Aluminosilicate zeolites as one of the most important catalytic materials are widely applied in industrial reactions,and understanding of their synthetic mechanism is one of key factors in this field.27Al and 29Si NMR...Aluminosilicate zeolites as one of the most important catalytic materials are widely applied in industrial reactions,and understanding of their synthetic mechanism is one of key factors in this field.27Al and 29Si NMR techniques are one of powerful tools for characterization of zeolite synthesis,but unfortunately the study on 27Al NMR spectra of aluminosilicate solutions is still argumentative,and the assignment of aluminosi-licate species in the solutions are challengeable.In this work,we have carefully compared 27Al NMR spectra of various aluminosilicate solutions,harmonizing the assignments reported previously.Furthermore,we assigned 29Si NMR spectra related to Al species.The peaks at δ:-75.1 and-82.5 in 29Si NMR spectrum are related to Q2 Al species,the peaks at δ:-84.5 and-90.8 are related to Q3 and Q4 Al species in aluminosilicate solutions,respectively.展开更多
在水热条件下改变合成参数合成了系列SAPO-11分子筛，采用XRD和^29Si MAS NMR等手段对样品进行表征，并考察了合成参数对SAPO-11分子筛性能的影响。结果表明，合成条件对SAPO-11分子筛的骨架Si分布有很大影响。延长晶化时间、升高晶化...在水热条件下改变合成参数合成了系列SAPO-11分子筛，采用XRD和^29Si MAS NMR等手段对样品进行表征，并考察了合成参数对SAPO-11分子筛性能的影响。结果表明，合成条件对SAPO-11分子筛的骨架Si分布有很大影响。延长晶化时间、升高晶化温度、降低硅／铝比（n（SiO2）／n（Al2O3））或控制初始溶胶pH值为5．0～5．4都可以促进骨架Si的均匀分布，得到具有较高Si分散度的SAPO-11分子筛。展开更多
The microstructural study was conducted on cement and cement-slag pastes immersed in different concentrations of Mg（NO3）2 solutions utilizing ^29Si, ^27Al NMR spectroscopy and XRD techniques. The results show that t...The microstructural study was conducted on cement and cement-slag pastes immersed in different concentrations of Mg（NO3）2 solutions utilizing ^29Si, ^27Al NMR spectroscopy and XRD techniques. The results show that the hydration of both the cement and cement-slag pastes is delayed when the pastes are cured in Mg（NO3）2 solutions as compared to the pastes cured in water. Moreover, Mg^2＋ ions also exhibit an decalcifying and dealuminizing effect on the C-A-S-H in cement and cement-slag pastes, and thereby decrease Ca/Si and Al[4]/Si ratios of the C-A-S-H. The dealuminization of C-A-S-H is mitigated for cement-slag paste as compared to pure cement paste. The depolymerized calcium and aluminum ions from C-A-S-H gel mainly enter the pore solution to maintain the pH value and form Al^[6] in TAH, respectively. On the other hand, Mg^2＋ ions exert an impact on the intra-transition between Al^[6] species, from AFm and hydrogarnet to hydrotalcite-like phase. NO3^-ions are interstratified in the layered Mg-Al structure and formed nitrated hydrotalcite-like phase（Mg1-xAlx（OH）2（NO3）x·nH2O）. Results from both ^27Al NMR and XRD data show that ettringite seems not to react with Mg^2＋ ions.展开更多
文摘Aluminosilicate zeolites as one of the most important catalytic materials are widely applied in industrial reactions,and understanding of their synthetic mechanism is one of key factors in this field.27Al and 29Si NMR techniques are one of powerful tools for characterization of zeolite synthesis,but unfortunately the study on 27Al NMR spectra of aluminosilicate solutions is still argumentative,and the assignment of aluminosi-licate species in the solutions are challengeable.In this work,we have carefully compared 27Al NMR spectra of various aluminosilicate solutions,harmonizing the assignments reported previously.Furthermore,we assigned 29Si NMR spectra related to Al species.The peaks at δ:-75.1 and-82.5 in 29Si NMR spectrum are related to Q2 Al species,the peaks at δ:-84.5 and-90.8 are related to Q3 and Q4 Al species in aluminosilicate solutions,respectively.
文摘以含氟的二胺5,5’-(六氟异丙基)-二-(2-氨基苯酚)(6FHP)及二酐4, 4’-(六氟异丙基)-苯二酸酐(6FDA)或均苯四甲酸酐(PMDA)为单体,以分散红 1(DR1)为活性生色分子合成具有非线性光学特性的含氟聚酰亚胺,并采用溶胶-凝胶(Sol-Gel)法合成相应的聚酰亚胺／SiO2杂化材料．采用固态29 Si MAS NMR谱研究了含氟聚酰亚胺／SiO2杂化材料的交联结构,结果表明杂化材料中是以T3、Q3、Q4结构为主,说明在杂化材料中形成了交联网状结构．采用衰减全反射(ATR)测定了聚酰亚胺和杂化材料在832 nm处的电光系数,其值分别为 32、28、34和29 pm／V,结果表明具有较高的电光系数．
文摘在水热条件下改变合成参数合成了系列SAPO-11分子筛，采用XRD和^29Si MAS NMR等手段对样品进行表征，并考察了合成参数对SAPO-11分子筛性能的影响。结果表明，合成条件对SAPO-11分子筛的骨架Si分布有很大影响。延长晶化时间、升高晶化温度、降低硅／铝比（n（SiO2）／n（Al2O3））或控制初始溶胶pH值为5．0～5．4都可以促进骨架Si的均匀分布，得到具有较高Si分散度的SAPO-11分子筛。
基金Funded by National Natural Science Foundation of China(Nos.51778513,51402003,51578004)China Ministry of Science and Technology(No.2015CB655101)
文摘The microstructural study was conducted on cement and cement-slag pastes immersed in different concentrations of Mg（NO3）2 solutions utilizing ^29Si, ^27Al NMR spectroscopy and XRD techniques. The results show that the hydration of both the cement and cement-slag pastes is delayed when the pastes are cured in Mg（NO3）2 solutions as compared to the pastes cured in water. Moreover, Mg^2＋ ions also exhibit an decalcifying and dealuminizing effect on the C-A-S-H in cement and cement-slag pastes, and thereby decrease Ca/Si and Al[4]/Si ratios of the C-A-S-H. The dealuminization of C-A-S-H is mitigated for cement-slag paste as compared to pure cement paste. The depolymerized calcium and aluminum ions from C-A-S-H gel mainly enter the pore solution to maintain the pH value and form Al^[6] in TAH, respectively. On the other hand, Mg^2＋ ions exert an impact on the intra-transition between Al^[6] species, from AFm and hydrogarnet to hydrotalcite-like phase. NO3^-ions are interstratified in the layered Mg-Al structure and formed nitrated hydrotalcite-like phase（Mg1-xAlx（OH）2（NO3）x·nH2O）. Results from both ^27Al NMR and XRD data show that ettringite seems not to react with Mg^2＋ ions.
