Atmospheric pollution hydrogen sulfide removal

Petroleum refining also produces substantial amounts of carbon dioxide, which with hydrogen sulfide, corrode refining equipment, harm catalysts, pollute the atmosphere, and prevent the use of hydrocarbon components in petrochemical manufacture. When the amount of hydrogen sulfide is high, it may be removed from a gas stream and converted to sulfur or sulfuric acid. Some natural gases contain sufficient carbon dioxide to warrant recovery as dry ice. 

ABSORPTION (Process). Absorption is commonly used in the process industries for separahng materials, notably a specific gas from a mixture of gases and in the production of solutions such as hydrochloric and sulfuric adds. Absorption operations are very important to many air pollution abatement systems where it is desired to remove a noxious gas, such as sulfur dioxide or hydrogen sulfide, from an effluent gas prior to releasing the material to the atmosphere. The absorption medium is a liquid in which (1) the gas to be removed, i.e., absorbed is soluble ill the liquid, or (2) a chemical reaction takes place between the gas and the absoibing liquid. In some instances a chemical reagent is added to the absorbing liquid to increase the ability of the solvent to absorb. 

Most newer plants and facilities contain control rooms, electric motor control centers, instrument control rooms, and computer centers. These are usually maintained under a slight positive pressure with makeup air being introduced from the outside. In many instances it is possible for this air to be contaminated with atmospheric pollutants such as sulfur oxides, hydrogen chloride, chlorides, hydrogen sulfide, dust, and others. These gases and dust can cause serious damage to sensitive circuitry found in computers, microprocessors, microswitches, and other delicate electronic equipment. If corrosive gases are removed from these makeup streams, costly maintenance and downtime will be prevented. 

Reduction of metal oxides with hydrogen is of interest in the metals refining industry (94,95) (see Metallurgy). Hydrogen is also used to reduce sulfites to sulfides in one step in the removal of SO2 pollutants (see Airpollution) (96). Hydrogen reacts directiy with SO2 under catalytic conditions to produce elemental sulfur and H2S (97—98). Under certain conditions, hydrogen reacts with nitric oxide, an atmospheric poUutant and contributor to photochemical smog, to produce N2 ... 

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