US2121998A - Kerosene - Google Patents

Description

Patented June 28, 1938 KEROSENE' Joshua A. Tilton, Baton Rouge, L a., assignor to Standard-I. G. Company No Drawing. Application August 1, 1936, Serial No. 93,765

6 Claims.

This invention relatesto improved burning oils and methods of producing same, and it relates more particularly to. improving kerosene stocks which are normallyof too low a quality to be used as burning oils.-

It is well known in the art, that kerosenes con-' taining appreciable quantities of either aromatic or unsaturated hydrocarbons or both give unsatisfactory performance when used as illumi- 10 nants as, is evidenced by smoking, fogging of chimney, streaking flames, soot formation, wick incrustations, clogging of wick, etc. The illuminating powers and burning characteristics of kerosenes are'usually judged by the paraifinicl6 ity which is generallymeasured in terms of the density of the oil in relation to its viscosity. It is known that with wick fed lamps of normal design the viscosity of the kerosene in the reservoir should not exceed 450 Saybolt-thermo viscosity (New and Revised Tag Manual for Inspectorsof Petroleum (1930) Test No. 6) or approximately -2 centipoises; but oils of Saybolt-thermo viscosities lower than 450 and around 325 to 375 are quite satisfactory. The lower the specific gravity (higher A. P. I. gravity) for kerosenes of similar viscosities the higher the paraflinicity and the better the quality. Generally the burning oils placed on the market are required to meet certain specifications as to gravity. For example, one large producer makes three grades of kerosenes of similar viscosities, having gravities A. P. "I.

of 41.0-44.0-and 46.0.minimum, respectively.

Inasmuch as the preparation or refinement necessary for the higher quality burning oils involv'es substantial expense, the difference in quality as expressed by A. P. I. gravity is generally reflected in a difference in market price as shown in the following table:

40 Table I A. P. I. gravity 55 leum' Congress'1933, Vol. II, 732), Kewley and Jackson (J. I. P. T., 1927, 13,364), Minchen (J. I. P. T., 1931, 1'7, 103), and Gilbert (Pro. World Petroleum Congress 1933, Vol. II, 735) is a satisfactory and simple test for measuring the relative quality of kerosenes. In this test the oil is burned in a Weber lamp and the flame height at the point at which a smoky flame is produced- The highest is determined as the smoke point.

quality kerosenes produce the highest flame height before smoke appears. Examples of flame heights for diiierent grades of kerosenes are as follows:

(1) Highest quality (2) Cheap quality (3) Inferior grade 29 to above 32 following formula:

S. P.=32 l00(d-0; 785) where S. P.=Smoke point E=Percentage extractable by 3 volumes of 98% sulfuric acid V d=Specific gravity after sulphonation Although kerosenes of low smoke point may where the parafiinicity or smoke point is not extremely low, or where the raw material has certain properties.

0n the other hand, the present invention ofiers a very simpleand economical method of improving the smoke poin and other properties of tions.

any kerosene stock up to the desired specifica- The invention comprises broadly adding to a kerosene, either a small or a large amount, depending upon the improvement desired, of a hydrogenated polymerized olefine product having the desired physical properties.

For example, hydrogenated tri-isobutylene has been found very satisfactory. This material may be made by polymerizing isobutylene with sulfuric acid to make a mixed polymerized product containing dimer, trimer and perhaps even higher polymers, separating the trimer by distillation These processes will be and lrvdrogenating it. described more in detail later on.

Instead of .using isobutylene, other iso-ol quantities in most refineries may be used advantageously. A typical composition of C4 cut is as follows;

Percent Isobutyleno 10.4 Total unsaturates (Isobutylene included) 32.4 Iso+normal butane 67.5 Pentane 0.1

If it isdesired to use pure isobutylene, this may be prepared by known methods such as the thermolyt'ic dehydration of tertiary butyl alcohol.

In carrying out the polymerization process, various methods may be used, but preferably the isobutylene or other olefines to be polymerized are contacted with sulfuric acid of various concentrations depending upon the temperature and time of contact used. One satisfactory method of operating is to concurrently disperse C4 cut containing 10 to 15% isobutylene through 60% sulfuric acid by means of porous alundum thimbles in a suitable absorption vessel, usinga superatmospheric pressure of 40 pounds per square inch, and a temperature of F., and using a feed rate of 20 parts per volume'of C4 cut per hour and three parts of acid per hour. The acid extract is then separated and polymerized at a suitable temperature which may be from F. to 300 F. or more, depending upon the concentration of acid used and upon the time of heating. When using an extract prepared as described above in detaiLthe heating is preferably carried out at a temperature of about 200 to 225 F. with a heating time of 5 to 15 minutes or so. As illustrative of the variations which may be made in the process, the extraction may be cara,121,oas

Table II 'Percent Diisobutyl n 35 Co-dimers- 10 Trimer 43 Higher polymers 5 Distillation loss (gas, etc.) 7

*Dimers produced by co-polymerization of isobutylene and alphaor beta butylene or some other constituent. of C, out, possibly butadiene or acetylenie compounds (some fractions with. boiling points between those of. (ii-isobutylene and tri-isobutylene have higher bromine numbers (e. g. 153, 181 and 167 as compared with 144 for (liisobutylene) If the lighter 40% is distilled over from such a crude polymer, the residual 60% bottoms makes a satisfactory stock for feeding to the hydrogenationunit, according to the purview of the present invention. If desired, still narrower cuts of the polymers may be. used. It is quite likely that in ried out by contacting the C4 cut with 65% sul- 1 furic acid at 32 F. and the polymerization by heating the extract at F.

Although sulfuric acid is the preferred polymerizing agent, other suitable catalytic liquids may be used, such as phosphoric acid or solutions of various salts such as zinc chloride or sulfates or phosphates of various metals, e. g., zinc, cadmium, etc., or polymerization catalysts of the active halide type such as aluminum chloride, boron fluoride, or the like may be used. In such cases the temperature may be even lower than indicated for the previous methods. For example, it maybe as low as, or even lower than room temperature. 1

Although low temperature polymerization is preferred, it is possible to carry out the polymerization at elevated temperatures, such as 600 to 900 F. in the presence of solid catalysts, such as charcoal, clay, bauxite, etc. or at still higher temperatures, such as from 900 to 1000 F. at elevated pressures of 200 to 3,000 pounds or even 15,000 pounds per square inch or more.

After the polymerization has been completed, a product having the desired boiling range is separated by distillation or fractionation. sample of the crude total polymerimade by polymerizing isobutylene with sulfuric acid) when subjected to fractionation gave the following.

results:-

addition to obtaining a substantial proportion of triisobutylene in the above-described polymerization process, co-polymers are probably formed by reaction of the isobutylene or other iso-oleflncs with some of the straight chain oleflnes present.

The polymers, however they may have been formed, are then subjected to a saturation or hydrogenation in any desired manner, for example, by treatment with gaseous hydrogen under pressure, e. g. 200-5,000 pounds per square inch, preferably above 1,000, the partial pressure of hydrogen being usually about 70% of this total pressure. Relatively low temperature may be used for this purpose, for example, below 100 to 200 F., although it is preferable to use higher temperatures, e. g. 200 to 500 F.; and it is also desirable to use hydrogenation catalysts, e. g. nickel, cobalt, copper, platinum, palladium, manganese or copper chromite. Even higher temperatures may be used if desired, for example, above 600 or 700 F., especially where it is desired to obtain a limited destructive or carbon-chainsplitting action. For example, if the polymerization feed to the hydrogenation zone contains any substantial amount of tetramers, or higher boiling polymers, a considerable portion of these higher boiling fractions may be cracked during the hydrogenation to yield saturated polymers of lower molecular weight, particularly the trimers, together with some dimers which may or may not be removed by distillation. Catalysts for this latter type of hydrogenation are preferably immune to sulfur poisoning and may comprise the oxides, sulfides and nitrites of metals of the 6th group of the periodic table, e. g. molybdenum, chromium, tungsten or mixtures thereofwith various other substances such as refractory oxides of the 2nd and 4th group, e. g. magnesium, zinc, titanium, etc., rare earths and the like.

The degree of hydrogenation may be varied accordingly to yield any quality desired. Generally the smoke point of the hydrogenated polymer increases directly with hydrogenation, and therefore, varies inversely with'the bromine number, which of course, is gradually reduced during the hydrogenation. The progress of hydrogenation may be illustrated by the following table:--

It has been found preferable, to carry out the hydrogenation process witha gas rate of about 4,000 to 50,000,. preferably 6,000 to 25,000-cu. ft.

' per barrel, and a low polymer feedrate (e. g.'

less than 3.0, and preferably even less than 1.0 or even as low as 0.3 volumes of feed per volume of catalyst per hour) when using a catalyst consisting of tungsten sulfide or molybdenum sulfide,

although somewhat higher temperatures are used,

'e. g. up to 400'or' 600 F. and super-atmospheric pressure. Such conditions give a yield of some 65 to 80% or hydrogenated product, boiling between the approximate limits of 300 and 425 F.

-and'having an A. P. Irgravity between the approximate limits of 55.5-to 56.0; and a viscosity (Saybolt thermo) of 325-360.

The hydrogenated polymer, as it issues from the hydrogenation unit is distilled to remove any cracked products, and then may be used directly as such, or may be further finished by washing with a caustic soda solution to remove hydrogen When hydrogenated polymerized products other than relatively pure hydrogenated tri-iso- As illustrative of the invention, theinspection v of one sample of tri-isobutylene and of three samples of hydrogenated tri-isobutylene fractions produced in accordance with the above-described preferred methods, 'are given in the following table:

'saturatedhydrocai'bons having 12 carbon atoms blend=26 and therefore belongs to the class of.dodecanes, its cloud and pour points are. much lower than those of the normal dodecane shown in the above list. Itmay also be noted that its boiling point,

333 to 356 F. (actually most or it boils between 343 and 348 F.) is considerably below 421 F., the

boiling point of the normal dodecane.

The above described hydrogenated oleflne polymers can be used alone as burning oils if desired, but it is mosteconomical to use them as blending agents for raising the smoke point of kerosene and other burning oil stocks which are 100 low in quality to meet the desired specificaons.

In such' blending, the increase in parafllnicity as judged by the smoke point of the blend may be estimated from the following simple formula:

x=% ilnprover to be added=lX S. P. of blend desir'edS. P. of burning oil stocks 45-S. P. of burning oil stock 7 Where S. P. Smoke point. For example, if the smoke point of the kerosen stock=23, and the smoke point desired in the zs-zs 45-23 In other words, 14% of hydrogenated tri-isobutylone. will raise the smoke point of a 23 S. P. kerosene up to 26. As another example, an 18 smoke point water-white kerosene stock can be improved to a 22 smoke point (Standard kerosene specification) by the addition of 15% hydrogenated trimer, both the kerosene stock and the hydrogenated trimer having a refined oil viscosity 01345.

As a further illustration of the invention, a

blend was made using the hydrogenated tri-isobutylene sample B, the properties of which were given in table IV, in an East Texas waterwhite kerosene stock with the following results:

TableIV Hydrogenated trl-isobntylene Property a ga Sample A Sample B Sample 0 A. P. I. gravity 53.4 52.8 55.8 55.8 Viscosity (Saybolt thermo) 345 345 330 330 Smoke point c. Above 32 Above 32 Above 32 Flash point (Abel 100 I 105 2 115 Bromine number"-.- 43 2 1 Initial boiling point 300 310 339 50% oil (F.) 350 350 Final boiling point (F.) 420 400 364 Cloud point (F.) Below Below 70 Pour point (F.) Below 70 Below 70 The low cloud point and pour point of the Table V hydrogenated polymers of the present invention 7 constitute a distinct advantage over saturated straight Blend 17% hydrocarbons of the normal paraffin type, such as East Texas $g$ the following: Water-VIM E315 No. carbon 422 46.0

cm 375 360 124 121 a; o 27 It is apparent that although hydrogenated triisobutylene consists essentially of one or.morer marked improvement in properties of the kerosene blended with hydrogenated tri-isobutylenel 6. Similar to high grade Pennsylvania kerosene. Excellent.

Similar to Mid-Comb nent kerosene.

Fair do (7) Flame color- (8) Flame shape.. (9) Chimney From the above table it is clear that the addition of 17% of hydrogenated tri-isobutylene to the kerosene base stock made a marked improvement in its properties for use as a burning oil, raising the smoke point from 23\to 2'7, and having substantially improved the flame and chimney characteristics.

It is not intended that the invention be limited to any of the specific examples given, nor any theories suggested as to the operation of the invention, but only by the appended claims, in which it is intended to claim all novelty inherent in the invention as broadly as the prior art permits.

I claim: 7

1. As a new composition of matter, a kerosene containing approximately 5 to of a hydrogenated polymerized oleflne having a molecular weight 0! approximately to 225.

2. As a new composition of matter, a kerosene containing approximately 5- to 50% of a hydro genated' polymerized isobutylene having a molecular weight or approximately 125 to 225.

3. As a new composition of matter, a kerosene containing approximately 5 to 50% of a. hydrogenated polymerized isobutylene having approximately the following properties.

Molecular weight 125-225 Boiling point range 275-450 ,F. Viscosity (Saybolt thermo) 300-400 seconds Brominenumber Less than 50 Pour point Below 20 F.

4. As a new composition of matter, a kerosene containing approximately 5 to 50% of hydrogenated tri-isobutylene.

5. The method of improving kerosene for illuminating purposes which. comprises adding thereto a hydrogenated polymerized oleflne having a. molecular weight of approximately 125 to 225, the product of such addition containing 5 to 50% of said hydrogenated oleflne.

6. The method of improving kerosene for illuminating purposes which comprises adding thereto a hydrogenatedpolymerized isobutylene having a molecular weight of approximately 125 to 225, the product of such addition containing 5 to 50% of said hydrogenated isobutylene.

JOSHUA A. TIL'ION.