SU1311764A1 - Method of cleaning gases from hydrogen sulphide - Google Patents

Abstract

The invention relates to wet methods for the purification of gases from hydrogen sulfide and can be used in any industry where it is necessary to neutralize and utilize hydrogen sulfide gas emissions. The goal is to simplify the cleaning process by eliminating the addition of promoter additives, as well as a more complete decomposition of the residual amount of sulfide complex formed during the washing step. The hydrogen sulphide-containing gas is washed with an alkaline solution of an iron complex (III) with ethylene diamine tetraacetate (EDTA). The absorption of hydrogen sulfide is carried out to a concentration of

Description

The invention relates to wet methods for the purification of gases from hydrogen sulfide and may find application in any industry where it is necessary to neutralize and utilize hydrogen sulfide gas emissions.

The purpose of the invention is to simplify the purification process by eliminating the introduction of promoting additives when maintaining a high degree of conversion, as well as more complete decomposition of the residual amount of the sulfide complex formed during the washing step.

The method is carried out as follows.

Hydrogen sulfide-containing gas is washed with an alkaline solution of an iron (III) complex with ethylene diamine tetraacetate (EDTA). When this occurs, the absorption of hydrogen sulfide and the simultaneous formation of a labile sulfide complex. The spent solution is sent to a special tank for oxygen-free oxidation and kept for 0.5-2 min at pH 8.8-9.8 until complete decomposition of the labile sulfide complex. Then, depending on the presence of the residual hydrosulfide content, the required amount of the regenerated solution is added to the spent solution until the hydrosulfide ions are completely oxidized. After that, the solution is sent for regeneration, where the oxidation of EDTA with air to Fe- + EDTA occurs.

Exposure of the spent solution before regeneration for 0.5-2 minutes allows to prevent the entry of free

The results show that while maintaining the ratio above stoichiometric due to low co-hydrogen sulfide ions (HS), formed during the absorption of hydrogen sulfide with alkali solution, as well as labile complexes of Fe EDTA with HS for regeneration, since their oxidation with air leads to the appearance of by-products , to reduce the degree of conversion of H2S to sulfur. Thus, the shutter speed of the spent solution ensures complete destruction of the complex of EDTA with HS to Fe + EDTA and sulfur. Excess

the amount of ions is oxidized by the regenerated solution.

Maintaining the pH of the solution during the aging process in the range of 8.8-9.8 provides optimal conditions for the destruction of the mixed sulfide complex. Increase

pH can lead to the destruction of the catalyst and its additional consumption, as well as unproductive increase in time for the destruction of the sulfide complex. At pH 8.8, the H2S absorbent capacity decreases markedly. leads to an increase in the cost of additional supply of the solution for the absorption of low-level carbon from gas. The effect of the regenerated solution, introduced after exposure to the spent solution, is that

some excess in the solution after the HS ion absorber is 100% oxidized to sulfur. Example 1. For the experiment take hydrogen sulfide-containing - gas. The absorption of hydrogen sulfide is carried out to a concentration of (0.4-1.0) X X 10 mol / l alkaline solution of Fe

EDTA with catalyst concentration 5 X

u - mol / l.

The results of experiments on the purification of gases from H2S are given in Table. one.

Table 1

holding in solution HS ions or by adding an additional amount of Fe EDTA, but with exposure.

A high degree of conversion is achieved without using additional promoter reagents, and the oxidation of the solution in the presence of HS ions or a sulfide complex leads to an increased yield of by-products (experiments 1 and 2).

Example 2. In a solution containing HS ions (0,., 0) 10 mol / l, 0.1 and are introduced. Fe EDTA solution to the conditional concentration (0.2-0.5) 10 mol / l. From the moment the solutions are mixed, the time during which the red color exists is noted. The monitoring of the change in the optical density (D) of the solution is carried out using a photoelectrocalimeter. The pH of the reaction medium is also changed within 7.5 g10.

table 2

Table continuation

ten

At pH 9.9, the complex decomposes to Fe (OH) s.

Claims (2)

1. A method for purifying gases from hydrogen sulphide by washing them with an alkaline solution of an iron (III) complex with ethylene diamine tetraacetate to form elemental sulfur with subsequent regeneration of the spent solution with air, characterized in that, in order to simplify the process by eliminating the introduction of promoter additives maintaining a high degree of conversion, the spent solution is kept for 0.5-2 min. PH 8.8-9.8. 2. A method according to claim 1, characterized in that, in order to more completely decompose the residual amount of the sulfide complex formed in the washing step, the spent solution after aging is injected regenerated solution in an amount that ensures complete oxidation of hydrosulfide ions.