用粉末XRD,FT—IR,^(29)Si MAS NMR,对高硅HZSM—5沸石及疏水硅沸石Silicalite-Ⅰ进行结构性质表征.在室温下,疏水硅沸石具有ZSM—5的单斜对称性.它的红外骨架振动谱及高分辨^(29)Si固体核磁共振谱均显示出高的分辨率.在红外光谱中,3700...用粉末XRD,FT—IR,^(29)Si MAS NMR,对高硅HZSM—5沸石及疏水硅沸石Silicalite-Ⅰ进行结构性质表征.在室温下,疏水硅沸石具有ZSM—5的单斜对称性.它的红外骨架振动谱及高分辨^(29)Si固体核磁共振谱均显示出高的分辨率.在红外光谱中,3700和3500^(-1)左右的表面Si-OH基振动消失.表明疏水硅沸石晶格中的[SiO_4]四面体排列完美.由—Si—O—Si—构成的微孔表面,具有优良的疏水性.展开更多
The structures of silicalite-1 and H、 Na form of ZSM-5 with various SiO2/Al2O3 ratios were characterized by powder XRD, 29Si MAS NMR, and the desorption process of р-xylene (p-x) on the zeolites was investigated by ...The structures of silicalite-1 and H、 Na form of ZSM-5 with various SiO2/Al2O3 ratios were characterized by powder XRD, 29Si MAS NMR, and the desorption process of р-xylene (p-x) on the zeolites was investigated by using TG/DTG/DTA. SiOH defects of ZSM-5 have no relation with the content of structural Al. Silicalite-1 possesses perfect framwork structure without SiOH defects and structural Al. On a curve of TG/DTG/DTA, p-x adsorbed by silicalite completely desorbs in the range of 57-174℃by two steps, accompaned with endothermal effect. While on the TG/DTG/DTA curves of H, Na-ZSM-5, there is a third desorption step of p-x in the range of 180-600℃ with exothermic effect. Below 180℃ the number of desorbed p-x molecules is related to pore space, but over 180℃，it is related to SiOH and positive ion linking with the structural Al.展开更多
对OFF沸石进行离子交换,制备出NH4-OFF沸石,然后通过Li2CO3/NH4-OFF体系的固态反应制备了不同锂离子交换度的Li-OFF沸石.对吸附氮气和氧气的Li-OFF样品进行了7Li MAS NMR表征,结果表明,所有吸附氧气样品的部分7Li MAS NMR共振峰均发生...对OFF沸石进行离子交换,制备出NH4-OFF沸石,然后通过Li2CO3/NH4-OFF体系的固态反应制备了不同锂离子交换度的Li-OFF沸石.对吸附氮气和氧气的Li-OFF样品进行了7Li MAS NMR表征,结果表明,所有吸附氧气样品的部分7Li MAS NMR共振峰均发生了顺磁位移.通过对实验谱的拟合,得知Li-OFF沸石中的锂离子可分布在3类阳离子位置(A,B和C)上,对应于3个不同位移的谱峰.Li+离子并非等比例地进入3类可交换的位置,而是优先占据主孔道中的A位置,随着交换度的升高,位能较高的C和B位置上的Li离子占有率逐渐增加.在100%固态交换度样品中,Li+离子在不同离子位的占有率分别为17%(位置B),29%(位置C)和54%(位置A).其中,位置B是O2分子不可接近的,所以Li-OFF沸石中有83%的阳离子是可以接近的.展开更多
Silicon clusters are produced by a new chendcal method. Comparing with theprepaxation method using laser evaporation, large amoun of silicon clusters could havebeen obtained by this cheforcal decomposition of silicane...Silicon clusters are produced by a new chendcal method. Comparing with theprepaxation method using laser evaporation, large amoun of silicon clusters could havebeen obtained by this cheforcal decomposition of silicane and the clusters produced is sta-ble in atm0sphere. The FAB-MS spectra of the clusters is also discussed in this paper.展开更多
文摘用粉末XRD,FT—IR,^(29)Si MAS NMR,对高硅HZSM—5沸石及疏水硅沸石Silicalite-Ⅰ进行结构性质表征.在室温下,疏水硅沸石具有ZSM—5的单斜对称性.它的红外骨架振动谱及高分辨^(29)Si固体核磁共振谱均显示出高的分辨率.在红外光谱中,3700和3500^(-1)左右的表面Si-OH基振动消失.表明疏水硅沸石晶格中的[SiO_4]四面体排列完美.由—Si—O—Si—构成的微孔表面,具有优良的疏水性.
文摘The structures of silicalite-1 and H、 Na form of ZSM-5 with various SiO2/Al2O3 ratios were characterized by powder XRD, 29Si MAS NMR, and the desorption process of р-xylene (p-x) on the zeolites was investigated by using TG/DTG/DTA. SiOH defects of ZSM-5 have no relation with the content of structural Al. Silicalite-1 possesses perfect framwork structure without SiOH defects and structural Al. On a curve of TG/DTG/DTA, p-x adsorbed by silicalite completely desorbs in the range of 57-174℃by two steps, accompaned with endothermal effect. While on the TG/DTG/DTA curves of H, Na-ZSM-5, there is a third desorption step of p-x in the range of 180-600℃ with exothermic effect. Below 180℃ the number of desorbed p-x molecules is related to pore space, but over 180℃，it is related to SiOH and positive ion linking with the structural Al.
文摘对OFF沸石进行离子交换,制备出NH4-OFF沸石,然后通过Li2CO3/NH4-OFF体系的固态反应制备了不同锂离子交换度的Li-OFF沸石.对吸附氮气和氧气的Li-OFF样品进行了7Li MAS NMR表征,结果表明,所有吸附氧气样品的部分7Li MAS NMR共振峰均发生了顺磁位移.通过对实验谱的拟合,得知Li-OFF沸石中的锂离子可分布在3类阳离子位置(A,B和C)上,对应于3个不同位移的谱峰.Li+离子并非等比例地进入3类可交换的位置,而是优先占据主孔道中的A位置,随着交换度的升高,位能较高的C和B位置上的Li离子占有率逐渐增加.在100%固态交换度样品中,Li+离子在不同离子位的占有率分别为17%(位置B),29%(位置C)和54%(位置A).其中,位置B是O2分子不可接近的,所以Li-OFF沸石中有83%的阳离子是可以接近的.
文摘Silicon clusters are produced by a new chendcal method. Comparing with theprepaxation method using laser evaporation, large amoun of silicon clusters could havebeen obtained by this cheforcal decomposition of silicane and the clusters produced is sta-ble in atm0sphere. The FAB-MS spectra of the clusters is also discussed in this paper.
