Raney-Cu催化剂在还原过程中的烧结行为

SINTERING BEHAVIOUR OF RANEY-Cu CATALYST IN VARIOUS REDUCING ATMOSPHERES

Raney-Cu催化剂可以用于甲醇合成及其他工业上的化学反应,但其活性衰减也比较迅速。影响其寿命的主要原因之一是由于在较高温度下的烧结。金属的烧结行为一般被认为温度在低于其熔点(绝对温度)的一半时即可发生,但迄今对于铜催化剂烧结的研究报导还比较少。

Raney-Cu catalyst was prepared by leaching Cu-Al alloy (1:1) and passivated in N_2O at 200℃.The passivated sample was reduced in pure H_2 or CO, and it is found that the surface structure and the crystallization in bulk change regulary with the space velocity of the reducing gas at 300℃. Methods of specific surface area measurement, XRD, proe size distribution, SEM and TEM were employed to detect the extent of sintering and the results agreed with each other.The reducing reactions of CuO in H_2 and in CO are strongly exothermic and proceed rapidly. The catalyst bed would then be overheated and the freshly reduced copper would sinter seriously. The specific surface area decreases, resulting in deactivation.If H_2(5%vol)+N_2 is used instead of pure H_2 or CO, sintering could be avoided successfully.