Evtushkova Angelina, Heinrichs Jason M J J, Parastaev Alexander, Kosinov Nikolay, Hensen Emiel J M
Laboratory of Inorganic Materials and Catalysis, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
ACS Catal. 2025 Jun 13;15(13):11217-11231. doi: 10.1021/acscatal.5c02380. eCollection 2025 Jul 4.
Achieving selective conversion of CO to CO, CH, or CHOH remains a key challenge in catalyst design for CO hydrogenation. Site-specific activity at the metal-support interface plays a crucial role, motivating efforts to optimize metal particles and their interactions with supports. In this study, we synthesized Co-CeO catalysts with varying Co contents via flame spray pyrolysis (FSP) to investigate how the location and structure of Co influence activity. All samples contain ∼8 nm CeO nanoparticles with a high surface area and approximately 3.8 mol % Co ions strongly interacting with CeO. Catalysts with ≥5 mol % Co feature segregated CoO and CoO particles, which are partially reduced to metallic Co at 300 °C. The highest Co-weight-normalized activity at 200 °C (3.9 ± 0.2 mmol CO/mol Co/s, CH selectivity 85%) was observed in 10 mol % Co-CeO, with ∼50% Co reduction and 4-5 nm Co nanoparticles. The 2.5 mol % Co sample exhibited only 10% reduction, forming small Co clusters and creating Co-O-Ce sites that mainly favor CO formation (79% selectivity). Low Co content facilitates CO hydrogenation to CO and minor CHOH formation, likely on oxygen vacancies, assisted by H dissociation on very small metallic Co clusters. Larger Co nanoparticles predominantly produce CH, with minor CO and no CHOH. These results demonstrate that FSP enables tuning of catalyst structures for selective CO hydrogenation, leveraging the synergy between small metallic Co particles and Co-O-Ce sites.
实现将CO选择性转化为CO₂、CH₄或CH₃OH仍然是CO加氢催化剂设计中的关键挑战。金属-载体界面处的位点特异性活性起着至关重要的作用，这促使人们努力优化金属颗粒及其与载体的相互作用。在本研究中，我们通过火焰喷雾热解（FSP）合成了具有不同Co含量的Co-CeO₂催化剂，以研究Co的位置和结构如何影响活性。所有样品均包含具有高比表面积的约8 nm CeO₂纳米颗粒和约3.8 mol%与CeO₂强烈相互作用的Co离子。Co含量≥5 mol%的催化剂具有分离的CoO和Co₃O₄颗粒，这些颗粒在300 °C下部分还原为金属Co。在10 mol% Co-CeO₂中观察到200 °C时最高的Co重量归一化活性（3.9 ± 0.2 mmol CO/mol Co/s，CH₄选择性85%），约50%的Co被还原，Co纳米颗粒尺寸为4-5 nm。2.5 mol% Co的样品仅表现出10%的还原率，形成小的Co簇并产生主要有利于CO形成的Co-O-Ce位点（79%选择性）。低Co含量有利于CO加氢生成CO₂和少量CH₃OH，可能是在氧空位上发生，由非常小的金属Co簇上的H解离辅助。较大的Co纳米颗粒主要生成CH₄，伴有少量CO且无CH₃OH。这些结果表明，FSP能够利用小金属Co颗粒与Co-O-Ce位点之间的协同作用来调整催化剂结构，以实现选择性CO加氢。
