Process for regenerating fluorosulfuric acid catalyst

An improved process for regenerating an alkylation catalyst comprising fluorosulfuric acid, said catalyst being at least partially deactivated, which comprises the method of: (1) removing a portion of the fluorosulfuric acid from said catalyst by contacting same with a paraffin to form a liquid acid phase containing fluorosulfuric acid and an organic sludge formed during said alkylation and a gas phase containing said paraffin and fluorosulfuric acid; (2) contacting the liquid acid phase formed in step (1) with water to form an acid-water mixture, thereby coverting at least a portion of the fluorosulfuric acid contained therein to hydrogen fluoride and sulfuric acid; (3) removing at least a portion of the hydrogen fluoride from said acid-water mixture formed in step (2) by contacting same with a paraffin to form a gaseous phase containing hydrogen fluoride and paraffin; and (4) treating the gas phases formed in steps (1) and (3) with sulfur trioxide to regenerate the fluorosulfuric acid. In a preferred embodiment, at least a portion of the regenerated fluorosulfuric acid is recycled to the alkylation zone for use as an alkylation catalyst therein.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a process for regenerating a catalyst of 
the type used in hydrocarbon conversion processes. More particularly, this 
invention relates to a process for regenerating a catalyst comprising 
fluorosulfuric acid, at least a portion of said catalyst having become 
deactivated due to the formation of stable catalytically inert species 
during contact with a hydrocarbon feedstock in an alkylation process. 
2. Description of the Prior Art 
It is well known in the prior art that as the alkylation reaction proceeds, 
an organic material will form and will accumulate in the fluorosulfuric 
acid catalyst phase. The material has been given a variety of names 
including red oil, sludge, organic sludge, acid oil and the like. This 
organic material is a natural by-product of acid-catalyzed hydrocarbon 
reactions such as occur during alkylation and has been described in the 
literature as a conjunct polymer (see Miron, S. and Lee, R. J., "Molecular 
Structure of Conjugated Polymers," J. Chem. Eng. Data, Vol. 8, p. 150-160 
(1963), the disclosures of which are incorporated herein by reference). 
These conjunct polymers are complex mixtures of olefinic, conjugated 
cyclic hydrocarbons that may be formed from any type of hydrocarbon except 
aromatics. More specifically, they are believed to be cyclic polyolefinic 
hydrocarbons with a high proportion of conjugated double bonds, no two of 
which are in the same ring. Five membered ring systems predominate, but 
larger, and possibily also smaller, rings are believed to be present. The 
accumulation of this material will ultimately cause the activity of 
fluorosulfuric acid catalysts to decline until said catalysts cease to 
exhibit economic activity. In such cases, depending upon economic factors, 
the catalyst may be replaced or regenerated to restore desired activity 
levels. 
One method for regenerating catalysts comprising fluorosulfuric acid has 
been suggested in U.S. Pat. No. 3,766,293, the disclosures of which are 
incorporated herein by reference. According to this metal, an alkylation 
catalyst comprising fluorosulfuric acid, at least a portion of which has 
become deactivated, may be regenerated by (1) contacting said catalyst 
with water so as to convert at least a portion of the fluorosulfuric acid 
to hydrogen fluoride and sulfuric acid; (2) removing at least a portion of 
the hydrogen fluoride from said catalyst by contacting the same with a 
paraffin so as to form a hydrocarbon phase containing hydrogen fluoride; 
and (3) treating said hydrocarbon phase with sulfur trioxide to regenerate 
the fluorosulfuric acid. However, since sulfur trioxide is a fairly 
expensive reagent, it would be desirable to have available a simple and 
convenient method for minimizing the consumption of sulfur trioxide in 
step (3) of U.S. Pat. No. 3,766,293. 
SUMMARY OF THE INVENTION 
Now according to the present invention, an improved process for 
regenerating an alkylation catalyst comprising fluorosulfuric acid has 
been discovered, said process comprising: 
(1) removing a portion of the fluorosulfuric acid from said catalyst by 
contacting same with a paraffin to form a liquid acid phase containing 
fluorosulfuric acid and an organic sludge formed during said alkylation 
and a gas phase containing said paraffin and fluorosulfuric acid; 
(2) contacting the liquid acid phase formed in step (1) with water to form 
an acid-water mixture, thereby converting at least a portion of the 
fluorosulfuric acid contained in said liquid acid phase to hydrogen 
fluoride and sulfuric acid; 
(3) removing at least a portion of the hydrogen fluoride from said 
acid-water mixture of step (2) by contacting same with a paraffin so as to 
form a gas phase containing paraffin and hydrogen fluoride; and 
(4) treating the gas phases from steps (1) and (3) with sulfur trioxide so 
as to regenerate the fluorosulfuric acid. 
Use of the present invention permits recovery of a portion of the 
fluorosulfuric acid present in the deactivated or partially deactivated 
catalyst prior to undergoing the reaction with water in step (2) above. 
This results in a reduced consumption of sulfur trioxide since, as will be 
discussed hereinbelow, one mole of sulfur trioxide is conserved for each 
mole of fluorosulfuric acid that is not reacted in step (2). This results 
in a significant reduction in regeneration costs because sulfur trioxide 
is fairly expensive. In a preferred embodiment, at least a portion of the 
regenerated fluorosulfuric acid is recycled to the alkylation process.

DETAILED DESCRIPTION OF THE INVENTION 
Having thus described the invention in general terms, reference is now made 
to the FIGURE which shows an alkylation process using a catalyst system 
such as that described in U.S. Pat. No. 3,887,635, the disclosures of 
which are incorporated herein by reference. Such details are included as 
are necessary for a clear understanding of how the present invention may 
be applied in the regeneration of an alkylation catalyst comprising 
fluorosulfuric acid, said catalyst being at least partially deactivated. 
No intention is made to unduly limit the scope of the present invention to 
the particular configuration shown as variations obvious to those having 
ordinary skill in the art of alkylation and other unit operation processes 
are included within the broad scope of the present invention. 
Referring now to the FIGURE, there is shown an olefin stream in line 2 
which is, preferably, admixed with a paraffin stream in line 4 before 
introducing the combined stream into alkylation zone 6. If desired, 
however, the olefin and paraffin streams can be fed directly into 
alkylation zone 6. The olefin concentration in the feed ranges from 0.5 to 
25 volume percent based on total feed and preferably below 10 volume 
percent. Translated into volume ratios, high volume ratios of paraffin to 
olefin ranging from 10:1 to 200:1 or higher are preferred, although 
somewhat lower ratios may be used, e.g., 3:1. Correspondingly high volume 
ratios of paraffin to olefin are also desired within the alkylation zone. 
Preferably, the parafin/olefin ratio therein ranges from about 5:1 to 
2,000:1 or higher. 
Suitable olefinic reactants include C.sub.2 -C.sub.12 terminal and internal 
monoolefins such as ethylene, propylene, isobutylene, butene-1, butene-2, 
the pentenes (e.g., trimethylethylene) and similar higher monoolefinic 
hydrocarbons of either a straight chain or a branched chain structure. 
Preferably, the C.sub.2 -C.sub.6 monoolefins are used, although the 
highly-branched C.sub.7 -C.sub.12 monoolefins may also be used. The 
reaction mixtures may also contain small amounts of diolefins and other 
type hydrocarbons normally present in refinery hydrocarbon streams. 
Although it is desirable from an economic standpoint to use the normally 
gaseous olefins as reactants, normally liquid olefins may be used. Thus, 
reactable polymers, copolymers, interpolymers, cross-polymers, and the 
like, of the above-mentioned olefins, such as, for example, the 
diisobutylene and triisobutylene polymers, the codimer of normal butylene 
and isobutylene of butadiene and isobutylene, may be employed as an 
olefinic reactant. Mixtures of two or more of the olefins described above 
can be used as the process feedstock. 
C.sub.2, C.sub.3, C.sub.4 and/or C.sub.5 olefin cuts from thermal and/or 
catalytic cracking units; field butanes which have been subjected to prior 
isomerization and/or partial dehydrogenation treatment; refinery 
stabilizer bottoms; spent gases; normally liquid products from sulfuric 
acid or phosphoric acid catalyzed polymerization and copolymerization 
processes; and products, normally liquid in character, from thermal and/or 
catalytic cracking units, are all excellent feedstocks for the present 
alkylation process. Such feeds are preferably dried to control excess 
water buildup, i.e., about 5 to 15 wppm or less of water, before entering 
the alkylation zone. 
The paraffinic feedstocks that can be reacted with the olefins desirably 
comprise straight and/or branched chain C.sub.4 -C.sub.10 paraffins such 
as hexane, butane and the like, and preferably C.sub.4 -C.sub.6 
isoparaffins such as isobutane, isopentane, isohexane and the like. While 
open chain hydrocarbons are preferred, cycloparaffins such as 
methylcyclopentane may also be used. 
Returning to the FIGURE, a catalyst comprising fluorosulfuric acid and one 
or more moderators is shown being introduced into alkylation zone 6 via 
line 8. Generally, the moderator contains at least one oxygen atom per 
molecule and includes water, aliphatic and cycloaliphatic alcohols and 
ethers, aliphatic, cycloaliphatic and aromatic sulfonic and carboxylic 
acids and their derivatives, inorganic acids and other oxygen-containing 
organic compounds. By the term "moderator" is meant a compound which, in 
combination with fluorosulfuric acid, produces a catalyst system of 
reduced acidity vis-a-vis the fluorosulfuric acid, and thereby decreases 
the probability of undesirable competing side reactions which have a 
detrimental effect on product quality, while increasing catalyst 
selectivity to desirable highly branched paraffinic products, thus 
resulting in high quality alkylate product. Various moderators that can be 
employed in the present catalyst system are shown at column 2, lines 
38-67, column 3, lines 16-68 and column 4, lines 1-23 of U.S. Pat. No. 
3,887,635. 
Preferred catalyst moderators contain either a hydroxy group such as 
alcohols or a hydroxy group precursor, such as ethers, which, it is 
speculated, can potentially cleave to form alcohols under the acidic 
conditions of the subject invention. Of these, the more preferred 
moderators are the alcohols and water, the most preferred being water. It 
is noted that the catalyst moderator and the fluorosulfuric acid can be 
premixed prior to introduction into the reactor, thereby forming the 
catalyst system. The catalyst may also be formed in situ. 
The exact mechanism by which the moderator compounds effectuate increased 
catalyst selectivity while reducing competitive side reactions is not 
known. However, the active catalyst species employed herein are postulated 
to be an equilibrium mixture comprising several components. By way of 
illustration, it is speculated that the addition of water to 
fluorosulfuric acid results in initial dissociation of the strong acid 
followed by hydrolysis: 
##EQU1## 
The equilibrium is believed to lie towards the right and, therefore, 
little, if any, free water should exist in the strong acid system. Similar 
mechanisms can be postulated for other moderators such as alcohols and 
ethers. 
By the very nature of the postulated mechanism, it is clear that the manner 
in which the active catalytic system is formed is immaterial. Thus, in the 
above illustration mixing HF and H.sub.2 SO.sub.4 in equal molar amounts 
should result in the same catalyst system as would be obtained by mixing 
water with HSO.sub.3 F. The active catalyst system may also be formed by 
mixing HF, H.sub.2 SO.sub.4 and HSO.sub.3 F in appropriate amounts. Hence, 
when the catalyst system is described as "being formed from" a strong acid 
and a moderator, it is not meant to be limited to any one catalyst 
formation mode; rather, this description is used merely for convenience in 
providing a simple definition of the active catalyst system. 
The amount of moderator used in forming the catalyst system is an important 
variable in the production of high quality alkylate. The desired amounts 
of moderator will vary dependent, in part, on the alkylation temperature. 
Thus, for example, at temperatures between about 0.degree. to 40.degree. 
F, useful amounts of moderator can range between about 5 and 45 mole % 
based on acid. In some instances, however, it may be desirble to use 
somewhat lower or higher amount of moderator, e.g., 50 mole % based on 
acid, where, for example, different catalyst activity or selectivity is 
desired. 
At high alkylation temperatures, e.g., between about 40.degree. and 
100.degree. F, increased amount of moderator may be desirable due to the 
increased strong acid activity. Thus, an amount of moderator ranging 
between about 50 and 100 mole % based on acid may be used at these higher 
temperatures. In fact, under appropriate conditions, these higher amounts 
of moderator may also be utilized at the lower temperatures disclosed 
hereinabove, if desired. A preferred catalyst is one formed from 
fluorosulfuric acid and from about 5 to 100 mole %, based on acid, of (1) 
water, (2) a C.sub.1 -C.sub.7 saturated aliphatic monohydroxyalcohol, or 
(3) a mixture of water and said alcohol. 
Although the broad concentration ranges are generally independent of the 
type moderator used, the preferred or optimal range will vary depending on 
the structure of the moderator, the reaction temperature, the 
concentration and nature of the olefin in the feed, the amount of organic 
sludge present, the olefin space velocity and the like. 
In addition to being used in classical alkylation processes as hereinabove 
described, the catalyst system employed herein may also be used in 
self-alkylation processes. The C.sub.4 -C.sub.16 branched chain olefins 
and C.sub.4 -C.sub.8 isoparaffins are preferred reactants. The process is 
generally conducted in the liquid phase whereby the isoparaffin is 
dimerized and the olefin is sacrificed by being saturated, thus producing 
an alkylate-type product of high quality. Self-alkylation processes are 
generally described in U.S. Pat. No. 3,150,204. Undesired side reactions 
are minimized using these catalyst systems, thereby providing high yields 
of the desired products. 
In general, the amount of olefin contacted with the catalyst can range from 
about 0.05 to 1000 volumes of olefin per hour per volume of catalyst 
inventory in the reactor (V/V/Hr.), i.e., olefin space velocity. 
Preferably, the olefin space velocity ranges from about 0.05 to 10.0 
V/V/Hr., and still more preferably from about 0.05 to 1.0 V/V/Hr., e.g., 
0.1 V/V/Hr. The volume % of total catalyst in the reaction mixture or 
emulsion (when liquid phase operations are used) in the alkylation zone 
can range from about 30 to 80 volume % based on total reaction mixture and 
preferably from about 50 to 70 volume %. The isoparaffin concentration, 
including alkylate, in the hydrocarbon phase (in a liquid phase process) 
can range from 40 to about 100 volume % based on the total volume of the 
hydrocarbon phase and preferably from 50 to 90 volume %. Such isoparaffin 
concentrations can be maintained by recycling unreacted isoparaffin to the 
alkylation zone. 
The process may be carried out either as a batch or continuous type of 
operation, although it is preferred for economic reasons to carry out the 
process continuously. It has been generally established that in alkylation 
processes, the more intimate the contact between the feedstock and the 
catalyst the better the yield of saturated product obtained. With this in 
mind, the present process, when operated in either a batch or in a 
continuous manner, is characterized by the use of vigorous mechanical 
stirring or mixing of the reactants with the catalyst. 
In continuous operations, as that of the embodiment shown in the drawing, 
the reactants may be maintained at sufficient pressures and temperatures 
to maintain them substantially in the liquid state and then continuously 
forced through dispersion devices into the alkylation zone. The dispersion 
devices may be jets, porous thimbles and the like. The reactants are 
subsequently mixed with the catalyst in alkylation zone 6 by conventional 
mixing means (not shown) such as mechanical agitators and the like. While 
the alkylation reaction can be carried out at a temperature within the 
range of from about -80.degree. to +100.degree. F, fairly low reaction 
temperatures, preferably within the range of from about -80.degree. to 
+70.degree. F, and most preferably within the range of from about 
-20.degree. to about +40.degree. F, are usually employed. Where the 
reaction is carried out at temperatures about +10.degree. F, or higher, it 
is necessary that the reaction be conducted under superatmospheric 
pressure, if the reactants and/or the catalysts are to be maintained 
substantially in a liquid state. Typically, the alkylation reaction is 
conducted at pressures varying from about atmospheric to about 300 psia. 
In general it is preferably to employ pressures sufficiently high to 
maintain the reactants in the liquid phase although a vapor phase 
operation is also contemplated. Autorefrigerated reactors and the like may 
be employed to maintain liquid phase operation. Although it is preferred 
to run the reaction neat, solvents or diluents may be employed if desired. 
After allowing sufficient residence time for the reaction to progress, 
typically on the order from about one minute to one hour or more, the 
reaction mixture which contains hydrocarbon and deactivated or partially 
deactivated catalyst (often referred to as the "emulsion mixture") is 
withdrawn from the alkylation zone 6 via line 10 and passed into a 
settling zone 12. The reaction mixture will separate in zone 12 into a 
heavy acid phase containing the fluorosulfuric acid, sulfuric acid, 
hydrogen fluoride and moderator (assumed to be water for the purpose of 
illustration in the following discussion), as well as organic sludge 
formed during said alkylation process, and a hydrocarbon phase containing 
the alkylate product along with smaller amounts of fluorosulfuric acid, 
hydrogen fluoride and water which are dispersed and/or dissolved in said 
alkylate product. The acid phase is withdrawn from settling zone 12 via 
line 14 and at least a portion thereof can be recycled to alkylation zone 
6 via line 8 or charged to another alkylation zone, if desired. The 
hydrocarbon phase is withdrawn from settling zone 12 via line 16. 
As shown in the FIGURE, a purge stream 18 of the heavy acid phase is 
withdrawn from line 14 and passed into the prestripping zone 20 and 
intimately contacted with a vaporized paraffin introduced via line 22. 
Preferred paraffins are C.sub.3 -C.sub.6 paraffins, more preferably 
C.sub.4 paraffins. Normal butane is the preferred paraffin. As a result of 
said contacting, a portion, preferably a major portion, more preferably 
from about 60 to 90%, of both the hydrofluoric acid and the fluorosulfuric 
acid is stripped from said purge stream, thereby forming a gas phase 
containing paraffin, fluorosulfuric acid and hydrogen fluoride and a 
liquid phase containing fluorosulfuric acid, organic sludge and sulfuric 
acid and traces of hydrogen fluoride. The amount of stripping agent 
employed is that required to remove the desired amount of fluorosulfuric 
acid. It should be pointed out that hydrofluoric acid and sulfuric acid 
are present in streams 14 and 18 because the fluorosulfuric acid is 
partially dissociated when contacted with the moderator, e.g., water. If 
no moderator is employed, small amounts of water are normally introduced 
into the alkylation zone (e.g., with the feed) such that said partial 
dissociation will occur. Be that as it may, however, the present 
regeneration process is also applicable to a fluorosulfuric acid catalyst 
that has not been hydrolyzed. 
The liquid phase then passes from pre-stripping zone 20 via line 24 to 
conversion zone 26 wherein it is contacted with water injected via line 28 
in an amount sufficient to convert the fluorosulfuric acid to free 
hydrogen fluoride and sulfuric acid according to the reaction: 
##EQU2## 
In one embodiment of the invention, it may be desirable to add up to a 
mole of water in excess of the stoichiometric amount required. Preferably, 
less than about 0.5 mole excess water is used. The resulting stream of 
water, hydrogen fluoride, sulfuric acid and organic sludge is then passed 
from conversion zone 26 via line 30 into stripping zone 32 and intimately 
contacted therein with a paraffin introduced via line 34, thereby 
stripping at least a portion, preferably a major portion, more preferably 
substantially all (i.e., about 95% or more) of the hydrogen fluoride from 
said stream. The gas phase from pre-stripping zone 20 is introduced into 
the upper section 36 of stripping zone 32 via line 38 wherein the hydrogen 
fluoride present therein, as well as that removed in the lower section of 
stripping zone 32, is reacted with at least a stoichiometric amount of 
sulfur trioxide, based on HF, so that at least a portion, preferably 
substantially all, of the hydrogen fluoride present is converted to 
fluorosulfuric acid according to the reaction: 
EQU HF + SO.sub.3 .fwdarw. HSO.sub.3 F + Heat (3) 
The sulfur trioxide, which is introduced via line 40, thus regenerates the 
fluorosulfuric acid catalyst which, together with the paraffin and perhaps 
a trace of water is taken overhead via line 42, condensed in condensation 
zone 44, and passed to separation zone 46 wherein the fluorosulfuric acid 
is separated from the paraffin present in the stream. The regenerated 
fluorosulfuric acid stream, which may contain negligible amounts of water 
(typically less than 100 wppm since most all of the water present will 
react with sulfur trioxide to form sulfuric acid), is withdrawn from the 
separation zone via line 48 and at least a portion thereof may be combined 
with the recycle stream 14 for return to alkylation zone 6 via line 8. The 
paraffin stream is removed from separation zone 46 via line 50. If 
desired, at least a portion of the paraffin stream may be recycled to 
conversion zones 26 and 36 for temperature control purposes or may be used 
as part of the stripping agent in zone 20. Additional hydrocarbon 
stripping agent can be introduced into said stripping zones if desired. 
Sulfuric acid and the sludge formed during the alkylation process can be 
removed from the bottom of stripping zone 32 via line 52 and sent to 
sulfuric acid regeneration (not shown) for sludge removal and 
reconcentration, or it can be discharged. Alternatively, the sulfuric 
acid-sludge stream can be employed for removing dissolved and/or dispersed 
fluorosulfuric acid from a hydrocarbon phage 16. 
The particular temperature and pressure employed in the conversion and 
stripping zones are, in general, determined by economic factors such as 
cost or availability of stripping agent, cost of SO.sub.3, etc. Normally, 
zone 20 should be operated at a temperature above that at which the vapor 
pressure of fluorosulfuric acid becomes sufficiently low such that 
uneconomical amounts of stripping agent are required. It is also desirable 
to operate zone 20 at as high a temperature as possible because better 
stripping is obtained and less stripping agent is required. However, as 
disclosed in application Ser. No. 772,636 filed on the same date herewith, 
undesirable side reactions between the fluorosulfuric acid and acidic 
components in the catalyst (e.g., HF, H.sub.2 SO.sub.4 and the like) and 
the hydrocarbon stripping agent become excessive at elevated temperatures, 
i.e., temperatures above about 250.degree. F. Such reactions result in the 
formation of a polymer-like material, e.g., coke, that could "plug" the 
system. Thus, while elevated temperatures would normally be preferred, it 
has been found necessary, as disclosed in Ser. No. 772,636, to avoid 
contacting the acid components with the hydrocarbon stripping agent at 
temperatures in excess of 250.degree. F. Therefore, as disclosed in Ser. 
No. 772,636, it is desirable that the temperature of the conversion and 
stripping zones be maintained below 250.degree. F and in the range of from 
about 120.degree. to about 250.degree. F, preferably in the range of from 
about 130.degree. to about 210.degree. F, and more preferably in the range 
of from about 140.degree. to 170.degree. F. Total pressure of the zones 
can also vary according to the economic factors mentioned above. In 
general, however, the total pressure will range from about atmospheric 
pressure to about 170 psia, preferably about 120 psia and more preferably 
from about 20 to about 90 psia. 
Stripping of the deactivated or partially deactivated catalyst with a 
paraffin in zone 20 prior to contact with water in zone 26 results in 
reduced consumption of sulfur trioxide since for each mole of 
fluorosulfuric acid that does not undergo reactions (2) and (3) above, one 
mole of sulfur trioxide is conserved. In addition, the sulfuric acid 
produced via reaction (2) is reduced by a corresponding amount, such that 
less sulfuric acid will be processed in the sulfuric acid regeneration 
process. Thus, when a deactivated or partially deactivated catalyst 
comprising fluorosulfuric acid is regenerated according to the present 
invention, both the sulfuric acid produced and the sulfur trioxide 
required are reduced by from about 35 to 90%, i.e., the amount of 
fluorosulfuric acid recovered ranges from about 35 to about 90% of that 
present in purge stream 18. This represents a significant cost reduction 
for regenerating fluorosulfuric acid. The lower level of recovery 
represents that expected using about one theoretical stripping tray and a 
molar ratio of stripping agent to catalyst plus sludge of about 7.5/1. The 
higher recovery represents that expected using about two theoretical 
stripping trays and a molar ratio of stripping agent to catalyst plus 
sludge of about 14/1. The specific amount of fluorosulfuric acid removed 
during pre-stripping is a function of economics incuding, for example, the 
lower overall consumption of sulfur trioxide versus the costs associated 
with paraffin stripping plus the conversion and recovery described in 
reactions (2) and (3). 
As previously noted, hydrocarbon phase 16 contains dissolved and/or 
dispersed fluorosulfuric acid, water, hydrogen fluoride from partial 
dissociation of the acid, and other acidic materials such as sulfur 
dioxide, etc. If desired, the acid materials which are dissolved and/or 
dispersed in hydrocarbon phase 16 can be effectively removed by scrubbing 
said hydrocarbon phase with sulfuric acid. The sulfuric acid is preferably 
concentrated, being 98.0 to 100% H.sub.2 SO.sub.4 as limited by the 
freezing point of the acid, but somewhat more dilute acid (95-97.9%) can 
also be used without substantial detriment to the efficiency of the 
process. The manner of scrubbing may be by any conventional means, such as 
by passing the sulfuric acid and hydrocarbons through a mixing orifice, a 
countercurrent contacting tower or by injecting them into a centrifugal 
pump, etc., as long as intimate contact between the hydrocarbon phase and 
the sulfuric acid is attacined. However, countercurrent-staged operations 
are preferred. The ratio of acid to hydrocarbon is not critical, but can 
vary from about 5 to 95% of the hydrocarbon stream. The temperature for 
scrubbing generally ranges from about 20.degree. to 100.degree. F, but 
must be above the freezing point of sulfuric acid. The pressure may be any 
pressure from atmospheric to about 500 psig. The resulting phases are 
settled after contacting. The hydrocarbon phase containing alkylate 
product may undergo further treatment to remove trace amounts of any acid 
materials present therein. Fluorosulfuric acid present in the sulfuric 
acid phase thus settled may be removed therefrom by introducing the acid 
phase into the regeneration process described above, e.g., into 
pre-stripping zone 20, or, preferably, directly into conversion zone 26. 
The stripping zones and conversion tower are conventional equipment 
suitable for gas-liquid or liquid-liquid contacting and are available from 
various equipment vendors. As such, they do not form a part of this 
invention. However, Hastelloy B or C is normally employed although at 
lower temperatures with substantially no free water present, carbon steel 
may be used. The conversion and stripping zones may comprise one vessel if 
desired. 
It should be pointed out that the level of activity at which the 
fluorosulfuric acid catalyst should be regenerated is not only a matter of 
ability to catalyze the alkylation reaction, but also a matter of 
economics. For example, it may be desirable to regenerate a mildly 
deactivated catalyst to essentially fresh catalyst activity rather than 
allow the catalyst to be reduced to a much lower level of activity and be 
regenerated to fresh or to less than fresh activity. Thus, as used herein, 
the term "regeneration" or "regenerated" means recovering a fluorosulfuric 
acid catalyst that possesses a greater activity for alkylation than that 
possessed by the deactivated or partially deactivated catalyst. It should 
be understood that the regeneration process of the present invention is 
applicable to catalysts such as those defined above which have lost some 
degree of activity and that the regeneration may only partially restore 
the lost activity. 
Although the present regeneration process has been discussed with reference 
to the alkylation process described in U.S. Pat. No. 3,887,635, it should 
be understood that it is applicable to any alkylation process that employs 
fluorosulfuric acid (see, for example, U.S. Pat. Nos. 3,922,319 and 
3,928,487, the disclosures of which are incorporated herein by reference), 
including those processes that form fluorosulfuric acid from a strong acid 
and a moderator, e.g., mixing sulfuric acid and hydrofluoric acid in 
appropiate amounts, alone or in the presence of HSO.sub.3 F. (See, for 
example, U.S. Pat. No. 3,956,418.)