Process of isoparaffin alkylation.

The present invention relates to the preparation of a normally liquid alkylation product, by reacting an isoparaffin on an olefin or a compound acting as an olefin. The present invention is very valuable in a process for the alkylation at hydrogen fluoride, although it may be equally applied to a process for the alkylation to sulfuric acid.

In this process, the alkylation, hydrofluoric-acid catalyzed, an isoparaffin with an olefin product an isoparaffin normally liquid, higher molecular weight. These isoparaffins have high octane numbers. These methods are well known, and used worldwide fuel obtained by alkylation at hydrogen fluoride (hereafter referred to as "RF").

One problem in alkylation to the IIF is that of producing heavy polymer which accumulates in the RF liquid. The separation of this polymer and Hf required stairway expensive. The regeneration of the IIF also produces a stream of low quality polymer.

Antérieurementf the polymer products were separated from the hydrofluoric acid at regular intervals, in order to prevent the accumulation of polymer causing deterioration in the characteristics of reaction stability, activity and catalyst efficiency. It was thought that this polymer could not be collected with the product of the alkylation, fear that the polymer on the quality of the alkylation product.

In a method of alkylation to the RF, polymer formation is equivalent to about 0.1 to 0.2 liquid volume ^C./ DEGREES the load.

In previous processes, the regenerator of the acid was used as about one day per week. The regenerators were "oversized" so that if the plant was "pushing" beyond its theoretical capacity, the regenerator may process the increased production of polymer. This sporadic results inherent cause temporary upsets, but significant, automated inspection system.

Many attempts have been made to improve the regeneration installations the RF which, in general, were unsatisfactory. Most of these regeneration devices prior had various schemes which cleaned acid distillation. These methods were poisoned by a number of problems as representative example which include of fouling by tar or polymer of any device used to vaporize hydrofluoric acid to regenerate.

It has now been found a means to remove the regenerator acid and collecting the polymer formed during the reaction of alkylation, simultaneously with the alkylation product, without impairing the quality of the latter, while eliminating operational disturbances caused by switching on, at regular time intervals, a regenerator acid.

Accordingly, the present invention relates to a process for the alkylation of an isoparaffin with an olefin, in contact with a catalyst based on hydrogen fluoride, to produce a product of the alkylation of normally liquid, which method:

(has) is reacted with the isoparaffin 1' olefin, in admixture with said catalyst, in an alkylation reactor, to obtain an effluent containing alkylation product, isoparaffin unreacted, catalyst and polymer,

(d) introducing at least a portion of the effluent in a first separation zone and is collected, to therefrom, a hydrocarbon phase and a hydrogen fluoride phase containing said polymer,

(c.) is recycling a portion at least of the hydrogen fluoride phase to the reactor,

(d.) is introduced into at least a portion of the remaining hydrogen fluoride phase and at least a portion of the hydrocarbon phase to a second separation zone, and

(i) is collected, from the second separation zone, (1) isoparaffin unreacted and (2) of the alkylation product containing polymer.

At attached drawing, given solely by way of example:

the fig. 1. - represents a simplified fonctionneraent scheme of a method of alkylation to the RF representative,

the fig. 2. - shows the changes necessary for eliminating the regenerator of the acid.

The isoparaffinic hydrocarbon feedstocks suitable are about 4 to 7 carbon atoms, including isobutane, 1' pentane, neopentane, one or more of the heptane isohexanes as well as various branched chain. The olefinic reactants suitable contain from about 3 to 7 carbon atoms such as, for example, the polypropylene, the 1-butene, the 2-butene, 1' isobutylene, the amylenes, hexenes and hepfcènes isomers.

The mixture used for the alkylation reaction comprises a catalyst ïïf, an isoparaffin and an olefinic hydrocarbon. The RF/hydrocarbon volume ratio, in the reaction zone, must be between 0,1/1 and about 3/1. The RF can be substantially anhydrous hydrogen fluoride, acid fluorhj ^ dric or hydrogen fluoride containing various additives or activators.

Representatively, is charged anhydrous hydrogen fluoride in the alkylating, as fresh catalyst. Hydrofluoric acid may contain up to 10fo water; however, excessive dilution water tends to reduce the activity of alkylating catalyst and causes corrosion problems. To reduce the tendency for polymerizing olefins of the load prior to alkylation, the molar ratio of isoparaffin to olefin, in the alkylation reaction zone, is maintained at a value comprised between 1/1 and 20/1 and, preferably, between 3/1 and 15/1, about.

The reaction conditions for the alkylation are well known and include a temperature of from 90 °c to -15, preferably 0 to 40 °c. The alkylation reaction is very exothermic, so that the reaction zone can also function as a heat exchanger, by removing heat from the reaction zone. The pressure of alkylation must maintain the liquid phase reaction mixture in the reaction zone and is, for example, between 2 and 40 atmospheres. Space-time, defined as the volume of catalyst in the reactor divided by the volumes per minute of hydrocarbon feedstock, is usually less than 5 minutes and, preferably, less than 2 minute.

Introduction of the effluent of the alkylation reaction zone in a first separation zone comprising generally a device with two stacked containers. The lower container is a maturation zone. The residence time of the effluent in the maturation zone is about 1 to 20 min. Turbulent flow is produced in the maturation zone using an internal device, e.g. perforated plates. The effluent then enters the top container as a separator, providing a hydrocarbon phase substantially free of Hf and a phase of the HP substantially free of hydrocarbons. Which can be emulsified a portion of the effluent from the reaction zone and recycled back to the reactor, but this is optional. The IIF separated is recycled to the reactor.

In general, the reactor effluent contains some polymer formed during the reaction of alkylation. These polymers appear in the phase of the Kf removed from the separator.

To prevent accumulation of polymer, according to the prior arts, there is introduced a small stream of the HP in a regenerator acid. In a facility representative of prior techniques, wherein the filler is about 66 m3/hour, the regenerator usually has 6 Ra of up and is constituted by a section of 4.2 m of perforated trays and by a lower portion 1, 8m collecting the polymer products. In general, the existing facilities, according to the prior arts, utilize the regenerator acid based on a certain periodicity because the improvement of operation techniques resulted in a decrease in the total amount of polymer products obtained. On the basis of feed acid of about 0.66 m3/day, the regenerator of the acid is used in cycles' of 7 to 10 days and processes of about 4.6 to 6.6 m3 hydrofluoric acid. The amount of polymer is from about 5 to collected liquid volumes 20 $ the total charge delivered to the regenerator. The IIF regenerated is recycled to the reactor with the separated hydrogen fluoride. The use periodic perturbations of the regenerator fatigue and each time it was used.

The hydrocarbon phase separated in the separator is introduced into a column for fractionating isoextraction, to collect the alkylation product normally liquid as a tail current. Propane, isobutane unreacted and a minor amount of HP are removed overhead and introduced into a separator from which the phase of HP is recycled to the reactor. The hydrocarbon phase is fed into a deethanizing wherein isobutane is separated as a bottoms fraction and recycled to the reactor to the regenerator and. In prior arts, isobutane was used to extract the IIF of the polymer in the regenerator. Is removed from the top of the deethanizing device a fraction comprising propane and a few horsepower. This moiety is introduced in an extraction column of the IIF wherein the IIF is removed overhead and the propane is removed by tail.

Generally treated the propane to alumina and 1' potassium hydroxide to remove all of the IIF. The alkylation product is typically collected substantially free of RF, but the product of alkylation may undergo similar treatment, remove trace amounts'd ' IPD.

The present invention eliminates the regenerator. The hydrofluoric acid is directly sent into the isoextraction device, or isoextracteur, the hydrocarbon phase from the separator. The temperature of these currents were usually about 27 to 40 °c. According to the present invention, it is preferable to raise the temperature to a value of about 50 to 95 °c, before 1' introduction into the isoextracteur•. The remainder of the method, using a separator after 1' isoextracteur, device deethanizing extraction device and at hydrogen fluoride is the same as in the methods of alkylation representative of prior techniques.

Gustatory maintaining at attached drawing, given solely by way of example, which illustrates a representative process for the alkylation of prior techniques as well as the improvement by the present invention.

The fig. 1 will describe for example. by taking a plant intended for the alkylation of isobutane by a mixed olefin feed containing propylene, butylene and amylene, type alkylation reactor heat exchanger. Is desired alkylation product normally liquid boiling in the entire extent of the range and collect quality propane LPG (liquefied petroleum gas) and normal butane.

About 86.75 m3/hour of olefins enter the apparatus through a duct 1; isobutane make-up by a conduit between 3 and 14.61 m3/hour butane enters through a conduit 20, the isobutane rich portion thereof being recycled by a conduit 2 for joining the olefins of the conduit 1.

The conduit conveys 789.44 m3 2/hour (7.699, 74 kg/hour mole) of butane-rich recycle stream containing 116.09 moles of RF. The conduit 3/hour 38.82 m3 adds (mole/hour 376.62) isobutane makeup, pure liquid volumes 95 The O/degrees. The mixture enters an alkylation reactor 4. The reactor is designed to function as a heat exchanger having multiple injection points of the load. This arrangement is well known and, accordingly, is not shown here. 1 .398,52 m3/hour (58c776, 5 mole/hour) of IIF 4 are introduced into the reactor via line 5. This includes 184.12 mole/hour of regenerated acid from a conduit 6, 322.08 mole/hour a stream rich in isobutane and 116.09 mole/hour D.^{the R} acid fluorli3 ' dric separated, collected in a conduit 7. In the reactor 4, the molar ratio of isobutane/hi ' I drocarbur 13/1 of olefin is about and the volume ratio of hydrofluoric acid/hydrocarbon is 1,48/1 about. The reactor pressure is about 4 atmospheres (abs.) 168 and hydrofluoric acid and the reactants are at a temperature of about 38 °c. The products, around the reaction zone 4, excluding IPD, is presented in table I values reported are expressed in moles per hour.

Table I: balance products about the reactor 4 The effluent load components

The heat of reaction is removed by cooling water entering through a conduit 8 and exiting through a conduit 9. The reactor effluent is removed by conduit 10, has 38 °c and the ATIA 15.8

The effluent enters a ripening device 11. The residence time of 8 minutes at Y is, about. The effluent is then transferred, by a conduit 12, in a separator hydrofluoric acid 13. Hydrofluoric acid separated is removed by conduit 14, amount of 1393.00 m3/hour (mole/hour 58,544.30), at a pressure of about 14.8 atms. On this amount, 1388.62 m3/hour are deflected by a conduit 5, exemplary acid recycle to the reactor 4. The 4.38 m3/hour remaining accumulate until the amount is sufficient for introduction into a regenerator acid 15o as an example, this acid is continuously drawn through the regenerator 15 through conduit 14. The regenerator 15 has, at its lower part, a pressure of 11.5 atms. and a temperature of 177 °c and, at its upper portion, a pressure of 10.9 atms. and a temperature of 71 °c. Hydrofluoric acid is extracted polymer products by introducing, by a conduit 16, 229.90 mole/hour of a stream rich to isobutane, to a temperature of 232 °c and pressure of 11.9 atms. The polymer products, in an amount of 0.05 m3/hour (0.18 moles/hour) are collected by a conduit 17, at a pressure of 11.5 atms. about and at a temperature of about 177 °c.

A portion of the feed current to isobutane rich from conduit 16 is deflected, by a conduit 32, in an amount of 92.18 mole/hour, cooled to 38 °c and introduced as reflux into the regenerator acid 15. The overhead stream, in the conduit 6, comprising 322.08 mole/hour hydrocarbon mole/hour 184.12 and hydrofluoric acid regenerated, is recycled so as to merge with the separated acid, in the duct 5, and returned to the reactor 4.

The feed is presented at Table II:

The hydrocarbon phase of the separator 13, and 14.8 atm. to 38 °c, is removed by conduit 18. It consists of 8.779, 21 mole/hour hydrocarbon mole/hour and 232.18 fluorhydriqué acid. It is heated to a temperature of 77 °c and introduced into a isoextracteur 19. 144.16 mole/hour of butane, to 38 °c, enter the upper section of the device 19, by the conduit 20. A stream rich in normal butane, amount of 96.59 mole/hour, is collected in the form of intermediate fraction, by a conduit 21 and is subjected to a treatment to 1' potassium hydroxide to remove trace amounts of RF. The device 19 operates, at a lower portion thereof, at a temperature of 189 °c and pressure of 11.9 atms. and, at its top, at a temperature of 60 °c and has a pressure of 11.3 atms. 93.88 m3/hour (mole/hour 628.30) alkylation product are collected by a conduit 22. A stream rich in isobutane is recycled, amount of 7.472, 22 mole/hour, by the conduits 1 and 2, to the reactor 4. Also collected, in the duct 2, 116.09 mole/hour of hydrofluoric acid.

The vapors passing overhead, 1.495, 08 mole/hour hydrocarbon mole/hour 130.92 and hydrofluoric acid, are removed by a conduit 23. On this amount, 747.54 mole/hour hydrocarbon mole/hour of 14.83 and RF are used as reflux to 1' isoextracteur 19. The balance (in moles) around the isoextrac

The current flowing in the conduit 23 in head and that is not sent as reflux to the device of isoextraction is mixed with 15.22 mole/hour of the HP from a conduit 24 and is introduced into a separator 25.

The separated acid is recycled, amount of 116.09 mole/hour, to the reactor 4, 5 and 7 through conduits " 761.70 mole/hour hydrocarbon mole/hour 15.22 and hydrofluoric acid are introduced, by a conduit 26, 27 in a deethanizing. A concentrate containing propane 15.22 mole/hour of hydrofluoric acid is collected at the head, in a conduit 28 which the introduced into an extractor of the IIF 29. The bottoms stream, either 585.03 mole/hour, is removed by conduit 30 and used as follows: 35.47 mole/hour as current α ℮ vidsrure, 322.08 mole/hour

to the regenerator 15 through conduit 16 and 227.52 mole/hour to the reactor 4 by the conduit 2, for recirculation. The deethanizing 27 operates, at its bottom, has a pressure of 22.4 atm.et a temperature of 104 °c and, at its top, at a temperature of 60 °c and pressure of 21.8 atms. The products, around the deethanizing 27, is presented in the table Y:

TABLE V: Balance products around the deethanizing

15.22 mole/hour of Hf are removed overhead through line 24 and mixed with the overhead stream of the isoextraction 23 in the conduit. 176.66 mole/hour of hydrocarbons are collected from the extractor of the IIF 29, by a conduit 31. The extractor of the IIF 29 operates, at its top, at a temperature of 60 °c and pressure of 22.0 atms. and, at its bottom, at a temperature of 66 °c and pressure of 22.8 atms.

The fig. 2. indicates the changes resulting from the implementation of the present invention. Has not been represented, in the drawing, the portion has_{the U} of the mixer device in arront maturation 11 and have been fastened isoextraction 19. The effluent enters the separator 13 through the conduit 12. The separated acid is removed through conduit 14 and is mainly returned to the reactor through the duct 5, as a recycle stream. The 184.30 mole/hour acid which, otherwise, would have been introduced into the regenerator, continue their path in the conduit 14 and are mixed with the hydrocarbon-rich phase of the conduit 18. The substance entering the device of isoextraction 19 is heated by a heat exchange device constituted by a conduit 33 containing pipeline valve 34, a conduit 35 containing a valve 36 and a valve 37 in the conduit 14.

Heat exchangers 38 and 39 may use, as a heat medium, the hot effluent from the bottom of the isoextracteur, the hot effluent from the lowest part of the deethanizing, or both. The temperature of the substance, in the conduit 18, is raised to a value of about 93 °c to 52 by influencing the amount of hydrofluoric acid passes into the conduits 33, 35 and 14. The technique to which will particularly uses will depend on many process variables, including the amount of acid not immediately recycled through line 5.

The currents drawn by the conduits 20, 21 and 23 have virtually the same composition as that indicated in the description of the fig. 1 ., except for hydrofluoric acid additional. The polymer products are collected in the conduit 22, in admixture with the normally liquid alkylation product. Experience has shown that the reverse of what is currently believed to date, the inclusion of these polymer products does not cause any degradation of the I>lb.

The overhead product clean from 1' isoextracteur 19 is mixed with the acid from the extractor hydrofluoric acid in the conduit 24 and continues, through line 23, into the separator 25. The conduit 26 transfers the hydrocarbon phase to the deethanizing, whilst the duct 7 causes the separated acid to the reactor along with the separated acid contained in the conduit 5. The conduit 30, joining the butane-rich recycle stream of the duct 2, transfers the bottoms product of the deethanizing to the reactor.

The product of the alkylation of normally liquid removed through conduit 22 has an octane number clear (search) of 93.3, of 104.2 with 3.0 cm3 tetraethyl lead, and a density of 15 °c to 0,686.

The results of a distillation of the product of the alkylation are presented at table VI:

TABLE VI : Distillation of the product of the alkylation of volumione percentage Initial boiling point 33 °C

5, 48 10' 58

20, 77

30, 91

40, 97

50 j00

60,103

70,106

80,112

90,135

Final boiling point 180

The present invention eliminates DP in many appliances. It is not necessary to perform a more thrust polymers contained in the acid and the disposal polymers do provides most problems. More importantly, the above have been achieved without degrading the quality of the product of the alkylation.