A new solid acid catalyst,SO4^2-/TiO2 modified with tin,was prepared using a sol-gel method and its physicochemical properties were revealed by nitrogen adsorption-desorption,X-ray powder diffraction,scanning electron...A new solid acid catalyst,SO4^2-/TiO2 modified with tin,was prepared using a sol-gel method and its physicochemical properties were revealed by nitrogen adsorption-desorption,X-ray powder diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,infrared spectroscopy of adsorbed pyridine,temperature-programmed desorption of ammonia and thermal gravimetric analysis.The structure,acidity and thermal stability of the SO4^2-/TiO2-SnO2 catalyst were studied.Incorporating tin enlarged the specific surface area and decreased crystallite size of the SO4^2-/TiO2 catalyst.The total acid sites of the modified catalyst increased and Bronsted acid strength remarkably increased with increasing tin content.The decomposition temperature of sulfate radical in the modified catalyst was 100 ℃ greater and its mass loss was more than twice that of the SO4^2-/TiO2 catalyst.The SO4^2-/TiO2-SnO2 catalyst was designed to synthesize 1,6-hexanediol diacrylate by esterification of 1,6-hexanediol with crylic acid.The yield of 1,6-hexanediol diacrylate exceeded 87% under the optimal reaction conditions：crylic acid to 1,6-hexanediol molar ratio = 3.5,catalyst loading = 7%,reaction temperature = 130 ℃ and reaction time = 3 h.The modified catalyst exhibited excellent reusability and after 10 cycles the conversion of 1,6-hexanediol was above 81%.展开更多
Bismuth-doped tin dioxide nanometer powders were prepared by co-precipitation method using SnCl4 and Bi（NO3）3 as raw materials. The effects of calcining temperature and doping ratio on the particle size, composition...Bismuth-doped tin dioxide nanometer powders were prepared by co-precipitation method using SnCl4 and Bi（NO3）3 as raw materials. The effects of calcining temperature and doping ratio on the particle size, composition, spectrum selectivity of bismuth-doped tin dioxide and the phase transition of Bi-Sn precursor at different temperatures were studied by means of X-ray diffraction, transmission electron microscopy, ultraviolet-visual-near infrared diffuse reflection spectrum and the thermogravimetric-differential scanning calorimetry. The results show that prepared bismuth-doped tin dioxide powders have excellent characteristics with a single-phase tetragonal structure, good dispersibility, good absorbency for ultraviolet ray and average particle size less than 10 nm. The optimum conditions for preparing bismuth-doped tin dioxide nanometer powders are as follows: calcining temperature of 600℃, ratio of bismuth-doped in a range of 0.10-0.30, and Bi-Sn precursor being dispersed by ultrasonic wave and refluxed azeotropic and distillated with mixture of n-butanol and benzene. The mechanism of phase transition of Bi-Sn precursor is that Bi 3+ enters Sn-vacancy and then forms Sn—O—Bi bond.展开更多
文摘A new solid acid catalyst,SO4^2-/TiO2 modified with tin,was prepared using a sol-gel method and its physicochemical properties were revealed by nitrogen adsorption-desorption,X-ray powder diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,infrared spectroscopy of adsorbed pyridine,temperature-programmed desorption of ammonia and thermal gravimetric analysis.The structure,acidity and thermal stability of the SO4^2-/TiO2-SnO2 catalyst were studied.Incorporating tin enlarged the specific surface area and decreased crystallite size of the SO4^2-/TiO2 catalyst.The total acid sites of the modified catalyst increased and Bronsted acid strength remarkably increased with increasing tin content.The decomposition temperature of sulfate radical in the modified catalyst was 100 ℃ greater and its mass loss was more than twice that of the SO4^2-/TiO2 catalyst.The SO4^2-/TiO2-SnO2 catalyst was designed to synthesize 1,6-hexanediol diacrylate by esterification of 1,6-hexanediol with crylic acid.The yield of 1,6-hexanediol diacrylate exceeded 87% under the optimal reaction conditions：crylic acid to 1,6-hexanediol molar ratio = 3.5,catalyst loading = 7%,reaction temperature = 130 ℃ and reaction time = 3 h.The modified catalyst exhibited excellent reusability and after 10 cycles the conversion of 1,6-hexanediol was above 81%.
基金Project(GC200603) supported by the Open Fund of Guangdong Provincial Key Laboratory for Green Chemicals projectsupported by the Key Laboratory of Enhanced Heat Transfer and Energy Conservation of Ministry of Education of China
文摘Bismuth-doped tin dioxide nanometer powders were prepared by co-precipitation method using SnCl4 and Bi（NO3）3 as raw materials. The effects of calcining temperature and doping ratio on the particle size, composition, spectrum selectivity of bismuth-doped tin dioxide and the phase transition of Bi-Sn precursor at different temperatures were studied by means of X-ray diffraction, transmission electron microscopy, ultraviolet-visual-near infrared diffuse reflection spectrum and the thermogravimetric-differential scanning calorimetry. The results show that prepared bismuth-doped tin dioxide powders have excellent characteristics with a single-phase tetragonal structure, good dispersibility, good absorbency for ultraviolet ray and average particle size less than 10 nm. The optimum conditions for preparing bismuth-doped tin dioxide nanometer powders are as follows: calcining temperature of 600℃, ratio of bismuth-doped in a range of 0.10-0.30, and Bi-Sn precursor being dispersed by ultrasonic wave and refluxed azeotropic and distillated with mixture of n-butanol and benzene. The mechanism of phase transition of Bi-Sn precursor is that Bi 3+ enters Sn-vacancy and then forms Sn—O—Bi bond.
