초록 ▼

A selective catalytic reduction (SCR) process with a palladium catalyst for reducing NOx in a gas, using hydrogen as a reducing agent is provided. The process comprises contacting the gas stream with a catalyst system, the catalyst system comprising (ZrO2)SO4, palladium, and a pre-sulfated zirconia

A selective catalytic reduction (SCR) process with a palladium catalyst for reducing NOx in a gas, using hydrogen as a reducing agent is provided. The process comprises contacting the gas stream with a catalyst system, the catalyst system comprising (ZrO2)SO4, palladium, and a pre-sulfated zirconia binder. The inclusion of a pre-sulfated zirconia binder substantially increases the durability of a Pd-based SCR catalyst system. A system for implementing the disclosed process is further provided.

대표청구항 ▼

The invention claimed is: 1. A process for selective catalytic reduction of nitrogen oxides (NOx) in a gas stream in the presence of H2, the process comprising contacting the gas stream with a catalyst system, the catalyst system comprising (ZrO2)SO4, palladium, and a pre-sulfated zirconia binder.

The invention claimed is: 1. A process for selective catalytic reduction of nitrogen oxides (NOx) in a gas stream in the presence of H2, the process comprising contacting the gas stream with a catalyst system, the catalyst system comprising (ZrO2)SO4, palladium, and a pre-sulfated zirconia binder. 2. The process of claim 1, wherein the pre-sulfated zirconia binder comprises sulfuric acid-treated ZrO2. 3. The process of claim 1, wherein a mass ratio of the pre-sulfated zirconia binder to the catalyst system is between 0.001 and 0.4. 4. The process of claim 1, wherein the catalyst system further comprises tungsten. 5. The process of claim 1, wherein the catalyst system further comprises SiO2 in the form of zirconia-silica-sulfate. 6. The process of claim 1, wherein a loading of the palladium is from 0.01 to 2.0% by wt of the catalyst system. 7. The process of claim 6, wherein the loading of the palladium is from 0.5 to 0.75% by wt of the catalyst system. 8. The process according to claim 1, wherein a catalytic bed comprising the catalyst system is installed in a flow path of an exhaust gas stream of a gas turbine, wherein the exhaust gas stream comprises NOx, H2O, O2, and SO2. 9. The process of claim 8, wherein H2O and hydrogen are injected into the exhaust gas between the gas turbine and the catalytic bed, to a concentration of about 5-25 vol. % H2O and a molar ratio for H2/NOx in the range of 10 to 100 in the exhaust gas. 10. The process of claim 8, wherein the exhaust gas is passed over the catalytic bed at a temperature maintained in a range of 100-140° C. 11. The process of claim 8, wherein the catalytic bed is installed in the flow path of exhaust gas of the gas turbine in an integrated gasification combined cycle (IGCC) power generation plant that synthesizes a hydrogen-containing fuel for the gas turbine, and further comprising: diverting a portion of the hydrogen-containing fuel to supply the H2 as a NOx reducing agent; injecting water and the diverted portion of the hydrogen-containing fuel into the exhaust gas between the gas turbine and the catalytic bed to a concentration of about 15-25 vol. % H2O and a molar ratio for H2/NOx in the range of 10-100 in the exhaust gas; and passing the exhaust gas over the catalytic bed at a temperature between 70-250° C. 12. The process of claim 11, wherein the H2O is injected to a concentration of about 17-21 vol. %. 13. A process for selective catalytic reduction of nitrogen oxides (NOx) in a gas stream using a hydrogen reducing agent, comprising: preparing a catalyst system on a catalytic bed, wherein the catalyst system comprises (ZrO2)SO4, palladium, and a pre-sulfated zirconia binder; positioning the catalytic bed in an exhaust stream of a gas turbine; injecting the hydrogen reducing agent into the exhaust stream upstream of the catalytic bed to a molar ratio for H2/NOx in the exhaust stream in the range of 10-100; injecting H2O into the exhaust stream upstream of the catalytic bed to maintain an H2O concentration in the exhaust stream of about 15-23 vol. %; and passing the exhaust stream over the catalytic bed at an operating temperature range of 70-250° C. 14. The process of claim 13, wherein the gas turbine is installed in an integrated gasification combined cycle plant (IGCC), and further comprising: producing a hydrogen-containing fuel in a gasifier of the IGCC for the gas turbine; diverting a portion of the hydrogen-containing fuel as the hydrogen reducing agent; and cooling the exhaust stream to the operating temperature range of the catalytic bed by means of a heat recovery steam generator in the IGCC, wherein a lower bound of the operating temperature range is established above a dewpoint in the exhaust stream. 15. A system for implementing a process for selective catalytic reduction of nitrogen oxides (NOx) in an exhaust gas from a gas turbine in an integrated gasification combined cycle power plant, comprising: a fuel gas synthesizer that produces a fuel gas containing at least 10 vol. % H2 and at least 10 vol. % nitrogen; a gas turbine that burns a portion of the fuel gas, producing the exhaust gas; a catalytic bed installed in a flow path of the exhaust gas, the catalytic bed comprising a catalyst system comprising (ZrO2)SO4, palladium, and a pre-sulfated zirconia binder; a hydrogen injector that mixes a diverted portion of the fuel gas into the exhaust gas between the gas turbine and the catalytic bed; an H2O injector that mixes H2O into the exhaust gas between the gas turbine and the catalytic bed; and sensors and valves at control points in the system connected to a controller that maintains operational conditions in the exhaust gas at the catalytic bed, wherein the operational conditions comprise a temperature between 70-250° C., a molar ratio for H2/NOx in the range of 10-100, and H2O at a concentration of about 15-23 vol. %. 16. The system of claim 15, wherein the pre-sulfated zirconia binder comprises sulfuric acid-treated ZrO2. 17. The system of claim 15, wherein a mass ratio of the pre-sulfated zirconia binder to the catalyst system is between 0.001 and 0.4. 18. The system of claim 15, wherein the catalyst system is installed in a flow path of an exhaust gas stream of a gas turbine, wherein the exhaust gas comprises NOx, H2O, O2, and SO2.