US2345114A - Estebificgmon of olefins - Google Patents

Description

March 28, 1944. H. M. GUlNoT ESTERIFICATION OF OLEFINES Filed Jan. 8, 1941 AII IIIVI Patented Mar. 28, 19

, 2,345,114 asrmmoerrou or' onm'ms nenn Martin Guinee, Niort. France; vested in the Alien Property Custodian Application January 8, 1941, Serial No. 373,691

- France January 23, 1940 l 1c Claims. (on. csc-4to) directly such mixtures, in gaseous phase or in liquid phase, in order to esterify olens contained therein without having preliminarily to separate diierent components thereof.

It has already ,been proposed to treat directly such mixtures, particularly propane-propylene fractions obtained by rectification of cracking products from crude petroleum oils, by means of hydrating and esterifying solutions.' such as con,- centrated sulphuric solution, in order to absorb olens comprised therein. 'Ihe solutions obtained are then diluted in order to bring about the hydrolysisof alkyl sulphuric acids transitorily formed. The liberated alcohols are nally isolated by suitable means, for example by distillation or extraction by means of solvents.

However, the processes heretofore propounded present many disadvantages, the principal ones residing in the impossibility of bringing about a complete exhaustion in olens of the mixture of hydrocarbons by the .hydrating solution, owing to an inadequate treatment, and in the necessity of putting in highly concentrated sulphuric solutions the recovery of which is costly and inv lves decreases in the yield of alcohols, the latter partially destroyed in the course of regeneration.

It is a primary object of this invention to improve the methods heretofore proposed for the esteriiication of olefins. More particularly the invention relates'to av process designed to overcome certain disadvantages of olefin esterlcation processes and to secure better yields of the desired products.

'Ihe process ofthis invention, substantially consists first in liquefying the mixture of hydrocarbons and thenin exhausting the liquefied mixture of its 'oleniccomponents in an absolutely methodical manner within a battery of absorption elements. Such battery comprises a number of decantation elements interconnected by means of vertical pipings which allow -both theolenic components to be esteried and the esterlfying solutionto circulate in Aa countercurrent manner. Such circulation vis ensured by means of blowing in an inert gas preliminarily compressed. At-the ends of the battery there? oleiin and employable for any suitable purpose, and, on the other part, an esteriiying solution, saturated with oleiin alcohol is caused to appear therein by dilution and heating. .l

'I'he intimate contact between the mixture of hydrocarbons and the esteriiying solution is er1- sured in the veryy course of the. upow by the inert gas; this permits of doing away with various means for intense mechanical stirring which have been employed in the most of prior processes and theretofore considered as absolutely necessary. It was then impossible lto foresee that the short contact between the two'liquids in a piping system designed for their l:upow would have been sufficient for obtaining a rapid action of the esterifying liquid upon the diluted olenn.

The esterifying solution, hydrolysed at the outlet end of the battery for causing the alcohol to appear, is completely exhausted in this compoundwithin a still of any suitable type scav- 'enged from its bottom to its top by a current of hot inert gas. In this manner. the regeneration of the acid by-concentration in the hot way is carried out in the absence of any trace of alcohol, whereby inevitable destructions inherent to prior processes are avoided. Thus, the forma- Ing' are gathered, on one part, a liquid constituted v 'l by saturated hydrocarbons, practically free from tion of charred products is prevented and the initial effectiveness of esterifying inilnitely maintained.

In order to show how the invention may readily be carried into practical effect, the same will now be d scribed with reference to the accompanying awing which diagrammaticalLv.,illus-' trates one embodiment thereof and is not to be construedin a limiting sense. v

'Ihe single gure of c drawing schematically shows an olefin hydrati'ng plant present invention.

The absorption portion of this a series of decantation elements Di, Da Dn,

the number of which varies according to the nature of the mixtureto be treated, the rate of con-' centration of hydrated acid and operative conditions selected. These decanters are interconf nected by means of suitable pipings which will be described further below. Respectively adjoined to each decanter is a gas exhaust head G1. G2 Gn.` The whole battery operates under a pressure made sumcient to maintain the mixture of hydrocarbons in liquid state at the temperature under consideration.

A compressor C permits of bringing to the necessary pressure the inert gas serving to eect the -upilow. This gas is stored in a tank B from which it is supplied to emulsion vessels E1,

bath is almostl according to the plant comprises I E: En by means of a pipe M and pipes t1, t2 'tu provided with suitable valves.

A collecting conduit N permits of recovering the gas which has served for the upilow in the different elements, and of directing the same back to the compressor C through the medium of a separator S and pipe 2. The liquid mixture of hydrocarbons to be treated and contained in a tank P is introduced through a pipe Pn into` one eli'd of the battery. while the esterifyingsolution, for example an aqueous solution of sulphuric acid supplied from a tank A, is introduced into the other end thereof through a pipe ai.

'I'he esterifying solution is met in the emulsion vessel Ei by the mixture of hydrocarbons which, being already almost exhausted in olen and constituting the upper layer in the decanter Dz, arrives at this vessel Ei through the pipe P1. Under the action of the inert gas blown in through the pipe ti both liquids, under the form of an emulsion, are forced to iiow up into the head G1, wherefrom after separation of the gas the mixture flows. into the decanter D1 and is therein divided into two layers. The upper layer constituted by saturated hydrocarbons practically free from olefin ilows out of the system through a conduit h. The lower layer of D1, constituted by sulphuric acid already comprising a certain proportion of alkyl sulphuric acid. flows through the pipe a: into the emulsion vessel E: in which it is met by the upper layer from decanter Dn arriving thereat through the pipe P2. FIom the vessel E: both liquids are caused by the inert gas to flow up into the head G2 to be thereafter separated in the decanter Da, and so on from element to element.

In the emulsion vessel En the esterifying solution, already charged almost at maximum with alkyl sulphuric acid, isencountered by a. fresh mixture of hydrocarbons outowing from the tank P. After ilowing up into Gn and decanting in Dn the esterifylng solution is finally drawn out of the battery through the pipe e.

The chemical phenomena produced in the battery are pretty complex owing to the fact that two reactions take place therein simultaneously but at different velocities, viz.:

(a) At first, at the contact with olen a certain proportion of sulphuric acid of the esterifying solution gets ixed under the form of alkyl sulphuric acid. This results in a decrease of the free acidity of the bath and, consequently, in a reductionof the concentration o! the latter, the quantity of water having remained without variation.

(b) Simultaneously there 'is observed partial hydrolysis of alkyl sulphuric acid, reaction which not only liberates sulphurlc acid, but also produces consumption of water and, consequently, tends to increase the concentration of esterifying solution.

The velocities of these two parallel reactions Y. depend upon a certain number of factors and. in

particular, upon the temperature of the esterifying bath, its degree of concentration and content in alkyl sulphuric acid. One therefore ascertains, from one element to the other in the battery, a variation of the free acidity and of the concentration o/f the sulphuric acid dened by the ratio:

` free H2804 H2804 plus water In order to insure the constancy of this ratio.

At any rate, the pressure of the esterifying solution charged with olefin owirgout of the battery through the pipe e is lowered to the ordinary vpressure at O and then heated in a tank H and diluted by water inilowing from a tank I through a pipe 3, for the purpose of hydrolysing as completely as possible alkyl sulphurc acid comprised therein and liberating alcohol therefrom.

The Aesterifying solution charged with alcohol is then introduced through a pipe 4 into the upper portion of a still K of bafile plate type or checker pile type travelled from its bottom to its top by a hot inert gas current. The esterifying solution, which falls down from plate to plate towards the bottom of such still, is gradually deprived of alcohol and of a portion of Water contained therein, whereafter it ows out through a pipe 5 into a boiler L. The latter is provided with heating means and a stirring device R and a strong current of inert gas is blown thereinto by means of a fan V.

Under the action of said heating and stirring the gas is saturated with steam, whereby the sulphuric solution in the boiler is caused to concentrate. Such concentration may be adjusted to the desired extent by acting upon the intensity of heating and upon the delivery of inert gas in proportion to the esterifying solution supply. In

this way there is effected a perfect regeneration of the esterifying reagent which after cooling at T is reintroduced into the tank A by means of a.

pump U and pipe 6.

The inert gas lcharged with steam penetrates through a conduit 1 into the bottom portion of the still K where, as has been seen, it causes the elimination of alcohol contained in the supplied solution. The gases and steam released at the top of the still K are introduced through a conduit 8 into a condenser Q; at the outlet end 9 of the latter there is gathered hydrated alcohol which may be concentrated in an apparatus of known kind (not shown). The non-condensed gases freed from alcohol and water are then'taken up by the intake end of the fan V, reheated at I 0, if desired, and then blown again into the boiler L, thereby accomplishing a complete closed cycle.

The invention is not limited to the particular embodiment above illustrated and described, for modiiications may be effected therein without departing from the scope of the invention. For instance, instead of separating alcohol by mere condensation, a washing tower may be employed to extract therein the alcohol from the entraining gas by means of a suitable solvent, as is indicated in the French Patent No. 850,938.

Also, the upow pipes ri, r2 rn pf the battery may be jacketed with a view to enable the regeneration of the temperature of reaction.

It may also be advantageous to make the upflow pipes of unequal length in different elements throughout the battery with a view to compensating, by a suitable time of contact, for variations .in the reaction velocity from one point to another Eample It was proposed to manufacture isopropylic alcohol from a liquid mixture constituted by:

Per cent Propane 80 Propylene 20 The operation was eileeted in the plant precedingly described and Athe operative conditions were as follows:

Esterifying solution: Soil-l? at 7,5%:

Number of elements in the battery: l2;

Temperature in the battery: 40 cent.;

Pressure: kgs/sq. cent.

Nature andpressure of the inert gas for upiiow:

nitrogen at kga/sq. cent.:

Delivery rate of liquid propane-propylene mixture introduced into the battery through Pn: 500 kgs/hour:

Delivery rate of esterifying solution entering into the battery through a1: 850 kgs/hour;

Hydrolysis of the esterifying bath leaving the battery: dilution to and heating at 80 cent. for one hour;

Inert gas employed in the phase of concentration-dealcoholization: hydrogen:

Regeneration temperature of the acid in L:

cent.;

'I'he following results were obtained:

Amoimt and purity of p'ropane leaving the battery through h: 400 kgs. of propane containing less than 0.25% propylene;

Amount of isopropylic alcohol gathered from pipe 9: 139 kgs. of pure alcohol;

Yield: 97.5% i

Although the above stated example was relevant to the treatment of a propane-propylene "mixtures containing hydrocarbons having 3 and 4 carbon atoms. The various alcohols formed will be simultaneously eliminated by the gaseous current in the still K and there will be gathered at 9 a mixture of corresponding alcohols which will be separated by ordinarymeans.

Finally the invention is applicable to mixtures rich in oleilns and comprising but somev percents of saturated hydrocarbons.

As an inert gas t0 serve for the operation oi'I the battery, there may be employed hydrogen instead of nitrogen, vor elsehydrocarbons', saturated or unsaturated, under the only condition that they be gaseous and practically withoutv action upon the hydrating solution within the conditions of temperature and pressure selected,

for example methane, ethane, ethylene, etc.

The same remarks also apply to the inert gas employed in the phase of regeneration-dealcoholization, but in this case it will be advantageous to make use of a light gas having the bestv qualities with regards to heat exchange, for example hydrogen. l

What I claim is:

l. In a method for esterifying the olenic component in a hydrocarbon substance containing saturated and olenic components by means of an esterifying solution, thesteps which comprise admixing said substance in liquid phase with the esterifying solution; contacting the esterifying solution and the hydrocarbon substance with an ascending jet of inert gas under pressure in a confined zone surrounding said gas jet, to produce an upwardly moving emulsion;l collecting said emulsion at a higher level than the original contact point of the solution and substance with the gas jet; causing the resulting emulsion to settle into two layers with simultaneous release 'of inert gas; and separating the layers.

2. In the art of esterifying the olenic comtacting the esterifying solution and the hydrocarbon substance with an ascending jet of inert gas under pressure in a conined zonel surrounding said gas jet, to produce an upwardly moving emulsion; collecting said emulsion at a higher levelthan the original contact point of the solution and substance with the gas jet;' causing said solution to settle into two layers with simultaneous release of inert gas; separating the layers and forwarding one ofthe layers to the next following .stance partially deprived stage and the other layer to the `next preceding stage. v

3. In ,the art of esterifying the oleinicr component in a hydrocarbon substance containing saturated and olenic components by means of an esterifying solution, the method which comprises simultaneously contacting the hydrocarbon i substance in liquid phase and the esterifying solution with an ascending jet of an inert gas under pressure in a conned zone surrounding said gas jet, to produce an upwardly moving emulsion; collecting said emulsion at a higher level and causing it to settle into two layers with simultaneous release of inert gas; and separating said layers.

4. In the art of esterifying the olefinic coniy ponent in a hydrocarbon substance containing saturated and oleilnic components by means of an esterifying solution, the method which comprises admixing the substance in liquid phase and the solution in a plurality of successive stages; contacting in each stage the esterifying solution from oneof the next proximate stages and the hydrocarbon substance from the .other next proximate stage simultaneously with an ascending jet of inert gas under pressure in a conned zone surroundingsaid gas jet, to produce an upwardly moving emulsion; collecting said emulsion at a higher level than the original contact point `of the solution and substance with the gas jet and causing it to settle into two layers at `said higher level with simultaneous release of gas, one of the layers containing hydrocarbon subof olellnic component while the vother layer contains esterifying solution partially charged with oleilnic component: separating said layers and causing the hydrocarbon substance layer to flow by gravity down to l'the iirst named proximatel stage and the esteri- 5..'I'he method of claim 1,` one of the layers containing hydrocarbon substance partially deprived of oleflnic component while the other layer contains esterifying solution partially charged with oienic component, which method'urther comprises adding water to the second named layer.

6. The method of claim 2, one of the layers in each stage containing hydrocarbon substance.

partially deprived of oleflnic component while the other layer contains esterifying solution partially charged with olenic component, which` method further comprises adding water to the second layer in at least one of the stages.

7. The method of claim 2, further comprising collecting the inert gas evolved in each settling step and recycling said gas to the emulsifying steps.

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