Abstract An efficient method for recovering and separating Ce3+ and La3+ rare earth elements from spent fluid catalytic cracking (FCC) catalyst is described. Initially, the spent FCC catalyst was leached with 2 M HNO3 at 80 °C then removal of iron from the leach solution was carried out by solvent extraction with 25% (v/v) diisooctyl phosphinic acid (DiOAP) in n-octane. Extraction of the above rare earths was then undertaken from the nitric acid leach solution using an organic phase consisting of 25% (v/v) di(2-ethylhexyl) phosphoric acid (D2EHPA) and 25% (v/v) tri-n-butyl phosphate (TBP) in n-octane. Both rare earths were stripped form the organic phase using H2SO4. Separation of the Ce3+ from La3+ was then achieved by means of an in situ electrochemical oxidation coupled with a simultaneous solvent extraction process. In this, the Ce3+ was electrochemically oxidized to Ce4+ and removed from the aqueous phase by solvent extraction employing 100 mM D2EHPA in n-octane. This led to efficient separation of the above rare earths, giving rise to La3+ in high purity of up to 99.5% and Ce4+ up to 100%. The separation occurs via a single extraction step without the need for pH adjustment or for the use of additional reagents.

中文翻译：

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通过原位选择性电化学氧化和从废流化催化裂化 (FCC) 催化剂中萃取分离和回收稀土

摘要 描述了一种从废流化催化裂化 (FCC) 催化剂中回收和分离 Ce3+ 和 La3+ 稀土元素的有效方法。最初，在 80 °C 下用 2 M HNO3 浸出用过的 FCC 催化剂，然后通过使用 25% (v/v) 二异辛基次膦酸 (DiOAP) 的正辛烷溶液进行溶剂萃取，从浸出溶液中去除铁。然后使用由 25% (v/v) 二(2-乙基己基)磷酸 (D2EHPA) 和 25% (v/v) 三正磷酸组成的有机相从硝酸浸出溶液中提取上述稀土正辛烷中的磷酸丁酯 (TBP)。使用 H2SO4 将两种稀土从有机相中汽提。然后通过原位电化学氧化结合同步溶剂萃取过程实现 Ce3+ 与 La3+ 的分离。在这方面，Ce3+ 被电化学氧化为 Ce4+ 并通过溶剂萃取从水相中去除，使用 100 mM D2EHPA 的正辛烷溶液。这导致上述稀土的有效分离，产生高达 99.5% 的高纯度 La3+ 和高达 100% 的 Ce4+。分离通过单个提取步骤进行，无需调节 pH 值或使用额外的试剂。