CATALYSTS FOR ENVIRONMENTAL-PROTECTION

The main emitters of anthropogenic air pollution are internal combustion engines, power plants, and production processes. Components of exhaust gases which are regarded as pollutants are hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO(x)), sulfur dioxide (SO2), and dust. Three main types of catalyst are understood to improve the environment; namely automotive emission control, NO(x) abatement and oxidation. To reduce the pollutants HC, CO, and NO(x) in automobile exhaust gas, three-way catalysts are currently applied. The reduction of particle emissions in diesel exhaust gas is achieved by diesel filters and oxidation catalysts. Pollutants from power plants are mainly the inorganic components NO(x) and SO2. In the SCR process, NO(x) is catalytically reduced to nitrogen and water. The DESONOX process is suited for the simultaneous catalytic abatement of NO(x) and SO(x). Exhaust gases from production processes in many areas require after-treatment. Therefore catalyst formulations depend on process parameters and exhaust gas components. This overview presents and explains catalyst types, design, mode of operation, and processes.