The preparation of alumina with large surface area, certain phase and porosimetry has always been one of important researches. A new method using much less sucrose (the molar ratio of sucrose to Al 3+=0 5) was develop...The preparation of alumina with large surface area, certain phase and porosimetry has always been one of important researches. A new method using much less sucrose (the molar ratio of sucrose to Al 3+=0 5) was developed to prepare γ-Al 2O 3 with large surface area and high thermal stability. Firstly,ammonium hydroxide was dropped to aqueous solution of aluminum nitrate and sucrose. The resulted precipitate in suspension was heated until a homogeneous gel was obtained. Then the gel was dehydrated at 110 ℃ to get a fluffy black precursor. Finally, γ-Al 2O 3 with A=345 m2/g was prepared by calcining the precursor at 600 ℃ for 24 h. The precursor and the obtained γ-Al 2O 3 were characterized by DTA-TG, N 2 adsorption-desorption isotherms, XRD and TEM. According to the dispersion behaviors of organic compounds on supports, the related mechanism was discussed.展开更多
Conventional and low-frequency Raman spectra of series of anatase TiO2 gels,which were prepared by sol-gel method in diffrent conditions, were measured. Xerogel and aerogel TiO2 were prepared by natural dry and superc...Conventional and low-frequency Raman spectra of series of anatase TiO2 gels,which were prepared by sol-gel method in diffrent conditions, were measured. Xerogel and aerogel TiO2 were prepared by natural dry and supercritical dry respectively.Conventional Raman Spectra show that the width of peaks of TiO2 was almost broaden linearly with its particle size decreased down to several nm and a few new peaks were observed. The phenomena can be explained as the effect of particle size and occurrence of new surface structure. It can be used as a method of determination of small particle size. Low-frequency Raman scattering shows that from the intensity of spectra, the fractal dimension of nanocrystal xerogels and aerogels can be obtained by comparing with the base intensity. Low frequency Raman peaks give the information of particle size, acoustic velocity and polydispersibility about gel samples. More detailed woks were undergoing in our laboratory.展开更多
Solid superacid catalyst SO4(2-)-WO3-ZrO2 was characterized by means of XRD,DTA-TG, and surface area measurement techniques. The dependence of the surface area, SO42- content of the catalyst on calcination temperature...Solid superacid catalyst SO4(2-)-WO3-ZrO2 was characterized by means of XRD,DTA-TG, and surface area measurement techniques. The dependence of the surface area, SO42- content of the catalyst on calcination temperature was measured. It was found that there is a synergy to a certain degree between SO42- and WO3 with respect to the delay of ZrO2 crystailization, the stabilization of the tetragonal ZrO2 and the enlargement of the surface area of the catalyst. The addition of WO3 is beneficial to the stabilization of SO42- and remarkably increases the stability of SO42- at high temperature.展开更多
The dispersion of K\-2CO\-3 on \%γ\%\|Al\-2O\-3 and the adsorption performance of K\-2CO\-3/\%γ\%\|Al\-2O\-3 to SO\-2 are investigated.The results show that K\-2CO\-3 can disperse onto the surface of \%γ\%\|Al\-2O\...The dispersion of K\-2CO\-3 on \%γ\%\|Al\-2O\-3 and the adsorption performance of K\-2CO\-3/\%γ\%\|Al\-2O\-3 to SO\-2 are investigated.The results show that K\-2CO\-3 can disperse onto the surface of \%γ\%\|Al\-2O\-3 as a monolayer and the dispersion threshold is 0.31\[\%m\%(K\-2CO\-3)/\%m\%(\%γ\%\|Al\-2O\-3), \%m\%/g\], which is close to the theoretical value calculated by assuming a bidentate vertical dispersion model of CO\-2 on the \%γ\%\|Al\-2O\-3 surface . The SO\-2 adsorption\|capacity on K\-2CO\-3/\%γ\%\|Al\-2O\-3 sample increases with the K\-2CO\-3 loading and reaches an extremum at its threshold. The adsorbent conversion of K\-2CO\-3/\%γ\%\|Al\-2O\-3 at the threshold is up to 72%. When the loading is higher than the threshold, the SO\-2 adsorption capacity decreases at first, then increases again. This phenomenon is caused by the reaction between SO\-2 and the bulk phase of K\-2CO\-3 crystallites. The sample decreases with the loading, and the sample with \{0.10\}\[\%m\%(K\-2CO\-3)/\%m(γ\%\|Al\-2O\-3), \%m\%/g\] loading shows the highest regeneration percentage of 63%. Compared with Na\-2CO\-3/\%γ\%\|Al\-2O\-3, K\-2CO\-3/\%γ\%\|Al\-2O\-3 might have some advantages.展开更多
文摘The preparation of alumina with large surface area, certain phase and porosimetry has always been one of important researches. A new method using much less sucrose (the molar ratio of sucrose to Al 3+=0 5) was developed to prepare γ-Al 2O 3 with large surface area and high thermal stability. Firstly,ammonium hydroxide was dropped to aqueous solution of aluminum nitrate and sucrose. The resulted precipitate in suspension was heated until a homogeneous gel was obtained. Then the gel was dehydrated at 110 ℃ to get a fluffy black precursor. Finally, γ-Al 2O 3 with A=345 m2/g was prepared by calcining the precursor at 600 ℃ for 24 h. The precursor and the obtained γ-Al 2O 3 were characterized by DTA-TG, N 2 adsorption-desorption isotherms, XRD and TEM. According to the dispersion behaviors of organic compounds on supports, the related mechanism was discussed.
文摘Conventional and low-frequency Raman spectra of series of anatase TiO2 gels,which were prepared by sol-gel method in diffrent conditions, were measured. Xerogel and aerogel TiO2 were prepared by natural dry and supercritical dry respectively.Conventional Raman Spectra show that the width of peaks of TiO2 was almost broaden linearly with its particle size decreased down to several nm and a few new peaks were observed. The phenomena can be explained as the effect of particle size and occurrence of new surface structure. It can be used as a method of determination of small particle size. Low-frequency Raman scattering shows that from the intensity of spectra, the fractal dimension of nanocrystal xerogels and aerogels can be obtained by comparing with the base intensity. Low frequency Raman peaks give the information of particle size, acoustic velocity and polydispersibility about gel samples. More detailed woks were undergoing in our laboratory.
文摘Solid superacid catalyst SO4(2-)-WO3-ZrO2 was characterized by means of XRD,DTA-TG, and surface area measurement techniques. The dependence of the surface area, SO42- content of the catalyst on calcination temperature was measured. It was found that there is a synergy to a certain degree between SO42- and WO3 with respect to the delay of ZrO2 crystailization, the stabilization of the tetragonal ZrO2 and the enlargement of the surface area of the catalyst. The addition of WO3 is beneficial to the stabilization of SO42- and remarkably increases the stability of SO42- at high temperature.
文摘The dispersion of K\-2CO\-3 on \%γ\%\|Al\-2O\-3 and the adsorption performance of K\-2CO\-3/\%γ\%\|Al\-2O\-3 to SO\-2 are investigated.The results show that K\-2CO\-3 can disperse onto the surface of \%γ\%\|Al\-2O\-3 as a monolayer and the dispersion threshold is 0.31\[\%m\%(K\-2CO\-3)/\%m\%(\%γ\%\|Al\-2O\-3), \%m\%/g\], which is close to the theoretical value calculated by assuming a bidentate vertical dispersion model of CO\-2 on the \%γ\%\|Al\-2O\-3 surface . The SO\-2 adsorption\|capacity on K\-2CO\-3/\%γ\%\|Al\-2O\-3 sample increases with the K\-2CO\-3 loading and reaches an extremum at its threshold. The adsorbent conversion of K\-2CO\-3/\%γ\%\|Al\-2O\-3 at the threshold is up to 72%. When the loading is higher than the threshold, the SO\-2 adsorption capacity decreases at first, then increases again. This phenomenon is caused by the reaction between SO\-2 and the bulk phase of K\-2CO\-3 crystallites. The sample decreases with the loading, and the sample with \{0.10\}\[\%m\%(K\-2CO\-3)/\%m(γ\%\|Al\-2O\-3), \%m\%/g\] loading shows the highest regeneration percentage of 63%. Compared with Na\-2CO\-3/\%γ\%\|Al\-2O\-3, K\-2CO\-3/\%γ\%\|Al\-2O\-3 might have some advantages.
