Structural Control Of Titanate And Its Electro-deoxidation Mechanisms

Titanium has many excellent properties and is widely used in many fields.In recent years,titanium market demand is on the rise.Aimed at the existing technical problems about the long technological process and low utilization of titanates,a new process was put forward that extracting titanium metal via electrolysis of titanate,an important intermediate of titanium-bearing ore during processed and developed.This dissertation concentrates on studying the regulation rules of titanate structure and its influencing mechanism on electrochemical dissociation.The main conclusions in this paper are as follows:(1)The regulation rules of different synthetic methods on the molar ratio of metal and titanium(M/Ti),crystallinity and morphology of titanate were investigated.Fusion reaction and Solid-phase sintering method are used to prepare titanates with different M/Ti ratio.Crystallization of amorphous phase method is used to synthesize sodium titanate with single crystal and high crystallinity.Microwave-assisted hydrothermal method is mainly suitable for the preparation of homogeneous and dispersed titanate.(2)Difficulty of electrolysis was obtained by comparing the potential of the first reduction peak from cyclic voltammetry and analyzing valence of Ti in electrolytic product.The results show that the electro-deoxidation sequences orderly are Na8Ti5O14,TiO2,Na2Ti03 and Na2Ti3O7 from easy to difficult.The potential of first reduction peaks of Na8Ti5O14,TiO2,Na2TiO3 and Na2Ti3O7 are-0.553,-0.571,-0.750 and-0.840 V,respectively.Ti valence of electrolysis products of Na8Ti5O14,TiO2,Na2TiO3 and Na2Ti3O7 are 0?+ 0.65,+ 0.65?+ 4.0,+ 3.5?+ 4.0 and + 4.0,respectively.In addition,the average Ti-O bond lengths of NagTi5O14,TiO2,Na2Ti03 and Na2Ti307 are 1.95,1.7,1.67 and 1.92 A,respectively,which shows that the average Ti-O bond lengths has important effects on electrolysis.The binding energy of Na8Ti5O14 and Ti02 calculated by Material Studio 8.0 software are-6.824 and-8.638 eV,which is consistent with the experimental results.(3)Constant voltage electrolysis of Ca3Ti2O7 and CaTiO3 were carried out.The result shows that Ca3Ti2O7 is relatively easy to be electro-reduced than CaTiO3.The important effects of Ca/Ti ratio and average Ti-O bond length on electrolysis of titanate were investigated.The Ca/Ti ratio of Ca3Ti2O7 and CaTiO3 are 1.5 and 1,respectively.The average Ti-O bond length of Ca3Ti2O7,CaTiO3 and TiO2 were 2.59,1.92 and 1.89 A.In addition,binding energy of Ca3Ti2O7,CaTiO3 and TiO2 calculated by Material Studio 8.0 software are-1.124,-7.599 and-8.638 eV,respectively,which show consistent results that electro-deoxidation sequences orderly are Ca3Ti2O7,CaTiO3 and TiO2 from easy to difficult.