCLOSURE The preparation of kerosene type petroleum hydrocarbon solvents from a starting petroleum hydrocarbon fraction which is characterized by markedly objectionable inherently present odors and substantially reducing said odors by a procedure which involves adducting said starting fraction with urea whereby to form (1) an adduct between the urea and hydrocarbons in said starting fraction, and (2) a non-adductible material, said non-adductible material containing the objectionable odor-causing materials, and then recovering the kerosene type petroleum hydrocarbon solvent, substantially free of objectionable odors, from the urea adduct.

This invention relates to a process for removing objectionable odors from inherently malodorous petroleum hydrocarbon solvent fractions of certain types, hereafter described in detail.

While petroleum hydracarbon solvents are widely used in various industrial and commercial products, such solvents as, for instance, kerosene, even in a quite purified state, have a very pronounced odor which, for many purposes, is highly objectionable and undesirable.

Various procedures have been proposed, and utilized, to reduce or eliminate this pronounced odor, including extensive sulfonation, hydrogenation, chlorination, oxidation, and various chemical and physical purification treatments. Such treatments, generally speaking, are relatively expensive and none has been adequately successful in producing a fully satisfactory substantially odor-free petroleum hydrocarbon solvent such as kerosene. Sulfonation procedures, while substantially changing the odor, produce a product which still has a quite intense odor of a somewhat sweet nature. Extensive hydrogenation produces a product with a reduced odor level, but appreciable undesirable odor is nevertheless present and the treatment is relatively expensive. Chlorination, oxidation and other chemical and physical treatments generally produce only a slight improvement in the odor of the product.

It has been discovered, in accordance with the present invention, that the malodors of malodorous petroleum hydrocarbon solvent fractions, notably those characterized as kerosene or boiling in the kerosene range, can be very substantially reduced and such fractions can be produced in a form in which the malodors are markedly reduced by contacting an inherently malodorous petroleum hydrocarbon solvent fraction having a boiling point between 415 and 490 F. and an A.P.I. gravity between 44 and 50, and an odor panel rating of at least 3, with urea thereby to form a solid urea adduct in a liquid non-adductible fraction, separating said solid adduct from the liquid non-adductible material, washing the separated adduct to separate therefrom adhering non-adductible material, breaking the adduct to provide said substantially odorfree petroleum hydrocarbon solvent and urea, and recovering said substantially odor-free petroleum hydrocarbon solvent. The urea adduct may easily be separated from the non-adducted fraction, as, for example, by filtration or the like, followed by washing, and then the adnited States Patent 0 ice duct is broken or decomposed to release the adducted fraction as, for example, by treatment with water, heating or the like, but especially (1) by heating to a tem perature of about 175190 F. in the presence of the deodoriZed petroleum hydrocarbon solvent previously recovered in the process, or (2) by heating to said temperature under substantially anhydrous conditions.

The treatment with urea is effected by contacting the inherently malodorous petroleum hydrocarbon solvent fraction with urea as, for example, at a temperature between 20 F. and 100 F. and preferably 60 F. to F. In general, the amount of urea is 20 to and preferably 40 to 60 weight percent based on the hydrocarbon fraction. The contacting may be effected in the presence of solvents, diluents or activators for the adduct formation as, for example, benzol, acetone, methyl ethyl ketone, methanol, petroleum ether, non-adductible fractions of material treated, etc. Amounts of solvent diluents ranging from about 0 to 500 and preferably 0 to weight percent based on the fraction being treated, and amounts of activators, such as methanol, of 1 to 10 and preferably 2-3 weight percent based on the urea, can be used. In accordance with a particularly advantageous embodiment of the invention, in place of the conventional solvents, the contacting to form the urea adduct can be effected in the presence of a non-adductible liquid fraction previously produced in the process, in which case preferably from 50 to 150 weight percent of this non-adductible fraction, based on the starting malodorous hydrocarbon, is used. Since it is the nature of the discovery, pursuant to the present invention, that the non-adductible fraction of the starting malodorous petroleum hydrocarbon contains the malodorous material, and since the purpose of the process of the present invention is to obtain a petroleum hydrocarbon solvent fraction substantially free from malodorous materials from malodorous petroleum hydracarbon feed-stocks, it is further surprising, indeed, that the process is not interfered with by utilizing a non-adductible fraction, which contains the malodorous bearing materials, as the diluent for the adduction.

After the adduct is formed, the solid adducted fraction is separated from the liquid non-adducted fraction by known procedures as, for example, by filtration, settling, centrifugal separation or the like, and the solid adduct is washed. The adduct washing may be effected with the organic solvents of various types as well as with an adducted fraction previously produced in the process. As a part of the overall process of the present invention, the adduct must be carefully washed in order to remove the adhering non-adductible material. This is because, as has been discovered, the odoriferous constituents are present in the non-adductible material and small portions of said malodorous constituents cause substantial objectionable odor. In an illustrative case, starting with a feed stock having an odor panel rating of 3.6, the hydrocarbon fraction recovered from the unwashed urea adduct cake, after breaking, had an odor panel rating of 3.2, after one washing had an odor panel rating of 2.8, after two washings had an odor panel rating of 1.7, and after three washings had an odor panel rating of 1.4. In each washing, the volume of wash solvent was one-tenth of the volume of the starting feed stock. After completion of the washing step, the urea adduct is broken, as indicated above, whereby to provide the desired substantially odor-free petroleum hydrocarbon solvent, and urea, and said substantially odorfree petroleum hydrocarbon solvent is then recovered. The treatment with urea, in accordance with the present invention, sometimes results in imparting a very slight urea ordor to the recovered substantially odor-free petroleum hydrocarbon solvent. To the extent that this may be regarded as undesirable, it can readily be removed by contacting said substantially odor-free petroleum hydrocarbon solvent with a small proportion of activated bauxite, as by percolating through a bed of said bauxite. It may be pointed out that activated bauxite has no effect in removing odors of the type which are responsible for the malodors in the starting inherently malodorous petroleum hydrocarbon fractions with the removal of which malodors the present invention is concerned.

The evaluation of odors by panel rating has been developed for the testing of Odor of Petroleum Wax (ASTM Method D 1833-61T). As adapted to the rating of odor in petroleum hydrocarbon solvents, such as kerosene, it involves the selection of a panel consisting of at least five people who are all qualified to detect varying odor intensities. This panel evaluates the odor intensity of a series of three to four samples at one time. Each panel member sniffs each sample and gives it a numerical rating. Each sample is coded. The average of the numerical ratings by the panel members is calculated and recorded as the Odor Panel Rating. Repeatability on the same sample tested by the panel on different days is 0.3; and this does not require that the same members be on the panel both times.

Rating description Rating No: Description of odor None. 1 Slight. 2 Moderate.

3 Strong. 4 Very strong.

The odor panel rating of the starting inherently malodorous petroleum hydrocarbon fraction, as pointed out above, is at least 3 and, in the case of an untreated hydrocarbon fraction, is commonly 3.5 or 4. Where a starting petroleum hydrocarbon fraction has undergone a certain refining treatment, for instance, acid refining, it will generally have a somewhat lower odor panel rating, for instance, 3, which is still highly objectionable for many purposes. The starting petroleum hydrocarbon fraction may be any petroleum hydrocarbon fraction of natural or synthetic origin within the boiling point, viscosity and gravity ranges set forth above and having an odor panel rating of at least 3. Thus, for example, the fractions may be obtained from Pennsylvania crudes, Mid-Continent crudes, Gulf Coast crudes, Middle Eastern crudes, Fischer-Tropsch products and the like.

The starting inherently malodorous petroleum hydrocarbon fractions which are utilized in the practice of the process of. the present invention can be prepared by any one of various known procedures. Thus, for example, kerosenes are commonly prepared, in the refining of crude petroleum hydrocarbons such as Pennsylvania crude oils or Mid-Continent crude oils, by taking 01f a fraction within certain boiling point ranges, kerosenes generally comprising mixtures predominately of paraffinic hydrocarbons in the range of decanes to hexadecanes.

Such kerosenes conventionally have odor panel ratings of 3.5 to 4. Even when subjected to known purification treatments of the character referred to above, such as sulfonation, hydrogenation, and chlorination, they are usually still characterized by odor panel ratings of 3 or more.

The specific chemical structure or nature of the malodorous constituents inherently present in the starting malodorous petroleum hydrocarbon fraction is not known and has not been characterized. That it is not aldehydic or ketonic in character, nor of amine, sulfide or mercaptan structure, would appear to follow from the fact that materials of such character form urea adducts (see, e.g. US. Patent No. 2,985,641 and the hereafter mentioned Brooks et al. article), nor is it of a character such as is exemplified by acetonitrile or similar nitrile compounds such as propionitrile or higher nitriles.

The following examples are given by way of illustration and not of limitation:

Example 1 A petroleum distillate (hereafter called Solvent A) of the following properties was treated:

API Gravity 46.0 Initial boiling point F 415 olT F "75 End point F 480 To 1,000 ml. of Solvent A were added 300 g. urea and 10 ml. methanol. The mixture was stirred at room temperature. After 10 minutes, adduction occurred as shown by a 15 F. temperature rise. After 30 minutes additional stirring, the precipitated adduct was filtered through a Buchner funnel and washed with 3-100 ml. portions of a previously produced adducted fraction. The adduct was decomposed with hot water F.) and the hydrocarbon layer liberated (48% by weight of the stock). Odor panel ratings were as follows:

Odor panel rating Solvent A (untreated stock) 4 Solvent A (acid refined stock) 3 Recovered solvent (adducted fraction) 2.5

Example 2 Example 1 was repeated except that the starting stock was initially diluted with an equal volume of a previously produced non-adductible fraction. Odor panel ratings were as follows:

Odor panel rating Solvent A (untreated stock) Solvent A (acid refined stock) Recovered solvent (adducted fraction) 1.5 Non-adductible fraction 4+ carbon fraction enriched in content of the desired type of hydrocarbon. Such techniques have been known particularly for separating straight chain hydrocarbons from branched chain hydrocarbons. The urea adducts generally form with the straight chained hydrocarbons, leaving the branched hydrocarbons as a non-adducted fraction, thus allowing a fractionation separation of the stragiht chain hydrocarbons from the branched chain hydrocarbons. Such procedures are shown in numerous patents and publications illustrative of which are US. Patents Nos. 2,656,342; 2,666,048; 2,672,457; 2,673,195; and 2,731,- 455; the article Crystalline Adducts of Urea with Linear Aliphatic Compounds, by Zimmerschied et al., Ind. and Eng. Chem., Vol. 42, N0. 7, pp. l3001306 (July, 1950); and Brooks et al. The Chemistry of Petroleum Hydrocarbons, Vol. I, Reinhold Publishing Co., New York. 1954, pp. 241-274. However, such prior patents and publications have nothing to do with and teach nothing whatsoever about removal of malodors from inherently malodorous petroleum hydrocarbon fractions. Indeed, the nature of the odors inherently present in certain petroleum hydrocarbons and the sensory perception thereof are not entirely understood, and there is no known or recognized relationship between properties of a petroleum hydrocarbon fraction which will form or will not form an adduct and the inherent odor of such a fraction. It is therefore entirely unexpected and surprising that a urea adduct treatment of the specific inherently malodorous petroleum hydrocarbon fractions described above will yield products having a substantially lower odor.

I claim:

1. A process for preparing a kerosene type petroleum hydrocarbon solvent which is substantially free from objectionable odors from a malodorous petroleum hydrocarbon fraction having a boiling point between 415 F. and 490 F., an A.P.I. gravity between 44 and 50, and having an odor panel rating of at least 3, which comprises adducting said malodorous petroleum hydrocarbon fraction with urea to form a mixture of a solid adduct fraction and a liquid non-adductible fraction, said non-adductible liquid fraction containing substantially all of the objectionable malodorous material present in said malodorous petroleum hydrocarbon fraction, separating said solid adduct from said non-adductible liquid fraction, washing the separated solid adduct to remove therefrom adhering non-adductible material, breaking the adduct to release the urea and recovering said petroleum hydrocarbon solvent having an odor panel rating of not more than 2.5.

2. A process according to claim 1, in which said malodorous petroleum hydrocarbon fraction is an untreated stock having an odor panel rating of 4.

3. A process according to claim 1, in which the adduction is carried out in a mixture containing a non-adductible liquid fraction which was separated from a previous urea adduction step involving said malodorous petroleum hydrocarbon fraction having an odor panel rating of at least 3.

4. A process according to claim 1, in which said malodorous petroleum hydrocarbon fraction is kerosene.

5. A process according to claim 4, in which said re covered kerosene is contacted with activated bauxite.

References Cited UNITED STATES PATENTS 3,231,489 1/1966 Mahar 208-308 2,221,301 11/1940 Kipper 208-289 2,834,716 5/1958 Champagnat et al. 208 2,914,455 1/1959 Keller 208-25 3,163,632 12/1964 Leas et al. 20825 3,328,313 6/1967 Dellow 208-25 FOREIGN PATENTS 708,597 4/1965 Canada. 1,408,798 7/1965 France.

215,199 10/ 1956 Australia.

DELBERT E. GANTZ, Primary Examiner G. J. CRASANAKIS, Assistant Examiner