To keep catalytic activity at a high level for a long time by making a support carry a mixture or porous active alumina and active manganese oxide in such a manner as to expose them outside in a poisoning-proof pretreatment agent used for performing purification treatment of exhaust gas from factories such as printing factory and the like by means of a catalyst.
A porous support is usually used as a support material constituting a poisoning-proof pretreatment agent having a catalytic activity, and organic supports such as cordierite, alumina, etc., are suitable. Such a support is made to support porous active alumina and active manganese oxide intermingled with each other in such a manner as to be exposed outside. As the porous active alumina, γ, δ, η and other active alumina, particularly γ-alumina is preferred and support amount of the porous active alumina is not less than 20 g in terms of Al2O3 per liter of the poisoning-proof pretreatment agent. The active manganese oxide may be electrolytic manganese dioxide or formation manganese dioxide, and support amount therof in terms of MnO2 is not less than 10 g per liter of the poisoning-proof pretreatment agent.
TEGAWA KAORU
ARAI HIDEO
SAKURAI TAKANOBU
