Alxneit Ivo, Garbujo Alberto, Carollo Giovanni, Ferri Davide, Glisenti Antonella
Paul Scherrer Institut, CH-5232, Villigen PSI, Switzerland.
Università degli Studi di Padova, Dipartimento di Scienze Chimiche, I-35131, Padova, Italy.
Phys Chem Chem Phys. 2020 Sep 8;22(34):18798-18805. doi: 10.1039/d0cp01064b.
Substitution of critical raw materials such as platinum group metals in automotive catalysts is challenging. In this work we prepared a nanocomposite in which CuO nanoparticles are highly dispersed on a La0.5Sr0.5CoO3 perovskite-type oxide. The behaviour and reactivity under three way catalyst conditions was monitored by operando time-resolved high-energy X-ray diffraction under oscillating rich/lean feed. The reducing environment converted CuO into Cu(0) in a two step process: Cu(ii) to Cu(i) and to Cu(0), while the perovskite evolved to an oxygen deficient brownmillerite phase. These structural transformations are shown to be crucial for catalytic activity. The in situ generated Cu(0)/Cu(i)/brownmillerite nanocomposite is active for NO reduction above 300 °C, reaching 90% NO conversion at 450 °C. The effect of feed composition on the diffraction patterns was studied by Rietveld refinement in order to rationalize the experimental observations under TWC conditions.
替换汽车催化剂中的关键原材料（如铂族金属）具有挑战性。在这项工作中，我们制备了一种纳米复合材料，其中CuO纳米颗粒高度分散在La0.5Sr0.5CoO3钙钛矿型氧化物上。在振荡富/贫进料条件下，通过操作时间分辨高能X射线衍射监测三效催化剂条件下的行为和反应性。还原环境通过两步过程将CuO转化为Cu(0)：Cu(ii)转化为Cu(i)，再转化为Cu(0)，而钙钛矿演变成缺氧的褐锰矿相。这些结构转变被证明对催化活性至关重要。原位生成的Cu(0)/Cu(i)/褐锰矿纳米复合材料在300°C以上对NO还原具有活性，在450°C时NO转化率达到90%。通过Rietveld精修研究了进料组成对衍射图谱的影响，以便合理解释三效催化剂条件下的实验观察结果。
