The preparation of peroxodisulfated zirconia titania(PSZT) solid super acid has been investigated as function of molar ratio of Ti to Zr, impregnation time, calcination time and temperature in esterification of maleic...The preparation of peroxodisulfated zirconia titania(PSZT) solid super acid has been investigated as function of molar ratio of Ti to Zr, impregnation time, calcination time and temperature in esterification of maleic anhydride with n octanol. The highest yield of dioctyl maleate was 98 2% at the optimum reaction conditions.展开更多
Sub-micrometer ultra fine CeO2-ZrO2 mixed oxides have been prepared by milling solid cerium carbonate and zirconium oxy-chloride with ammonia and followed by filtering, drying and calcining procedures. The effects of ...Sub-micrometer ultra fine CeO2-ZrO2 mixed oxides have been prepared by milling solid cerium carbonate and zirconium oxy-chloride with ammonia and followed by filtering, drying and calcining procedures. The effects of Ce/Zr molar ratio, milling time and calcining temperature on the phase composition, particle size and morphology, surface charge, as well as the polishing property were investigated. The results show that the mixed oxide calcined at 1 000 ℃ is composed of cubic ceria doped with zirconium and tetragonal zirconia doped with cerium, and the phase composition varies with calcination temperature and the Ce/Zr molar ratio. The monoclinic zirconia is observed when decreasing calcination temperature and shortening milling time, demonstrating that milling and calcining can force the phase transformation from monoclinic zirconia to cerium stabilized tetragonal zirconia and zirconium doped cubic ceria solid solutions. The removal rate for the optical glass polishing varies with Ce/Zr molar ratio. A synergetic polishing effect is found when Ce/Zr molar ratio below 4, and the optimal Ce/Zr molar ratio is 1∶1. At the same time, the cubic ceria content, density, particle size and surface charge all increase when calcination temperature increasing from 800 ℃ to 1 100 ℃. However, the particle morphology changes from disperse quasi-sphere to irregular aggregation and the maximal removal rate for optical glass polishing lies at 1 000 ℃.These facts show that the polishing property of the synthesized ceria-zirconia mixed oxide is affected by the particle physical characteristics comprehensively.展开更多
文摘The preparation of peroxodisulfated zirconia titania(PSZT) solid super acid has been investigated as function of molar ratio of Ti to Zr, impregnation time, calcination time and temperature in esterification of maleic anhydride with n octanol. The highest yield of dioctyl maleate was 98 2% at the optimum reaction conditions.
文摘Sub-micrometer ultra fine CeO2-ZrO2 mixed oxides have been prepared by milling solid cerium carbonate and zirconium oxy-chloride with ammonia and followed by filtering, drying and calcining procedures. The effects of Ce/Zr molar ratio, milling time and calcining temperature on the phase composition, particle size and morphology, surface charge, as well as the polishing property were investigated. The results show that the mixed oxide calcined at 1 000 ℃ is composed of cubic ceria doped with zirconium and tetragonal zirconia doped with cerium, and the phase composition varies with calcination temperature and the Ce/Zr molar ratio. The monoclinic zirconia is observed when decreasing calcination temperature and shortening milling time, demonstrating that milling and calcining can force the phase transformation from monoclinic zirconia to cerium stabilized tetragonal zirconia and zirconium doped cubic ceria solid solutions. The removal rate for the optical glass polishing varies with Ce/Zr molar ratio. A synergetic polishing effect is found when Ce/Zr molar ratio below 4, and the optimal Ce/Zr molar ratio is 1∶1. At the same time, the cubic ceria content, density, particle size and surface charge all increase when calcination temperature increasing from 800 ℃ to 1 100 ℃. However, the particle morphology changes from disperse quasi-sphere to irregular aggregation and the maximal removal rate for optical glass polishing lies at 1 000 ℃.These facts show that the polishing property of the synthesized ceria-zirconia mixed oxide is affected by the particle physical characteristics comprehensively.
