Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane（TEOS） and aluminum nitrate（ANN） as the starting materials.DTS,TEM,SEM and BET were employed to study the effect...Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane（TEOS） and aluminum nitrate（ANN） as the starting materials.DTS,TEM,SEM and BET were employed to study the effects of process parameters on the size,specific surface area and structure（morphology） of powders.The alkali-activation reactivity of the powders was tested for manufacturing geopolymers and their hydrothermal reactions were performed for fabricating zeolites.The results show that the optimum process parameters and drying method for preparing Al2O3-2SiO2 nanopowders are as follows：the molar ratio of water and ethanol to TEOS are 0：1 and 12：1 respectively at synthetic temperature of 50 ℃ and the drying method is azeotropic distillation with microwave drying.The average particle diameters of the powders were about 70 nm and the largest BET specific surface area was up to 669 m^2·g^-1.The compressive strength of the geopolymer and the calcium exchange capacity（by CaCO3） of NaA zeolite prepared with the powders reached to 29 MPa and 366 m^2·g^-1 respectively.展开更多
A hydrothermal method was successfully used for synthesis of CuO/ZnO/AI203 （CZA） nanopowder with atomic ratio of 6：3：1. The effect of crystallization time （3, 6, 9, and 12 h） on physicochemical properties of nan...A hydrothermal method was successfully used for synthesis of CuO/ZnO/AI203 （CZA） nanopowder with atomic ratio of 6：3：1. The effect of crystallization time （3, 6, 9, and 12 h） on physicochemical properties of nanopowder was investigated. Nanopowders were characterized using XRD, FESEM, EDX, FTIR, TG, and BET techniques. The XRD patterns confirmed metal oxides formation and their good crystallinity with average crystallite size of 20nm as obtained by the Scherrer equation. Relative crystallinity was shown to increase with increasing crystallization time. In agreement with XRD results, FESEM images also illustrated nanosized particles. EDX mapping indicated homogenous dispersion of elements. BET specific surface area analysis showed acceptable surface area for CZA nanopowder, FTIR spectroscopy confirmed metal oxides formation during hydrothermal and calcination processing. TG results illustrated high thermal stability of the synthesized nanopowders. TG-DTG and FTIR analyses were used to propose a reaction mechanism for nanopowder formation during processing. Physicochemical characterization showed optimal crystallization time to be 6 h.展开更多
基金Supported by the National Natural Science Foundation of China (50962002,50602006)Opening Funds of State Key Laboratory of Chemical Resource Engineering of Beijing University of Chemical Technology (201008)
文摘Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane（TEOS） and aluminum nitrate（ANN） as the starting materials.DTS,TEM,SEM and BET were employed to study the effects of process parameters on the size,specific surface area and structure（morphology） of powders.The alkali-activation reactivity of the powders was tested for manufacturing geopolymers and their hydrothermal reactions were performed for fabricating zeolites.The results show that the optimum process parameters and drying method for preparing Al2O3-2SiO2 nanopowders are as follows：the molar ratio of water and ethanol to TEOS are 0：1 and 12：1 respectively at synthetic temperature of 50 ℃ and the drying method is azeotropic distillation with microwave drying.The average particle diameters of the powders were about 70 nm and the largest BET specific surface area was up to 669 m^2·g^-1.The compressive strength of the geopolymer and the calcium exchange capacity（by CaCO3） of NaA zeolite prepared with the powders reached to 29 MPa and 366 m^2·g^-1 respectively.
基金Sahand University of Technology for the financial support of the project and Iran Nano-technology Initiative Council for supplementary financial supports
文摘A hydrothermal method was successfully used for synthesis of CuO/ZnO/AI203 （CZA） nanopowder with atomic ratio of 6：3：1. The effect of crystallization time （3, 6, 9, and 12 h） on physicochemical properties of nanopowder was investigated. Nanopowders were characterized using XRD, FESEM, EDX, FTIR, TG, and BET techniques. The XRD patterns confirmed metal oxides formation and their good crystallinity with average crystallite size of 20nm as obtained by the Scherrer equation. Relative crystallinity was shown to increase with increasing crystallization time. In agreement with XRD results, FESEM images also illustrated nanosized particles. EDX mapping indicated homogenous dispersion of elements. BET specific surface area analysis showed acceptable surface area for CZA nanopowder, FTIR spectroscopy confirmed metal oxides formation during hydrothermal and calcination processing. TG results illustrated high thermal stability of the synthesized nanopowders. TG-DTG and FTIR analyses were used to propose a reaction mechanism for nanopowder formation during processing. Physicochemical characterization showed optimal crystallization time to be 6 h.
