The elegant 2D multiquantum (MQ) MAS NMR has been applied to investigate the coordination of Al atoms in SAPO-34. The results show that the effects of the template and/or water on the coordination of Al atoms are sig...The elegant 2D multiquantum (MQ) MAS NMR has been applied to investigate the coordination of Al atoms in SAPO-34. The results show that the effects of the template and/or water on the coordination of Al atoms are significant, which lead to the formation of various Al species. Up to four kinds of Al species are distinctly resolved.展开更多
分子筛骨架铝及非骨架铝的定量测定对于分子筛酸中心机理研究以及指导和监测分子筛改性工艺均有重要意义。众所周知,化学和X—Ray分析方法定量确定分子筛骨架和非骨架铝量比率有困难。目前多以NMR方法为主,综合化学及其它手段来获得有...分子筛骨架铝及非骨架铝的定量测定对于分子筛酸中心机理研究以及指导和监测分子筛改性工艺均有重要意义。众所周知,化学和X—Ray分析方法定量确定分子筛骨架和非骨架铝量比率有困难。目前多以NMR方法为主,综合化学及其它手段来获得有关信息:即对经脱铝热处理后的分子筛样,藉29Si MAS NMR方法测定骨架硅铝比。展开更多
The excitation functions were measured in the reaction of 27Al+27Al at incident energies from 114MeV to 127MeV in steps of 200keV. The detection angles were continuously covered from 10o to 57° in the laboratory ...The excitation functions were measured in the reaction of 27Al+27Al at incident energies from 114MeV to 127MeV in steps of 200keV. The detection angles were continuously covered from 10o to 57° in the laboratory system. The energy autocorrelation functions of the dissipative fragments were analyzed by using different approaches. The nonself-averaging oscillations in the excitation functions were considered due to the angular momentum coherence and damping of the coherent nuclear rotation. The damping results from a quantum chaotic motion.展开更多
The coordination structure of aluminum in magnesium aluminum hydroxide was studied by 27Al NMR. The result showed that tetrahedral aluminum (AlIV) existed in magnesium aluminum hydroxide, and the contents of AlIV inc...The coordination structure of aluminum in magnesium aluminum hydroxide was studied by 27Al NMR. The result showed that tetrahedral aluminum (AlIV) existed in magnesium aluminum hydroxide, and the contents of AlIV increased with the increase of the ratio of Al/Mg and with the peptizing temperature. AlIV originated from the so-called Al13 polymer with the structure of one Al tetrahedron surrounded by twelve Al octahedrons.展开更多
基金We are grateful to the support of the National Natural Science Foundation of China and the Ministry of Science and Technology of China. We appreciate Dr. R. Fu (NHMFL Tallahassee) for his kind help regarding the MQ MAS NMR experiments.
文摘The elegant 2D multiquantum (MQ) MAS NMR has been applied to investigate the coordination of Al atoms in SAPO-34. The results show that the effects of the template and/or water on the coordination of Al atoms are significant, which lead to the formation of various Al species. Up to four kinds of Al species are distinctly resolved.
文摘分子筛骨架铝及非骨架铝的定量测定对于分子筛酸中心机理研究以及指导和监测分子筛改性工艺均有重要意义。众所周知,化学和X—Ray分析方法定量确定分子筛骨架和非骨架铝量比率有困难。目前多以NMR方法为主,综合化学及其它手段来获得有关信息:即对经脱铝热处理后的分子筛样,藉29Si MAS NMR方法测定骨架硅铝比。
基金the National Natural Science Foundation (No.19775057), and by the Chinese Academyof Sciences and the Laboratori Nazionale del
文摘The excitation functions were measured in the reaction of 27Al+27Al at incident energies from 114MeV to 127MeV in steps of 200keV. The detection angles were continuously covered from 10o to 57° in the laboratory system. The energy autocorrelation functions of the dissipative fragments were analyzed by using different approaches. The nonself-averaging oscillations in the excitation functions were considered due to the angular momentum coherence and damping of the coherent nuclear rotation. The damping results from a quantum chaotic motion.
基金This research is supported by NNSFC No:20273041.
文摘The coordination structure of aluminum in magnesium aluminum hydroxide was studied by 27Al NMR. The result showed that tetrahedral aluminum (AlIV) existed in magnesium aluminum hydroxide, and the contents of AlIV increased with the increase of the ratio of Al/Mg and with the peptizing temperature. AlIV originated from the so-called Al13 polymer with the structure of one Al tetrahedron surrounded by twelve Al octahedrons.
