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US 6,551,564 B1Granted
Process for eliminating oxides of nitrogen
AssigneeInstitut Francais du Petrole
InventorsThierry Becue, Gil Mabilon, Philippe Villeret
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AssigneeInstitut Francais du Petrole
InventorsThierry Becue, Gil Mabilon, Philippe Villeret
Estimating the term…
The invention concerns materials for eliminating oxides of nitrogen NO and NO2 present in exhaust gases, in particular from the internal combustion engines of automotive vehicles operating in a medium which is super-stoichiometric in oxidising agents, which can adsorb oxides of nitrogen then desorb the oxides of nitrogen by elevating the temperature with respect to the adsorption temperature or by passage of rich mixture, said materials comprising mixed oxides the metals of which are in octahedral coordination, with the octahedra connecting together so that the structure generates micropores in the form of channels. These materials adsorb oxides of nitrogen by insertion and do not become poisoned in contact with oxides of sulphur and carbon contained in the gases. In the presence of a group VIII metal, these materials are capable of eliminating oxides of nitrogen absorded by reduction during passage of a rich mixture.
A process for eliminating oxides of nitrogen from exhaust gases, from automotive vehicle internal combustion engines, comprising contacting the exhaust gases with a material selected from materials with a cryptomelane, hollandite, romanechite or todorkite structure, comprising MO6 octahedra connected together such that the structure generates micropores in the form of channels, said octahedra comprising at least one element M selected from the group consisting of elements from groups IIIB, IVB, VB, VIB, VIIB, VIII, IB, IIB and IIIA of the periodic table, said octahedra excluding tin, said material further comprising at least one element (B) selected from the group consisting of alkali-metal elements, alkaline-earth elements, rare earth elements, transition metals and elements from groups IIIA, IVA of the periodic table.
A process for eliminating oxides of nitrogen from exhaust gases, from automotive vehicle internal combustion engines, comprising contacting the exhaust gases with a material selected from materials with a cryptomelane, hollandite, romanechite or todorkite structure, comprising MO6 octahedra connected together such that the structure generates micropores in the form of channels, said octahedra comprising at least one element M selected from the group consisting of elements from groups IIIB, IVB, VB, VIB, VIIB, VIII, IB, IIIB and IIIA of the periodic table, said material further comprising at least one element (B) selected from the group consisting of alkali-metal elements, alkaline-earth elements, rare earth elements, transition metals and elements from groups IIIA, IVA of the periodic table, said material further comprising at least one noble metal (C) from group VIII of the periodic table.
A process for eliminating oxides of nitrogen from exhaust gases, from automotive vehicle internal combustion engines, comprising contacting the exhaust gases with a material selected from materials with a cryptomelane, hollandite, romanechite or todorkite structure, comprising MO6 octahedra connected together such that the structure generates micropores in the form of channels, said octahedra comprising at least one element M selected from the group consisting of elements from groups IIIB, IVB, VB, VIB, VIIB, VIII, IB, IIB and IIIA of the periodic table, said material further comprising at least one element (B) selected from the group consisting of alkali-metal elements, alkaline-earth elements, rare earth elements, transition metals and elements from groups IIIA, IVA of the periodic table, said contacting comprising adsorbing oxides of nitrogen at a temperature in the range of 50° C. to 400° C., thermally and desorbing said oxides of nitrogen at a temperature in the range 300° C. to 500° C.°, further comprising a step for reducing the oxides of nitrogen to molecular nitrogen and/or nitric oxide, and wherein the step for adsorbing the oxides of nitrogen, the step for desorbing the oxides of nitrogen and the step for reducing the oxides of nitrogen take place in the contact with said material further comprising a noble metal from group VIII of the periodic table.
Dependencies are inferred from the claim text.