초록 ▼

The invention relates to a novel catalyst having excellent activity, selectivity and stability for reducing nitric oxide to gas nitrogen, with hydrogen being used as a reducing agent, in the low temperature range 100-200째 C. and in the presence of an excess of oxygen (e.g. 5% vol), H2O (5% vol) and/

The invention relates to a novel catalyst having excellent activity, selectivity and stability for reducing nitric oxide to gas nitrogen, with hydrogen being used as a reducing agent, in the low temperature range 100-200째 C. and in the presence of an excess of oxygen (e.g. 5% vol), H2O (5% vol) and/or SO2 (20 ppm) in the supply. The inventive catalyst consists of platinum crystals which are in contact with the phases of a mixed MgO and CeO2 medium or in the form of platinum supported on the mixed MgO--CeO2 medium which has already been sulphated in a selective manner. The Pt/MgO--CeO2 catalyst can be used to obtain NO conversion levels which are greater than 40% and nitrogen selectivity values of greater than 80% under NOx oxidation conditions in the 100-400째 C. temperature range and for a surface contact time of 0.045 s. In particular, full NO conversion is obtained as well as N2 selectivity levels of 83% at 150째 C. with a reaction mixture of 0.25% NO/1% H2/5% O2/5% H 2O/He.

대표청구항 ▼

The invention claimed is: 1. A catalyst comprising Pt in an amount of between 0.1 and 2 wt. % dispersed on a pre-sulphated mixed oxide support of Mg and Ce. 2. A catalyst in accordance with claim 1 wherein the metal content is 0.1% of Pt dispersed on the mixed oxide support of Mg and Ce. 3.

The invention claimed is: 1. A catalyst comprising Pt in an amount of between 0.1 and 2 wt. % dispersed on a pre-sulphated mixed oxide support of Mg and Ce. 2. A catalyst in accordance with claim 1 wherein the metal content is 0.1% of Pt dispersed on the mixed oxide support of Mg and Ce. 3. A catalyst in accordance with claim 1 comprising Pt supported on a mixed oxide of 50% MgO and 50% CeO2. 4. A catalyst in accordance with claim 1 further comprising more than one compound selected from the group consisting of Pt, MgO, CeO2, MgSO4 and Ce2(SO4)3. 5. A process for preparing a catalyst comprising Pt in an amount of between 0.1 and 2 wt. % dispersed on a pre-sulphated mixed metal oxide support of Mg and Ce as defined in claim 1, said process comprising: impregnating a MgO and CeO2 support with an aqueous solution containing NH4NO3, impregnating the MgO and CeO2 support with an aqueous solution containing a sulphate precursor, impregnating the mixed sulphated MgO and CeO2 support with an aqueous solution of the platinum precursor, heating at 600째 C. in a flow of air for at least 2 hours and reducing the catalyst in a flow of H2 at 300째 C. for at least 2 hours. 6. A process according to claim 5 further comprising: impregnating a MgO and CeO2 support with an aqueous solution containing NH4NO3, evaporating water, drying of a resulting residue, sieving the residue, heating at 300째 C. in the presence of air for 2 hours, impregnating the MgO and CeO2 support with an aqueous solution containing a sulphate precursor, evaporating water, drying a resulting residue, sieving the residue, heating at 600째 C. in the presence of air for 2 hours, cooling to room temperature obtaining a mixed sulphated MgO and CeO2 support, impregnating the mixed sulphated MgO and CeO2 support with an aqueous solution of the platinum precursor, evaporating water, drying the resulting residue, sieving and heating to 600째 C., heating at 600째 C. in a flow of air for at least 2 hours, and reducing the catalyst in a flow of H2 at 300째 C. for at least 2 hours. 7. A method of reducing a product selected from the group consisting of NO, NO2, and a mixture of NO and NO2 to N2 gas using hydrogen as reducing agent in the presence of O 2 in the presence of a catalyst comprising Pt highly dispersed between 0.1 and 2 wt. % dispersed on a pre-sulphated mixed metal oxide support of Mg and Ce, as defined in claim 1. 8. A method in accordance with claim 7 wherein a reactor selected from the group consisting of a fixed bed reactor and a monolith type reactor is used.