PROCESS FOR THE REMOVAL OF HYDROGEN SULPHIDE FROM GASEOUS STREAMS BY CATALYTIC OXIDATION OF HYDROGEN SULPHIDE TO SULPHUR WHILE INHIBITING THE FORMATION OF SULPHUR OXIDES

摘要

1501200 Removing HIS and mercaptans from gases RHONE-POULENC INDUSTRIES 11 July 1975 29260/75 Heading CIA Alkyl mercaptan and/or H 2 S are removed from a gas stream by (1) contacting the stream with an aqueous solution (pH 3-11) of (a) a chelate of a polyvalent metal (e.g.Fe) with where n = 1 to 3, X is acetic or propionic acid group, A is 2-hydroxyethyl, 2-hydroxypropyl or C 1-4 alkyl; or where 2 to 4 of X (same or different) are acetic or propionic acid groups, the remaining X (if any) being 2-hydroxyethyl, 2-hydroxypropyl or (X as in II); and R is ethylene, propylene, isopropylene or 1,2-N-substituted cyclohexane or bezene; and (b) an alkali metal, alkaline earth metal, ammonium or amine salt of an acid having pK a at 25‹ C. of 1À2-6; (2) contacting the chelatecontaining solution with a gas containing molecular O 2 , and separating the resulting sulphur and/or dialkyl disulphides from the aqueous solution. The polyvalent metal is preferably Fe, Cu or Mn, using N-hydroxyethylethylene diamine triacetic acid (HEDTA) as chelating agent. Other metals and amino-acids are specified. Component (b) is usually sodium formate, but salts of other weak acids are specified. In Examples 1-31, air is added to H 2 S/N 2 mixture and the gas stream is fed to a chelate solution under conditions that ensure intimate phase mixing, the reduction and reoxidation of the chelate take place simultaneously. In Example 32, the chelate solution is mixed with H 2 S/N 2 and then regenerated with air, so that the redox reactions are sequential.