Mechanism of chlorinating lanthanum oxide and cerium oxide with ammonium chloride

来源期刊：中国有色金属学报(英文版)2003年第6期

论文作者：朱国才 李赋屏 肖明贵

文章页码：1454 - 1458

Key words：lanthanum; cerium; mechanism; chlorination; thermal decomposition

Abstract: Using ammonium chloride (NH₄Cl) as a chlorinating agent, the effects of chlorinating temperature, chlorinating time and NH₄Cl dosage on chlorination of La₂O₃ and CeO₂, and the thermal decomposition of LaCl₃·7H₂O and CeCl₃·7H₂O were investigated. The results show that 80% of both La₂O₃ and CeO₂ can be chlorinated at 300℃ for 90min, and have no advantage to chlorination of lanthanum and cerium oxides at higher temperature. The thermal decomposition of LaCl₃ and CeCl₃ is carried out to explore the mechanism of chlorinating lanthanum and cerium oxides. At the same time, the chlorination of lanthanum and cerium oxides is not devoted to the HCl decomposed from NH₄Cl, but to NH₄Cl directly taking part in the chlorination of La₂O₃ and CeO₂. The lanthanum and cerium oxides in chlorination firstly form intermediate LaOCl and CeOCl, and then transfer to LaCl₃ and CeCl₃, finally to La₂O₃ and CeO₂, respectively. The thermal decomposition analyses of LaCl₃·7H₂O and CeCl₃·7H₂O further prove the existence of the intermediates LaOCl and CeOCl. Therefore the chlorinating temperature and time should strictly be controlled when the lanthanum oxide and cerium oxide are chlorinated with NH₄Cl. And over-dosage of NH₄Cl should be also applied in the process of chlorination.