Design of Pd-based pseudo-binary alloy catalysts for highly active and selective NO reduction
Design of Pd-based pseudo-binary alloy catalysts for highly active and selective NO reduction
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DOI：
10.1039/c8sc05496g
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发表时间：
2019-04-21
期刊：
影响因子：
8.4
通讯作者：
Furukawa, Shinya
中科院分区：
文献类型：
--
作者：
Jeon, Jaewan;Kon, Ken-ichi;Furukawa, Shinya
研究了高活性、高选择性CO还原NO的Pd基合金催化剂的开发。对Pd基N2催化剂（PdM/Al 2 O3：M = Cu、In、Pb、Sn和Zn）的研究表明，PdIn/Al 2 O3催化剂即使在低温下（在200 ℃下为100%）也显示出优异的N-2选择性。通过Cu取代部分In，形成Pd（In 1-xCux）伪二元合金结构，进一步提高了PdIn的催化活性。优化的催化剂，即Pd（In0.33Cu0.67）/Al 2 O3，即使在200 ℃和更高的温度下也促进NO完全转化为N-2（100%产率），这是使用金属催化剂从未实现的。通过HAADF-STEM-EDS、EXAFS和CO-FT-IR分析证实了伪二元合金结构的形成。通过动力学分析、XAFS和密度泛函理论计算，揭示了In和Cu对催化剂性能的影响：（1）N_2O的吸附和分解（2）In促进CO氧化，提高了催化剂的低温活性; Cu取代促进了NO的吸附和解离（NO -> N + O），从而促进了催化剂的高温活性。
The development of Pd-based alloy catalysts for highly active and selective reduction of NO by CO was investigated. A survey of Pd-based bimetallic catalysts (PdM/Al2O3: M = Cu, In, Pb, Sn, and Zn) revealed that the PdIn/Al2O3 catalyst displayed excellent N-2 selectivity even at low temperatures (100% at 200 degrees C). The catalytic activity of PdIn was further improved by substituting a part of In with Cu, where a Pd(In1-xCux) pseudo-binary alloy structure was formed. The optimized catalyst, namely, Pd(In0.33Cu0.67)/Al2O3, facilitated the complete conversion of NO to N-2 (100% yield) even at 200 degrees C and higher, which has never been achieved using metallic catalysts. The formation of the pseudo-binary alloy structure was confirmed by the combination of HAADF-STEM-EDS, EXAFS, and CO-FT-IR analyses. A detailed mechanistic study based on kinetic analysis, operando XAFS, and DFT calculations revealed the roles of In and Cu in the significant enhancement of catalytic performance: (1) N2O adsorption and decomposition (N2O -> N-2 + O) were drastically enhanced by In, thus resulting in high N-2 selectivity; (2) CO oxidation was promoted by In, thus leading to enhanced low-temperature activity; and (3) Cu substitution improved NO adsorption and dissociation (NO -> N + O), thus resulting in the promotion of high-temperature activity.