DE2050323A1 - Process for sweetening hydrocarbons - Google Patents

Description

DIPl-INO.

HELMUT GORTZ Frankfurt «m MiIn 70

TLfITW Oct 11, 1970

Gzy / goe UNION CARBIDE CORPORATION

Process for sweetening hydrocarbons.

The invention relates to a method for sweetening flowing acidic hydrocarbons by removing sulfur-containing hydrocarbons Impurities from contacting the flowing hydrocarbon with a crystalline zeolitic Molecular sieve, subsequent regeneration of the molecular sieve by desorbing the sulfur-containing ones Substances and reuse of the regenerated molecular sieve for renewed sweetening of flowing acidic hydrocarbons.

The removal of sulfur compounds, especially from Hydrogen sulfide and from alkyl mercaptans, flowing out Hydrocarbons are desirable for many reasons. Here the intended use of the sweetened end products plays a role in part. As a very large proportion of the lighter hydrocarbons are used as fuel for themselves is the presence of sulfur compounds because of the unpleasant odor and pollution of the Air objectionable due to dxo combustion products. Vfenn

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the hydrocarbons for internal combustion in Machines used so are the sulfur compounds harmful to the effectiveness of anti-knock agents, such as Tetraethyl lead. The heavier hydrocarbons are by far. Scope converted, with the necessary Catalysts usually easily through sulfur compounds can be poisoned.

Various methods of sweetening flowing hydrocarbons have been proposed and used, to which chemical and physical processes belongIn the chemical processes, nan purely chemical conversions are used, like washing out with monoethanolamine or countercurrent extraction with a hot solution of potassium carbonate. Chemical sorption processes are also known in which the sulfur compounds on the surface of Achwamra-shaped egg oxide can be collected

To the selective physical adsorption process for Removal of sulphurous contaminants is one of them more recently the use of crystalline zeolitic molecular sieves. This procedure will likely now widely used. Processes for the treatment of liquids and vapors have been developed here been. The treatment of liquids is

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drawn by flowing olefins and low-boiling paraffinic hydrocarbons.

When sweetening liquid hydrocarbons, one leaves one Fraction of a sulfur-containing hydrocarbon, e.g. a stabilized natural gasoline, flow through a bed of adsorbent molecular sieve This sieve has pores of such a diameter that the sulfur-containing impurities are adsorbed · the one flowing through Hydrocarbon with its non-adsorbed constituents is obtained until the desired Loading of the adsorbent with the sulfur-containing impurities is reached. Then you rinse the adsorbed Hydrocarbons and regenerates the adsorbent 'by desorbing the sulfur-containing compounds. "·, *

Usually used when regenerating the adsorbent a thermal pendulum process or a combined · «thermal and pressure pendulum process. The necessary Heat is supplied by a hot gas that is opposed to the molecular sieve and the hydrocarbons the sulfur-containing adsorbate is relatively inert " Natural gas is particularly well suited for flushing and regeneration.

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can be turned. This can at least partially offset the relatively high costs for the natural gas. Often, however, more natural gas is needed for sweetening during regeneration than can be used as fuel. This leads to an imbalance in consumption. This fact is a serious · * obstacle to the successful implementation of a ψ sweetening process, especially if desulphurisation is carried out in a location which, as is often the case, is remote from the refinery. *

To create an inert atmosphere for regeneration, fuel and air are mixed in approximately "stoichiometric" proportions so that a combustion gas is obtained without free oxygen - times the volume of the natural gas used. The combustion gas obtained in this way is then further treated in order to reduce the contents of carbon dioxide and water: The costs of such an inert gas depend to a large extent on the required purity and that required moisture content. the cost of a plant for the production of an inert gas with niedrigen'Druckes, a dew point of -'iO ° C · may be twice that cost can be comparable with which a gas obtained with a dew point of +38 ⁰ C.

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The invention is based on the surprising finding that large-pore zeolitic molecular sieves can contain larger amounts of residual adsorbed water without their selectivity or their ability to adsorb sulfur-containing impurities from liquid * flowing hydrocarbons being reduced, in clear contrast to this fuel It is well known that when sweetening in the vapor phase, the presence of relatively small amounts of water in Molβkμlarβiβb has a damaging effect on the selectivity and the adsorption capacity, so that the process is economically impracticable. that the equilibrium weight capacity at a pressure of 31 * 5 kg / o "and at a temperature of 30 ° C of a completely dehydrated sodium zeolite X with about 0.1% by weight (residual water for hydrogen sulfide from a natural gas with 40 ppm HS is practical is the same as for liquid butane, with about 1050 ppm H £. If the adsorption is carried out in the gas phase - at the same temperature and pressure by means of a content of 1.8% by weight of several water in the Sodium zeolite X shows a decrease in the equilibrium adsorption capacity for H ₃ S by 48 9 (.,. In contrast to this, a sodium zeolite X with a content of 4.1% by weight of residual water has a decrease in the equilibrium β capacity at for HS from a liquid of only -30 wt .- #

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with comparable concentrations of hydrogen sulfide. With this knowledge it has now become possible to sweeten a liquid hydrocarbon, using a purge gas to remove the sulfur-containing compounds from the Molecular sieve a gas with a high water content can be used «You can even use water vapor as a flushing gas and that is a preferred embodiment of the method according to the invention

According to the invention, it is not critical which origin or what composition the hydrocarbon is One can, for example, sweeten the wholesalers, which are used in the de- ^ Structural hydrogenation of coal arise., or from Erdags or Fri, Ι, -I < >; ritrnnrien are «sulphurous condensates of natural gas, i.e. the LPG additions that are rich to propane and uutanes are, are for the invention P process just as well suited as natural gasoline and relatively light petroleum fractions with boiling ranges between - * »2 and about 82 ° C, which is an essential part Hydrocarbons with 3 to 6 carbon atoms in the Molecule included. According to the invention, liquid can also be used or liquefiable olefins or mixtures containing olefins, use mixtures as needed for alkylation

the

will contain / Propy1 on, Dutylen, AmyJen and the like.

8AD ORIGINAL

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The sulfur-containing impurities in the al · starting material Serving hydrocarbon can be a compound but usually consist of a mixture of two or more compounds, such as hydrogen sulfide, mercaptans, like> ethyl mercaptan, n-propyl mercaptan, iaopropyl mercaptan, n-butyl mercaptan, tsobutylsiercaptan, p-butyllaercaptan and the isomeric forms of amyl and hexyl mercaptan, heterocyclic Sulfur compounds such as thiophene and 1,2-dithiol " aromatic mercaptans such as phenyl mercaptan, organic sulfides and disulfides and carbonyl sulfides.

As an adsorbent "in the process according to the invention are natural or synthetic crystalline zeolite ^ aluminosilicates used, which are usually referred to as molecular sieves or ζ eoJ. £ this before molecular sieves · as opposed to to other adsorbents with pores of different dimensions, the molecular sieves are at least partially characterized by that they have pores of uniform dimensions · The particular molecular sieves to be used must have pores whose diameter is large enough to accommodate those in the hydrocarbons to let in sulfur compounds contained * Molecular sieves with a minimum pore diameter of at least 3.8 X are suitable for adsorbing hydrogen sulfide. For normal mercaptans with fewer than 7 fillet atoms in the molecule, the apparent pore size should

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at least about 4.6A. Sulfur compounds with larger molecular dimensions, such as isopropyl mercaptan, Isobutyl mercaptan, p-butyl mercaptan, the isomers Forms of aryl and hexyl mercaptan, and the heterocyclic ones Sulfur compounds such as thiophene or the aromatic mercaptans such as phenyl mercaptan require this Use of zeolite molecular sieves with apparent pore openings of at least about 6 Å. Since it seldom before « comes ι that an acidic hydrocarbon does not have sulfur compounds larger molecular dimensions. contains, should ■ to preferably use molecular sieves whose apparently fr pore diameter at least 8 X, preferably at at least 10 A.

The term "apparent pore diameter" denotes the maximum critical dimensions at which, under normal conditions, adsorption in zeolitic molecular sieves takes place. The apparent diameter of the forum is always larger than the actual pore diameter . This _{t <latter} lsi the free diameter "wipe neighboring Silicatringen in the zeolite. ~

The natural zeolites which can be used according to the invention include mord en it and chabazite, both of which have an apparent pore diameter of about k% . Erionite with a

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apparent pore diameter of about 5 Å and faujasite a pore diameter of about 10 A. These natural ones Substances are described in the relevant literature »Among the preferred synthetic, crystalline zeolitic Molecular sieves include the zeolites X, Y, JL and XX and synthetic mordenite with large pores. Zeolite L has one apparent pore diameter of about 1Q A and is described in US Pat. No. 3,216,789. Zeolite X has an apparent pore diameter of about 10 Å and is described in Ju of US Pat. No. 2,882,244. Zeolite Y has an apparent pore diameter of about 10 y? and is described in U.S. Patent No. 3,130,007. Zeolite -Ω- is proposed in US patent application No. 65 ^ i3l8. Zeolite L is described in U.S. Patent No. 3,216,789. The production of large-pore synthetic mordenite is described in US Pat U.S. Patent No. 3,436,174.

The pore size ο of the zeolitic molecular sieves can be changed by using different metallic cations. For example, a sodium zeolite A according to US Pat. No. 2,882,243 has an apparent pore diameter of about 4 Å, while a calcium zeolite A has an apparent pore diameter of about 5 Å.

8AO ORIGINAL

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The zeolites are agglomerates of fine crystals or they are al. «fine powders produced synthetically and then preferably brought in the form of tablets or pellets, to use them on a large scale as adsorbents ^ It is known that pelletizing is very satisfactory for the sorption properties of the .Zeolite, namely the selectivity and the capacity, essentially unchanged allow. Suitable inert binders are also known for this purpose, e.g. clays, heat-resistant netaloxides and silicates of alkali metals, if nan wants to use the adsorbents in agglomerated form The single crystal of the molecular sieves is very small, about 10 Micron and for use in a fixed bed it is therefore

expediently, the crystals into beads, pellets, extrudates and the like to agglomerate, either old or without an added binder

The method of bringing the flowing acidic hydrocarbon into contact with the adsorbent molecular sieves is not critical to the invention. For example, one or more fixed beds of adsorbent material, movable beds, slurries, or combinations of these methods can be used. The hydrocarbon used as starting material can flow in cocurrent, countercurrent or cross-current with the molecular sieve

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6AD ORIGINAL

Adsorbent materials are most commonly used in sweetening used by flowing carbon hydrogen · So to be the following process steps in the usual order performedί (a) Adsorption of unwanted "" sulfur-containing impurities from the flowing liquid hydrocarbon; (b) displacing the liquid from the interstices of the adsorbent;

(c) volatilizing the entrapped liquid;

(d) regenerating the molecular sieve; (e) cooling the Adsorbents; (f) filling the bed for further cleaning.

According to Fig. 1, two beds 10 and 11 of crystalline zeolitic molecular sieves are used ι they are arranged parallel to each other, so that when in the one Bed adsorption takes place ^ through the other bed Rinsing and cooling is regenerated * In this way, one can continuously be freed from sulfur compounds Liquid can be removed. If continuous work is not required, β »may be preferable, a single bed of zeolitic molecular sieves · to use »Here the starting material is only used at time intervals supplied «

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The acidic liquid hydrocarbon containing sulfur compounds is fed through line 12, preferably at room temperature, although this is not critical. The choice of the optimum temperature depends on economic factors. Considerations from because the zeolite molecular sieves have a higher adsorption capacity at lower temperatures, and considering the cost of Waraeaustau- w shear to obtain the lower temperature · Viscosity can also play a role in heavy hydrocarbons * The pressure zua feeding reactants mis only so high "that the liquid is pressed through the bed of the adsorbent without the individual parts of the molecular sieve badly touching each other, adevu. that abrasion takes place.

The liquid hydrocarbon can with a linear Qefc .speed between 3 ce and 6 ■ per minute, as a precaution «I see 30 ca and 3 ■ per minute evaluate« The Gor and β for this are the. the following: At low linear speeds a thin layer of the liquid • on the outer surface of each zeolite particle, ine.besoxide.re because of the viscosity of the hydrocarbon. The sulfur compound can pass through this layer and enter the pores and the crystal lattice and are adsorbed there. A thicker film or a thicker one

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However, this layer creates a resistance to this passage and thereby reduce the rate of adsorption. As the flow velocity increases, it increases the layer thickness of the liquid Pilsiee from, which also the resistance is reduced and the Adsorptionsge <~ speed is increased «as the linear Flow velocity disappears the liquid Filsi practically complete, and the adsorption depends primarily on the contact time between the flowing Hydrocarbon and the zeolite molecular sieve Sufficient time must therefore be provided for the sulfur compound to be removed from the stream of hydrocarbons " gets into the molecular sieve · Higher flow velocities naturally reduce the contact side · Bine Another consequence of higher flow velocities is increased costs for the pumping · line flow velocity less than 3 cm per minute leaves films with a high resistance ^ against the passage arise · Bine flow velocity of more than 6 m per minute does not allow sufficient- ^ de ~ contact time for effective adsorption «within In this wide range the damaging effect of the liquid film is practically largely eliminated at flow velocities of more than 30 cm per minute. At flow velocities of more than 3 · j · minute the required length of the bed is very great, because of the reduced contact time and the low effectiveness of adsorption. 109817/1883 - / -

~ can.

Invention equipment can process flowing hydrocarbons be, dip only traces of sulfur in the size

■ · ■ · ■■ _ij

Order of 5 x 10 wt .-% to 2 wt.% ₇ au sulfur compounds. The process according to the invention is particularly advantageous in the case of a low content of sulfur compounds, since the crystalline zeolitic molecular sieves take up large amounts of sulfur compounds

The upper limit of 2 wt .-? 6 of sulfur compounds in the starting materials is based on the fact that an adsorption becomes impractical in the liquid phase if the sulfur content exceeds this · limit · .wall the Ad « The sorption phase is relatively short in comparison with the deeorption phase and cooling. Se would be Adsorbent bed too large · required. s «in, to at 'a sulfur content of more than 2 wt To achieve adsorption of a certain period of time

The sulfur-containing liquid hydrocarbon comes from

the line 12 to the connecting line 13. Pas entg · -.

opposite end is connected to the inlet and the

upper end of the first bed of zeolitic molecular ... '♦

10. The screen contains line 13 control valve 15 and · ik dfe, are arranged in series one behind the other.

BAD ORiGtNAl _ / _

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The outlet line 16 communicates with the lower end of the bed 10, it contains control valves 17 and 18 in series, the valve 17 being at least partially closed during the beginning of the adsorption phase so that the bed can be filled with liquid hydrocarbon. By operating the valves Ik and 15, the speed at which the liquid flows in during filling can be regulated, so that cavities within the liquid down through the bed 10 are avoided. Such cavities can arise from premature evaporation in the lower parts of the bed, which can result in pressure and violent movements of the bed *. Means for distributing the flow can be used in customary arij to the formation of such voids $ u prevent · s,

■■■ -... J

When the bed 10 of the zeolitic molecular sieve is filled with liquid, the purification of purified hydrocarbons begins from the lower end of the bed through the line 16 and the control valve 17, un4 18. The sweetened liquid hydrocarbon is _{withdrawn from the} connecting lines 19 ". Similarly, the acidic liquid starting material is introduced through the valve $ 4 and t5 at such a rate that the bed 10

completely filled with the liquid t * t. When continuing

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2Ü50323

- 16 -

During the adsorption phase, the sulfur compounds become selectively adsorbed by the molecular sieve in a downward moving zone. In this zone is the first adsorbed hydrocarbon by the Displaced sulfur compounds. The liquid will after deducted below, thereby increasing the effectiveness of adsorption to increase.

Adsorption continues until the presence of sulfur compounds in the final product indicates that the capacity of the molecular sieves has been reached. At this point the spaces between the molecular sieves in the bed are filled with an acidic liquid hydrocarbon. This must either be conveyed to a fresh molecular sieve or drained. The valve 15 through which the acidic starting material reaches the bed 10 is preferably closed! when the bed still has sufficient adsorbing ability _t remove the sulfur compounds from the bed contained in the liquid.

At this point in time the valves 17 and 18 are closed. The acidic starting material is led out of line 12 through the connecting line 20 to the second bed 11 of the zeolitic molecular sieve, which previously deeorbed and

ORIGINAL BATHROOM - / -

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is cooled. The emptying of the first bed 10 should be carried out gradually in order to vaporize and to prevent movement of the pellets with their abrasion; -A Drawing off for 15 minutes is usually sufficient. A hot flushing gas with a temperature is used for desorbing of preferably between 230 and 370 ° C. through line 21. The purge gas should neither contain the sulfur compounds nor the hydrocarbons oxidize. It should contain enough moisture that there is a dew point between -12 and +70 C. You can use the usual SpCTl like methane, hydrogen, nitrogen and Kofilendicrryd in Use in combination with appropriate amounts of steam. Economic success is achieved, you know an oxygen-free combustion gas of air and methane is used as the flushing gas, which was previously due to the high moisture content was not balanced without prior drying. * A typical implementation of the process Using this type of purge gas is shown in the Flow diagram 1 shown. Into the combustion chamber 38 stoichiometric amounts of natural gas and air become ^ e * - permit. After burning, the gas contains large amounts of moisture, but is practically free of oxygen « Carbon dioxide and nitrogen are the other major components. When the combustion gas cools down, condensate

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Eates a be eight Ji rather proportion of the water ·. Therefore, the gas mixture is passed from the combustion chamber 38 through the heat exchanger 42 and into the condenser kk. Liquid water is drawn off from the condenser kk. When the condenser is operated at a sufficiently low temperature, the gas emerging from it contains moisture in such quantities that "its dew point under the conditions of temperature and pressure in the bed of the adsorbent is sufficient during regeneration. At pressures between about

2
1 to 7 kg / cm do the following equations apply?

(l) (b) Maximum permissible dew point temperature, F) ■■ λ Ο, · ¹ «(Regener i« r temperature, F) -120

(2) · Normal * Limit for the temperature of the dew point, ° F a 0, k (regeneration temperature, ° F) -l40

(3) (a) Minimum suggested temperature of the dew point, ^a F m 0.3 (regeneration temperature, ° F) -1 * 10.

The following equations can be calculated using the above equations Limits-for the 'dew points of this purge gas with usual regenerated emper atures between approx. 250 and approx

8AD ORIGINAL _ / _

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Regeneration temperature ⁰ C

Dew point temperature of the Regeneriergaaea, C

Suggested minimum temperature (a)

Recommended maximum allowable upper limit for a norme- temperature, (b) lea procedure

370 21st 315 k 26o 12th

16 "

71

49

27

(a) residual water content of the molecular aiebea of about

2 wt .-? I,

(b) residual water content of the molecular aiebea of about

5% by weight.

The purge gas is then in the warm> auatauecher. k2 heated and through the line 21 to the control valve 22 xu the «. Branch line 23 with the valve 2k. * The power 23 connects the inlet lines 13 between the valves ".1%" and 15 · The hot purge gas is through this line to the upper end of the first bed .10 .de *. zeolitic · * ». Mo leku "* ^ larsiebes out. Flows downward and away DLE" deque- »· _u bierten sulfur compounds" .Daa cooled and EIT sulfur compounds laden purge gas is ouch de "lower end dea first Bettee 10 through the line l6 with the valve 17 deducted. Through the branch line 25 with the valve 26

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ea reaches the aclass line 27. Since the water content of the rinsing, gases is chosen in accordance with the above equations, one stops with the desorption when the desired Amount of sulfur-containing compounds removed from the bed is · This creates a regenerated adsorption bed with a content of about 2 to about 5 G ** r »-J < adsorbed P water

In a preferred embodiment, the liquid hydrocarbon is in the interstices of the first bed 10 withdrawn after the end of the adsorption before the desorption described above begins. That allows one Recovering this fluid and improving the effectiveness of the cycle · This peeling can be seen in on known way after closing the valve l4

fc schehen “At this point in time, you can flush with a ™ at a temperature below t.

cool glass / to be made about 120 C before getting old the desorption begins. In this way, retained hydrocarbons can also be effectively removed

Cools after the end of the desorption phase described the reactivated first bed 10 by the regulated introduction of an acidic liquid starting toffee through the lines 13 into the top of the bed. The pre-cooling

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happens downwards from the inlet to the outlet. This avoids strong temperature rises and evaporation, because the downward-moving front of the liquid cools down any rising vapor streams In order to achieve such a flow, the valves 1A, 15, 17 and 26 are opened and the valve 2k is closed * Vaporized

«
Starting materials can be condensed and fed back again. «If the quantities are very small, they can be drained or flared. The coolant is preferably supplied in an amount of kO to 16 l / e cross-section per minute, the maximum amount being around 320 l / m ² per minute {cooling is continued until the bed is filled with the liquid and about the Temperature of adsorption is reached. Then the valve 26 is closed and the valve 18 is opened, whereupon the adsorption phase in the first bed 10 begins again.

The second bed 11 with the zeolitic molecular sieve is operated in the same way as the first bed 10 * during the

Adsorption becomes the sour starting material through the pipe

«12 and the connecting line 20 with the control valves

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31 and 32 introduced in series into the upper end of the bed 11. The sweetened hydrocarbon is withdrawn at the lower end of the second bed 11 through the line 33 with the control valves Jk and 35 in series. During the déorplion phase, the hot purge gas is introduced through valve 6 in branch line 23 in communication with line 20, and the gas laden with sulfur compounds ™ is released from the lower end of the second bed

11 withdrawn through the valve 37 in the line 25.

According to the invention it is not necessary to use a flushing gas with a specific water content, as described above. The invention is based on the knowledge that adsorptive molecular sieves with a content of up to 5% by weight of adsorbed water are useful in sweetening liquid hydrocarbons. The drainage ψ from molecular sieves to a water content of 2 to

5 Gew.-S is easy and economical to carry out. Therefore According to the invention, steam can also be used as the flushing gas, which is a preferred embodiment of the invention Procedure is. It is only necessary that the adsorbent after regeneration is dried.

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The temperature and pressure of all purge gas used Water vapor are not critical if only care is taken that the agglomerates are not destroyed and that the zeolites are not hydrolyzed at the elevated temperatures. The agglomerates can be destroyed due to uneven thermal stresses when hot activated agglomerates are brought into contact with liquid water. The hydrolytic stability is dependent on the quantity ratio of silicon dioxide to Aluminum oxide in the zeolite and also depending on the type of crystal lattice. The stability is also at least partly dependent on the metal cations or on their removal from the zeolite. So you can use it as a purge gas " Wet steam or superheated steam at cleaning temperatures between ■ see 100 and ~ 200 ° C use.

When using steam as the purge gas sweetening as ^"1 is carried out as besehrieben above, except that after completion of the desorption of sulfur" compounds the adsorbent contains more water than the allowable 5 weight j4 · Therefore, a Drying connected. For this purpose, a vain stream of inert gas, such as nitrogen, hydrogen, natural gas, and the like, with a dew point no greater than that given by the equation, is passed

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- 2k -

0.4 T - 14O, where T is the temperature of the purge gas in ° P means in contact with the adsorbent in such an amount during and at such a time Temperature that the content of the zeolite of adsorbed

Water is between 2 to 5 wt.

Figures 2, 3 and 4 show three typical systems used in the use of steam as a purge gas can be used for desorbing. Of course, professionals know others or similar to those shown. Systems

According to FIG. 2, an inert dry purge gas, such as methane or nitrogen, is supplied through line 50. By means of a fan 51 it reaches a heater 52, from which it exits at a temperature of about 290 ° C. The hot gas then passes cocurrently into the bed 53 of the molecular sieve, which is desorbed with wet steam. The flushing gas containing water passes from the outlet end of the bed into a water-cooled condenser 54 which is cooled to such an extent that the water condenses and the gas has a dew point below 25 ° C cycle, if necessary with another gas «'"

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3 shows a somewhat different embodiment. According to it, a bed 56 is provided with a desiccant through which the drying gas from the condenser 5k before _v of the recycle is passed · This embodiment of the system according to Fig. 2 allows a less strong cooling in the condenser 54, wherein the dew point of from the gas escaping it is increased accordingly · The drying bed 5 ^ can be an activated molecular sieve, silica gel, calcium chloride or some other adsorbent. Desiccants contain '· After exiting the drying bed, the gas is circulated through the blower 51, the heater 52 and the bed with the molecular sieve 53 back again. According to the embodiment according to FIG. 3, the drying time is considerably shortened, since the moisture from the molecular sieve in bed 53 reaches the dryer more quickly.

According to Fig. K , butane or another easily condensable substance is used for regeneration. This substance is pumped into the evaporator and superheater ^ 58 by the pump 57 before it reaches the wet molecular sieve in direct current * The dry gas from the bed 53 loaded with "Vaseer" is cooled, the butane condensing in the condenser. Subsequently, the liquid butane is separated from the water which it has pumped out of the bed 53 and returned.

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Claims (1)

- 26 patent claims , - Process for sweetening flowing acidic hydrocarbons by removing sulfur-containing impurities by bringing the flowing hydrocarbon into contact with a crystalline zeolitic molecular sieve, then regenerating the molecular sieve by desorbing the sulfur-containing substances and reusing the regenerated molecular sieves * for sweetening flowing acidic hydrocarbons again that a liquid acidic hydrocarbon is treated and that a ^{purge gas containing 1} water is used to regenerate the molecular sieve * and that about 2 to about 5% by weight of water is left in the regenerated "molecular sieve". 2 · The method according to claim 1, characterized in that n- · »Draws that one. a purge gas is used, which contains so much water that it is in GJ. eh weight not one .Water content of about 2 to 5 percent by weight in the molecular sieve stands" · ' · : 3. The method according to claim 1 or 2, characterized g e- ..- characterizing t, ¹ that a purge gas with a 109817/1883 Temperature from about 230 to about 370 C, a pressure from about 1 to about 7 kg / cm in contact with the molecular sieve, and a dew point between -12 and +70 C used. 'i' The method according to claim 3i thereby geken n- • ze refuses to use a purge gas with a dew point used between 15 and 60 C. 5. The method according to any one of claims 1 to k , characterized in that a flushing gas is used which contains so much water that the regenerated molecular sieve after the desorption of the sulfur-containing compounds more than about 5 parts by weight of water, and after being brought into contact with a drying gas stream contains about 2 to about 5% by weight of water. 6. The method according to claim 5, characterized in that that steam is used as the purge gas. 109817/1883