| In this paper,ammonium bicarbonate is used to prepare cerium carbonate by precipitation method.The experimental conditions were changed by adjusting the pH value?using ammonia?,the content of OP-10 dispersant and the concentration of cerium nitrate.When using only ammonia to adjust pH,when pH=9,the particle size of CeO2 after roasting is the smallest,with an average value of 2.810?m;when only OP-10 is added,and the OP-10 content is 15%,the particle size of CeO2 after roasting is the smallest.The average value is 2.182?m;when the content of OP-10 is 15%and the concentration of cerium nitrate is 0.6mol/L,the particle size of CeO2 after roasting is the smallest,and the average value is 0.742?m.The cerium carbonate prepared at pH=9 has two parts when it is decomposed into cerium oxide.The activation energy of the first part is 163.2890521kJ/mol,and the most probable mechanism function is G???=[-ln?1-??]2.The value range of the pre-factor A is14.67258?lnA?15.37155.The activation energy of the second part is 192.4346309kJ/mol,the most probable mechanism function is G???=[-ln?1-??]3/4,the range of the pre-factor A is 15.713?lnA?16.41197.The cerium carbonate prepared with 15%OP-10 content has two parts when decomposed into cerium oxide.The activation energy of the first part is194.0051358kJ/mol,and the most probable mechanism function isG???=[-ln?1-??]1/4.The value range of the pre-factor A is 19.63884?lnA?20.33781.The activation energy of the second part is 195.0184666kJ/mol,and the most probable mechanism function is G???=[-ln?1-??]3/4.The value range of the pre-factor A is18.83442?lnA?19.53339..The cerium carbonate prepared with a cerium nitrate concentration of 0.6 mol/L has two parts when it is decomposed into cerium oxide.The activation energy of the first part is 171.7739893 kJ/mol,and the most probable mechanism function is G???=[-ln?1-??]1/4.The value range of the pre-factor A is 17.67608?lnA?18.37505.The activation energy of the second part is 446.013629kJ/mol,and the most probable mechanism function is G???=[-ln?1-??]1/4,the range of the pre-factor A is 44.12309?lnA?44.82206.As the content of OP-10 increases,the endothermic peak of the DSC curve of cerium carbonate becomes an exothermic peak,probably because OP-10 is a carbon-containing organic substance and contains a large amount of C.When heated,C will react in an O2atmosphere and A large amount of heat is emitted,which cancels out the heat required for the decomposition of cerium carbonate,so it shows an exothermic peak on the DSC curve.Most of the morphologies of cerium carbonate prepared with 15%OP-10 content are long strips,and non-equivalent carbonate ions are present in the unit cell.In the TG-DSC test,there were two distinct exothermic peaks at 236°C and 256°C,and the total weight loss was 35.4636%.The decomposition process isCe2?CO3?3·8H2O?Ce?CO3?2O·H2O+Ce2O?CO3?2·H2O?CeO2?... |
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