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
The structural changes of silicate anions in the desilication process with the addition of calcium hydrate alumino-carbonate were studied by measuring Raman spectra, infrared spectra and corresponding second derivativ...The structural changes of silicate anions in the desilication process with the addition of calcium hydrate alumino-carbonate were studied by measuring Raman spectra, infrared spectra and corresponding second derivative spectra. The results show that the desilication ratio in the solution prepared by the addition of sodium silicate(solution-SS) is much greater than that in the solution by the addition of green liquor(solution-GL), and low alumina concentration in the sodium aluminate solutions facilitates the desilication process. It is also shown that alumino-silicate anions in the solution-GL, and Q^3 polymeric silicate anions in solution-SS are predominant, respectively. In addition, increasing the concentration of silica favors respectively the formation of the alumino-silicate or the Q^3 silicate anions in the solution-GL or the solution-SS. Therefore, it can be inferred that the low desilication ratio in the silicate-bearing aluminate solution is mainly attributed to the existence of alumino-silicate anions.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.
基金Project(51274242)supported by the National Natural Science Foundation of ChinaProject(2015CX001)supported by the Innovation-driven Plan in Central South University,China
文摘The structural changes of silicate anions in the desilication process with the addition of calcium hydrate alumino-carbonate were studied by measuring Raman spectra, infrared spectra and corresponding second derivative spectra. The results show that the desilication ratio in the solution prepared by the addition of sodium silicate(solution-SS) is much greater than that in the solution by the addition of green liquor(solution-GL), and low alumina concentration in the sodium aluminate solutions facilitates the desilication process. It is also shown that alumino-silicate anions in the solution-GL, and Q^3 polymeric silicate anions in solution-SS are predominant, respectively. In addition, increasing the concentration of silica favors respectively the formation of the alumino-silicate or the Q^3 silicate anions in the solution-GL or the solution-SS. Therefore, it can be inferred that the low desilication ratio in the silicate-bearing aluminate solution is mainly attributed to the existence of alumino-silicate anions.
