Continuous synthesis of Cu/ZnO/Al2O3 nanoparticles in a co-precipitation reaction using a silicon based microfluidic reactor,Reaction Chemistry & Engineering

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Continuous synthesis of Cu/ZnO/Al2O3 nanoparticles in a co-precipitation reaction using a silicon based microfluidic reactor
Reaction Chemistry & Engineering ( IF 3.4 ) Pub Date : 2021-12-17 , DOI: 10.1039/d1re00499a
Ghazal Tofighi ₁ , Henning Lichtenberg _{1,

2} , Abhijeet Gaur _{1,

2} , Wu Wang ₃ , Stefan Wild ₂ , Karla Herrera Delgado ₂ , Stephan Pitter ₂ , Roland Dittmeyer ₄ , Jan-Dierk Grunwaldt _{1,

2} , Dmitry E. Doronkin _{1,

2}

Affiliation

CuO/ZnO/Al₂O₃ catalysts were continuously synthesized in a microfluidic reactor, analyzed by X-ray diffraction (XRD), physisorption (BET), chemisorption, electron microscopy and X-ray absorption spectroscopy (XAS), and tested for methanol synthesis from CO-rich synthesis gas. The results were compared to those obtained from CuO/ZnO and CuO/ZnO/Al₂O₃ produced by conventional co-precipitation in a batch reactor. The predominant phase of the aged precursor from microfluidic co-precipitation was identified as zincian malachite. After calcination the microfluidically synthesized catalyst exhibited smaller CuO crystallites, a larger BET surface area, a rather uniform morphology and a homogeneous distribution of Cu and Zn compared to catalysts prepared by batch co-precipitation. H₂-Temperature programmed reduction (TPR) showed that Cu species in CuO/ZnO/Al₂O₃ from microfluidic co-precipitation were more easily reducible. In situ Cu and Zn K-edge XAS during the TPR indicated reduction of Cu²⁺ to Cu⁰ between 150 °C and 240 °C, without detectable reduction of Zn. N₂O pulse chemisorption evidenced an enlarged Cu surface area of the nanoparticles from the microfluidic synthesis. Based on activity tests in methanol synthesis, at 250 °C the microfluidically synthesized Cu/ZnO/Al₂O₃ catalysts showed better performance than the catalyst from batch preparation when 1 mol% CO₂ was present in the synthesis gas. Dimethyl ether formed as a side product. As the microreactor is specially designed for high X-ray transmission with a thin Si/glass observation window, this study opens interesting perspectives for investigating the formation of catalyst precursors at the early stage of precipitation in future.

中文翻译：

使用硅基微流体反应器在共沉淀反应中连续合成 Cu/ZnO/Al2O3 纳米颗粒

CuO/ZnO/Al ₂ O ₃催化剂在微流控反应器中连续合成，通过 X 射线衍射 (XRD)、物理吸附 (BET)、化学吸附、电子显微镜和 X 射线吸收光谱 (XAS) 分析，并测试甲醇由富含 CO 的合成气合成。将结果与从 CuO/ZnO 和 CuO/ZnO/Al ₂ O ₃获得的结果进行比较在间歇式反应器中通过常规共沉淀法生产。来自微流体共沉淀的老化前体的主要相被确定为锌孔雀石。与通过分批共沉淀制备的催化剂相比，煅烧后微流体合成的催化剂表现出更小的 CuO 微晶、更大的 BET 表面积、相当均匀的形态以及 Cu 和 Zn 的均匀分布。H ₂ -程序升温还原(TPR) 表明来自微流体共沉淀的CuO/ZnO/Al ₂ O ₃中的Cu 物质更容易还原。TPR期间的原位Cu和Zn K-edge XAS表明Cu ²⁺还原为Cu ⁰在 150 °C 和 240 °C 之间，没有检测到 Zn 的减少。N ₂ O 脉冲化学吸附证明来自微流体合成的纳米颗粒的铜表面积扩大。根据甲醇合成中的活性测试，在 250 °C 下，当合成气中存在1 mol% CO ₂时，微流体合成的 Cu/ZnO/Al ₂ O ₃催化剂表现出比批量制备的催化剂更好的性能。二甲醚作为副产物形成。由于微反应器是专为高 X 射线透射率而设计的，具有薄的 Si/玻璃观察窗，这项研究为研究未来沉淀早期催化剂前体的形成开辟了有趣的前景。

更新日期：2021-12-24

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