US 2060871 A
Description (OCR text may contain errors)
Patented Nov. 17, 1936 UNITED STATES 7 2,060,871 MANUFACTURE or nrnaocnanons Vladimir Ipatiefl, Chicago, Ill., as signor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application June 22, 1933,
Serial No. 677,079
8 Claims. (Cl. 196-10) This invention relates more particularly to the treatment of olefinic hydrocarbons which are normally gaseous at ordinary temperatures and pressures.
Olefinic hydrocarbons with which the present invention is concerned occur along with corresponding paraflinic or saturated hydrocarbons in commercial hydrocarbon mixtures such as those encountered in the cracking of petroleum, in gas making processes and as by-products in various chemical industries. In general they are more chemically active than other classes of hydrocarbons, particularly it they contain more than one double bond or triple bonds between carbon atoms. Even when under mild catalytic influence they exhibit this reactivity in their pronounced tendency to polymerize and form substances of higher molecular weight. In some instances this instability may be -a disadvantage, particularly in the case of cracked hydrocarbon oil distillates which are of suitable boiling range to permit their use in internal combustion engines, since the polymers which develop on storage are or a gummy character and impart color to the oil.
The present process provides for more eil'ectively utilizing the oleflnic constituents of commercial hydrocarbon mixtures particularly those occurring in the gases from oil cracking processes to produce valuable derivatives therefrom and it may also be applied to individual oleflns produced by special chemical methods or by fractionation of mixtures.
In one specific embodiment the invention comprises the treatment of normally gaseous oleflnic hydrocarbons with phosphoric acid' containing metal salts as promoter catalysts to controllably produce polymers therefrom which are utilizable as constituents of motor fuel. Salts of zinc are preferred.
To assist in developing the exact character of the invention the following table is introduced, which gives the formulas and boiling points of some of the lower molecular weight oleflns:
Compounds Formula ai ga 852813 2551 2: op one Ethy ethylene CH;CH;OH=CH: -5 dimethylethylene CH;.CH=CH.CH= Unsym. dimethylethylene (0H,)1C=CH| 6 n-Propyl ethylene nmunylene CH;CH:CH;CH=CH1- +39 Isopropylethylene a-isoamylene (CH;)1CH.CH=CH2--- +21 Bo Compounds roman Ef Sym. methyl ethyl ethylene fi-amylene CHa.OH|.CH-=CH.CH| +86 Unsynninethyl ethylethylene CH CH 'y-flllly ene S- r 31 V o=orn.... Tral gethyl lethylene CH) c oamy one =CH.CH Tetramethyl ethylene CHfliC =C(CH:):
The boiling points given in the table indicate that the tour carbon atom members are gaseous at ordinary temperatures and that the flve carbon atom members may readily exist in minor' proportions in commercial gas mixtures, such as the cracked hydrocarbon mixtures with which the present invention in specially concerned.
The present process is particularly directed to the production of dimers and trimers i'rom monooleflns, particularly such oleiins whose dimers and trimers boil between the approximate range of commercial motor fuel, say, for example, from 100 to 400 F. It has been found that the dimers and some of the trimers of propylene, the butylcues and amylenes boil within this range and furthermore, that these compounds have unusually high anti-knock characteristics. The following table shows the approximate boiling points of the dimers of propylene, butylenes, amylenes and hexylenes which all occur in appreciable quantities in the gases from oil cracking processes:
Boiling points of olefin dimers "F. Hexylene 155 Octylene 255 Decylene 323 Dodecylene 417 Ethylene is as a rule the most resistant to the action of the preferred catalyst mixtures but by a suitable choice of promoter catalysts and conditions of operation it may be caused to polymerdesired direction without the formation of the higher molecular weight substances mentioned. Concentrated phosphoric acid of commercial grade may be employed and in some instances. particularly where theconcentration of oleflns is .low in the gas mixture, the temperature may be raised considerably, sometimes as high as 200 C. so that the desired reactions are accelerated and yet there is no undue formation of undesirably heavy polymers. Any desired pressure may be employed, the influence of this factor being principally to increase the capacity of; apparatus though pressure may also accelerate the reactions of polymerization. When low or moderate temperatures are employed liquefaction of some olefins will occur if the pressure employed is above the critical pressure, this further assisting in increasing capacity of equipment and intimacy of contact.
The compounds which may be employed as promoter catalysts in phosphoric acid comprise various salts of metals such as, for example, phosphates, chlorides or sulphates of aluminum, zinc, cadmium, mercury, iron, nickel, cobalt, copper, magnesium, etc. The use of any particular metal salt will be limited by its solubility in phosphoric acid of any particular strength. Concentrations of salts as high as 20% of the phosphoric acid may be used when the salts are suillciently soluble though as a rule amounts of from 2 to 10% are sufllcient for accomplishing the desired acceleration of the catalytic eifect of the acid. The additional catalytic effect observed in these cases may be due either to the basic or the acid radicals, or both. It is obvious that metal oxides or metals themselves may be dissolved in phosphoric acid to an extent depending upon the solubility of the phosphates formed.
The salts which may be thus employed to accelerate and modify the catalyzing eflect of phosphoric acid upon oleilns comprise a number of classes which differ from each other in many of their physical and chemical characteristics. 'Itis to be understood that the different salts which may be used are not exact equivalents in their action but that each exerts its own peculiar influence upon the catalyzing power of the base ma-,
'terial, to-wit: the phosphoric acid. The field of catalysis is to a large extent still in an experimental state even though many substances have been found by empirical methods to have special value in certain reactions. erally the best catalyst for hydrogenatlng fatty oils and the oxides of vanadium are generally the fist for catalyzing the production of sulphur trl oxide from sulphur dioxide-oxygen mixtures. In the present instance diiferent salts may be chosen which will produce decidedly better results than others when working with olefln gas mixtures of varying composition. Particular instances. of metal salts which have positive accelerating action and others which have a neutral or a negative effect will be developed in subsequent examples.
Ordinary ortho-phosphoric acid, HsPO4, is generally the preferred acid of phosphorus for use in connection with reactions of the present character. However, it is within the scope of the invention to employ other acids of phosphorus insofar as they possess suilicient catalyzing activity either alone or after the addition of promoter catalysts.
Thus, nickel is gen- In producing low boiling polymers from gaseous oleflns or mixtures thereof such as are encountered in commercial hydrocarbon gases, the
simplest mode of operation consists in bubbling the gas mixture through a stationary body of acid catalyst mixture of regulated strength and composition containing a selected promoter catalyst, using cooling coils or precooled gases to keep down the temperature rise if this is shown to be necessary. Atmospheric temperatures and pressures are frequently sumcient to produce good treating effects but,aspreviously stated,temperatures as high as 200 C. may be employed and superatmospherlc pressures of the order of 10 to 20 atmospheres may be used with safety if the time of contact and the amount of catalyst are properly chosen. When operating with more or less pure olefins or gas mixtures of high olefin content, a control is ofiered in blending the mixture with some inert gas such as hydrogen or nitrogen to assist in controlling the rate of reaction. Batch treatments may be conducted in autoclaves, or, if desired, continuous counterflow treatments may be employed as these are known in the art, and in such cases the gas mixture may be passed upwardly counter-current to descending streams of acid catalyst mixture in towers containing filling or packing material or regularly spaced trays to assist in subdividing the stream of ,catalyst. The polymerized oleflns will appear as a layer upon the surface of the acid in the case of the first mentioned batch method of treatment, from which they may be removed continuously or intermittently. When employing the counter-current tower operation, liquid will be recovered from above the acid after settling in intermediate accumulators.
A marked advantage in the use of phosphoric acid catalysts containing metal salt promoters resides in the fact that very little solution of original oleflns or their polymers occurs therein. The consumption of acid is small and a given amount may be used repeatedly without the necessity for purification steps which must ordinarily be employed in removing sludge products from such powerful polymerizing and condensing agents as sulphuric acid, aluminum chloride, etcetera. Neither phosphoric nor phosphorous acid has any pronounced oxidizing action under suitable conditions of treatment so that condensation reactions due to removal of hydrogen or abstraction of water are substantially absent.
The present type of catalyst comprising phosphoric acid as a base and containing minor amounts of metal salts as promoters possess the advantage of maintaining their activity over long periods of time and producing high yields of relatively low'boiling liquid hydrocarbon polymers per unit weight of catalyst material. Use of the invention indicates that there is some ester formation with the phosphoric acid, which reaction, however,
does not lower but frequently enhances the catalytic power of the mixture. Extensive formation of esters after a certain concentration is reached may result in the formation of small yields of 7 alcohols such as, for example, isopropyl alcohol, but this production is seldom oi! serious consequence. Such alcohols as may be formed, it not desired as a constituent oi the liquid hydrocarbon polymers, are removable by solution in water.
In carrying out the invention the apparatus used and the conditions of operation chosen in respect to temperature, pressure, proportioning of reacting constituents, choice of acid and promoter catalyst, etcetera, will be varied to suit individual cases. when the process is used to polymerize individual oleflns or mixtures of known composition, it is possible to so regulate the treatments that compounds or mixtures of compounds of very definite composition may be produced. For example, any one oithe olefins given in the first table (with the possible exception oiethylene) may be polymerized to form a corresponding polymer with a mixture 2 TABLE I Polymerization of propylene with 89% phosphoric acid at atmospheric pressure Tom rature Per cent Catalyst 0. liquid yield I 89% mro. 155-160 a. s 89% HsPOrl-5% Z11. 150-160 7. 7 89% HSPO+5% 150-155 15. 2 89% H:P MgCiz 155-160 16. 0
This data shows that the presence of zinc phosphate (resulting from the solution of zinc in phosphoric acid) doubled the liquid yield under a given set of experimental conditions, while the same percentage increased the yield tour times over that obtainable with the acid alone.
The following data shown in Table II shows the results of two comparative experiments run at atmospheric pressure using 100% phosphoric acid with and without the addition of 5% anhydrous copper sulfate:
Table II Tom rature Percent liquid Catalyst yield 100% HsPO4 100% HsPO4-5% 01.1304
The effect of the promoter in this case was to double the yield of liquid products, even when employing a higher rate of gas flow in the apparatus. Owing to the use of the anhydrous salt there may have been some efiect due to the dehydration of the acid.
In Table 111 data is introduced to show that minimum production oi undesirable by-products from side reactions.
' slum borofluoride slowed up chloride in approximately the certain salts may have a neutral or negative eflect;
Table III Part 1 Max. Final Percent Catalyst Temp. C. pres. pres. liquid kg./cm. kg./cm. y old 89% HaPO4 150 39 25 41. 8 89% HsPO|+Cds(P04):-.- 150 40 25 43. 0 89% H3P0|+Cd(CiH!OI)L 150 41 31. 5 29. 0 89% HsPO|+CuCh 150 43 37 21. 4 89% HaPOrl-KBF; 150 35 28 22. 2
Part 2 100% H.Po.+ouci. 125 as as o. o 100% H:PO4+CHSO4 125 38 24 32. 8
The data shows that cadmium phosphate (produced by dissolving metallic cadmium in the acid) had a very slight positive catalytic action while cadmium acetate, cuprous chloride and potasthe catalytic activity of the acid, and therefore stance were not desirable. Such salts, however, in the case 0! more readily polymerizable olefins, may have value in preventing over-polymerization with concurrent production of high boiling polymers of a tarry character which are unsuitable as constituents of motor fuel.
The comparative data shown in Part 2 of the table between cupric chloride and cupric sulfate indicate some of the variations to be expected when using diiierent salts. The copper sulfate is again of outstanding value in accelerating the action under the conditions of the experiment which it will be noted difier from the conditions in Part 1 in the use oi a lower temperature;
- The character of the invention is sufliciently described in the preceding specification and its value is brought out by the experimental data introduced, but neither is to be construed as im- .posing undue limitations thereon except as hereinbefore specified.
I claim as my invention:
1. A process for converting normally gaseous olefins into hydrocarbon liquids which comprises polymerizing the olefins in the presence of a catalytic acid of phosphorus and a metallic salt which promotes the catalytic activity of the acid and selectedfrom the group consisting of the phosphates, chlorides, and sulphates oi aluminum, zinc, cadmium, mercury, iron, nickel, cobalt, copper, and magnesium.
2. A process for converting normally gaseous olefins into hydrocarbon liquids which comprises polymerizing the olefins in the presence of a phosphoric acid and a metallic salt which promotes the catalytic activity of the acid and selected from the group consisting of the phosphates, chlorides, and sulphates of aluminum, zinc, cadmium, mercury,'lron, per, and magnesium.
3. A process for converting normally gaseous oleflns into hydrocarbon liquids which comprises polymerizing the oleflns in the presence of pyrophosphoric acid and a metallic salt which promotes the catalytic activity or the acid and selected from the group consisting of the phosphates, chlorides, and sulphates of aluminum,
nickel, cobalt, copin the present ina zinc, cadmium, mercury, iron, nickel, cobalt, copper, llld 11118116811118.
converting, normally saseous liquids which com- 4. A process for olenns into pxisespolynierizingtheoiennsinthepresence' 01' a phosphoric acid solution having dissolved therein a metallic salt which promotes the catalytic activity of the acid and selected from the group consisting of the phosphates, chlorides, and sulphates of aluminum, zinc, cadmium, mercury. iron. nickel, cobalt, copper, and magnesium. 5. A process for converting normally-gaseous olenns into hydrocarbon liquids which comprises polymerizing the olenns in the presence oi. a phosphoric acid and a'zinc salt.
oleflns into hydrocarbo liquids which comprises the oleflns in the presence 01' pyrophosphoric acid and a zinc salt.
7. A process for converting normally olenns into hydrocarbon liquids which comprises polymerizing the olcnns in the presence of a phosphoric acid solution having a zinc salt dissolved therein.
8. A process for converting normally gaseous oleflns into hydrocarbon liquids which comprises polymerizing the oleflns in the presence or a catalytic acid of phosphorus and a zinc salt.
VLADDIIR IPA'I'IEFF. 1