US2010949A - Manufacture of hydrocarbons - Google Patents

Description

'ug. 13, 1935. G EGLOFF v 2,010,949

MANUFAGTURE or` HYDRocARBoNs Filed March 24, 1935 Coole?q fece Ver Patented Aug. 13, 1935 PATENT lOFFICE MANUFACTURE OF HYDROCARBONS Gustav Egloff, Chicago, Ill., assigner to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware Application March 24, 1933, Serial No. 662,472

2 Claims.

This invention relates more particularly to the manufacture, by synthetic reactions, of hydrocarbons utilizable as constituents of motor fuel.

In a more specific sense the invention has reference to a process which may be employed to supplement the cracking process and increase the yield of high antiknock material obtainable. The particular steps by which this object is accomplished and the novel and useful effects produced will be shown in the following specification.

Gasoline boiling range hydrocarbons produced by decomposition reactions accompanying the pyrolysis of relatively heavy fractions of petroleum contain relatively higher percentages of unsaturated hydrocarbons of both an open chain and a closed chain character than similar boiling range straight run gasolines due to the dehydrogenating character of the decomposition reactions involved in cracking. The olefins and cyclic compounds thus produced are characterized by a greatly reduced tendency to detonate when used as fuel in internalcombustion engines so that cracked motor fuels are uniformly superior to straight run for present day automobile engines which for the most part employ high compression ratios.

When attempts are made to increase the antiknock value of cracked gasolines beyond a certain point, losses in gas and coke reach serious proportions and a balance must be struck between yield and quality of product. The present process may be employed to produce greatly increased yields of high antiknock gasoline hydrocarbons while utilizing the olenic constituents of the xed gases, which for the most part are used only as fuel in present commercial practice.

In one specic embodiment the invention comprises treatment of aromatic or similarly reactive hydrocarbons with olens in the presence of sulphuric acid to produce alkylated derivatives, separating said derivatives from sludge reaction products and fixed gases, fractionating said derivatives to produce a high antiknock overhead gasoline which is cooled, condensed and collected and a reflux comprising hydrocarbons boiling higher than gasoline, and recycling said reflux to further contact with aromatics and sulphuric acid to produce further yields of gasoline boiling range fractions.

The reactions between olens and aromatic hydrocarbons in the presence of sulphuric acid catalyst which lead to the production of alkylated derivatives of aromatics are quite general and are typified by the following equation showing the condensation of propylene and benzol to form iso-propyl benzol:`

CxBq -I- CIHI 1:2 CIHLCIH;

Propylene A Benzol Iso-propyl benzol The mechanism of this and similar reactions involving other aromatics and other olens is apparently explained by assuming rst the formation of alkyl sulfates and aromatic sulphonic acids and second the interaction of these primary acid derivatives to form the alkyl ring compound while the acid is regenerated. Some side reactions occur, of course, resulting on the one hand in loss of sulphuric acid due to oxidation reactions and the formation of undecomposable sulfo derivatives but in general the reactions may be forced from left to right as shown in the equation by suitable choice of conditions, particularly in respect to limiting the strength of the acid employed and the maintenance of a temperature not far removed from ordinary atmospheric.

In all such alkylating reactions there is an attendant formation of more highly alkylated derivatives than the one shown on the right `hand side of the equation, that is, di, tri, tetra and possibly even more highly alkylated derivatives. Many of the more highly alkylated aromatics have boiling points too high to permit their use. .m as components of motor fuel and it is the purpose of the present invention to Work over-these higher boiling fractions which are incidentally produced and effectively reform them into hydrocarbons of desired boiling range, thereby increasing the yield of gasoline. Even when the amount of hydrocarbons boiling above the end point desired in gasoline is not excessive there may be too great a production of compounds boiling within the upper range of gasoline since many of the compounds formed in the reactions between propylene, butylenes and amylenes boil within the range of approximately 200 to 240 C. Thus not only may the compounds boiling above the gasoline end point be de-alkylated but also those boiling within the upper boiling range which are produced in too great quantity for a balanced gasoline.

To indicate in a general way the sequence of operations involved in the present invention the attached diagrammatic drawing has been prepared which shows by the use of conventional iigures in side elevation an arrangement of elements in which the process may be conducted although the invention does not limit it to the particular details of the present drawing since other modiiications of plant equipment may be employed.

Referring to the drawing, line I is an inlet gas line through which gas mixtures containing olens may be admitted through valve 2, it being assumed that the gases are under sufncient pressure to take care of the pressure needs of the treatment both in respect to static conditions and necessary ow differentials. Thus olenic gas mixtures resulting from the cracking of petroleum or other hydrocarbon oils either for gasoline or gas production may be admitted, the olenic content of such gases varying with the charging stock used and the conditions of cracking. Sulphuric acid is most effective in causing the union of oleflns higher than ethylene with aromatics and the most effective mixtures therefore are those containing high percentages of propylene, the butylenes and the amylenes which may run from 30 to 40% of many gas mixtures encountered as by-products in oil cracking operations.

Benzol or other aromatic homologs or mixtures thereof may be introduced to the system through line 3 containing control valve 4 and be delivered by pump 5 through a line 6 containing control valve 1 to mix with the gases in line I.

The necessary amount of sulphuric acid may be introduced through line 8 containing control valve 9 and be delivered by pump I0 through a line II containing a control valve I2. 'Ihe acid may be added also by utilizing thecustomary blow case although this is not shown in the present drawing. Olefinic gases, aromatic hydrocarbons (both fresh compounds from outside the process and recycled overalkylated materials from line 58) and sulphuric acid are thus brought together in line I and may be passed through perforated plates or other obstructions or mixing devices to insure thorough contact, the mixture passing through a cooling coil I3 for maintaining some optimum low temperature which will depend upon the character of the hydrocarbons undergoing re` action and the products desired. In general since the object of the invention is to handle the alkylation reactions so that improved yields of compounds suitable for use in gasoline are produced, the temperature is maintained at some fairly low point and may be carried as low as 30 to 40 F. if desired.

The proportions of olefin-containing gas, sulphuric acid, fresh aromatics and recycled highlyalkylated aromatics are preferably adjusted to produce the optimum possible yield of gasoline boiling range fractions. Owing to the number of factors involved and the highly complex nature of the reactions, particularly when mixtures of both olens and aromatics are used, it is not always possible' to calculate the best conditions of operation but theseA may be adjusted for any given set-up after a few experimental trials.

` The reaction products consisting of sludge acid, alkylated hydrocarbons, unchanged aromatics and residual gases then pass through a line I4containing control valvey I5 and enter a separator I6. In this separator layer I1 has been `marked olf to indicate a layer of settled sludge oleflnic content indicates. or used as fuel if the olens have been economically removed.

Since a certain amount of alkyl sulfates may be dissolved in the liquid hydrocarbon reaction products it is usually advantageous to destroy these by reaction with caustic soda both because they add sulphur to the products and because they have a tendency to decompose in the subsequent fractionating step and cause difficulties due to foaming. Thus caustic soda solution may be picked up by pump 3IJ through line 28 containing control valve 29 from a source of supply not shown and pumped through line 3| containing control valve 32 into line 25 containing the hydrocarbon effluent from the separator, the mixture of neutralized oil and sludge caustic then passing through valve 26 to separator 21. This separator may be provided with a gas release line 33 containing control valve 34 for releasing any gas which may be carried over, this gas being generally similar to those released through line 2I and disposed of in a similar manner. Line 35' containing control valve 36 indicates a draw line for the removal of the spent neutralizing caustic.

The alkylated hydrocarbons are then preferably subjected to fractionation and the heavier portions thereof partially de-alkylated in the second stage of the process. To this end line 35 containing control valve 36 leads to a pump 31 which discharges through line 38 containing control Valve 39 into and through a tubular heating element 40 disposed to receive heat from furnace 4I. During passage through the heating element the mixture is heated sufficiently to enable the substantially complete separation and removal of gasoline fractions, the heated and partly vaporized hydrocarbons then passing through line 42 containing control valve 43 into a fractionator 44, of suitable design and capacity for eiectively removing the gasoline as an overhead product.

The gasoline vapors evolved at this po-int as a nal product of the process are subjected to the ordinary processes of condensation and collection, passing through line 45 containing control valve 46, condenser 41, through run-down line 48 containing control valve 49 and entering receiver 50 which has a gas release line 5I containing control valve 52 and a liquid draw line 53 containing control valve 54 for the removal of the product to storage.

The hydrocarbon refluxes from fractionator 44 which comprise hydrocarbons heavier than gasoline are then preferably returned to the original treating zone for de-alkylation. As previously mentioned, a balance is struck in this zone in respect to fresh or unalkylated aromatic and the amount of acid and gas used so that the best yield of gasoline is obtained at this point. I have found that these reactions involving the shift of alkyl groups from the more highly alkylated to the less highly alkylated hydrocarbons occurs readily so that the process is in every sense operatable and efficient.

Thus the high boiling over-alkylated compounds are discharged from the fractionator through a line 55 containing control valve 56 to a recycling pump 51 which returns the refluxes back to the original treating zone through line 58 containing control valve 59.

The reactions occurring when "over-alkylated" hydrocarbons are returned to contact with fresh aromatics and sulphuric acid may be typified by thev equation given below. However, the reaction shown is of a relatively simple character in comparison to the sum total of those which may occur when reaction is brought about between fresh hydrocarbons and alkylated products of a highly mixed character such as may have been produced when alkylating aromatics with mixed olefins in the rst stage.

HzSO

CsH4(CaH1): CaHe 1:2

Di-isopropyl benzol Benzoi Mono-isopropyl benzol Cracking yields Percent by Product Yield weight of charge Gas, 1.20 sp. gr 700 cu. itA /bbLoi oil 20 Gasoline, 56 A. P. I. 65% by volume 56 gravity. Intermediate recycle stock, 5% by volume 5 28 A. P. I. gravity. Coke 60lbs./bbl. of oil 19 The gas produced may contain approximately 20 to 25% of olefins such as propylene and the butylenes with the percentage of propylene predominating.

The total fixed gases thus produced may be passed together with approximately 6 gals. of commercial benzol per bbl. of stock cracked and about 8% by weight of 66 B. sulphuric acid (based on the benzol) through mixing and cooling devices generally similar to those described in connection with the drawing. By continuously returning the over-alkylated products from the fractionator to the primary treating stage according to the invention, the overall yield of synthetic products per barrel of oil originally cracked may be approximately 7 gallons, this product having an antiknock value twice that of the original benzol which was added to combine with the olefins. By blending this synthetic liquid with the cracked gasoline as produced the volume yield of gasoline is therefore raised from to 81%, the antiknock value being at the same time raised from 64 to 81.

On a basis of the foregoing figures there is no question of the value of the process when operated in conjunction with cracking since both the yield and quality of the gasoline is increased and a large percentage of the gaseous products are conserved. However, the specific numerical data given are not to limit the scope of the invention thereto nor is the description of operations given in connection with the drawing to exercise a limiting action since many other types of plants may be utilized to eiect similar economies.

I claim as my invention:

1. In a process for the treatment of aromatic hydrocarbons of the benzene series with normally gaseous olefinic hydrocarbons in a reaction zone in the presence of a contact agent comprising sulphuric acid to produce alkylated derivatives suitable for motor fuel, the improvement which comprises distilling said derivatives to produce a product within the boiling range of motor fuel possessing high anti-knock properties and a reflux condensate higher in boiling range than motor fuel, cooling, condensing and collecting the overhead product of distillation, and returning the reflux condensate to the reaction zone.

2. In the alkylation of aromatic hydrocarbons of the benzene series by reaction thereof in a reaction zone with normally gaseous oleiin hydrocarbons and wherein there is formed a mixture of alkylated derivatives boiling within and above the gasoline range, the improvement which comprises separating said mixture into a fraction boiling within the gasoline range and a heavier fraction, returning said heavier fraction to the reaction zone and dealkylating the same therein conjointly with the alkylation of the aromatic hydrocarbon.

GUSTAV EGLOFF.

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