KNO_3／Al_2O_3上强碱位的产生和表征

FORMATION AND CHARACTERIZATION OF STRONG BASIC SITES ON KNO 3/Al 2O 3

报导了碱性催化能力强于Ｋ２ＣＯ３／Ａｌ２Ｏ３或ＭｇＯ的新型固体碱ＫＮＯ３／Ａｌ２Ｏ３，并研究了ＫＮＯ３在Ａｌ２Ｏ３上的分解以及强碱位的产生．ＫＮＯ３负载在Ａｌ２Ｏ３上，活化过程中６７３Ｋ才开始分解并形成碱位．由于催化反应在原位情况下进行，活性位未受到污染而保持高效率．

The KNO 3/Al 2O 3, a new type of solid base with higher basic catalytic ability than K 2CO 3/Al 2O 3 and MgO, was reported in the present study, and the decomposition of KNO 3 on Al 2O 3 and generation of strong basic sites were investigated. Interaction between KNO 3 and Al 2O 3 is not strong enough to decompose KNO 3, so that before activation, KNO 3 supported kept its original structure, and no basic sites thus formed and was poisoned by CO 2 in atmosphere, In the process of activation, KNO 3 began to decompose at 673 K on Al 2O 3 and created basic sites through the surface reaction: KNO 3+Al-OH→Al-OK+N 2O 3+H 2O. After evacuated at 673￣973 K, KNO 3/Al 2O 3 was active for cis 2 butene at 273 K, CO 2 poisoning experiment showed that only those strong basic sites adsorbed CO 2 above 673 K were proved to be the active centre on KNO 3/Al 2O 3. Calcination combined evacuation at 773 K was proved to be the best process for producing a very strong basicity on 26%KNO 3/Al 2O 3. In situ activation prior to reaction, the formed active centre on KNO 3/Al 2O 3 could avoid contamination and consequently kept higher efficiency than that on K 2CO 3/Al 2O 3 and MgO in the isomerization of butene at 273 K.