Fuel gases in refineries are almost by definition low-value gases composed of off-gases from a variety of sources within the refinery. They are typically light, methane rich gases, as the more valuable heavier components have been extracted, but they may still contain significant amounts of olefins and diolefins. An overwhelming content of sulfur compounds is not unusual, including 1 to 10 % or more of H2S and hundreds of ppm of organic sulfur species such as mercaptans and thiophenes. Hence, for environmental reasons, these gases must be cleaned, e.g., in an amine wash removing H2S and some mercaptans, before combustion. As environmental regulations become stricter, however, the wash must be complemented by more versatile and sophisticated catalytic desulfurization in order to keep the sulfur emissions at an acceptable level.
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