Study On The Cerium Dioxide Nanotubes Supported Gold For CO Oxidation

CeO₂ nanomaterials can promote the reduction of Ce⁴⁺and increase the oxygen vacancy when the active material is supported,so as to promote the activation and flow of the active oxygen species,enhance the interaction between the active components of the catalyst and the CeO₂ carrier.When the CeO₂ nanometer materials are supported with metal or metal oxide,it will have better catalytic activity,Different morphology of cerium oxide show different catalytic effect,and because its potential performance the nanotubes are sought after.At the same time,the catalyst has a particularly superior activity in catalyzing the oxidation of CO.Therefore,we have chosen cerium dioxide nanotubes as carrier and loading gold as catalysts,to investigate their catalytic performance for CO oxidation and the effects of different gas treatments and the metal iron addition on the activity.details as follows:1.Hydrothermal preparation of cerium dioxide nanotubes and the Ce?OH?CO₃ as the precursor,loading content of 1%,3% of the gold by precipitation precipitation method,in order to compare,select the same method to prepare the gold catalyst which the carrier is cerium oxide nanocube.The results showed that the cerium dioxide nanotubes as carrier has better activity than that nanometer cubes.Through the BET,H2-TPR,XPS,TEM,SEM and other methods.The results showed that the nanotubes and nanocubes expose different crystal faces,So have different interaction between gold and Au.Au/CeO₂-NT catalyst contains more oxidation state gold and trivalent cerium so that the oxygen vacancy increased,has more active oxygen,mobility becomes faster,greatly improve the speed of CO reaction.2.Selecting the non-calcined catalyst of Au/CeO₂-NT?3%?for different gas treatment and find that the catalyst after oxygen treatment has better activity than the catalyst after calcination.This is because the catalyst surface is oxygen-enriched state after treating with oxygen,more active oxygen species on the surface of the carrier are increased,so that the gaseous oxygen is more active and is conducive to the reaction.3.modified the less active catalyst of Au/CeO₂-NT?1%?by adding metal iron,preparation the catalyst of content of iron is 0.2%,0.4%,0.6%,0.8% and 1%.The activity of 1%Au0.4%Fe/CeO₂-NT catalyst was the best,and CO was completely transformed at 80?.It was found that the addition of iron increased the specific surface area of the catalyst and the dispersion of the active components.The iron and gold solid solution,the interaction between iron and gold,iron and the carrier all can improve the activity of the catalyst.In general,cerium dioxide nanotubes as carrier-supported gold to catalyze the CO oxidation have good activity,and the catalytic activity is improved by O₂?N₂ treatment and iron addition,and the reason is analyzed by a series of characterizations.