Abstract:

Natural minerals have become a hotspot in catalyst research due to their large reserves, rich active components, low price, and environmental greenness. In the paper, rare earth tailings were modified with Cu by immersion-hydrothermal method, and the effect of Cu modification on the catalytic performance of rare earth tailings was investigated by XRD, SEM-EDS, XPS, NH₃-TPD, H₂-TPR and BET. The results showed that the denitrification performance of the rare earth tailings catalysts was substantially improved after Cu modification, and the active reaction temperature window was broadened to 200—350℃. The denitrification efficiency of the catalyst increased and then decreased with the increase of Cu content, and the most obvious performance enhancement was achieved at an amount of 2.5%. Cu modification increased the specific surface area of the rare earth tailings catalyst, and Cu existed mainly as CuO on the catalyst surface which interacted with Fe₂O₃,_{making the binding energies of Cu²⁺, Fe²⁺ and Fe³⁺ shifted significantly. The electron cloud density around Fe ions was induced to decrease, and the strongest interaction between the two in the 2.5% Cu modified catalyst enhanced the redox ability and acid activity center of the catalyst, and the reduction temperature of CuO had stronger influence on the denitrification activity than its oxidation ability, while the oxidation ability of Fe2O3 had stronger influence on the denitrification activity than its reduction temperature. The more mobile adsorbed oxygen on the catalyst surface was favorable for the denitrification reaction.}

Key words: rare earth tailings, modification, selecitve catalytic reduction, catalyst, reactivity

摘要：

近年来，天然矿物由于储量大、活性组分丰富、价格低廉、绿色环保等优点成为脱硝催化剂研究的热点。本文以稀土尾矿为研究对象，利用浸渍-水热法对稀土尾矿进行Cu改性，通过XRD、SEM-EDS、XPS、H₂-TPR、NH₃-TPD、BET等表征探究Cu改性对稀土尾矿催化剂性能的影响。结果表明，Cu改性后，稀土尾矿催化剂的脱硝性能有大幅提升，且活性反应温度窗口拓宽至200~350℃。随着Cu改性量的增加，催化剂的脱硝效率先升高后降低，改性量为2.5%（质量分数）时，性能提升效果最明显。Cu改性提高了稀土尾矿催化剂的比表面积，Cu元素主要以CuO形式存在于催化剂表面，且与Fe₂O₃存在相互作用，催化剂中Cu²⁺、Fe²⁺和Fe³⁺的结合能发生明显的偏移，诱导Fe离子周围电子云密度降低，且质量分数2.5%Cu-稀土尾矿催化剂中两者相互作用最强烈，提升了催化剂的氧化还原能力和酸活性中心，CuO的还原温度对脱硝活性的影响大于氧化能力的影响，Fe₂O₃的氧化能力对脱硝活性的影响大于还原温度的影响。催化剂表面流动性较强的吸附氧更有利于脱硝反应的进行。

关键词: 稀土尾矿, 改性, 选择催化还原, 催化剂, 活性