TY - JOUR
T1 - Effect of silicate ratio on the distribution of silicate and aluminosilicate anions in TPA aluminosilicate solutions
AU - Mortlock, R. F.
AU - Bell, A. T.
AU - Chakraborty, A. K.
AU - Radke, C. J.
PY - 1991
Y1 - 1991
N2 - 29Si and 27Al spectroscopies were used to characterize dilute, highly alkaline tetrapropylammonium (TPA) aluminosilicate solutions The solution compositions ranged from 0.1 to 2 mol % SiO2, silicate ratios (R = [SiO2]/[(TPA)2O]) from 0.05 to 1, and Si/Al molar ratios from 0.25 to 5. 29Si NMR resonances were observed for Al incorporation into the dimer, linear trimer, cyclic trimer, branched cyclic trimer, double three-membered ring (D3R), and double four-membered ring (D4R) anions. In aluminosilicate solutions with 2 mol % SiO2, silicate ratios of less than 1.5 lead to the stabilization of D3R(1Al) anions. The addition of DMSO to TPA aluminosilicate solutions provides the solutions with a high concentration of D3R(1Al) and D4R(1Al) anions. Semiempirical quantum mechanical calculations were performed to calculate the partial charges on Si atoms in silicate and aluminosilicate anionic structures. A correlation between the Si atom partial charge and its experimentally observed chemical shift assists in the assignment of 29Si NMR peaks due to soluble aluminosilicates.
AB - 29Si and 27Al spectroscopies were used to characterize dilute, highly alkaline tetrapropylammonium (TPA) aluminosilicate solutions The solution compositions ranged from 0.1 to 2 mol % SiO2, silicate ratios (R = [SiO2]/[(TPA)2O]) from 0.05 to 1, and Si/Al molar ratios from 0.25 to 5. 29Si NMR resonances were observed for Al incorporation into the dimer, linear trimer, cyclic trimer, branched cyclic trimer, double three-membered ring (D3R), and double four-membered ring (D4R) anions. In aluminosilicate solutions with 2 mol % SiO2, silicate ratios of less than 1.5 lead to the stabilization of D3R(1Al) anions. The addition of DMSO to TPA aluminosilicate solutions provides the solutions with a high concentration of D3R(1Al) and D4R(1Al) anions. Semiempirical quantum mechanical calculations were performed to calculate the partial charges on Si atoms in silicate and aluminosilicate anionic structures. A correlation between the Si atom partial charge and its experimentally observed chemical shift assists in the assignment of 29Si NMR peaks due to soluble aluminosilicates.
UR - http://www.scopus.com/inward/record.url?scp=0000309341&partnerID=8YFLogxK
U2 - 10.1021/j100164a060
DO - 10.1021/j100164a060
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AN - SCOPUS:0000309341
SN - 0022-3654
VL - 95
SP - 4501
EP - 4506
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
IS - 11
ER -