Fabrication And Catalytic Activities Of The Ce-based Oxide Fibers

As a novel structured catalyst,the paper catalyst with low specific gravity,high porosity,and excellent gas-diffusion properties have outstanding effects on improving catalytic efficiency,reducing loading amounts of noble metals,and extending their service life,which exhits great potential application value in the fields of fuel cells,waste gas treatment,and etc.Due to their super high oxygen storage capacity?OSC?,the Ce-based oxides are considered as the ideal catalyst support till now.Thereby,the exploration of Ce-based oxide fibers with high peformance is of great significance to develop the Ce-based paper catalyst towards practical application.In this work,the series of Ce-based oxide fibers have been fabricated by using sol-gel method and dry-spinning techniques.The influences of various kinds of hybrid oxides,composition proportion,synthesis systems on the crystallization phase were analyzed,as well as the OSC and catalytic activities.The Raman spectra,X-ray photon energy spectra?XPS?,cycled Thermal gravity analyzer?TGA?,and H2-Temperature programmed reduction?TPR?,were utilized to disclose the relationship between the structure and the catalytic activities of the Ceria-based oxide fiber catalyst.The results showed that:The continuous CeO₂-ZrO₂ crystal fibers with different Ce/Zr ratio?1:9-1:1?have been fabricated by using Zirconium basic carbonate and Ce?NO3?3·6H2O as raw materials,the distilled water as solvent,the glacial acetic acid as accelerating agent.It was found that the fibers Ce/Zr ratio of 3/9 have the largest OSC value?533?mol O₂/g?.In our opinion,the OSC depends on the crystal structure,oxgen defects,Ce/Zr ratio,and etc.After loading the active constituent of CuO,the CeO₂-ZrO₂ fiber catalysts exhibit good catalytic activity towards soot oxidation,which can be influenced by the interaction between Ce ions and Cu ions with different valence.The Si O₂/Ce_0.5Zr_0.5O₂ mesoporous fibers with several centimeters in length and various silica contents have been fabricated via the chemical template method by using the triblock co-polymer of Pluronic P-123 as the templating agent,and the hydrous ethanol as solvent.Ce?NO3?3·6H2O and ZrOCl2·8H2O and?C2H5O?4Si were used as inorganic sources.The result showed that the cubic fluorite structure can be stablized by the silica doping,which enhanced the thermal stability and surface areas of the Ce_0.5Zr_0.5O₂ mesoporous fiber.From the H2-TPR results,it was concluded that the CuO@SiO₂/Ce_0.5Zr_0.5O₂ mesoporous fiber catalysts exhibited great reduction capacity with a reduction peak as low as 224 ° C.The CeO₂-Ti O₂ mesoporous fibers with large specific surface area and several centimeters in length has prepared by chemical template method coupled with a sol-gel process.Ce?NO3?3 and?C2H5O?4Ti were used as raw materials.The results showed that the crystal phase of CeO₂-TiO₂ mesoporous fibers transfered from antase to cubic fluorite structure with the increase of cerium contents.The CuO@CeO₂-TiO₂ mesoporous fibers exhibits good low temperature reduction ability which can be seen from the H2-TPR spectra with lowest reduction peak at 184 °C.The paper-structed catalyst with large porosity and good flexibility was fabricated through traditional paper-making route by using the above CeO₂-ZrO₂ crystal fibers,CeO₂-TiO₂ mesoporous fibers,and SiO₂/Ce_0.5Zr_0.5O₂ mesoporous fibers as matrix fibers.