| abstract |
Systems and methods of removing at least nitrogen oxides from an exhaust fluid generally include introducing a first reducing agent and a hydrogen gas co-reductant agent into the exhaust fluid upstream of a catalyst bed optimized for a hydrocarbon selective catalytic reduction process to reduce nitrogen oxides present in the exhaust fluid and then reacting residual nitrogen oxides in a second catalytic bed optimized for an ammonia selective catalytic reduction process. The use of hydrogen gas permits efficient reduction of nitrogen oxides over a wide temperature range, which is minimally affected by the presence of sulfur dioxide in the exhaust fluid. |