devoid of water a preferred polyvalent metal chelate is iron acetylacetonate and a preferred solvent is n methyl pyrrolidone the chelated metal catalyst solution of the present invention is preferably prepared by dissolving commercially available ferric acetylacetonate in the non aqueous solvent at an appropriate concentration for example 10 wt another method involves taking a saturated aqueous solution of ferric sulfate and combining it with an appropriate amount of the non aqueous solvent containing a threefold molar excess of acetylacetone this method produces a catalyst solution concentrate that contains a minor amount of water however when mixed with non aqueous solvent in the industrial plant the quantity of water present in the circulating non aqueous polyvalent metal catalyst solution becomes trival and is considerably less than 5 wt yet another method of preparing the catalyst takes advantage of the fact that certain polyvalent metal salts are soluble in the non aqueous solvent for example ferric chloride can be dissolved in n methyl pyrrolidone hence a polyvalent metal chelate catalyst solution can be prepared by dissolving ferric chloride in n methyl pyrrolidone and adding a threefold molar excess with respect to iron of acetyl acetone the polyvalent metal content of the operating solution can vary over a wide range dependent upon the composition of the gas being treated and other factors typically when an iron chelate catalyst is used the iron content of the operating solution may be from about 5 ppm to about 20 000 ppm with 200.