高温焙烧对Pd-Au/SiO_2体系中Pd-Au合金聚集态的影响

Study on Calcination of Pd-Au/SiO_2 Catalyst

以XRD作为主要的表征手段,研究了在Pd-Au/SiO2体系的制备过程中引入高温焙烧技术后对此体系的影响。实验结果表明,制备过程中的还原阶段对Pd-Au合金相的形成起着决定性作用,还原之前的高温焙烧对Pd和Au的化合物产生各自不同的影响,使得Pd,Au不能最终形成均一的合金结构;而还原后的高温焙烧则不影响Pd,Au的合金结构,但会引起金属微粒的凝聚生长,使得晶粒变大,晶粒增长的程度受焙烧气氛、焙烧温度的影响,与焙烧时间无关。

In the preparation of Pd-Au/SiO2 the effect of calcination on Pd-Au alloy was studied by means of XRD. Reduction process of Pd-Au/SiO2 was the key step for Pd- Au alloy formation on the catalyst. The calcination before reduction prevented Pd and Au species from forming Pd - Au alloy, but calcination after reduction merely increased the size of Pd-Au alloy rnicrocrystal without affecting the alloy structure.