Potentiometric Determination of Mercaptans in Presence of Elemental Sulfur

Abstract

acetamide, studies of the former method (5) have shown that if 50 ml. of solution, 0.6VF in hydrochloric acid, which contains 500 mg. of arsenic(V) is heated almost to boiling, saturated with hydrogen sulfide, diluted to 100 ml. and cooled, resaturated with hydrogen sulfide, and heated to 100°C. in a pressure bottle, quantitative precipitation of the arsenic will require at least 30 minutes in the pressure bottle.By contrast it is calculated from the present study that in 100 ml. of solution, 0.3FF in hydrochloric acid and 0.5VF in thioacetamide, 500 mg. of arsenic(V) should be 99.9% reduced at 90°C. in approximately 1 minute and that sufficient hydrogen sulfide should be produced to precipitate the arsenic completely in about 6 minutes. (This

Potentiometric Electrode Systems In Nonaqueous Titrimetry

“…The silver-silver sulfide electrode has been used in the titration of mercaptans in gasoline with alcoholic silver nitrate (102,125,198). Back titration of excess mercaptan permits the indirect potentiometric titration of acrylonitrile (99).…”

Use of Hg-Electroplated-Pt Ultramicroelectrode for Determining Elemental Sulphur in Naphtha Samples

“…In light fractions, the sulphur species are elemental sulphur, hydrogen sulphide, mercaptans, and disulphides, with the acid mercaptan forms dominating [ 8 ]. The complexity of these sulphur compound mixtures depends not only on the origin of the petroleum but also on the refining process [ 9 ].…”

“…Sulphur causes corrosion and damages refining catalysts, decreasing the quality of the final product. Even in low concentrations, it is capable of catalysing the formation of other sulphur species in petroleum [ 9 , 10 ]. The limit for total sulphur allowed in Brazilian naphtha samples is 500 ppm.…”

Electrochemical determination of elemental sulfur in Brazilian naphtha: method and validation

“…The complexity of these sulfur compound mixtures depends not only on the origin of the petroleum but also on the refining process. Some of the compounds (such as elemental sulfur), either alone or in combination, have been associated with undesirable characteristics in the final products [7].…”

“…It can also impair the efficiency of lubricants and antioxidants. Elemental sulfur, even in low concentrations (less than 1 ppm), deserves special attention because it is capable of catalyzing the formation of other sulfur species in petroleum, such as sulfides, disulfides, polysulfides, and mercaptans, significantly changing their concentrations [7,8]. In addition, in the presence of mercaptans, elemental sulfur has a synergistic corrosive effect [9,10].…”