Recovery of HCl from Chloride Leach Solution of Spent HDS Catalyst by Solvent Extraction

Abstract

In the present work, amine based extractant and its mixture with cationic and solvating extractants were tested for the extraction of HCl from chloride solution containing Al(III). The chloride feed solution resulted from the leaching of spent HDS (hydro-desulfurization) catalysts. For this purpose, amine extractants, such as TOA (trioctyl amine), Alamine 336 (a mixture of tri-octyl/decyl amine), Alamine 308 (tri-isooctyl amine), and TEHA (tri 2-ethylhexyl amine) were used and the extraction and stripping behavior of HCl was compared. The extracted HCl was easily stripped from loaded TEHA phase, when compared with the other tested tertiary amine system. Solvent extraction reaction of HCl by TEHA was determined from the extraction data. Unlike TOA and Alamine 336, adding cationic extractant to TEHA had negligible effect on the extraction and stripping of HCl. In our experimental ranges, no Al was extracted by amines and pure HCl was recovered. MaCabeThiele diagrams for the extraction and stripping of HCl by TEHA were constructed.

Liquid – Liquid Extraction of Hydrochloric Acid from Aqueous Solutions by Tri-n-dodecylamine and Tri-n-octylamine / diluents

“…Tertiary amines such as: Tri-n-dodecyl amine, tri-n-octylamine, Alamine 308 (tri-isooctylamine), TEHA (tri-2-ethyl hexyl amine), Alamine 336 (a mixture of triocty/decyl amine) have been proven to be effective extractant to recover HCl and H 2 SO 4 from aqueous solutions [5][6][7][8]. The extraction reaction of HCl by tertiary amines can be written as follows:…”

“…Banda et al [6] studied the extraction of HCl from chloride leach solution of hydro-disulfurization catalyst using trioctylamine, Alamine 330, Alamine 308 and TEHA. He found that stripping of HCl from the loaded extractant TEHA is easier when compared with other tested tertiary amines and a pure HCl was recovered.…”

Extraction of hydrogen chloride by a coupled reaction-solvent extraction process

“…The extraction of HCl by tertiary amines is frequently assumed to be accompanied by the formation of an amine salt, which exists as an ion pair in the organic phase [17,35].…”

“…Many studies have been reported on the recovery or the removal of mineral acids. High concentrations of mineral acids can be extracted using various extractants including Cyanex 923, tri-n-octylphosphine oxide, Alamine 336, Aliquat 336, trin-butyl phosphate (TBP), tris-(2-ethylhexyl) amine (TEHA), and Alamine 308 [12][13][14][15][16][17][18]. Often diluents are added to modify the physical properties (viscosity, specific gravity and surface tension) of the extractants and to cause different extraction complexes to form [19].…”

Separation of Platinum(IV) and Rhodium(III) from Acidic Chloride Solution by Solvent Extraction with Tri 2-Ethylhexyl Amine(TEHA)

“…The extraction percentage of HCl decreased with the increase of HCl concentration in the feed. The solvent extraction reaction of HCl by TEHA (R 3 N) can be represented as 16,18) …”