Selective Catalytic Reduction System and Process for Treating NOx Emissions Using a Palladium and Rhodium or Ruthenium Catalyst

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, the catalyst system comprising zirconia-silica washcoat particles, a pre-sulfated zirconia binder, and a catalyst combination comprising palladium and at least one of rhodium, ruthenium, or a mixture of rhodium and ruthenium;
• 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. %.