一、引言金属催化剂一般是使金属以微小结晶分散于大表面的担体上。采用有担体的金属催化剂可使金属原子大部分位于担体的表面上,同时担体质点又可以物理地分隔一些小结晶不使其聚结为大结晶颗粒,从而使催化剂具有较高的活性和稳定性。尽管这样,金属颗粒仍要逐渐长大,特别是在高温下,熔结或老化过程更为明显。金属的分散情况,通 I. INTRODUCTION Metal catalysts are generally metals that are dispersed on a large surface support by tiny crystals. The use of a supported metal catalyst enables most of the metal atoms to be located on the surface of the support while the support particles physically separate the small crystals from agglomerating them into large crystalline particles resulting in a catalyst with high activity and stability . In spite of this, the metal particles are still growing, especially at high temperatures, the sintering or aging process is more pronounced. Metal dispersion, pass