A novel cerium(Ⅲ) salt of Dawson type tungstophosphoric acid(Ce2P2W18O62·16H2O) was prepared by doping cerous nitrate in H6P2W18O62·13H2O powder and characterized by thermogravimetry and differential therma...A novel cerium(Ⅲ) salt of Dawson type tungstophosphoric acid(Ce2P2W18O62·16H2O) was prepared by doping cerous nitrate in H6P2W18O62·13H2O powder and characterized by thermogravimetry and differential thermal analyses(TG/DTA),Fourier transform infrared spectroscopy(FT-IR),X-ray powder diffraction(XRD),pyridine infrared spectroscopy(Py-IR) and scanning electron microscopy(SEM).Its catalytic activity was evaluated by the probe reaction of synthesis of n-butyl acetate with acetic acid and n-butanol.The effects of various parameters such as molar ratio of n-butanol to acetic acid,reaction temperature,reaction time,and catalyst amount have been studied by single factor experiment.The results show that Ce2P2W18O62·16H2O behaved as an excellent heterogeneous catalyst in the synthesis of n-butyl acetate.The optimum synthetic conditions were determined as follows︰molar ratio of n-butanol to acetic acid at 2.0︰1.0,mass of the catalyst being 1.44% of the total reaction mixture,reaction temperature of 120 ℃ and reaction time of 150 min.Under above conditions,the conversion of acetic acid was above 97.8%.The selectivity of n-butyl acetate based on acetic acid was,in all cases,nearly 100%.The catalysts could be recycled and still exhibited high catalytic activity with 90.4% conversion after five cycles of reaction.It was found by means of TG-DTA and Py-IR that the catalyst deactivation was due to the adsorption of a complex of by-product on the active sites on catalysts surface or the catalyst loss in its separation from the products.Compared with using sulfuric acid as catalyst,the present procedure with Ce2P2W18O62·16H2O is a green productive technology due to simple process,higher yield,catalyst recycling and no corrosion for the production facilities.展开更多
Four complexes K8[P2W 17TiO 62]·5H2O, K8[P2W 17TiO 61]·9H2O, K8[P2W 17TiO 62]·7H2O and K8[P2W 17（ZrO2）O 61]·4H2O were synthesized by the cubic selective method and characte- rized by IR and UV sp...Four complexes K8[P2W 17TiO 62]·5H2O, K8[P2W 17TiO 61]·9H2O, K8[P2W 17TiO 62]·7H2O and K8[P2W 17（ZrO2）O 61]·4H2O were synthesized by the cubic selective method and characte- rized by IR and UV spectroscopy, polarography, cyclic voltammetry and 183W NMR methods. The results indicate that they all have Dawson structure with high catalytic activity in the epoxidation of maleic acid by H2O2. Peroxotitanium mono-substituted tungstophosphate, K8[P2W 17（TiO2）O 61]·9H2O, has the highest catalytic activity to give sodium epoxy-maleate in yield of 86.21%.展开更多
基金Supported by the National Natural Science Foundation of China（21161009）the Natural Science Foundation of Jiangxi Province（20122BAB213001,20114BAB213002）the Science and Technology Foundation of Jiangxi Province（GJJ11613）
文摘A novel cerium(Ⅲ) salt of Dawson type tungstophosphoric acid(Ce2P2W18O62·16H2O) was prepared by doping cerous nitrate in H6P2W18O62·13H2O powder and characterized by thermogravimetry and differential thermal analyses(TG/DTA),Fourier transform infrared spectroscopy(FT-IR),X-ray powder diffraction(XRD),pyridine infrared spectroscopy(Py-IR) and scanning electron microscopy(SEM).Its catalytic activity was evaluated by the probe reaction of synthesis of n-butyl acetate with acetic acid and n-butanol.The effects of various parameters such as molar ratio of n-butanol to acetic acid,reaction temperature,reaction time,and catalyst amount have been studied by single factor experiment.The results show that Ce2P2W18O62·16H2O behaved as an excellent heterogeneous catalyst in the synthesis of n-butyl acetate.The optimum synthetic conditions were determined as follows︰molar ratio of n-butanol to acetic acid at 2.0︰1.0,mass of the catalyst being 1.44% of the total reaction mixture,reaction temperature of 120 ℃ and reaction time of 150 min.Under above conditions,the conversion of acetic acid was above 97.8%.The selectivity of n-butyl acetate based on acetic acid was,in all cases,nearly 100%.The catalysts could be recycled and still exhibited high catalytic activity with 90.4% conversion after five cycles of reaction.It was found by means of TG-DTA and Py-IR that the catalyst deactivation was due to the adsorption of a complex of by-product on the active sites on catalysts surface or the catalyst loss in its separation from the products.Compared with using sulfuric acid as catalyst,the present procedure with Ce2P2W18O62·16H2O is a green productive technology due to simple process,higher yield,catalyst recycling and no corrosion for the production facilities.
文摘Four complexes K8[P2W 17TiO 62]·5H2O, K8[P2W 17TiO 61]·9H2O, K8[P2W 17TiO 62]·7H2O and K8[P2W 17（ZrO2）O 61]·4H2O were synthesized by the cubic selective method and characte- rized by IR and UV spectroscopy, polarography, cyclic voltammetry and 183W NMR methods. The results indicate that they all have Dawson structure with high catalytic activity in the epoxidation of maleic acid by H2O2. Peroxotitanium mono-substituted tungstophosphate, K8[P2W 17（TiO2）O 61]·9H2O, has the highest catalytic activity to give sodium epoxy-maleate in yield of 86.21%.
