水熱老化は,鉄交換ゼオライトよりも窒素酸化物の減少を150°Cで強化する

Xuechao Tan¹, Pablo García-Aznar², German Sastre²

¹Center for Ordered Nanoporous Materials Synthesis, Division of Environmental Science and Engineering, POSTECH, Pohang 37673, Korea.

Journal of the American Chemical Society

|February 22, 2024

まとめ

水熱老化により,鉄ゼオライトの低温アンモニア選択的触媒還元 (NH3-SCR) 活性が著しく増加する. この突破は排気ガスから窒素酸化物の除去を強化し,より効果的な環境ソリューションを提供します.

科学分野:

環境カタリシス
材料科学
化学工学

背景:

銅と鉄を交換したゼオライトを用いたアンモニア選択的触媒還元 (NH3-SCR) は,排気ガスからの窒素酸化物 (NOx) の除去に不可欠です.
現在のNH3-SCR技術の大きな限界は,低温,特に150°Cの低性能です.

研究の目的:

NH3-SCRに対する鉄交換ゼオライトの低温活性に対する水熱老化の影響を調査する.
老化後の触媒性能の強化の構造的および機械的起源を理解する.

主な方法:

Fe-β,Fe-ZSM-5,Fe-フェリエライトゼオライトを650°C以上で水熱老化させる.
高速NH3-SCR条件下で150°Cで老化した触媒の評価
反応メカニズムを解明するために,触媒構造の特徴化と密度関数理論 (DFT) の計算の適用.

主要な成果:

水熱老化は,Fe-β,Fe-ZSM-5,およびFe-フェリエライトの約30%から80%まで劇的に増加しました.
熟成したFe-βと新鮮なCu-SSZ-13の複合触媒は,ほぼ90%のNOx変換を達成しました.
DFTの計算は,老化中に形成された提案された中性異核ビス-μ-オクソアイロナリウムジメのサイトは,単核鉄-オクソサイトと比較して速度決定段階の低活性化自由エネルギーを示していることを示した.

結論:

水熱老化は,鉄交換ゼオライトの低温NH3-SCR活性を大幅に強化する効果的な戦略です.
新しいbis-μ-oxoアイロナルミウムジメルの活性部位の形成は,触媒性能の改善に起因する重要な要因として提案されています.
この発見は,より低い動作温度で排気ガス排出量を制御するためのより効率的な触媒を開発するための有望な経路を提供します.

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