Pokorny Tomas, Vykoukal Vit, Machac Petr, Moravec Zdenek, Scotti Nicola, Roupcova Pavla, Karaskova Katerina, Styskalik Ales
Department of Chemistry, Masaryk University, Kotlarska 2, CZ-61137 Brno, Czech Republic.
Consiglio Nazionale delle Ricerche, Istituto di Scienze e Tecnologie Chimiche "G. Natta", Via Golgi 19, 20133 Milano, Italy.
ACS Sustain Chem Eng. 2023 Jul 20;11(30):10980-10992. doi: 10.1021/acssuschemeng.2c06777. eCollection 2023 Jul 31.
Non-oxidative ethanol dehydrogenation is a renewable source of acetaldehyde and hydrogen. The reaction is often catalyzed by supported copper catalysts with high selectivity. The activity and long-term stability depend on many factors, including particle size, choice of support, doping, etc. Herein, we present four different synthetic pathways to prepare Cu/SiO catalysts (∼2.5 wt % Cu) with varying copper distribution: hydrolytic sol-gel (sub-nanometer clusters), dry impregnation ( = 3.4 nm; σ = 0.9 nm and particles up to 32 nm), strong electrostatic adsorption ( = 3.1 nm; σ = 0.6 nm), and solvothermal hot injection followed by Cu particle deposition ( = 4.0 nm; σ = 0.8 nm). All materials were characterized by ICP-OES, XPS, N physisorption, STEM-EDS, XRD, RFC NO, and H-TPR and tested in ethanol dehydrogenation from 185 to 325 °C. The sample prepared by hydrolytic sol-gel exhibited high Cu dispersion and, accordingly, the highest catalytic activity. Its acetaldehyde productivity (2.79 g g h at 255 °C) outperforms most of the Cu-based catalysts reported in the literature, but it lacks stability and tends to deactivate over time. On the other hand, the sample prepared by simple and cost-effective dry impregnation, despite having Cu particles of various sizes, was still highly active (2.42 g g h acetaldehyde at 255 °C). Importantly, it was the most stable sample out of the studied materials. The characterization of the spent catalyst confirmed its exceptional properties: it showed the lowest extent of both coking and particle sintering.
非氧化乙醇脱氢是乙醛和氢气的可再生来源。该反应通常由具有高选择性的负载型铜催化剂催化。活性和长期稳定性取决于许多因素，包括粒径、载体选择、掺杂等。在此，我们展示了四种不同的合成途径来制备具有不同铜分布的Cu/SiO催化剂（约2.5 wt% Cu）：水解溶胶-凝胶法（亚纳米团簇）、干浸渍法（ = 3.4 nm；σ = 0.9 nm且颗粒尺寸达32 nm）、强静电吸附法（ = 3.1 nm；σ = 0.6 nm）以及溶剂热热注射法随后进行铜颗粒沉积（ = 4.0 nm；σ = 0.8 nm）。所有材料通过电感耦合等离子体发射光谱法（ICP-OES）、X射线光电子能谱法（XPS）、N物理吸附法、扫描透射电子显微镜-能谱仪（STEM-EDS）、X射线衍射法（XRD）、射频化学发光氮氧化物分析仪（RFC NO）和氢气程序升温还原法（H-TPR）进行表征，并在185至325°C的乙醇脱氢反应中进行测试。通过水解溶胶-凝胶法制备的样品表现出高铜分散性，因此具有最高的催化活性。其乙醛产率（255°C下为2.79 g g h）优于文献中报道的大多数铜基催化剂，但缺乏稳定性且随时间会失活。另一方面，通过简单且经济高效的干浸渍法制备的样品，尽管具有各种尺寸的铜颗粒，仍具有高活性（255°C下乙醛产率为2.42 g g h）。重要的是，它是所研究材料中最稳定的样品。失活催化剂的表征证实了其优异性能：它显示出最低程度的结焦和颗粒烧结。
