氢型丝光沸石的氨吸附特性与催化活性的关系

RELATIONSHIP BETWEEN ADSORPTION CHARACTERISTICS OF AMMONIA ON H-MORDENITE AND ITS CATALYTIC ACTIVITY

采用氨吸附-差热技术、红外光谱对氢型丝光沸石(HM)在不同温度氨吸附性质进行了研究,得到氨的可逆吸附与不可逆吸附的相对量及其随温度的变化。在接近甲苯岐化反应实际进行的条件下,测定了HM上吸附氨的红外光谱和催化活性。实验结果表明氨在L酸中心上的吸附是可逆的,在B酸上的吸附是不可逆的,从而证实了B酸是甲苯岐化反应的催化活性中心。在我们实验条件下,L酸中心似乎对岐化反应没有直接的作用。

Adsorption characteristics of ammonia on H-mordenite (HM) at various temperatures have been studied by IR spectra and .differential thermal techniques. The relative amounts of reversible and irreversible adsorption of ammonia and their changes with temperature are measured. Moreover, IR spectra of ammonia on HM and its catalytic activity for toluene disproportionation reaction are determined under conditions approximating those that are actually carried out for this. Experimental results show that the adsorption of ammonia on L-site is reversible, but that on B-site is irreversible. It has been proved that B-site is the catalytic active center for toluene disproportionation reaction.It seems that under our experimental conditions L-sites do not play a direct role in disproportionation reaction.