Transiton Metal Doped Ceria-Zirconia Solid Solution Templated By Tobacco For Catalytic Oxidation Of CO

The rapid development of social economy nowadays has brought about an increasing car exhaust emissions,resulting in the severity of air pollution.There is a large number of CO,which generated from incomplete oxidation in oxygen-poor environment exist in the car exhaust gas.It is well-known that CO is a toxic gas.It will combine with the hemoglobin in human blood to cause symptoms of poisoning.In addition,CO is also one of the seven harmful substances in cigarette smoke.Therefore,to remove CO by oxidation is practically important.Cerium-zirconium solid solution is a good material for oxygen storage.It can be used to catalyze the oxidation of CO.The oxygen storage capacity and redox performance of the cerium-zirconium solid solution is determined by its structural defects,oxygen vacancy mobility,oxygen vacancy concentration and specific surface area.In order to enhance the catalytic oxidation ability of cerium-zirconium solid solution,herein,we try to synthesize cerium-zirconium solid solution doped with transition metal through tobacco material(tobacco stem,tobacco leaf and tobacco stem)templating.Doping of the transition metal(Cu,Fe,Ni,Cr and Mn)can change the structure of the cerium-zirconium solid solution defects,increase the oxygen vacancy concentration and oxygen anion mobility.Moreover,the materials templated by tobacco biotemplate always have unique structures and the templates could be easily obtained and removed.In this work,a series of transition metal doped cerium-zirconium solid solutions were synthesized by using tobacco stem,tobacco leaf and tobacco stem as biotemplates.The obtained samples were characterized by a combination of physicochemical techniques such as scanning electron microscopy(SEM),N2 adsorption-desorption mesurement,H2 temperature programmed reduction(H2-TPR),X-ray diffraction(XRD),oxygen storage capacity(OSC),X-ray photoelectron spectroscopy(XPS)and so on.The results show that different templates resulted in differences in microstructures and properties of the as-synthesized materials.CO oxidation activities of the cerium-zirconium solid solutions were then estimated.Different templates caused different activities of the catalysts.The copper-cerium-zirconium solid solution templated by tobacco leaf has a very high oxygen storage capacity of 2961 ?mol/g,but its activity for catalytic oxidation of CO was not the best.The copper-cerium-zirconium solid solution prepared by using tobacco stem wire as template has a good catalytic activity when the cerium-zirconium ratio is 45:45:10,and the ignition activity temperature(T50)is 91 ?.The cobalt-cerium-zirconium solid solution prepared without template has a good catalytic activity.The ignition activity temperature of CO catalytic oxidation is only 61 ?.The cerium-zirconium solid solutions were also used as a tobacco catalyst,which act on cigarette smoke to reduce the CO content of the cigarette smoke.Tobacco leaf templated copper-cerium-zirconium solid solution TSL-CZCu20(Copper content of 20%)can reduce 0.13 mg CO in per flue gas,and 2.93 mg of CO produced could be reduced per cigarette.