沸石骨架脱羟与脱铝数量之间关系的NMR研究

NMR INVESTIGATION OF RELATION BETWEEN THE AMOUNT OF DEHYDROXYLATION AND DEALUMINATION ON THE FRAMEWORK OF FOUR SPECIES ZEOLITES

本文讨论了用小板倒角脉冲技术测试具有半整数自旋四极核２７Ａｌ的ＮＭＲ谱．通过ＮａＣｌ反交换测量不同温度焙烧的ＨＺＳＭ－５，ＨＭ，ＨＦｕ－９和Ｈ－镁碱沸石Ｂ酸位的变化以及用ＥＰＲ测试Ｌ酸位变化，发现在５００～７００℃温域四种沸石各自有一个脱羟的突变温区．用小板倒角脉冲２７ＡｌＮＭＲ技术观察到这些样品仅有少量非骨架铝，从而确定这四种分子筛脱羟与脱铝是不同步的．

mall flip angle pulse NOR technique of nuclei with half integerspin in powdered sample was discussed.A series of HZSM-5,HM,HFu-9 and H--Ferrierite samples was calcinated at different temperatures.The change of the amount of B acid sites of zeolites was determined by inverse exchange with NaCI solution and i-acid sites weremeasured by EPR spectroscopy after adsorption of benzene vapor.Itwas found that during the calcination the B acid sites were transformedinto the l-acid sites and there was a sudden change. Zeolite sampleswhich had been calcined at different teml>eratures were then impregnated with a solution of 38% vol. acetylacetone in ethanol and observed insmall flip angle pulse 27Al MAS NMR. only a few nonframework aluminum were existed in those calcined samples according'to the 27AlNMR observation to provide that the dehydroxyl process and the formation of L acids for HZSM-5,Ha,HFu-9,H-Ferrierite would not accompany simultaneously with the dealumination process.