An increasing number of heavy-duty vehicles are using liquefied natural gas (LNG) as a fuel due to the expanding refuelling station network for LNG and lower overall emissions compared to diesel vehicles. The latest EURO VI regulation or natural gas fuelled vehicles set a limit for NH₃ of 10 ppm, and N₂O exhaust is expected to be restricted in Europe in the near future. Poisonous and corrosive NH₃ and the greenhouse gas N₂O are formed as by-products in a three-way catalyst used to minimize the emissions of stoichiometric heavy-duty engines. In this work, we studied how high temperature NH₃ and N₂O formed in modern, fresh and aged bimetallic Pd/Rh three-way catalysts in simulated exhaust gas. More precisely, the exhaust gas composition and temperature were examined. Decreases in NO concentration and increases in temperature lowered the formation of NH₃ and N₂O, whereas a decrease in CH₄ concentration reduced only NH₃ formation. According to Raman and powder X-ray diffraction experiments, the structure of the catalyst changed during the ageing, and this reputedly affected the function of cerium-zirconium mixed oxides and thus the formation of NH₃ and N₂O. Temperature programmed reduction (H₂-TPR) measurements showed changes in cerium-zirconium mixed oxide performance after ageing supporting Raman spectroscopy findings. Catalyst ageing in oxidizing conditions increased the formation of N₂O. This study showed that exhaust gas composition plays an important role in the formation of undesired NH₃ and N₂O emissions.

由于使用液化天然气（LNG）的加油站网络不断扩大，并且与柴油车辆相比，总排放量降低，因此越来越多的重型车辆正在使用液化天然气（LNG）作为燃料。最新的EURO VI法规或以天然气为燃料的车辆将NH ₃的限值设定为10 ppm，并且预计在不久的将来欧洲将限制N ₂ O的排放。毒性和腐蚀性的NH ₃和温室气体N ₂ O在三效催化剂中作为副产物形成，用于最小化化学计量重型发动机的排放。在这项工作中，我们研究了高温下的NH ₃和N ₂在现代，新鲜和老化的双金属Pd / Rh三效催化剂中，在模拟废气中形成O。更精确地，检查排气成分和温度。NO浓度的降低和温度的升高降低了NH ₃和N ₂ O的形成，而CH ₄浓度的降低仅减少了NH _3的形成。根据拉曼和粉末X射线衍射实验，催化剂的结构在老化过程中发生了变化，据说这会影响铈锆混合氧化物的功能，从而影响NH ₃和N ₂ O的形成。程序升温还原（H _2个-TPR）测量显示了老化后铈锆复合氧化物性能的变化，这有助于拉曼光谱学的发现。在氧化条件下催化剂老化会增加N ₂ O的形成。这项研究表明，废气成分在不希望的NH ₃和N ₂ O排放物的形成中起着重要作用。