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Evidence of Structure Sensitivity in the Fischer–Tropsch Reaction on Model Cobalt Nanoparticles by Time‐Resolved Chemical Transient Kinetics
Angewandte Chemie International Edition ( IF 16.6 ) Pub Date : 2017-05-24 , DOI: 10.1002/anie.201701186
Walter T. Ralston 1, 2 , Gérôme Melaet 1, 2 , Tommy Saephan 1 , Gabor A. Somorjai 1, 2
Affiliation  

The Fischer–Tropsch process, or the catalytic hydrogenation of carbon monoxide (CO), produces long chain hydrocarbons and offers an alternative to the use of crude oil for chemical feedstocks. The observed size dependence of cobalt (Co) catalysts for the Fischer–Tropsch reaction was studied with colloidally prepared Co nanoparticles and a chemical transient kinetics reactor capable of measurements under non‐steady‐state conditions. Co nanoparticles of 4.3 nm and 9.5 nm diameters were synthesized and tested under atmospheric pressure conditions and H2/CO=2. Large differences in carbon coverage (ΘC) were observed for the two catalysts: the 4.3 nm Co catalyst has a ΘC less than one while the 9.5 nm Co catalyst supports a ΘC greater than two. The monomer units present on the surface during reaction are identified as single carbon species for both sizes of Co nanoparticles, and the major CO dissociation site is identified as the B5‐B geometry. The difference in activity of Co nanoparticles was found to be a result of the structure sensitivity caused by the loss of these specific types of sites at smaller nanoparticle sizes.

中文翻译:

时间分辨化学瞬态动力学的模型钴纳米颗粒费-托反应中结构敏感性的证据

费-托工艺或一氧化碳(CO)的催化加氢产生长链碳氢化合物,提供了将原油用作化学原料的替代方法。使用胶态制备的Co纳米粒子和能够在非稳态条件下进行测量的化学瞬变动力学反应器,研究了钴(Co)催化剂对费托反应的尺寸依赖性。合成了直径为4.3nm和9.5nm的Co纳米颗粒,并在大气压条件下和H 2 / CO = 2下进行了测试。在碳覆盖率(Θ大的差异Ç,观察两种催化剂):4.3纳米钴催化剂具有Θ Ç小于一,而9.5纳米钴催化剂支持Θ Ç大于两个。在反应过程中,存在于表面的单体单元被识别为两种纳米尺寸的Co纳米颗粒的单一碳,主要的CO解离位点被识别为B 5 -B几何。发现Co纳米颗粒活性的差异是由于在较小的纳米颗粒尺寸下这些特定类型的位点的损失引起的结构敏感性的结果。
更新日期:2017-05-24
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