Patent ID: 7188470

Claim:
Process of combustion of a combustible material in a combustion chamber associated at least with an admission means conducting and admitting an oxygen containing gas in the combustion chamber and exhaust means exhausting combustion chamber out of the combustion chamber and conducting said exhaust flue gases at least partly towards an outlet, in which: at least one surface of an element selected from the group consisting of the combustion chamber, admission means in contact with flue gases and combinations thereof is at least partly provided with a primary NO x reducing catalyst, said primary NO x reducing catalyst being deposited in less than 24 hours when the primary NO x reducing catalyst is deposited in presence of combustion gases with an average temperature of more than 400° C., whereby said primary NO x reducing catalyst is present in an effective amount for ensuring a first average reduced NO x content in the flue gases, said average being measured for a combustion time of one hour, and said primary NO x reducing catalyst is intermittently treated with an effective amount of a composition containing at least one atom selected from the group consisting of cerium, europium, ytterbium, praseodymium and mixtures thereof, in presence of at least a gaseous medium comprising at least a gas selected from the group consisting of water vapor, combustion gases and mixtures thereof, at a temperature higher than 200° C., whereby said primary NO x reducing catalyst is treated for maintaining an average reduced NO x content in the flue gases lower than 5 times the first average reduced NO x content.