DE1593597A1 - Use of sulfuric acid in the alkylation - Google Patents

Description

«BEB · im * ■» 8 MUNICH

1BERLIN33 Df.- Ing. H AN SRUSCHKE _Pieri zenauer Strasse

Auguste-Viktoria-Strasse 65 ^ "» ", .... _ArmAD Pat. Attorney Agular

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M 873

Texaco Development Corporation, New York 17, New York, USAo

Use of sulfuric acid in the alkylation

The invention relates to improvements in the use of sulfuric acid catalysts in chemical Reactions are used, in particular, relates to them Improvements in the alkylation of olefins with isoparaffins or aromatics in the presence of a sulfuric acid catalyst, the catalyst being deteriorated by the accumulation of alkylation impurities and ^ wherein the catalyst efficiency is restored by absorption of an olefin in the sulfuric acid used, Treatment of the absorption mixture to eliminate the alkylation impurities and alkylation of the treated absorption product. According to the invention, the absorption of the olefin in the sulfuric acid used is with made a stoichiometric excess of the olefin, with practically all of the sulfuric acid contained therein converted to dialkyl sulfates and the unabsorbed

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Olefin is passed to the alkylation zone. At a Embodiment of the process v / ird the liquid olefin with which an absorption zone is fed through the The exothermic heat of the olefin absorption evaporates and the resulting vapor is passed through a preceding absorption zone.

There are numerous sulfuric acid alkylation plants for the production of high quality motor fuels, which are operated by converting isobutane with olefins using a sulfuric acid catalyst. These systems operate with a rather high acid consumption of catalyst in the order of 0.181 to 0.454 kg of acid per 3.79 1 alkylate and in some cases even MENR ₀ or The spent catalyst from these plants used must / else be further used in any V. In most cases it is returned to the acid supplier for little profit as a source of sulfur. In any event, the total cost of the acid catalyst to those operating an alkylation plant is a major contributor to the total cost of alkylate production. The problem has now become more serious as more alkylate is used in automotive fuels and the prices of sulfur and sulfuric acid rise. The acid consumption in the alkylation and the corresponding costs have decreased over the years since 1938

09 * 4-1 / 185

fall, but it is in the process of recovering in spite of one No fundamental improvements have been made for many years when there is a great corresponding need. In general the used alkylating acid is destroyed by burning to convert the sulfur into sulfur dioxide and ultimately recovered as sulfuric acid. The burning acid recovery is a very drastic measure and also costly. This applies to ^ especially when you consider that the alkylating acid used from the alkylation of isobutane with Olefins has a titratable acidity of about $ 90 and is still well suited for many purposes, with the exception of one use as an alkylation catalyst, for which it is needed at the moment.

The alkylation process according to the invention comprises a special combination of steps in the recovery of sulfuric acid and is integrally connected with the alkylation of isobutane by means of olefin under (

Use of a sulfuric acid catalyst. It is known to use acid catalysts in the alkylation reaction zone can recover and regenerate in situ by absorption or reaction of an olefin with the used Sulfuric acid alkylation catalyst with the formation of Dialkyl sulfates, separation of the sialkyl sulfates, e.g. by Extraction with isobutane and alkylation of the dialkyl sulfates with isobutane using a sulfuric acid Eataly-

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sators. The alkylation step becomes practically pure 100 $ sulfuric acid regenerates or «from the dialkyl sulfates regained. The effect of this measure is that less of the freshly set acid in the alkylation zone must be introduced, and that the Acid consumption and overall costs are significantly reduced will. According to the invention, the sulfuric acid catalyst which has been separated off is carried along in an absorption zone an olefinic hydrocarbon such as propylene in a stoichiometric excess Complete conversion of the sulfuric acid into dialkyl sulphates - containing the unreacted olefin flowing off Hydrocarbon phase is added to the olefin feed Alkylation zone passed, and the acid phase flowing off, which contains dialkyl sulfates, is treated for the purpose of separation the dialkyl sulfates, which in turn are also sent as feed to the alkylation zone. if the olefin is kept in the liquid phase in the absorption zone, some of the dialkyl sulfates and dissolves therein flows with the hydrocarbon absorption effluent to the alkylation zone. Advantageously, the absorption zone is cooled by evaporation of a portion of the olefin hydrocarbon feed, and the obtained olefin-containing Gas is circulated to a gas phase absorption stage. In one embodiment of the invention becomes a gaseous olefin stream containing less olefin than

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containing the stoichiometric amount, brought into contact with the sulfuric acid catalyst in a first absorption zone for the purpose of converting all of the sulfuric acid into dialkyl sulfates, whereby practically complete removal of the olefin from the absorber tail gas is effected o The effluent from the first absorption zone, containing both monoalkyl sulfates and dialkyl sulfates, is then passed to a second absorption zone - in contact with a stoichiometric excess of olefin based on complete conversion of monoalkyl sulfates and sulfuric acid to dialkyl sulfates. In addition to scientific interest and economic significance, it is necessary to recover at least about 80 $ of the used alkylating acid available for recovery, preferably an even higher percentage. Otherwise, since sulfuric acid has such a low unit price, the investment and process costs can be higher than the savings in acid.

After this general explanation, the invention is best understood from the detailed description of the drawings _o Although the drawings show specific devices with which the invention

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According to methods can be carried out, the invention is intended not be limited to these particular devices and materials.

In the accompanying drawings, which form a part of the specification, Fig. 1 shows the invention with two absorbers operating to result in countercurrent contact of olefin and acid in combination with a fine alkylation unit using effluent cooling. Fig. 2 explains the use of gaseous olefin in a first absorption stage and of liquid olefin in a second absorption stage with self-cooling of the second absorption stage _{or the like}

With reference to FIG. 1, the acid phase from settling vessel 14 containing monopropyl sulfate, dipropyl sulfate and sulfuric acid is passed via line 13 to absorber 11, the propane-propylene feed is passed through line 10 to absorber 11 in an amount such that a stoichiometric excess of propylene is created, which converts all of the monoalkyl sulfate and the remaining sulfuric acid into dipropyl sulfate. The contents of the absorber 11 are intimately mixed by being circulated by means of the high-speed stirrer 6, which is driven by the motor 5. The temperature of the absorber 11 is kept at about -1.1 to +4.4 ⁰ C, by the alkylating hydrocarbon reaction mixture is passed through the lines 16 and 16a and the pressure reduction valve 15, whereby Ver

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vaporization of part of the hydrocarbon and cooling of the resulting vapor-liquid mixture is effected « The cooled vapor-liquid mixture is passed through the cooling coil 17 with direct heat exchange the implementation participants in absorber 11.

The alkylation acid catalyst used, which has an acidity of about 90%, is conveyed to the absorber 12 through the lines 21, 21a and 21b. The reaction mixture J from the absorber 11 is conveyed through the line 24 to the. Sedimentation vessel 23 passed. The hydrocarbon phase, containing unreacted propylene and dipropylene sulfate, which is separated in the settling vessel, is passed through line 25 to adsorber 12. The acid and hydrocarbon phases are brought into contact in the adsorber 12 by rapid circulation by means of the high-speed stirrer 7 which is driven by the motor 8. The temperature of the adsorber 12 is maintained at -1.1 to +4.4 ⁰ C by circulating the reaction mixture through the Alkylierungskohl'enwasserstoff-managerial f obligations 16 and 16b, the pressure reducing valve 19 and the cooling coil 20 in the adsorber 12. The drains of Coils 17 and 20, containing vapor-liquid mixtures of alkylation products, unused reactants and diluents, are collected in lines 1Sa and 1Sb and passed through line 18 to conventional compression and distillation devices listed as product recovery unit 22.

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The implementation mix. of adsorber 12 is through Line 27 passed to the sedimentation vessel 14. The severed one Hydrocarbon phase from settling vessel 14, containing unreacted propylene and dipropyl sulfate, is through the * Line 28 led to the alkylation reactor 31, wherein that propylene and dipropyl sulfate as described below be reacted with isobutane with formation of alkylate and release of 100% sulfuric acid.

The acid phase from settler 23 is passed through line 32 to countercurrent extractor 33 near its top directed. Isobutane is also introduced into the extractor through line 34a near the bottom. That through Isobutane running through the extractor 33 dissolves dipropyl sulfate from the descending acid phase containing an acid-oil complex of alkylation impurities and water is discharged from the extractor 33 through line 36. The hydrocarbon head fraction (overhead) from extractor 33, containing an isobutane extract of dipropyl sulfate, is through line 37 to Acid handler 38 led. A small stream of used alkylating acid is also fed through line 21c Acid handler 38 led. The acid treatment device 38 is a mixer driven by a paddle stirrer 45 by motor 46. All of the polymeric oil and the acid-oil complex in the extract from the extractor 33 may be present is removed by the acid in the acid treatment 38. The conversion mixture from the acid treatment 3Ö

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is passed through line 40 into the sedimentation vessel 41

The acid-treated head portion from the settling vessel 41, which is practically free from alkylation impurities and contains isobutane * and dipropyl sulfate, is made by the Lines 42 and 28 led to the alkylation reactor 31

Alkylation reactor 31 is a common contactor equipped with the cooling coil 47 and the high speed stirrer 3 driven by the motor. Fresh olefin feed, which may contain propylene, butylenes, butylene polymers and the like, is conveyed in line 29, the isobutane feed in line 30 and the recirculated isobutane in line 34 to the alkylation reactor 31 21 and a small amount of fresh sulfuric acid with a strength of 97.5 - 99.5 fo - in order to compensate for the small loss from the system of spent acid from the extractor 33, which has been added through line 43 - (to the alkylation reactor 31 The isobutane is alkylated by the olefins and alkyl sulfates in the alkylation reactor to form a high quality alkylate and liberate 100% sulfuric acid from the alkyl sulfates.

The reaction mixture from reactor 31 is passed through line 44 into settling vessel 39. As above mentioned, part of the separated hydrocarbon

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phase from the sedimentation vessel 39 used to the absorber 11 and 12 to cool by indirect heat exchange or to maintain a suitable low temperature in them. Another part is used to cool the alkylation reactor 31 by passing it through lines 16 and 16c, pressure reducing valve 48 and cooling coil 47. The liquid and the Steam from cooling coil 47 containing propane, isobutane and alkylate is withdrawn through line 18c and combined with the same mixture in lines 18a and 18b for recovery and distillation in the Product Recovery Plant 22. In Plant 22, conventional compression and distillation systems are used for the separation of the alkylate product, which is delivered via line is discharged, the isobutane, which is recycled via line 34, and the propane, which is via line 50 is discharged.

In the process described above in connection with Figure 1, the fresh olefin feed is used only for Absorber 11 conveyed, and it is shown that unreacted olefin passed from absorber 11 to absorber 12 to which the alkylating acid used is also passed. This current brings about a contact in the Countercurrent flow of both the olefin and the acid and results in maximum olefin adsorption as the weaker one Olefin stream is reacted with the stronger acid. Fresh

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However, olefin can also pass into the absorber 12 an olefin feed line, not shown, are guided; In this case the hydrocarbon head fraction becomes (overhead) from settling vessel 23 in line 25 »containing Isobutane and dialkyl sulfate, diverted from adsorber 12 and fed directly into the alkylation reactor 31. By supplying the isobutane and dialkyl sulfate from the settling vessel 23 directly to the alkylation and not to Absorber 12 allows a greater percentage of acid to be converted into extractable dialkyl sulfate, with a lower total acid consumption in the alkylation and also with lower olefin loss than Alkyl acid sulfates in the consumed Acid from extractor 33.

If this olefin is fed to beiasn Jtbscrrtions £ * ones \ ir. ~ Rr such conditions that virtually geerx olefin is absorbed in the hydrocarbon phase of one of the contact devices (contactor), it may be desirable, this portion of the separated hydrocarbon phase from the Divert alkylation system because of the diluent hydrocarbons present. In this case it is advantageous to obtain the dissolved dialkyl sulfate from the hydrocarbon, for example by evaporation (flashing), and to feed it to the alkylation.

As much acid as possible should be used in the adsorption step be reacted with olefin to form dialkyl sulfate.

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Propylene is preferred as the olefin feed. The absorption can either be carried out in the vapor or liquid phase or in a combination the same. For example, most of the adsorption can be carried out in the vapor phase and subsequently in the liquid phase for the last part of the absorption step for the purpose of high conversion of the acid Dialkyl sulfates. Advantageously, a concentrated Olefin feed in the liquid phase, e.g. from catalytic cracking, fed to a mixing pump which is used to transfer the acid phase from vapor phase adsorption to the extractor for the purpose of extraction of Pump dialkyl sulfate. If desired, the entire unreacted olefin separated or passed on to the extractor and obtained in the isobutane extract and finally be passed to the alkylation zone.

Used alkylating acid with a titratable acidity of 88-93 wt% is the preferred acid feed for the absorption step, although in some cases, e.g. when amylenes are to be alkylated, they have a lower concentration of $ 80 to $ 85 can. Acid from other sources, such as fresh acid or acid from chemical reactions and acid treatment petroleum naphtha or lubricating oil can also be used.

When using strong acid together with propylene

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A temperature of -6.67 to +15.56 ⁰ C satisfied-.stellend. When using butylenes, particularly isobutylene or isobutylene containing feedstocks, fairly low temperatures and short times are advantageous. Isobutylene can first be advantageously removed by using a weak acid of about 60-70% concentration »

Relatively concentrated olefin material, ZoB. from catalytic cleavage, it is preferred although from an economical point of view lean feedstocks such as propylene lean with only low value as a fuel, are advantageous "

The absorption step can be carried out in touch devices known from the art, e.g. in mixer settlers, centrifugal contact devices (contactors), G-egenstromtürmen, or in awei or more mechanically stirred reactors, which under Creating a countercurrent plus working, the bringing into contact countercurrent flow is preferred to achieve high acid to dialkyl sulfate conversion and in most cases for the purpose of high conversion of the olefin.

When the absorbers operate in the liquid phase, the unreacted hydrocarbon dissolves a significant amount Part of the dialkyl sulfate, e.g. about 20% by weight

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at about -1.1 ⁰ C in propane-propylene. Although it is desirable to add the dipropyl sulfate to the "alkylation" process, this is undesirable if too much propane or η-butane is present because such diluents have an unfavorable effect on the alkylation reaction. Such diluents can be removed and at the same time provide cooling for the absorber by flashing ) of the settling vessel at the top (overhead) and forwarding of the cooled liquid-vapor mixture obtained in indirect heat exchange with the absorber. or butange, which has been substantially reduced, is then fed to the alkylation.

It is desirable to extract substantially all of the dialkyl sulfate in the acid phase from the absorber for maximum yield of recovered acid. There are used extraction temperatures below ⁰ C 37.78, and low temperatures, for example from about 4.44 to 15.56 C, and short times of less than about 20 min. Are preferred. The extraction property ride can be conducted in known in the art> devices, aB in mixer-settling vessels, centrifugal contacting devices, or · countercurrent towers, for example, in a disc touch extractor (rotating disc contactor).

Isobutane is preferably used to extract the dialkyl sulfates from the absorber-implementation mixture, but normal paraffins, such as propane and η-butane, or olefins can also be used.

Dialkyl sulfates have a greater relative solubility in hydrocarbon solvents than that Alkyl acid sulfates. It is therefore desirable to use effective conditions in the extraction step so that not only the dialkyl sulfates but also the alkyl acid sulfates are extracted. Such conditions. Close a high solvent dosage of the order of 6 moles of solvent per mole of alkyl sulfate or higher, Raffinate recirculation, multi-stage countercurrent extraction and optimum feed rate for a given extraction vessel. In approaches with test facilities have been much better results with a ratio of hydrocarbon solvent containing substantially Isobutane, obtained from dipropyl sulfate of about 6 than with a ratio of 3 and slightly better results with a ratio of 16 than with a ratio of 6. Under the working conditions is the volume ratio of isobutane to dipropyl sulfate about the same as the molar ratio. For dibutyl sulfate is the molar ratio slightly higher than the volume ratio, since the molecular weight of dipropyl sulfate is 180 and that of Dibutyl sulfate is 210. The exact solution required

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Funding depends to some extent on the other Conditions. For example, the solubility of dialkyl sulfates increases with temperature, and a column is given Dimensions, e.g. an extraction tower with a rotating disk, has an optimal throughput »It seems however, that the volume ratio of isobutane to dialkyl sulfate should always be above 3 and preferably above 6 should.

The raffinate or the spent acid from the extraction stage contains water, alkyl acid sulfates, dialkyl sulfates and the reaction product of acid and polymeric oil that is formed during the alkalization-absorption and Acid treatment steps formed. The extract contains the hydrocarbon solvent, dialkyl sulfate and a relatively small amount of alkyl acid sulfate. The extraction conditions are usually chosen so as to minimize the presence of only the acid-oil reaction product and of water in the spent acid or acid phase, all alkyl sulfates in the Extract or the organic phase are located »

When Palis occurs this difficulty can be causing good separation of the acid and hydrocarbon phases in the settling vessel 23, this separation can be facilitated by introducing isobutane into the absorption mixture by means of precautions not shown here. E.g. can you introduce isobutane into the line 24, which extends from the outlet

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sorber extends to the sedimentation vessel. It is advantageous to add an amount up to the full amount with which the extraction stage is normally charged, up to 6 parts by volume for each volume of dialkyl sulfate or more or 5 volumes per volume of the acid phase with mixing, so that the major part of dialkyl sulfate is extracted and good separation takes place. When this is done, the hydrocarbon phase from settler 23 is sent to alkylation and less dialkyl sulfate remains in the acid phase to be extracted in the usual extraction stage use an extraction tower of smaller dimensions «,

The solubility of dialkyl sulfate in isobutane decreases with temperature too. For example, a higher solvent dosage is generally required at lower temperatures. The balance between alkyl sulfate and the desired dialkyl sulfate is more favored at lower temperatures and at these also takes place less Degradation of the acidic material takes place. One can take advantage of these factors to achieve superior results, namely a higher yield of extracted dialkyl sulfate with less solvent. This can be done are using a reverse temperature gradient, i.e. a higher temperature in the Final stages of a multi-stage countercurrent extraction or am

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Bottom of the tower than at "the initial stage or in the upper part of the tower. Relatively warm isobutane is fed into the final stage or near the bottom of a tower to such an extent that at least 3 volumes of isobutane per volume of dialkyl sulfate are present at a temperature of about 15.6 ^° C. result in the tower bottom. in a previous step, or approximately half-way up the tower is additionally isobutane, as the cold coolant introduced Umlaufisobutan of about -6.7 to -1.1 ⁰ C, so that the temperature in the upper part of the tower is about 7.2 to 10.0 ^° C.

If one carries out the extraction at Extracts discharge temperatures of about 7.2 to 37.8 ⁰ C, a large percentage of dialkyl sulfates can be removed from the solution by cooling the extract to a temperature below about 4.4 C, or preferably below about -1.1 ⁰ C. The dialkyl sulfate separated off in this way is very pure and free from alkylation impurities. } Therefore, it is a preferred feedstock for the alkylation, the cooling can be carried out in various ways, for example, the coal has hydrogen or by evaporation of a part by indirect heat exchange with the refrigerant-Umlaufisobutan containing about -6.7 ⁰ C. This cooling step can also be applied to the hydrocarbon phase from one adsorber, for example _o the head portion from the settling vessels 14 and 23, particularly when the Absetzgefäße be operated at about 4.4 ⁰ C or higher. The unreacted propane-propylene in

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Settling vessel 14 is about 20 $ dipropyl dissolves at about -1.1 ⁰ C and even more above -1.1 ⁰ G. Approximately 50 $ of Dipropylsulfatβ can be got out from the solution by cooling the separated hydrocarbon phase to about -6.7 ⁰ G .

The polymeric oil contamination in the adsorber-extractor extract is atark unsaturated and reacts easily with strong sulfuric acid, for example with acid freshly prepared for the alkylation or with used alkylating acid of about 90% concentration. The strong sulfuric acid also removes all of the acid-oil complex present. Thus, if desired, the absorbent extract can be acid treated prior to being fed to the alkylation and optionally after removing any excess unreacted olefin Temperature of 29.4 ⁰ C and for a time of 1 hour. However, a temperature of n / rficht is about 4.4 ° C to 15.6 ⁰ and a short time in the order of several minutes or less are preferred. In fact, such a short time seems to be sufficient, which results from mixing by means of a pressure relief port.

In general, the conditions for the alkylation step are those known in the art. However the main

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Amount of the acid treated is fed as alkyl sulfates from the recovery section to the alkylation and only a smaller proportion of the acid is used as freshly made acid of the usual 98-99.5 concentration fed. Since the alkyl sulfates are essentially anhydrous, the system catalyst has the tendency when you do this Acid recovery process uses to have a lower water content and is generally of over- " poor quality, because an alkylate of lower final boiling point and higher octane number is obtained. Of course If necessary, the drying of the Feed materials can be used, but in such a case the water content of the system catalyst can be so high as in the usual way of working without acid recovery. Usually the water content of the system catalyst is without acid recovery above 2.5 wt .- ^ or in the range from about $ 2.5 to $ 4.5 if you have freshly made acid from 97.5-99.5 $ concentration gives up. Among the same Conditions - using the present recovery process - the water content is usually under about $ 2.5 or in the range of about $ 1.0-2.5. the Sulfuric acid in the alkylation system is usually within a range of about $ 88- $ 95 held by the acid consumed by the system is cleaned. In a system with a plurality of reactors, it is preferred . the acid of the lowest concentration is purified and fed to the acid recovery system.

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A large excess of isobutane is used, for example, "such 60 - recovered $ of hydrocarbons in the Alkyljierungs-reaction mixture, must consequently a large amount of isobutane and" be recycled for reuse in the alkylation process in circulation, it is also for the - 80 vol _e described recovery process available.

In addition to the olefin, which is fed to the alkylation stage in the form of alkyl sulfates, there is usually additional fresh olefin fed to the alkylation stage. For example, if propylene and / or butylene, but special Propylene can be used for the absorption stage, it is advantageous to use butylenes also in the alkylation stage to use. As the total acid consumption is reduced, the amount of olefin required also becomes Conversion in the acid recovery section, decreased, and is usually in the range of $ 10-25 based on all of the olefin, although it can be even less.

example 1

In the following example, the feed materials used in Table I are used in the apparatus according to 1 used.

Table I- in 6.9 Propane-
Propylene. Butane-
Butylene Isobutane 91.1 Weight # 2.0 0.4 - Ethane 62.3 0.1 Propylene 33.7 2.7 propane 3.6 34.6 Isobutane 11.0 n-butane 15.9 Isobutylene 9.5 Butylene-1 22.9 Butylene-2 3.0 Pent on

100.0

100.0

100.0

10 ml of alkylating acid used per minute from the settling vessel 39 with a titer of $ 91.0 were fed into the absorber 12 at about -3.9.degree. Fresh propane-propylene feed at a rate of 45.0 ml per minute, was fed into the absorber 11 at about -1.1 ⁰ C "Unreacted propane Prοpylen of absorber 11 that has been separated in the settling vessel 23 was the absorber 12 supplied. The hydrocarbon phase or the unconverted propane-propylene from adsorber 12, separated in settling vessel 14, contained 11.8 $ dipropyl sulfate, the acid phase from absorber 11, which was separated in settling vessel 23, and 80.6 $ dipropyl sulfate and 15.3 $ Propyl acid sulfate (propyl acid sulfate ©) contained, wuM «with a

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speed of 24.2 ml per minute to an extraction tower with a rotating disk near the top. 315 ml per minute of the isobutane feed was fed to the rotating disk extraction tower near its bottom. It was maintained, a temperature gradient in the extractor, wherein the bottom temperature of about 12.8 ° C and the top temperature was about 18.3 ⁰ C. The head portion (overhead) from the extractor, containing 83.8 $ isobutane, 5.7% dipropyl sulfate and 0.3% propyl sulfate, was fed to a mechanically stirred reactor of 600 ml at about 26.7 ° C. along with 0.2 ml per min the used alkylating acid of 91% above concentration. The acid treated product was passed to a settler where a hydrocarbon phase was separated at a rate of 341.2 ml per minute containing 84.2% isobutane, 5.8% dipropyl sulfate and 0.1% propyl acid sulfate.

105.5 ml per minute of the butane-butylene feed in line 29, 315 »4 ml per minute of the isobutane feed in line 30 'and 0.181 kg per hour supplied from the settling vessels 14 and 41, the circulating acid in line 21 and the line 34 Umlaufisobutan in a StratCo alkylation reactor, which was maintained with efficient mixing at 4.4 ° C to 7.2 ^0. The reaction mixture was continuously passed to a settling vessel.

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Di e hydrocarbon phase, which was produced at a rate of 749 ml per min., Was stabilized alkaline (caustic) and washed with water as well as to the main quantity of butane and lighter Kohlenw _a wherein about 189 "1 sserstoffen remove, per day of desired alkylate product.

Spent acid from the acid handler was produced at a rate of 1.3 ml per minute. This corresponds to an acid consumption of 0.081 kg per 3.75 1 alkylate. A corresponding control experiment without acid recovery showed an acid consumption of 0.39 kg per 3.79 liters of alkylate. About $ 90 of the alkylating acid used was converted to dipropyl sulfate, and about 90 $ des Dipropyl sulfate formed was returned to the alkylation, in which the sulfuric acid was regenerated. All in all $ 80 of the alkylating acid used was recovered.

ι The used acid from the acid handler possessed

an analysis of about $ 2.5 water, $ 10 acid-polymer oil complex, $ 10 dipropyl sulfate and $ 77.5 propyl sulfate.

The octane value of the total alkoxide from the acid recovery experiment was pure 95.5 and 107.0 with 3.0 ml of TEL (tetraethyl lead). The motor octane value was pure 92.6 and 106.8 with 3.0 ml TEL. The alkylate from the control experiment without acid recovery had an octane value of 94.7 pure and 105.9 with 3.0 ml TEL. -, - / ■.

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Referring to Pig x 2 a lean Olefinbesehickungsgas, Z is an absorber tail gas (tail gas) through line 155 together with the boil-off gas absorber (flash gas) "led from line 125 ₀ B. for the first absorber 112th absorber 112 is a _{Countercurrent contact tower for contacting vapor and liquid β} In absorber 112, the flowing gas is countercurrently contacted with the sulfuric acid alkylation catalyst used, which is fed into the top of absorber 112 through line 112a. The absorber 112 is equipped with an in the trap tray 156 located in the middle for separating the downward flowing liquid, which is drawn off through line 157 and cooled in the intercooler 120 before it is returned to the absorber 112 via line 158 »coolant for the intercooler 120 is supplied through line 116b, and the coolant drain is withdrawn through line 118b. The absorber 112 operates with an excess of acid, < so that virtually complete stripping of olefin from the feed gas is achieved. The remaining exhaust gas, which is withdrawn through line 160, is practically free of olefins and can be removed for fuel purposes. The acid, which contains dissolved monoalkyl and dialkyl sulfates, collects at the bottom of the absorber 112 and is drawn off through line 113 and passed to the second absorber 111.

In the second absorber 111 a liquid charge is

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kung flow rich in olefin through line 110 with The acid phase is brought into contact in a first subdivision formed by the overflow 163. The acid and hydrocarbon phases are agitated by mixer 161 driven by motor 162. The absorption temperature is maintained by self-cooling, i.e. by evaporation of part of the Hydrocarbon feed from the reaction mixture. The vaporized hydrocarbon from the conversion partition is withdrawn through line 125 and returned to the first absorber 112. The overflowing at 163 Hydrocarbon acid phase collects in a central partition of the absorber 111, the is located between the overflows 163 and 164, and separates therein into an acid phase, which by conduction is withdrawn, and in a hydrocarbon phase that overflows overflow 164 for the division of bands. The hydrocarbon phase, containing unreacted olefin and dissolved alkyl sulfates "is passed through line 128 deducted. The acid phase in line 132 becomes the alkyl sulfate separation plant 133 transferred, where the dissolved alkyl sulfates are separated from the acid, e.g. by / Extraction with isobutane from line 134a. The separated alkyl sulfates in line 142 along with the hydrocarbon phase in line 128 are passed through line 134 with isobutane to the alkylation contactor

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guided. The from the alkyl sulfate separation plant 133 Discharged acid phase is withdrawn through line 136.

An isobutane olefin feed in line 129 is combined with the isobutane in line 134 and the alkyl sulfates containing streams from lines 128 and 142 and to alkylation touch device 131. The hydrofluoric acid in line 121 and recycled acid in line 143 are added to the alkylation touch device 131 introduced. The alkylation touch device 131 is a common container in which the contents with the Stirrer 103, driven by motor 104, is intimately mixed, and the heat of decomposition through the coolant which is introduced into the cooling coil 147 through line 1i6e and discharged through line 118c will. React in the alkylation touch device the alkyl sulfates and the olefin with isobutane to form the alkylate product. The product mixture obtained is withdrawn through line 144 to separator 139 where the hydrocarbon phase is removed from the sulfuric acid catalyst is separated '. The sulfuric acid catalyst is recycled through line 121 and the separated The hydrocarbon phase is withdrawn through line 116 and transferred to the distillation gas treatment plant 122. In the plant 122 propane is separated and through Discharge line 150 and the butanes and product alkoxide are discharged separately through line 149. The ab-

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separate isobutane is withdrawn through line 134 for recirculation back to the alkylation touch device 131. ""

Example 2

In the following example, the feed materials shown in Table II are used in the plant according to Fig «2 applied.

Table II Propylene
Loading
kung Butylene
Loading
kung Isobutane
Loading
kung Mon: Gas off
Cleavage
system non-condensing
sable
Components 17.0 hydrogen 21.0 0.5 methane 28.0 1.0 Ethylene 6.0 51.0
43.9
1.9 0.1
2.7
34.6 6.9 Ethane 11.5 1.3 48.3 91.1 Propylene
propane
Isobutane 8.5
6.3
0.8 0.4 11.0 2.0 Butylenes 0.4 η-butane 0.4 100.0 100.0 100.0 C5 + 0.1 All in all 100.0

009841/1855

Gas from a fission plant in a quantity

■ 2

Speaking 44.4 m per day of propylene in line 155 and .Absorber exhaust gas in line 125, containing an equivalent of 6.8 m propylene are fed to the bottom of tower 112 at a pressure of about 0.35 kg / cm. The alkylation catalyst used is at a rate of 43.55 kg per day with a titratable acidity of 90.0 $ and at a temperature of -1.1 ⁰ C through line 121a introduced near the top of the tower 112th As the acid flows down through tower 112, the heat of reaction with the olefin causes the temperature to rise. The heat is discharged from the tower in an intercooler 120 by withdrawing a stream downwardly flowing liquid from the Abscheiderboden 156 through line 157 to the radiator 120 and returning the liquid to the tower through line 158 C. at about -1.1 ⁰ Virtually all of the propylene and Butylenes are converted and retained by the acid, converting 75% of the sulfuric acid to propyl sulfate and dipropyl sulfate. Virtually all unsaturated hydrocarbons, non-compressible components, hydrogen and ethylene are discharged from the top of the tower as waste gas through line 160.

009841/1855

The acid phase from the bottom of the absorber 112 becomes the absorber 111 led, which is in the liquid phase with mechanical stirring under a pressure of 1.05 kg / cm and a temperature of 4 »4 ° G works. The propylene feed shown in Table II is fed to absorber 111 at 46.6 nr per day. This feed contains about a 40% excess of olefin based on the original acid to convert all of the sulfuric acid and propyl sulfate therein to dipropyl sulfate. By maintaining the pressure of the absorber 111 at 1.05 kg / ca, some of the hydrocarbon feed is vaporized while absorbing the exothermic heat of reaction, a temperature of about 4 »4 C being maintained. Containing a gas about 6.8 m per day equivalent liquid propylene Developed from the absorber and returned to absorber 112 in circulation. The liquid absorption mixture is separated into acid and hydrocarbon phases, each of which is dissolved dipropyl sulfate contains.

The acid phase from the second absorber 111 containing about 85 ßew »- $ Dipropylsulf.at, is brought into contact in countercurrent in the liquid phase with 6 parts by volume of the isobutane charge extracted. The dialkyl sulfate extract obtained is separated from a raffinate which contains most of the alkylation impurities, contained in the spent alkylating acid catalyst are led to the ssua absorption syetea, as well as all aäurölöeliohen substances that are formed in the two absorbers have »contains»

0098A1 / 1855

The isobutane extract, the hydrocarbon phase separated from absorber 111, 580 m per day of the butylene feed shown in Table II, an excess of isobutane feed, 435-5 kg per day of fresh 99-5% sulfuric acid and circulating acid catalyst are fed to the alkylation contact device 131. The reaction products are separated by conventional means to give 595 P ^{m ro} day of entbutanisierten Alkylatee. The alkylate product has a pure octane value of 96.0 x * tx and 106.0 with 3.0 ml TEL and a motor octane value of 93.0 pure and 107 # 0 with 3.0 ml TEL. The acid consumption amounts to 0.0208 kg per 3.785 liters of alkylate compared to a consumption rate of about 0.317 kg per 3.785 liters, which is to be expected with a conventional alkylation conventional alkylation apparatus since gas streams of such low olefin content containing non-condensable hydrocarbons and other gases are unsuitable for direct feed to the alkylation.

009841/1855

Claims (1)

Claims 1. A process for the alkylation of an isoparaffin with an olefin in the presence of a sulfuric acid catalyst in a Alkylation zone containing a reaction mixture consisting of isoparaffin, olefin, alkyl sulfates and sulfuric acid, where the κ / effectiveness of sulfuric acid as a catalyst deteriorates due to the accumulation of alkylation impurities, and wherein the effectiveness of the sulfur catalyst is restored is obtained by contacting at least a portion of the sulfuric acid catalyst, which is separated off from the reaction mixture, with an olefin to form alkyl sulfates, which alkyl sulfates are separated from the alkylation impurities and passed to the alkylation zone, characterized in that contacting the separated sulfuric acid catalyst with an olefinic hydrocarbon feedstock which brings a stoichiometric excess of olefin based on complete conversion of sulfuric acid to dialkyl sulfates contains in an absorption zone; that one withdraws an absorption effluent hydrocarbon phase from the absorption zone, the contains unreacted olefin and an absorption effluent acid phase containing dialkyl sulfates and alkylating impurities comprises} passing at least a portion of the absorption effluent hydrocarbon phase into the alkylation zone; that he Separating dialkyl sulfates from the absorption effluent acid phase; 009841/1855 and that at least some of the dialkyl sulfates »those of the absorption-effluent-acid phase have been separated, leads to the alkylation zone 2. The method according to claim 1, characterized in that the olefinic hydrocarbon feed is a liquid and the absorption effluent hydrocarbon phase is liquid and dialkyl sulfates in solution. 3. The method according to claim 1-2, characterized in that that the olefinic hydrocarbon feed is a liquid, the absorption zone being maintained under such pressure becomes that the exothermic heat of the reaction of the olefin and sulfuric acid by evaporation of a portion of the olefinic hydrocarbon feed is absorbed, whereby an absorption ·· effluent hydrocarbon vapor phase, an absorption effluent hydrocarbon -Liquid phase and an absorption drainage acid phase are withdrawn from the absorption zone and at least a portion of the absorption effluent hydrocarbon liquid phase is passed to the alkylation zone. 4 · Method according to claims 1-3 »characterized in that that the olefinic hydrocarbon feed contains propylene. 5. Method according to one of the preceding claims, characterized in that at least 80 ^ of the sulfuric acid in the separated sulfuric acid catalyst converted to dialkyl sulfates will. 009841/1855 ^BAD 6. Terfahren according to one of the preceding claims, because » characterized in that the absorption effluent acid phase contains at least 75 wt .- # dialkyl sulfates. 7 · Method according to one of the preceding claims, characterized characterized in that prior to contacting the separated sulfuric acid catalyst with each stoichiometric Excess of the olefin feed in a second absorption zone of the separated sulfuric acid catalyst with a first Hydrocarbon feed is contacted that is less than the stoichiometric amount of olefin based contains complete conversion of sulfuric acid to dialkyl sulfates in a first absorption zone, from which first absorption zone, a first absorption effluent hydrocarbon phase and withdrawing a first absorption effluent acid phase which unconverted lionoalkyl sulfates, dialkyl sulfates Contains acid and alkylation impurities. 8. The method according to claim 7 »characterized in that the first olefinic hydrocarbon feed is a gas. 9 · Method according to claim 7-8 »characterized in that J that the stoichiometric excess olefinic hydrocarbon feed is a liquid, the stoichiometric excess absorption zone being maintained at a pressure such that the exothermic heat of reaction of the olefin with the monoalkyl sulfate and sulfuric acid 009841/1855 BATH ORIGINAL ~ ³⁵ - by evaporation of a portion of the second olefinic hydrocarbon feed is absorbed and with a second absorption effluent hydrocarbon vapor phase, a second Absorption effluent hydrocarbon liquid phase and a second absorption effluent acid phase are withdrawn from the second absorption zone and at least a portion of the second absorption effluent hydrocarbon -Flüasigkeitphase is passed to the alkylation zone. 10 · Method according to claim 7-9t characterized! that the second absorption effluent gas phase in circulation to the first Absorption zone is performed. 11. The method according to claim 7 ·· 10 »characterized in that that the first olefinic hydrocarbon feed comprises propylene. 12. The method according to claim 7 - Ht characterized in that that the second olefinic hydrocarbon feed comprises propylene. IJ. Method according to one of the preceding claims, characterized in that the dialkyl of the absorption effluent acid phase are separated by contacting the absorption effluent acid phase with a paraffinic hydrocarbon at a temperature within the range from 7.2 to 37.8 ⁰ C to form an extract containing dialkyl sulfates. 009841/1855
BATH ORIGINAL 14 · The method according to claim 13 »characterized in that the paraffinic hydrocarbon contains isobutane» '15 · Method according to claims 13-14 »characterized in that the end
that the effluent of the absorption zone is brought into contact with a paraffinic hydrocarbon, the separation of this effluent into a hydrocarbon phase and an acid phase being facilitated » 16. The method according to claim 13-15 »characterized in that that the extract is cooled to a temperature below 4 »4 C. is with separation of a dialkyl sulfate phase, and that the dialkyl sulfate is passed to the alkylation zone. 17. Method according to claims 13-16, characterized in that that the extract is cooled to a temperature below about -1.1 C. 18. The method according to claim 13-17f, characterized in that that the olefinic hydrocarbon feed contains propylene, and that the dialkyl sulfate is dipropyl sulfate. 009841/1855 BATH ORIGINAL Blank page