Carbon monoxide sulfur dioxide poisoning effect

The space velocity was varied from 2539 to 9130 scf/hr ft3 catalyst. Carbon monoxide and ethane were at equilibrium conversion at all space velocities however, some carbon dioxide breakthrough was noticed at the higher space velocities. A bed of activated carbon and zinc oxide at 149 °C reduced the sulfur content of the feed gas from about 2 ppm to less than 0.1 ppm in order to avoid catalyst deactivation by sulfur poisoning. Subsequent tests have indicated that the catalyst is equally effective for feed gases containing up to 1 mole % benzene and 0.5 ppm sulfur (5). These are the maximum concentrations of impurities that can be present in methanation section feed gases. 

NOXIOUS CAS. Any natural or by-product gas or vapor that has specific toxic effects on humans or animals (military poison gases are not included in this group). Examples of noxious gases are ammonia, carbon monoxide, nitrogen oxides, hydrogen sulfide, sulfur dioxide, ozone, fluorine, and vapors evolved by benzene, carbon tetrachloride, and a number of chlorinated hydrocarbons. Oases that act as simple asphyxiants are not classified as noxious. See also Pollution (Air). 

Single-Bed Isothermal Catalysts. Detailed analyses of exit gases from single-bed isothermal catalysts were determined with 2 g of red bauxite at 475°C. The inlet gas contained 3.4% sulfur dioxide, 5.9% carbon monoxide, and 90.7% helium. Figure 2 (Section A) shows that the sulfur dioxide analysis decreased from 3.4 to 0.8. In other words, about 76% of the sulfur dioxide was removed in the dry state at a carbon monoxide ratio, r, of 0.87. However, when 3% water vapor was added (Section B), the sulfur dioxide in the exhaust gas increased to 1.9%, illustrating the poisoning effect of water. When water vapor flow was stopped, the sulfur dioxide exhaust analyses decreased slowly (Section... 

Volcanic eruptions can cause some harmful health effects. Tourists were kept at some distance from the 2011 eruption of the Kilauea volcano (see Section 9.4.1) because of its emissions of sulfur dioxide gas. People may suffocate in the carbon dioxide or be poisoned by the toxic carbon monoxide and hydrogen sulfide. (If the geothermally active Yellowstone National Park in the United States was an industrial installation, it is likely that authorities would consider placing some areas off limits because of emissions of hydrogen sulfide, readily detected by visitors by its foul odor.) Fine particles blown into the atmosphere from volcanic eruptions can cause respiratory problems when inhaled. Plants may be killed or their growth stunted by exposure to sulfur dioxide and hydrogen sulfide from volcanoes. 

Impurities and Poisons The presence of any impurities or catalyst poisons in the reacting flow can have a highly deleterious effect on performance. Some impurities such as carbon monoxide and sulfur dioxide can reduce performance dramatically for certain fuel cells, even in levels as low as parts per million (ppm) or parts per billion (ppb). Each catalyst and fuel cell has different poisons. For instance, carbon monoxide is a serious poison for low-temperature PEFCs but can be oxidized as a fuel in high-temperature MCFCs and SOFCs. 

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