蒸气相合成BZSM—5沸石用于间二甲苯异构化反应

首次利用蒸气相法合成的BZSM-5沸石作为异构化催化剂,测定了BZSM-5沸石对间二甲苯异构化的活性和选择性。当B_2O_3/Al_2O_3(摩尔比)为1.8时异构化活性(50.97%)和选择性(20.86%)均达到较佳值。用IR、NH_(?)-TPD表征了BZSM-5沸石的酸强度及酸分布,同时与异构化活性和选择性进行了关联。实验结果表明,在合成中加入适量的硼有利于提高异构化活性和选择性。

ISOMERIZATION OF m-XYLENE ON BZSM-5 SYNTHESIZED BY VAPOUR PHASE METHOD

Zeolite BZSM-5 synthesized by vapour-phase method is a catalyst for m-xylene isomerization. Its activity and selectivity were examined by pulsed microreaction gas chromatography. The conversion of m-xylene on BZSM-5 reaches 50.97% when moderate amount of boron is added during synthesis. The activity and selectivity of the catalyst achieve the best value when the molar ratio B_2O_3/A1_2O_3 is 1.8. The acidity of BZSM-5 which exerts effect on the activity of m-xylene conversion and the selectivity of p-xylene, was charact(?)rized by temperature programmed desorption of NH_3 as well as pyridine-IR.The Influence of calcination procedure was also examined. Both the activity for m-xylene isomerization and acidity of BZSM-5 increase with incresing moderate amount of boron added during synthesis. Increasing total acid sites results in increase in activity of BZSM-5. These experimental results showed the boron added during synthesis is in favour of the activity and selectivity for m-xylene isomerization.