US3617533A - Refining of hydrocarbon with boron trifluoride - Google Patents

Abstract

Hydrocarbon stocks containing undesirable impurities are refined by admixing between about 0.1 percent and 5 percent by weight of water with said hydrocarbon stocks and then treating said admixture with an amount of gaseous boron trifluoride in excess of that necessary for complex formation with the water. An insoluble precipitate is formed of said undesirable impurities that is readily separated from the hydrocarbon.

Description

United States Patent [72] Inventor [21] Appl. No. [22] Filed [45] Patented [73] Assignee [54] REFINING OF HYbROCARBON WITH BORON TRIFLUORIDE 7 Claims, No Drawings [52] US. Cl 208/292 [51] lnt.Cl Clog 29/02 [50] Field of Search 208/292, 249, 279, 290, 291, 208, 223, 24l 254, 255, 256, I77

[56] References Cited UNITED STATES PATENTS 2,062,377 12/1936 Schneider 208/241 I 2,416,465 2/l947 Axe .Q 208/254 2,495,851 1/1950 Lien et al 208/241 2,602,770 7/1952 Johnson et al. 208/223 2,745,792 5/1956 Shiah 208/241 2,796,387 6/1957 Schmidt 208/292 OTHER REFERENCES Chem Abstracts, 53385k, Vol. 69, Sept. 30, [968 pp. 4997 and 4998.-

Primary Examiner- Delbert E. Gantz Assistant Examiner-G. J. Crasanakis Attorneys-Jordan J. Driks, Albert L. Gazzola and John J.

Mahon ABSTRACT: Hydrocarbon stocks containing undesirable impurities are refined by admixing between about 0.! percent and 5 percent by weight of water with said hydrocarbon stocks and then treating said admixture with an amount of gaseous boron trifluoride in excess of that necessary for complex formation with the water. An insoluble precipitate is formed of said undesirable impurities that is readily separated from the hydrocarbon.

REFINING F HYDROCARBON WITH BORON TRIFLUORIDE This invention relates to the refining of mixed hydrocarbons, particularly petroleum hydrocarbons. More particularly, it relates to the refining of petroleum hydrocarbons or'fractions of petroleum hydrocarbons containing, in addition to other hydrocarbon compounds undesirable constituents such as organic sulfur compounds (e.g. mercaptans, alkyl sulfides and disulfides, sulfoxides, sulfones and thiophene and its homologs), unsaturated hydrocarbon compounds, nitrogen compounds and oxygenated compounds, by treatment of said hydrocarbons with boron trifiuoride and water.

Processes for treating petroleum hydrocarbons with boron trifluoride, boron fluoride hydrate and with certain boron trifluoride complexes are known and disclosed, for example, in U.S. Pat. Nos. 2,257,627; 2,416,465; 2,495,851; 2,691,622; 2,745,792; and 2,767,120. These processes are generally based upon the extraction of hydrocarbons with BF, complexes, the polymerization of unsaturates which remain in solution and can be removed by distillation of the BF,-treated hydrocarbon, or the fonnation of partially soluble sludges of nonhydrocarbons impurities by treating with BF, that are then extracted with suitable solvents. In the case of heavy stocks or previously unrefined stocks it has been found that extraction with boron fluoride does not readily afford complete phase separation of the impurities from the refined hydrocarbon.

In accordance with the present invention, it has been discovered that hydrocarbon stocks may be advantageously refined by admixing a small portion of a member selected from the group consisting of water and boron trifluoride monohydrate with said hydrocarbon stocks and then treating said admixture with gaseous boron trifluoride thereby forming an insoluble precipitate of the undesirable impurities in the hydrocarbon stocks that can be readily separated from the refined stock. It is an essential feature of the present invention that the amount of gaseous boron trifiuoride used is in excess of that stoichiometrically necessary for complex formation with the water.

The process according to the present invention may be carried out on crude petroleum hydrocarbon distillates, upon fractions produced therefrom by distillation, upon crude petroleum stocks and artificial mixturesof petroleum fractions, on partly refined hydrocarbons or other untreated or treated hydrocarbons on byproducts obtained from the refining or dewaxing of petroleum fractions, or stocks obtained by cracking hydrocarbons and on coal tar and coal tar distillates. This list of products is illustrative only and other hydrocarbon stocks may be effectively treated in accordance with the present invention.

1n practicing the process of the present invention small proportions of water is first thoroughly admixed with the hydrocarbon stock and gaseous boron trifluoride is then added to the admixture. Between about 0.1 percent to about percent by weight and preferably between about 0.5 percent and 1.5 percent by weight of water based on the hydrocarbon stock is admixed with the hydrocarbon stocks. Boron trifluoride monohydrate is also suitable for use, preferably in amounts ranging between about 1.5 percent and 4 percent by weight based on the hydrocarbon stock.

The amount of gaseous BF, employed may vary within wide limits depending on the type of hydrocarbon stock to be refined and the content of undesirable constituents to be removed. It is essential when water is employed that the amount of gaseous boron trifluoride used is greater than stoichiometrically necessary for complex formation with said water, an excess of between about percent and 50 percent by weight of gaseous BF, being advantageously employed. An amount of gaseous BF, ranging between about 2 percent and 5 percent by weight based on the hydrocarbon stock has been advantageously employed in combination with boron trilluoride monohydrate-hydrocarbon admixtures.

The process of the present invention may be carried out over a wide range of temperatures and pressures. Temperatures of from about 0 to 150 C. have been found convenient for carrying out the refining process, while temperatures falling within the range of 60 to 120 C. are especially suitable and preferred. The process may be carried out at atmospheric pressure, but higher pressures accelerate procedure and are generally preferred.

The treatment in accordance with the process of the present invention removes certain components by formation of compounds which are incompatible with the refined hydrocarbons, as for example, by polymerization, complex formation, formation of highly polar compounds, coagulation of asphaltic compounds, etc. After the treatment two phases are formed,

one phase consisting of the refined hydrocarbons and a second which is composed of the incompatible compounds, that may be readily separated from each other by gravity settling or other known methods. It is an important feature of the present invention that the undesirable constituents are removed from the treated hydrocarbon by precipitation, a relatively simple and inexpensive technique, rather than by extraction or distillation.

The refined oil phase will contain only a very small percentage of boron trifiuoride that can be easily removed by distillation under a slight vacuum. The oil can then be used as a finished petroleum oil as such or can be subjected to a finishing treatment, as for instance, treatment with activated clay or sulfuric acid, hydrogenation or any other finishing treatment. The result will be an improved product with significantly improved color, improved stability and with a reduced content of undesirable constituents.

The precipitated phase will contain most of the boron trifluoride together with the incompatible undesirable impurities and it is possible to recover the boron trifluoride from the precipitate by distillation at appropriate temperatures with or without the application of a vacuum.

It has been discovered that particularly advantageous method for recovering BF, from the precipitate is by the use of a falling film evaporator to carry out the distillation recovery procedure. In this technique the precipitated phase flows in the form of a thin film down along a tube heated to between 250 and 300 C. and the BF, is readily recovered. The recovered BF, is suitable for reuse in the refining process, enabling the process to be carried out continuously using recycled BF,. The precipitate may be continuously supplied to the film evaporator and recovered BF, and sludge residue continuously taken off.

The process of the present invention can be applied to petroleum distillates'to improve the quality of heavy gas oil and light spindle oil and similar products originating from the atmospheric distillation of crude petroleum, but is also valuable for refining vacuum distillates used for lubricating oils and for special applications such as for transformer and electrical oils. It is also very effective for the refining of residual products.

The following examples are illustrative of the practices of the present invention'but are not to be considered as limitative of its scope. Percentages stated are by weight.

EXAMPLE I A reaction vessel, provided with stirring equipment, was filled with 500 grams of an unrefined cylinder oil (see specification in table 1, column 1). Y

The oil was heated to a temperature of C., and 3 grams (0.6 percent by weight) of water were added with agitation.

Gaseous boron trifluoride was introduced into the admixture of cylinder oil and water maintained at a temperature of about 90 C. until 15.5 grams were absorbed. The reaction mixture was then allowed to separate into an upper layer of refined oil and a lower layer consisting of compounds which were immiscible with the upper layer. Alter decanting, an upper layer weighing 455 grams and containing 0.12 grams BF, was obtained. The immiscible lower layer had a weight of 63.3 grams.

The refined oil phase was heated to 200 C. under a vacuum of 30 mm. H, vacuum in order to separate the dissolved BF,. Thereafter the refined oil was neutralized with lime and the refining treated during 30 minutes with 5 percent of activated clay at a temperature of 120 C. The refined oil fraction thereby obtained has the properties as set out in column 2 of table I below.

The separated immiscible precipitate layer was distilled employing a falling film evaporator at a temperature of 250- 300 C. and atmospheric pressure. The BF;, present in this phase was substantially completely recovered and collected for reuse.

From the aforementioned figures it is apparent that the treatment as described yields an oil with considerably improved .characteristics, with a yield before clay treatment of over 90 percent. A conventional refining method applied to the same cylinder oil, consisting of solvent refining with a selective solvent followed by acid treatment with sulfuric acid, neutralizing and clay treatment, will give a yield of about 70 percent refined oil, but with a color of only 5.5/6 ASTM.

EXAMPLE 2 3 grams of H,O were added with agitation to 500 grams of a partly refined bright stock oil (see specification in table II,

column I) in the reaction vessel described in example I. The

admixture was heated to a temperature of 90 C. and BF, was added until 20 grams were absorbed.

The immiscible products were separated by centrifugation and a refined oil phase of 377 grams was obtained, which contained 0.4 grams BF Table II Column l Column 2 Spec. Gravity 20/4'C. 0.890 0.880 Vise. cenlistokes H0" F. l03.4 90

Visc. centistoku 200' F. 30.3 27

Basic Nitrogen I: 0.0l2 0.00!

k Sulfur L28 0.6 Color ASTM Dl500 6 1.5

Color after aging 48 hour: at 120' C. dil. B 2.5

EXAMPLE 3 L5 grams H,O were added with agitation to 750 grams of a light spindle distillate (see specification in column 1, table III) at a temperature of 60 C. in the same way as described in example 1.

BF, gas was added to the heated admixture until 21 grams of BF were absorbed. The immiscible phase was separated by gravity settling and 735 grams of a refined oil were obtained, which contained 0.37 grams of BF,,. The BF, was separated from this oil fraction by distillation as described in example 1.

The oil was then neutralized by washing with lime and treated with 2 percent activated clay for 30 mins. at 120 C.

The specification of the oil thereby obtained is stated in table lll, column 2. The original product (table lll, column 1) was treated with 5 percent activated clay, to compare the result with the BF, treated oil.

Both oils were then stored at temperatures of 120 C. for 96 hrs. After storage the oil not treated with BF, had a color of 4.5 ASTM Dl500, while the oil treated with BF; had a color of 1.5 ASTM D1500.

Color Lovibond 2" cell. 0.5 (Yellow series) EXAMPLE 4 500 grams of a selected light lubricating oil extract obtained from furfural extraction of a lubricating oil stock to which 0.63 percent by weight of water was added, was agitated for about 3 hours at C. During this time gaseous BF; was passed through the agitated extract. At the end of the treatment 5.3 weight percent of BF;, gas was absorbed. After settling two layers were obtained. The refined oil product and a sample of the starting furfuraL extract were clay treated with 6 percent by weight of an activated clay. The results of the treatment are listed below:

Light extract B Fg-Wfltel Clay and clay Untreated treated treated Yleld, percent 96 86 Vise. centlstokes 20 C 698 690 451 Vlsc. centlstokes 60 C 31 30 25 Vise. centlstokes 100 C 7 7 6 Color ASTM D1500 Dll. L7.6 Dll. 7.0 4. 0

EXAMPLE 5 Boron trifluoride monohydrate was admixed with a cylinder oil rafi'mate havinga specific gravity at 20 C. of 0.936, an NPA (National Petroleum Association) color of 8 and a viscosity of 664,v centistokes at 50 C. and said admixture was treated with BF; gas in the proportions of ingredients described in the table below. Color properties of the treated hydrocarbon is summarized in the accompanying table. Other samples of the above described cylinder oil were separately 3 with BF, gas and BF l-l O and the comparative results are summarized below. When the oil was treated with BF gas only no color improvement was noted. Refining with the combination of 3 percent BF H,O and 2 percent BF gas resulted in color properties comparable with 10 percent BF, H 0 refining, indicating obvious economic advantages. All of the refining procedure of this example were carried out at 80 C.

BFgHzO BF: gas

Percent Percent Color after g ms Grams by wt. Grams by wt. Time treatment 3 10. 7 2 4.5 hours 2% NPA An NPA color of 8 corresponds to a deep red color; NPA colors in the range of 4 to 2 correspond to orange pale, 4, to extra pale, 2. See W. L. Nelson, Petroleum Refinery Engineering, 4th Ed. (New York: McGrawl-lill Book Company, Inc., 1948), Chapter 3 for a comparison of commonly used petroleum color scales.

Other variations and modifications of the details of this invention will be apparent to those skilled in the art within the scope of the appended claims.

What is claimed is:

1. A process for refining hydrocarbon stocks which comprises admixing a small portion of water with the hydrocarbon stocks and then treating said admixture with gaseous boron trifluoride, said gaseous boron trifluoride being added in an amount in excess of that stoichiometrically necessary for complex formation with said water, to obtain an insoluble precipitate of undesirable constituents that can be readily separated from the refined hydrocarbon.

2. A process according to claim 1 which is carried out at a 7 temperature between about 0 and 150 C.

3. A process according to claim 1 wherein between about 0.1 percent and 5 percent by weight of water based on the weight of hydrocarbon stock is admixed with said hydrocarbon stock.

4. A process according to claim 3 which is carried out at a temperature between about 60 and C.

5. A process according to claim 1 wherein an excess of between about 10 percent and 50 percent by weight of gaseous BF over the amount stoichiometrically necessary for complex formation with said water is employed.

6. A process according to claim 1 which includes recovering of said boron trifluoride treating agent by distillation from said precipitated and refined hydrocarbon phases.

7. A process according to claim 1 which includes recovering of said boron trifluoride treating agent from the precipitated phase with a falling film evaporator.

0 i i i 0

Claims (6)

1. 2. A process according to claim 1 which is carried out at a temperature between about 0* and 150* C.
2. 3. A process according to claim 1 wherein between about 0.1 percent and 5 percent by weight of water based on the weight of hydrocarbon stock is admixed with said hydrocarbon stock.
3. 4. A process according to claim 3 which is carried out at a temperature between about 60* and 120* C.
4. 5. A process according to claim 1 wherein an excess of between about 10 percent and 50 percent by weight of gaseous BF3 over the amount stoichiometrically necessary for complex formation with said water is employed.
5. 6. A process according to claim 1 which includes recovering of said boron trifluoride treating agent by distillation from said precipitated and refined hydrocarbon phases.
6. 7. A process according to claim 1 which includes recovering of said boron trifluoride treating agent from the precipitated phase with a falling film evaporator.