Study On The Cerium Oxide Prepared By Pyrolysis Of Cerium Chloride Solution

This paper aims to explore a kind of process for the preparation of cerium oxide (CeO2) which is CeO2preparated by CeCl3solution direct pyrolysis. This process is characteristiced with environmental protection,efficientand hydrochloric acid recycling which is different from the traditional production process.This paper work on the stuy of process and reaction mechanism of CeO2preparated by CeCl3solution direct pyrolysis.Thermodynamic studies have shown that:There are two possibilities way for CeO2preparated by CeCl3solution pyrolysis. On the one hand, CeO2preparated by CeCl3solution direct pyrolysis;on the other hand,CeCl3solution first reaction generated CeOCl and then generated CeO2by hydrolysis and oxidation reaction.The initial reaction temperature of CeO2preparated by CeCl3solution direct pyrolysis is650℃Which is lower than the temperature of CeOCl preparated by CeCl3solution pyrolysis is1850℃. Obviously,if CeOCl had preparated by CeCl3in sytem,there will no CeO2products conversion by CeOCl.Drawing CeCl3(CeO2,CeOCl)-H2O-HCl system phase diagrams search for technological conditions which match with①process.Comparing with each other phase diagram with different conditions can demonstrate that CeO2preparated by CeCl3solution direct pyrolysis is also happened by the control of reaction conditions-the press of H2O,O2and HCl in the situation that the initial reaction temperature of reaction①identical reaction②.Establishing the mathematical model of Chlorinated cerium droplets movement and preliminary designing a pyrolyzing furnace associated with the experiment condition of CeO2preparated by CeCl3solution direct pyrolysis.Based on these work,we can get some parameters of this pyrolyzing furnace:pyrolyzing period of radius is about0.088m; the expand section radius is0.143m; the pyrolyzing period of high is0.602m; transition period of high is0.080m; expand section height is0.412m.In addition, two indicators which are thermal efficiency its value is71.3%and production capacity its value is0.0529g/s can be obtain by calculating.The optimal condition of pyrolyzing temperature for950℃, Material liquid concentration for270g/L and feeding speed for0.23ml/s is obtain by orthogonal regression equation about pyrolyzing temperature,material liquid concentration and the feeding speed,which is base on the Two orthogonal regression results of this experiment. In the optimal condition, conversion rate of CeO2can amount to98.4%.pyrolyzing product XRD analysis further proof that CeOCl could be suppressed appear by adjusting the press of H2O stem,02and HCl in the pyrolyzing system. XRD analysis and SEM images of these products demonstrate that the percent conversion of CeO2products will get higher at the optimal condition pyrolyzing conditions-roasting temperature for950℃, material liquid concentration for270g/L and feeding speed for0.23ml/s;when the pyrolyzing conditions cannot meet the optimal condition, the higher the temperature, feeding speed and material liquid concentration are, the higher the conversion rate and quality of products.Dynamics research shows that the process of CeO2preparated by CeCl3solution direct pyrolysis in accordance with chemical reaction mathematical model-2-(1-α)1/3+2(1-α)-3(1-α)2/3=Kt;and incontrol by Chemical reaction speed and diffusion velocity.