熔铁催化剂比表面与钾溶出的关系

INFLUENCE OF POTASSIUM LEACHING OUT ON SPECIFIC SURFACE AREA OF FUSED IRON CATALYST

引言固体催化剂的比表面是决定其活性大小的重要因素之一。对于氨合成催化剂影响其比表面的因素很多,K2O含量就是其中的重要因素之一。有关资料报导随着钾含量的升高,比表面下降。我们首先制备了一系列钾含量不同的催化剂,有的还添加了稀土氧化物,分别测定比表面,又将钾含量很高（2.3％左右,超过一般工业用催化剂含量）的催化剂,通过浸泡使水溶性钾减少,测定不同浸泡时间催化剂的比表面,从中了解不同催化剂钾含量大小对比表面的影响情况。有关钾的溶出对比表面的影响还未见报导。另外,由碱表面和铁表面的测定初步考察了含钾量很高的催化剂在水中浸泡后钾的分布情况。

Specific surface area of fused iron catalysts with different amounts of potassium (K_2O) has been determined. It is found that the prolonging of leaching time in water will decrease the amount of water-soluble potassium of catalyst and increase its specific surface area. When the leaching time is long enough the specific surface area approches constant, As water-soluble potassium almost has been removed the water-insoluble potassium is left. The water soluble potassium distributes in the interface of α-Fe crystalites as the catalyst reduced for surface area determination. It affects the specific surface area greatly. An addition of rareearth oxides by soaking or melting has a little influence on specific surface area. Some valuable information is obtained from the CO_2 and O_2 adsorption measurements. A condensed discussion is also given.