DD156466A3 - METHOD FOR REMOVING SULFUR HYDROGEN FROM GASES - Google Patents

Abstract

The invention is particularly suitable for the purification of natural gases, which in addition to hydrogen sulfide also in small amounts containing methyl, ethyl, n-propyl and n-butylmercaptans can be removed with. The inventive method works on the principle of cyclic adsorption and desorption, being used as adsorbent zeolitic molecular sieves of the A-type, initially loaded at temperatures between 573 K and 673 K with normal paraffins and then with ammonia and optionally at temperatures below 373 K. have been treated with water, such containing gases or aqueous solutions of alkaline earth salts. The process is particularly to operate with molecular sieves that were already used for the adsorptive dewaxing of diesel oil and expanded after exhaustion of the corresponding Adsorptionskapazitaet and are usually discarded.

Description

- A-

VEB Leuna-Werke »γ / old Ulbricht» Merseburg, 4 · 3 · 1980

DI "R / Ky

L.P.7983

Title of the invention

Process for the removal of hydrogen sulphide from gases Field of application of the invention

The invention relates to a process for the adsorptive removal of hydrogen sulfide and / or alkylmeicaptans from gases containing them. The alkyl mercaptans in this case are methyl, ethyl, n-propyl and n-butyl mercaptans Invention suitable for removing said sulfur compounds from gases substantially free of water and / or ammonia. A suitable field of application of the invention is, for example, the removal of hydrogen sulphide from natural gas.

Characteristic of the known technical solutions

It is known that hydrogen sulfide and organic sulfur compounds can be removed from industrial gases by means of molecular sieves, the adsorption of the sulfur compounds in at least two series-connected, with

21 9 892

Molecular sieve type 4 A or 5 A or 13 X filled adsorbers is made, the last adsorber, which was thermally desorbed in the previous cycle, is cold-run using the purified gas (DDR ~ WP 80 797) · The disadvantage of this method is the high cost of the expensive molecular sieves used here, the complete desorption also requires a lot of time.

It is further known that hydrogen sulfide can be separated from such containing gases using a zeolite-containing sorbent which is treated with a solution of ammonium chloride prior to its use (U.S. Patent No. 490,488). The disadvantage is incomplete removal of Hydrogen sulfide from these gases containing, as well as the expense of modifying the zeogenthic sorbents

Object of the invention

The object of the invention is to avoid expensive molecular sieves and the high expenditure of time for their complete desorption in the removal of hydrogen sulphide from gases which contain alkyl mercaptans.

Explanation of the essence of the invention

The object was to develop a process for the removal of hydrogen sulfide from gases which optionally contain methyl, ethyl, n-propyl and n-butyl mercaptans by cyclic adsorption and desorption, in which the adsorption at temperatures below 373 K and desorption at temperatures above 473 K,

The object is achieved by a method in which a sufficient for the virtually complete removal of hydrogen sulfide capacity of the adsorbent over a long period of time and good adsorption and desorption is achieved when erfindungsgeinäß the cyclic adsorption-desorption on erdalkalihaltigen

zeolitic molecular sieves of the A - - type which have been initially loaded at temperatures between 573 K and 673 K with normal paraffins and then treated with ammonia and optionally at temperatures below 373 K with water or gases containing aqueous alkaline earth metal salts; is carried out*

Such prepared zeolitic molecular sieves are inevitably formed in the adsorptive dewaxing z. B of diesel oils, vsenn here the adsorption in the presence of corresponding zeolitic molecular sieves and the desorption by ammonia takes place. Surprisingly, molecular sieves exhausted for the process of dewaxing are therefore expanded and generally discarded, and are excellently suited for the process of the invention. In the use of such waste molecular sieves, the adsorbent is particularly inexpensive to dispose of, making the process according to the invention particularly advantageous can be designed economically.

It is advantageous if the cyclic adsorption-desorption process on magnesium and / or calciümhaltigen zeolite molecular sieves of the Α-type, initially loaded at temperatures between 573 and 673 K with normal paraffins and then with ammonia and optionally at temperatures below 373 K with water , such containing gases or aqueous solutions of alkaline-earth salts have been treated, is carried out «

However, it has proved to be useful if, as aqueous solutions of alkaline earth salts, those of the sulfates, chlorides, nitrates or acetates of magnesium and / or calcium are used.

embodiments

example 1

An adsorption column with a length of 5OQ mm and an inner diameter of 20 mm is filled with 150 ml of a magnesium-containing zeolitic molecular sieve type 5 A »which has a particle size of 1.2 to 1.6 mm, and 6 hours at a temperature of .723 K drained ,,

Subsequently, at a temperature of 653 K and under normal pressure conditions, a hydrocarbon mixture in the boiling range of 453 to 593 K and a normal paraffin content of 21.4% by volume is passed together with hydrogen as carrier gas from top to bottom over the molecular sieve.

After the subsequent desorption of the normal paraffins with ammonia at 653 K and normal pressure conditions, the molecular sieve is removed.

10 g of the thus-treated magnesium-containing molecular sieve are filled into a glass column having an inner diameter of 8 mm and a length of 200 mm. Thereafter, 20 l / h of a methane-nitrogen gas mixture containing 3.3 mg of hydrogen sulfide per liter are added thereto passed through the molecular sieve at 298 K until the hydrogen sulfide concentration at the column exit exceeds 5 ppm, this point being referred to as breakthrough for hydrogen sulfide, the molecular sieve at 643 κ and normal pressure conditions with 2 l / h of a methane-nitrogen gas mixture until complete desorption of the hydrogen sulfide Treated for 3 hours »This adsorption-desorption cycle is then repeated ten more times ·

From the adsorbed to the breakdown point amount of hydrogen sulfide breakthrough capacity (Kq) is reached. It is 5.8

Example 2

The procedure of the pretreatment and the adsorption-desorption process correspond to those of the execution example 1 Ib Modification for this purpose, a calcium-containing zeolitic molecular sieve of the type 5 A is used as the adsorbent. The breakthrough capacity here is 6.3 %.

Example 3

The operation of the pretreatment and the adsorption-desorption process are the same as in Embodiment 1 "In modification, as the adsorbent, mag ·? nesium- and calcium-containing zeolitic molecular sieve of type 5 A used * The breakthrough capacity is in this case 6.4 % o

Example 4

An adsorption column with a length of 500 mm and an inner diameter of 20 mm is filled with 150 ml of a magnesium-containing molecular sieve type 5 A, which was removed from a large-scale dewaxing after it had no sufficient capacity for Uormalparaffine there ·

It is then treated with water for 7 hours at 348 K under normal pressure conditions and dewatered at 723 K for 6 hours.

10 g of the molecular sieve treated in this way are placed in a glass column having an inner diameter of 8 mm and a length of 200 mm. Thereafter, 20 l / h of a methane / nitrogen gas mixture containing 1.1 mg of a mixture consisting of methylene chloride and , Ethyl, n-propyl and n-butyl mercaptan, per liter, while passing over the molecular sieve until the mercaptan concentration at the column exit exceeds 5 ppm, then the molecular sieve at 643 K and normal pressure conditions with 2 l / h of methane Nitrogen mixture until complete desorption

the mercaptans are treated for 3 hrs. This adsorption-desorption cycle is then repeated ten more times. The breakthrough capacity is 5.0

Example 5

The operation of the pretreatment corresponds to that of the exemplary embodiment 4 * In contrast to the embodiment, the treatment is carried out with a 5 # Jägagnesiumnitratlösung ·

10 g of the thus treated molecular sieves are placed in a Gisssäule with an inner diameter of 8 mm and a length of 200 mm. Thereafter, 20 l / h of a Methan nitrogen gasgemischa, which 1.4 mg of hydrogen sulfide and 1.8 mg of a Mixture consisting of methyl, ethyl, n-propyl and n-butylmercaptan, per liter, as long as passed over the molecular sieve until the concentration of sulfur compounds at the column exit exceeds 5 ppm · thereafter, the molecular sieve at 643 K and Normal pressure conditions treated with 2 l / h of a methane ~ nitrogen gas mixture until complete desorption of the sulfur compounds for 3 hours, This adsorption-desorption cycle is thereafter repeated ten times · The breakthrough capacity is 6.1 %.

Claims (3)

invention claim 1 «Procedure for the removal of hydrogen sulfide By cyclic adsorption and desorption, the adsorption occurring at temperatures below 373 K and the desorption at temperatures above 473 K, characterized in that the
cyclic adsorption-desorption process on alkaline earth-containing zeolitic molecular sieves of the Α-type, which initially loaded at temperatures between 573 K and 673 K with normal paraffins and then with ammonia and optionally
at temperatures below 373 K, with water containing such gases or aqueous solutions of alkaline-earth salts. 2 «method according to item 1, characterized in that the
cyclic adsorption-desorption process at magnesium
and / or calcium-containing zeolitic molecular sieves
of the A type, initially at temperatures between 573 K
and 673 K loaded with Jjormalparaffinen and then with
Ammonia and optionally at temperatures below
373 K with γ / asser, such containing gases or aqueous solutions of alkaline earth metal salts have been carried out. 3 · Method according to item 1 and 2, characterized in that
as aqueous solutions of alkaline earth salts such
Sulfates, chlorides, nitrates or acetates of magnesium
and / or calcium are used ·