Advanced catalyst for NOx reduction using hydrocarbons from lean-burning gas engine

For a catalytic NOx reduction process for natural gas-fueled lean-burning engines, selective catalytic reduction of NOx by propane was studied on metal ion-exchanged zeolite catalysts. A comparative study on Cu- and Co-ZSM-5 showed the superiority of Co-based catalysts for C3H8-SCR in the presence of water vapor. Investigation into various Co-zeolite catalysts showed that Co-Beta has superior activity and selectivity for NOx reduction. Durability tests of the catalyst in a model gas simulating gas engine exhaust showed that the activity of Co-Beta is sufficient even in the presence of SOx after 5000 h of operation, whereas Co-Mordenite and Co-ZSM-5 lost their activity in several hundred hours of operation.