Sulfur capturing capabilities

The biochemical basis for the toxicity of mercury and mercury compounds results from its ability to form covalent bonds readily with sulfur. Prior to reaction with sulfur, however, the mercury must be metabolized to the divalent cation. When the sulfur is in the form of a sulfhydryl (— SH) group, divalent mercury replaces the hydrogen atom to form mercaptides, X—Hg— SR and Hg(SR)2, where X is an electronegative radical and R is protein (36). Sulfhydryl compounds are called mercaptans because of their ability to capture mercury. Even in low concentrations divalent mercury is capable of inactivating sulfhydryl enzymes and thus causes interference with cellular metaboHsm and function (31—34). Mercury also combines with other ligands of physiological importance such as phosphoryl, carboxyl, amide, and amine groups. It is unclear whether these latter interactions contribute to its toxicity (31,36). 

Improved gasifier designs would be more durable and capable of handling a variety of carbon-based feedstocks. Advanced gas cleaning technologies would capture virtually all of the ash particles, sulfur, nitrogen, alkali, chlorine and hazardous air pollutants. 

Since the Selectox process is capable of well over 90 percent sulfur recovery, the authors recommend a careful cost-benefit study to see if Claus tail gas processing should be required with such plants. It might well be found that—say—95 percent capture of sulfur in the coal conversion plant is acceptable. 

The ability of lime to sorb AS4O6 increases as temperatures increase between 400 and 1000 °C (Li et al., 2007). The presence of either sulfur dioxide (SO2) or carbon dioxide (CO2) gases did not substantially interfere with the ability of lime to capture AS4O6. CaSCL is also capable of sorbing at least some AS4O6 (Li et al., 2007). 

Under severe thermolysis conditions both sulfur bonds to the naphthalene skeleton in sulfone 36 can suffer homolytic cleavage with SO2 liberation and formation of 1,8-dehydronaphthalene (40) capable of electrocyclic capture with dimethyl acetylenedicarboxylate (40 54). 

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