Disulfides mercaptans

Cha.in-Tra.nsferAgents. The most commonly employed chain-transfer agents ia emulsion polymerisation are mercaptans, disulfides, carbon tetrabromide, and carbon tetrachloride. They are added to control the molecular weight of a polymer, by transferring a propagating radical to the chain transfer agent AX (63) ... 

Present formula gasolines contain approximately 300 ppm. No. 2 fuel oil contains 2,200 to 2,600 ppm by weight of sulfur. Even pipeline gas contains sulfur-containing odorants (mercaptans, disulfides, or commercial odorants) for leak detection. Metal catalysts in the fuel reformer can be susceptible to sulfur poisoning and it is very important that sulfur in the fuel reformate be removed. Some researchers have advised limiting the sulfur content of the fuel in a stream reformer to less than 0.1 ppm, but noted the limit may be higher in an autothermal... 

N2. Sulfur containing odorants (mercaptans, disulfides, or commercial odorants) are added for leak detection. Because neither fuel cells nor commercial reformer catalysts are sulfur tolerant, the sulfur must be removed. This is usually accomplished with a zinc oxide sulfur polisher and the possible use of a hydrodesulfurizer, if required. The zinc oxide polisher is able to remove the mercaptans and disulfides. However, some commercial odorants, such as Pennwalf s Pennodorant 1013 or 1063, contain THT (tetrahydrothiophene), more commonly known as thiophane, and require the addition of a hydrodesulfurizer before the zinc oxide catalyst bed. 

Sulfur. Sulfur commonly exists as mercaptans, disulfides, or thiophenes in reformer feeds (Fig. 4). Mercaptans and disulfides are significantly more reactive than thiophene during hydrotreating (4). Sulfur contamination results in poisoning of the platinum metal. Studies have shown that the sulfur reacts with the platinum, changing the reactivity of the platinum in a manner more extensive than a simple blocking of metal sites (5). Typical maximum allowable concentrations of sulfur are 0.5 ppm or less. With proper hydrotreating, levels of 0.2-0.3 wt. ppm are reached and these lower levels are beneficial to reformer performance. 

We can at last turn to the question of the quantitative examination of the mercaptan-disulfide redox system. For about thirty years chemists and biochemists (Prof. H. T. Clarke among the earliest) have been trying to determine the oxidation potential of Ibis system ... 

Natural Gas Processing The major constituents of pipeline gas are methane, ethane, propane, CO2, and, in some cases, N2. Sulfur-containing odorants (mercaptans, disulfides, or commercial odorants) are added for leak detection. Because neither fuel cells nor commercial reformer... 

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