Removal of nitrogen oxides from gases

• Main Authors: KARL BAUR, HARTMUT NEUMANN, HANS-PETER LANGEBACH, ULRIKE WENNING
• Format: Patent
• Language: English
• Published: 26.08.1998
• Edition: 6
• Subjects: ACYCLIC OR CARBOCYCLIC COMPOUNDS; CHEMISTRY; CRACKING HYDROCARBON OILS; FUELS; LUBRICANTS; METALLURGY; MINERAL WAXES; ORGANIC CHEMISTRY; PEAT; PERFORMING OPERATIONS; PETROLEUM, GAS OR COKE INDUSTRIES; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVEHYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, ORGASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; SEPARATION; TECHNICAL GASES CONTAINING CARBON MONOXIDE; TRANSPORTING

For selectively removing nitrogen oxides from a carrier gas that contains hydrocarbons, the nitrogen oxides are removed by chemisorption on metal oxides, without the occurrence of undesirable secondary reactions. The metal oxides are preferably formed from metals of the 6th to 8th subgroups, whereby manganese dioxide (MnO2,) is especially preferred as a metal oxide. The process can be conducted with one or more reactor beds, which preferably operate at 10 to 40 DEG C. and are regenerated with nitrogen at a temperature of 130 to 170 DEG C. By removing nitrogen oxides from an olefin-rich gas, for example from the waste gas of an FCC unit, the resultant gas can then be fed to a cryogenic olefin extraction stage without danger of explosion. Such a waste gas contains unsaturated hydrocarbons, hydrogen, carbon monoxide, and oxygen, the oxygen having a concentration preferably between 100 and 5000 mol ppm.