载体孔结构特性对三效催化剂性能的影响

Influence of Carrier Pore Structure Character on the Properties of Three-Way Catalyst

以相同的催化涂层材料和具有不同孔密度和壁厚的圆柱形蜂窝陶瓷载体制成2颗Pd/Rh型低贵金属三效催化剂,载体的孔密度和壁厚分别为62孔/cm2,0.165mm和93孔/cm2,0.102mm。通过发动机台架试验和整车转鼓试验研究了具有不同孔结构特性载体催化剂的催化性能。试验结果表明,高孔密度薄壁的载体不仅明显改善了催化剂的起燃特性和空燃比特性,而且显著提高了对HCs的处理能力。为此建议可通过载体的改进解决欧Ⅳ等高标准车的HC排放问题,但同时还要充分考虑到与NOx的排放控制平衡问题,在尽量不影响发动机动力的情况下,实现燃油经济性和低排放。

Two columns of three-way catalysts with the same low Pd/Rh type precious metals loadings are prepared with different pore densities of 62/cm^2 and 93/cm^2 and different wall thickness of 0.165 mm and 0.102 mm, respectively. The catalytic performances of catalysts are studied on engine bench and vehicle rotating drum test system. The results indicate that the carrier with high pore density and thin wall improves the catalyst light-off characteristics and air-fuel ratio characteristics markedly, and enhance their capability of purifying HCs. So some proposals can be put forward that improving the carrier pore structure can solve the problem of high HCs emission for high standard vehicles, at the same time, to control the emission balance of NOx with HCs. The best method is to realize both of fuel economy and low emission without influencing engine power.