Three PMoV heteropoly acids(HPAs)with different number of V atoms were synthesized and characterized by ICPAES,TG,IR and XRD.The IR spectra indicated that they are Keggin structure.Compared the IR spectrum of P...Three PMoV heteropoly acids(HPAs)with different number of V atoms were synthesized and characterized by ICPAES,TG,IR and XRD.The IR spectra indicated that they are Keggin structure.Compared the IR spectrum of PMo HPA with those of PMoV HPAs,it was found that the characteristic absorption peak values(CAPV)of all of the PMoV HPAS were redshifted.展开更多
Influence of total aluminum concentration (CAlT) on the generation and transformation of nanosized Al13 and Al30 in hydrolytic polyaluminum aqueous solutions was in-vestigated using high field 27Al NMR and time-develo...Influence of total aluminum concentration (CAlT) on the generation and transformation of nanosized Al13 and Al30 in hydrolytic polyaluminum aqueous solutions was in-vestigated using high field 27Al NMR and time-developed Al-Ferron complex colorimetry. When prepared at the opti-mal basicity (B) of Al13 generation and 80℃, the Al13 species in polyaluminum solution tends to further polymerize and convert to Al30 and higher polymers when CAlT >0.2 mol·L?1, but Al13 does not convert to Al30 quantificationally, as the formation of Alu from Al13 and Al30 is accelerated in the same way. The conversion rate of Al13 is accelerated by the in-crease in CAlT. When CAlT >0.75 mol·L?1, Al13 content de-creases rapidly, and Al30 content increases continuously and becomes the dominant nanometer polynuclear aluminum species. Alm is one of prerequisites of Al13 conversion to Al30. When CAlT increases and B reduces, the polymerization rate between Al13 and Alm increases, and at the same time, the dissociation reaction rate of Al13 and Al30 by H+ also increases. The latter becomes the dominant reaction in polyaluminum solution with low B value, so Al30 decreases with the increas-ing CAlT. The hydrolytic polyaluminum solution with Al13 content beyond 80% can only be prepared under the condi-tion of CAlT<0.5 mol·L?1 and optimal B value.展开更多
文摘Three PMoV heteropoly acids(HPAs)with different number of V atoms were synthesized and characterized by ICPAES,TG,IR and XRD.The IR spectra indicated that they are Keggin structure.Compared the IR spectrum of PMo HPA with those of PMoV HPAs,it was found that the characteristic absorption peak values(CAPV)of all of the PMoV HPAS were redshifted.
基金supported by the National High Technology Research and Development Key Program of China(863 Program)(Grant No.2002AA601290)the National Natural Science Foundation of China(Grant No.50178067).
文摘Influence of total aluminum concentration (CAlT) on the generation and transformation of nanosized Al13 and Al30 in hydrolytic polyaluminum aqueous solutions was in-vestigated using high field 27Al NMR and time-developed Al-Ferron complex colorimetry. When prepared at the opti-mal basicity (B) of Al13 generation and 80℃, the Al13 species in polyaluminum solution tends to further polymerize and convert to Al30 and higher polymers when CAlT >0.2 mol·L?1, but Al13 does not convert to Al30 quantificationally, as the formation of Alu from Al13 and Al30 is accelerated in the same way. The conversion rate of Al13 is accelerated by the in-crease in CAlT. When CAlT >0.75 mol·L?1, Al13 content de-creases rapidly, and Al30 content increases continuously and becomes the dominant nanometer polynuclear aluminum species. Alm is one of prerequisites of Al13 conversion to Al30. When CAlT increases and B reduces, the polymerization rate between Al13 and Alm increases, and at the same time, the dissociation reaction rate of Al13 and Al30 by H+ also increases. The latter becomes the dominant reaction in polyaluminum solution with low B value, so Al30 decreases with the increas-ing CAlT. The hydrolytic polyaluminum solution with Al13 content beyond 80% can only be prepared under the condi-tion of CAlT<0.5 mol·L?1 and optimal B value.
