原位引入有机组分对氧化硅体系改性是合成有机-无机杂化硅材料的重要方法.利用原位的^(29)Si液体核磁,研究了甲醇为溶剂、氨水催化条件下的四乙氧基硅烷(TEOS)和二甲基二乙氧基硅烷(DDS)原位共水解的动力学过程.通过改变反应体系中氨和...原位引入有机组分对氧化硅体系改性是合成有机-无机杂化硅材料的重要方法.利用原位的^(29)Si液体核磁,研究了甲醇为溶剂、氨水催化条件下的四乙氧基硅烷(TEOS)和二甲基二乙氧基硅烷(DDS)原位共水解的动力学过程.通过改变反应体系中氨和水的浓度,拟合出单体及中间产物浓度随时间的变化曲线,得到了TEOS和DDS各自的水解速率常数以及相应各反应物的反应级数.与单前驱体水解一致的是,在双前驱体系中TEOS和DDS自身的反应级数仍保持一级,但是氨和水的反应级数都有不同程度的增大.与单前驱体水解速率方程相比,混合体系中TEOS的水解速率常数增大.同时,DDS在双前驱体中比单前驱体中的水解速率常数有很大程度的减少.水解动力学表明,TEOS和DDS在双前驱体体系中显示出更平行的水解速率.利用固体^(29)Si MAS NMR,XPS及小角X射线散射(SAXS)手段对双前驱体体系研究得到的信息显示,碱催化条件下原位的TEOS水解中间物与DDS中间产物的原位共缩聚程度很弱.展开更多
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
Sol-gel method is a technique to synthesize inorganic materials based on wet-chemical reaction theory. The results have shown that reactants tetraethyl orthosilicate （TEOS） and Ca（NO3）2·4H2O can form sol and ...Sol-gel method is a technique to synthesize inorganic materials based on wet-chemical reaction theory. The results have shown that reactants tetraethyl orthosilicate （TEOS） and Ca（NO3）2·4H2O can form sol and gel in solution at 50-60 ℃, and the cosolvents are propyl alcohol （NPA） and H2O, the catalyst is HNO3. This sol-gel is burned for 12 hat 1 350-1 450 ℃ so that the organic matter, free water （moisture） in sol-gel system are removed and a solid reaction has taken place to form the resulting product. The product has been confirmed to be C3S by XRD, SEM and 29Si MAS NMR, as well as free lime content of the product which is less than 0.2% was determined by propanetriol-ethanol-method. The analysis determined by EDXA has indicated that the n（Ca）/n（Si） ratio in corresponding to micro-region is close to theoretical value of 3∶1. This resulting product is C3S with Si sites of Q0 polymerization, and has higher purity and hydraulic activities at earlier age of hydration.展开更多
Based on the study of <sup>29</sup>Si,<sup>27</sup>Al NMR spectra for some orthoclases determined byX-ray powder diffraction method,Zhou et al.found that there are three maxima for the<sup&g...Based on the study of <sup>29</sup>Si,<sup>27</sup>Al NMR spectra for some orthoclases determined byX-ray powder diffraction method,Zhou et al.found that there are three maxima for the<sup>29</sup>Si NMR spectra of these orthoclases.In order to explain the three maxima the authorsexamined the <sup>29</sup>Si NMR spectrum and microstructure of Taiping orthoclase occurring ingranitic dyke.展开更多
RECENTLY a new family of mesoporous molecular sieves,M41S,was reported by researchers atMobil R&D Corporation.As a member of the family,MCM-41,which exhibits a hexagonalarray of uniform channel mesopores,has been ...RECENTLY a new family of mesoporous molecular sieves,M41S,was reported by researchers atMobil R&D Corporation.As a member of the family,MCM-41,which exhibits a hexagonalarray of uniform channel mesopores,has been synthesized.The channel size can be variedfrom approximately 1.5 nm to greater than 10 nm by choosing different surfactants,auxiliarychemicals(1,3,5-trimethylbenzene)in the reactant,and by changing the reaction condi-tions.The wall thickness of this kind of molecular sieve is in the range of 0.3 to 1.3 nm esti-展开更多
12 natural alkali feldspars have been studied by(29)~Si and(27)~Al MAS NMR as well as XRD,IR,EPMA and chemical analysis.Three kinds of(29)~Si NMR spectra,i.e.the spectra of microcline,perthiteand perthite with minor p...12 natural alkali feldspars have been studied by(29)~Si and(27)~Al MAS NMR as well as XRD,IR,EPMA and chemical analysis.Three kinds of(29)~Si NMR spectra,i.e.the spectra of microcline,perthiteand perthite with minor plagioclase,have been obtained.There are two types of(27)~Al NMR spectra.The(27)~Alspectrum of microcline is the same as that of perthite,but is different from the spectrum for perthite contain-ing plagioclase.Through this study,we found that the results of NMR and IR are inconsistent with that ofXRD,which shows that the transition of alkali feldspar from monoclinic to triclinic system might be a rathercomplicated process.展开更多
文摘原位引入有机组分对氧化硅体系改性是合成有机-无机杂化硅材料的重要方法.利用原位的^(29)Si液体核磁,研究了甲醇为溶剂、氨水催化条件下的四乙氧基硅烷(TEOS)和二甲基二乙氧基硅烷(DDS)原位共水解的动力学过程.通过改变反应体系中氨和水的浓度,拟合出单体及中间产物浓度随时间的变化曲线,得到了TEOS和DDS各自的水解速率常数以及相应各反应物的反应级数.与单前驱体水解一致的是,在双前驱体系中TEOS和DDS自身的反应级数仍保持一级,但是氨和水的反应级数都有不同程度的增大.与单前驱体水解速率方程相比,混合体系中TEOS的水解速率常数增大.同时,DDS在双前驱体中比单前驱体中的水解速率常数有很大程度的减少.水解动力学表明,TEOS和DDS在双前驱体体系中显示出更平行的水解速率.利用固体^(29)Si MAS NMR,XPS及小角X射线散射(SAXS)手段对双前驱体体系研究得到的信息显示,碱催化条件下原位的TEOS水解中间物与DDS中间产物的原位共缩聚程度很弱.
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.
基金Financially supported by National Basic Research Program of China (973Program)(No. 2009CB623200)National Natural Science Foundation of China(No.50972109)Doctoral Program of Higher Education (No. 20090141110021)
文摘Sol-gel method is a technique to synthesize inorganic materials based on wet-chemical reaction theory. The results have shown that reactants tetraethyl orthosilicate （TEOS） and Ca（NO3）2·4H2O can form sol and gel in solution at 50-60 ℃, and the cosolvents are propyl alcohol （NPA） and H2O, the catalyst is HNO3. This sol-gel is burned for 12 hat 1 350-1 450 ℃ so that the organic matter, free water （moisture） in sol-gel system are removed and a solid reaction has taken place to form the resulting product. The product has been confirmed to be C3S by XRD, SEM and 29Si MAS NMR, as well as free lime content of the product which is less than 0.2% was determined by propanetriol-ethanol-method. The analysis determined by EDXA has indicated that the n（Ca）/n（Si） ratio in corresponding to micro-region is close to theoretical value of 3∶1. This resulting product is C3S with Si sites of Q0 polymerization, and has higher purity and hydraulic activities at earlier age of hydration.
基金Project supported by the National Natural Science Foundation of China.
文摘Based on the study of <sup>29</sup>Si,<sup>27</sup>Al NMR spectra for some orthoclases determined byX-ray powder diffraction method,Zhou et al.found that there are three maxima for the<sup>29</sup>Si NMR spectra of these orthoclases.In order to explain the three maxima the authorsexamined the <sup>29</sup>Si NMR spectrum and microstructure of Taiping orthoclase occurring ingranitic dyke.
文摘RECENTLY a new family of mesoporous molecular sieves,M41S,was reported by researchers atMobil R&D Corporation.As a member of the family,MCM-41,which exhibits a hexagonalarray of uniform channel mesopores,has been synthesized.The channel size can be variedfrom approximately 1.5 nm to greater than 10 nm by choosing different surfactants,auxiliarychemicals(1,3,5-trimethylbenzene)in the reactant,and by changing the reaction condi-tions.The wall thickness of this kind of molecular sieve is in the range of 0.3 to 1.3 nm esti-
文摘12 natural alkali feldspars have been studied by(29)~Si and(27)~Al MAS NMR as well as XRD,IR,EPMA and chemical analysis.Three kinds of(29)~Si NMR spectra,i.e.the spectra of microcline,perthiteand perthite with minor plagioclase,have been obtained.There are two types of(27)~Al NMR spectra.The(27)~Alspectrum of microcline is the same as that of perthite,but is different from the spectrum for perthite contain-ing plagioclase.Through this study,we found that the results of NMR and IR are inconsistent with that ofXRD,which shows that the transition of alkali feldspar from monoclinic to triclinic system might be a rathercomplicated process.
