Optimization Of Preparation Parameters And Study On The Grain Growth Kinetics Of The YBaCo₄O_7+? Oxygen Carrier

YBaCo4O7+?(referred to as Y114)is a new type of perovskite type compounds,because of its good performance in absorbing and releasing oxygen in low temperature,and has the characteristic of stable circulation,so it is an ideal oxygen carrier can be used in low temperature chemical separation technology in the chain of air.Because the YBaCo4O7+? oxygen carrier needs to be synthesized,so the preparation parameters of the oxygen carrier is bound to affect the absorption of oxygen releasing performance,but is not for the preparation parameters of systematic research,at the same time in the preparation process of the grain growth behavior research on its absorption and release of oxygen can also have certain guide.In conclusion,we first determined the optimum preparation parameters of YBaCo4O7+? oxygen carrier,and then further explored the grain growth behavior during the preparation process from the perspective of grain growth kinetics.This paper uses the solid phase reaction method and sol coagulation method at different calcination temperature(1050?,1100?,1150?,1200? and 1250?),different calcining time(25h,30h,40h),different cooling(air cooling and furnace cooling)to prepare YBaCo4O7+?oxygen carrier,characterization and analysis of the use of XRD,SEM and TGA,the parameters of the optimal preparation method of analysis using multi index comprehensive evaluation for YBaCo4O7+? oxygen carrier.Two grain growth kinetics models were used to study the growth kinetics of YBaCo4O7+? oxygen carriers.The goodness of fit of two models was compared,and the main conclusions were as follows:The optimum preparation parameters of the solid state reaction method are as follows:the calcining temperature is 1100?,the calcining time is 30h,and air cooling.The optimum preparation parameters of the sol-gel method are:the calcining temperature is 1050?,the calcining time is 30h,and air cooling.With the increase of calcination temperature,the extension of time and the decrease of cooling rate,the grains gradually change from ellipsoid to irregular polyhedron.Grain by grain growth kinetics analysis method of solid phase reaction growth index n=2,belongs to the normal grain growth;grain growth index n=3 sol gel method,grain growth by solid block control;solid state reaction method so the grain growth activation energy is less than the sol-gel method.Under the two methods,the activation energy of the grain growth calculated by the new model is obviously smaller than that of the classical model.The new model not only considers the effect of diffusion on the grain growth and the surface active effect on grain growth at the same time,the new model fit better,so the new grain growth kinetics model can more accurately reflect the grain growth of YBaCo4O7+? arrier behavior.