Method of purifying oxygen-excess exhaust gas

摘要

Catalysts for purifying an exhaust gas containing an excess amount of oxygen, to remove nitrogen oxides, carbon monoxide and hydrocarbons therefrom, the catalyst containing silicon dioxide (SiO2) and alumina (Al2O3) in a molar ratio of SiO2 to Al2O3 of at least 15, and containing cobalt alone or in combination with at least one metal selected from alkali earth metals and rare earth metals, and a method of purifying the exhaust gas using the described catalyst. The catalyst exhibits less thermal deterioration of the properties and performances thereof during use at an elevated temperature for an extended time, and accordingly, has an excellent durability. The catalyst is particularly useful for the purification of exhaust gases originating from an internal combustion engine of an automobile, and a nitric acid production plant.