FTIR和XPS对含低价Cr混合物物相分析的应用研究

因Cr的可变价态较多,且在制备低价Cr氧化物过程中,经常出现不同价态的中间体过渡产物,这些过渡产物的性质各异,往往对最终产物的形貌特征产生显著影响.以KCrO2为原料制备低价Cr化合物的过程中出现了组成比较复杂的中间产物,为探讨反应机理并优化工艺流程,文章结合光电子能谱(XPS),傅里叶变换红外光谱(FTIR),X射线衍射(XRD),电感耦合等离子发射光谱(ICP-AES)元素分析和化学滴定分析对KCrO2的还原中间产物进行了物相分析.XPS能谱分析表明,还原中间产物中Cr元素是以三价形态存在的;对不同还原温度所得的中间产物的FTIR与其他方法所得的水合氧化Cr的FTIR进行比较,并结合XRD测试,元素分析,化学分析结果可以得出下面结论:中间产物主要组成为Cr(OH)3·nH2O,CrOOH.还有少量的KOH或KCrO2.在对中间物相分析的基础上,对还原过程可能发生的反应进行了推测.

Application of FTIR and XPS Technique to the Analysis of the Mixture Containing Chromium in a Low Valence State

Chromium has various valence states and in the process of preparing chromium oxides with low valence state of chromium, chromium compounds with different valence state of chromium can usually be produced as intermediates. Due to the difference in property of these intermediates, they always have remarkable influences on the morphological characteristics of the final product. The composition of the intermediate was very complicated in the process of synthesizing chromium oxide with low valence state of chromium by reducing potassium chromate with hydrogen. To explore the reaction mechanism and further optimize the technical process, the composition of the intermediate obtained from the reduction of K2CrO4 with hydrogen was investigated through the combination of XPS, FTIR and XRD. The XPS results revealed that the intermediate of reducing potassium chromate with hydrogen is trivalent chromium compound; the results of FTIR and XRD indicated that the intermediate mainly consists of Cr(OH)3 x nH2O, HCrO2 and a little amount of KOH or KCrO2. On the basis of the above analysis of the intermediate, the possible reactions that occurred in the reduction process were suggested.