Study On Surface Modification And Catalytic Performance Of Cordierite Honeycomb Ceramic

Inspired by microstructure of the human respiratory system and the inner wall of bronchus,this article modified the surface of cordierite honeycomb ceramic particulate filter by whiskers on it,where was a microstructure similar to the inner wall of the bronchus.This structure can improve the filter’s effect on trapping soot.At the same time,the surface of the whiskers was loaded with catalysts that has a high-efficiency catalytic combustion performance for soot particles,which can realize the self-cleaning function of the filter.In the second chapter of this paper,mullite whiskers was prepared by gas-phase method on the surface of cordierite honeycomb ceramics,which was proposed first in this article.And successfully confirmed the synthesis of mullite whiskers by XRD,SEM,FT-IR,TEM and other characterization methods.EDS,TEM analysis showed that the mullite whiskers were firmly grown on the surface of cordierite honeycomb ceramics.The optimum fired temperature is 1000°C and the optimum burning time is 2 hours.The gas-phase method has characteristics of low reaction temperature,tight bonding of modified surface and low sample size requirement compared to other methods.In the third chapter,a series of high-efficiency,economical and long-life Ce-Zr solid solution catalysts were prepared by sol-gel method using MNO₃ and citricc acid.XRD,XPS,EDS and SEM characterization results showed that catalysts have a flaky structure and well crystallinity.TG-DSC and platform testing results showed that the catalyst can effectively reduce the ignition temperature and the temperature of maximum oxidation rate of soot particles.These catalysts have good thermal stability and high repetitive stability,which can be attributed to the synergistic effect of the combination of K/Co/Zr and Ce-Zr solid solution.In this article,these catalysts can reduce the ignition temperature of soot to 294°C.In the fouth chapter,the c DPF with high efficiency,long life and economy was fabricated using dip-molding method to load catalysts Co/Zr_0.84Ce_0.16O₂ and Co/Ce_0.75Zr_0.25O₂ in the surface of mullite whiskers prepared by gas-phase method.These c DPF samples were characterized by SEM,EDS,XRD.The results showed that samples treated successively by gas phase growth method and dip-molding method did not change and destroy the pore structure of cordierite honeycomb ceramic and crystal structure,which means catalyst was loaded evenly.The performance testing results of c DPF samples showed that the whisker growth,catalyst loading can improve its effect to trap soot particles.The Co/CZ@M/C c DPF sample can reduce the ignition temperature of soot to the range of 50～100°C,and the stability testing showed that the Co/CZ@M/C c DPF still had excellent catalytic combustion effect after multiple cycle tests.