US2051612A - Method of treating oils - Google Patents

Description

Aug. 18, 1936. A. LoEBEL METHOD OF TREATING OILS Filed July 6, 1934 Patented Aug. 18, 1936 UNITED STATES PATENT 'OFFICE y METHOD F TREATING OILS Albert Loebel, Amsterdam, Netherlands, assigner to Shell Development Company, San Francisco, 'Calif., acorporation of Delaware Application July 6, 1934, Serial No. 733,985 In the Netherlands July 15, 1933 10 Claims.

merization of unsaturated hydrocarbons obtained by cracking, it has been customary to subject the initial material to a vapour phase crackl ing process before refining it, since it was thought that a higher yield of the most suitable olenes could be obtained in this way than by using a liquid phase cracking process.

This method, however, has serious disadvantages, especially in the case of oils containing only a small amount of volatile components. The conversion of vsuch oils into the vapour phase presents many diiiiculties, even though the cracking be effected in the presence of steam, hydrogen, cracking gases, etc. With a high boiling material, very large quantities of such gases are required and the process becomes wasteful and uneconomical.

Moreover, various impurities present in the oil, 30 such as nitrogen and sulphur compounds, not

only tend to form deposits of carbon on the cracking apparatus, but also contaminate the nal product and detract from its value.

Finally, when the refining process consists in 35 a treatment with selectivsolvents applied after a vapour phase cracking, there occurs a considerable loss of lower olefines, which are a product valuable for the manufacture of, for example, lubricating oils. This loss is due to the fact that 40 the oleines are readily soluble in many of the solvents used, such as, for example, liquid sul phur dioxide.

I have now discovered that all these disadvantages may be easily remedied, and that higher 45 yields of oleflnes capable of producing by polymerization lubricating oils of superior quality may be obtained by using the method of my invention. Briey, this method consists in cracking the 50 initial stock in the liquid phase, subjecting the products of crackingl to a refining treatment. and then recracking them in the vapour phase. If desired, a second rening treatment may then be applied. 55 According to my process, any mineral oil may This invention pertains to the manufacture of beused as initial material, but preferably such materials which consist of relatively non-volatile hydrocarbons or contain substantial amounts thereof, such as parailn wax, wax tailings, par- `aiilnous shale oil, paraiiinous distillates, ozokerite, 5

ceresine, residues of brown coal-tar treatment, etc., are used. The initial material is subjected to cracking in the liquid phase, according to any conventional method, and any conventional catalysts may be used if desired. The cracking conditions should be preferably be adjusted so as to give a main fraction boiling approximately between 300 and 850 F. which according to the prior art is most yreadily achieved at temperatures between about 800 and 900 F. 15 y At these temperatures formation of a certain amount of aromatics invariably takes place, some of which aromatics boil within the boiling range of the main fraction. This fraction is subjected to a refining treatment with the object of removing aromatics, nitrogen and sulphur compounds which contaminate the oil. This treatment may be eiected as an extraction process using such selective solvents as liquid sulphur dioxide, nitrobenzol, furfural, phenol, BB' dichloroethyl ether, alcohol ether, acetone-benzol, etc. The simultaneous use of more than one of these solvents, or their mixtures, in a countercurrent process will also give excellent results.

Instead of an .extraction process, the products of the liquid phase cracking may be subjected to rening with adsorption agents such as clay, bauxite, .fullers earth, diatomaceous earth, silica gel, etc. It is particularly advantageous to apply such treatment to the oil-at a relatively high temperature, since in that case the acidic impurities contained in the oil, such as naphthenic acid, sulphonic acid, etc., are completely removed by the adsorptive treatment'.

It is also possible to treat the selected frac- 40 tion with sulphuric acid of a suitable concentration, whereby undesirable oxygen, nitrogen and sulphur compounds, as well as substances containing phenols and amines, are removed as sludge. The product may then be neutralized with lye or other suitable alkali.

After the selected fraction has been refined by any of the above means, it is again cracked, this time in the vapour phase under conditions known to be conducive to the formation of olefines from non-aromatic hydrocarbons boiling between 300 and 850 F., and preferably at a higher 'temperature of about 1000-l100 F. Again, -the cracking may be eifected in the presence of desired catalyst. After condensation,

..- Fuel oil the-liquid products obtained may be re-treated for the removal of undesirable compounds formed during the vapour phase cracking, such especially as the dioleiines. This treatment may be physical, such as distillation, or chemical, for example, a refining treatment at an elevated temperature with aluminium or zinc chloride, which gives especially goodresults.

To more fully explain my invention, reference is had to the drawing which represents a flow diagram of my process.

Raw stock of the type hereinbefore described enters liquid phase cracking plant I from a source not shown. In this plant the stock is cracked under conditions to produce a large middle fraction, some light hydrocarbons and tar and/or coke. The middle fraction which preferably boils between about 300 and 850 F. is taken to refining plant 2, while the other incidental products of the cracking are discarded from this process. During the treatment in refining plant 2, aromatics and/or non-hydrocarbon impurities are removed from the middle fraction, which now is transferred to vapor phase cracking `plant 3. In the vapor phase cracking plant a distillate rich in oleiines is produced, which, after suitable fractionation, is treated in refining plant 4 for the removal of diolefines, aromatics and other impurities which tend to interfere with the manufacture of stable lubricating oils by polymerization, and then is polymerized in polymerization plant 5; or else the distillate may go directly from the vapor phase cracking pla-nt 3 to polymerizing plant 5 without passing through refining plant 4.

Example 275 gallons of parainous Pacura oil were cracked in the liquid phase at 850 F. under reiiux of all constituents boiling above 750 F. The following yield was obtained:

.Gallons Gasoline (F. B. P. 400 F.) 38 Oil (F. B. P. 750 F.) 223 The 223 gals. of oil obtained were subsequently treated with liquid SO2, yielding 190 gals. of raffinate. The raffinate was then cracked in the vapour phase at 1050 F. The following yield was obtained:

Gas kgs.. Unsaturated oil gals 116 Fuel oil gals-- 38 The unsaturated oil was then polymerized with AlClg, giving a. stock from which more than 83 gallons of excellent lubricating oil were manufactured. Moreover an oil which is very well suited for use in Diesel engines and a spindle oil were obtained during the process.

I claim as my invention:

1. In the process of producing olefines, which are capable of being converted to stable lubricating oils by polymerization with an active catalyst of the type of aluminum chloride, from ahydrocarbon oil containing not more than a relatively small amount of volatile components, an improvement which comprises the steps of cracking said oil in the liquid phase in the absence of excess hydrogen under a superatmospheric pressure at a cracking temperature for a time sufficient to convert a portion of said oil into aromatic hydrocarbons boiling within the range from 300 to 850 F., separating from the cracked oil a fraction boiling below about 850 F., containing said aromatic hydrocarbons, subjecting said fraction to a refining treatment capable of removing at least a substantial portion of said aromatic hydrocarbons, and cracking the refined fraction containing a substantially diminished amount of aromatic hydrocarbons in the vapor phase at a temperature `higher than the liquid phase cracking temperature for a time sumcient to increase substantially the content of oleflnes without a substantial. increase in the aromatic content of the fraction.

2. In the process of producing olenes which are capable of being converted to stable lubricating oils by polymerization with an active catalyst of the type of aluminum lchloride from a hydrocarbon oil containing sulfur compounds, and not more than a relatively small amount of volatile components, an improvement which comprises the steps of cracking said oil in the liquid phase in the absence of excess hydrogen under a superatmospheric pressure at a cracking temperature for a time suiiicient to convert a portion of said oil into aromatic hydrocarbons boiling within the range from 300 to 850 F., separating from the cracked oil a fraction boiling below 850 F., containing said aromatic hydrocarbons and sulfur compounds, subjecting said fraction to a refining treatment capable of removing at least a substantial portion of said aromatic hydrocarbons and sulfur compounds, and cracking the refined fraction containing a substantially diminished amount vof aromatic hydrocarbons and sulfur compounds in the vapor phase at a temperature higher than the liquid phase cracking temperature for a time suicient to increase substantially the content of oleiines without a substantial increase in the aromatic content of the fraction.

3. The process of claim 1, wherein the liquid phase cracking is effected in the presence of a cracking catalyst.

4. The process of claim 1, wherein the fraction boiling below 850 F. is refined by extracting said products with a preferential solvent for aromatic hydrocarbons.

5. The process of claim l, wherein the fraction boiling below 850 F. is extracted with a solvent chosen from the following group: liquid sulphur dioxide, nitrobenzol, furfural, phenol, BB' dichlorethyl ether alcohol-ether mixture, acetonebenzol mixture and wherein the raflinate is the refined fraction.

6. The process of claim 1, wherein the fraction boiling below 850 F. is refined by treatment with an adsorption agent.

7. The process of claim 1, wherein the fraction boiling below 850 F. is refined by treatment with sulphuric acid.

8. The process of claim 1, wherein the vapour phase cracking is effected in the presence of a cracking catalyst.

9. The process of claim 1, wherein the products of vapour phase cracking are subjected to chemical reiining treatment to remove dolenes.

10. The process of claim 1, wherein the products of vapour phase cracking are subjected prior to polymerization to a refining treatment under polymerizing conditions using a catalyst chosen from the following group: aluminium-chloride and zinc-chloride.

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