Study On Preparation And Characterization Of Nano-ceria Using Hypergravity Rotating Bed

This article describes the characteristics,applications,and development of nanomaterials,introduces the structural properties,resource status,and practical applications of cerium dioxide,summarizes the preparation methods of nanometer cerium dioxide,and explains the preparation of nanometer cerium dioxide.Research status and problems.The main content of this article is to study the influence of various parameters on the particle size of ceria during the preparation of nano-cerium oxide using a super-gravity rotating bed,and at the same time compare with the supercritical water oxidation technology to prepare nano-cerium oxide.Supergravity rotating bed preparation engineering studied the influence of material concentration,pH,amount of dispersant,parameters of supergravity rotating bed,roasting temperature and roasting time on the particle size of ceria powder during the preparation process,and obtained the best preparation conditions.At the same time,Zeta potential,wetting properties,TG-DSC,XRD,scanning electron microscopy and transmission electron microscopy analysis were performed on the prepared powder,and the agglomeration state of cerium oxide powder during the preparation of nano-cerium oxide was further analyzed.Morphology,microstructure and crystal growth;In the process of supercritical water oxidation,the preparation of nano-CeO₂ powder under different conditions of cerium nitrate concentration,pH,filling degree and reaction time was studied,and the crystal structure and morphology of the prepared samples were characterized and analyzed by XRD and FE-SEM.The particle size,specific surface area of the sample and the Zeta potential of the sol are included.The main conclusions are as follows:The initial concentration of cerium nitrate solution is 0.7mol/L,the initial pH is 4-5,the molar ratio of cerium nitrate and ammonium bicarbonate is 1:3,the mass fraction of dispersant OP-10 is 30%,and the flow rate of the material into the rotating bed It is300ml/min,the rotating bed rotation speed is 1200r/min,and the cerium oxide particle size obtained after calcining the precursor powder of cerium at 650?for 1.5h is the smallest,and the crystallization effect is the best.The nano-cerium oxide precursor exists in a colloidal state in the solution.When the pH value of the precursor solution is adjusted to 9 by ammonia,the absolute value of the Zeta potential is the largest.The presence of the cerium precursor solution is more stable and is not prone to agglomeration.OP-10 dispersant solution shortens the wetting time of the precursor and shows better wetting performance than aqueous solution.Adjusting pH=9 with ammonia in the dispersant solution can maximize the hydrophilicity and the best dispersion effect.Qualitative analysis by XRD shows that the product obtained by drying the precursor at 50?is Ce₂?CO₃?₃·8H₂O.When dried at 100?,the precursor decomposes into Ce₂O?CO₃?₂·H₂O and Ce?CO₃?₂O·H₂O,When the temperature is greater than 350?calcined to obtain ceria nano powder.However,the crystallization effect of cerium oxide powder obtained by firing at 650?is the best.Through electron microscopy analysis,the small particles of the precursor were wrapped by the dispersant,and the shape was fine strip-shaped particles.When calcined at 650?for 1.5h,the nanometer and cerium oxide shape was obtained,and the appearance was similar to the spherical shape,and the particle dispersion effect was better,the particle size About 200nm.The lattice fringes and crystal diffraction of the prepared cerium oxide were analyzed by TEM.DigitalMicrograph software was used to measure the interplanar spacing of the regular region of the lattice fringe.The interplanar spacing obtained was 0.19nm,0.27nm and0.32nm,which corresponded to three crystal planes?220?,?200?and?111?.After the diffraction analysis,the diffraction spots also correspond to the three crystal planes?220?,?200?and?111?.According to the XRD test results,the growth crystal planes of cerium oxide are?220?,?200?and?111?.Using Ce?NO₃?₃·6H₂O as raw material,the powder prepared by supercritical water oxidation method is nano-CeO₂ with single face-centered cubic structure and good crystallinity.When the concentration of cerium nitrate is low,the particles prepared are fine and the morphology is nearly spherical;as the concentration of cerium nitrate increases and the pH of the solution decreases,the particle morphology changes from nearly spherical to fiber rod-like and then changes to a cubic structure,but the particle size increases significantly;The fiber rod-shaped particles have a large specific surface area of 83.4 m²/g.When the concentration is 0.1 mol/L and pH=2,the CeO₂ sol has the highest Zeta value,the solution has good stability and is not easy to agglomerate.Hypergravity technology has obvious advantages in the preparation of nano-cerium dioxide,whether it is equipment cost,use environment and operating requirements,or the results of nano-cerium oxide preparation.Supergravity technology is an ideal method for industrial preparation of nano-cerium oxide.