Laura Uson, Arruebo Manuel, Sebastian Victor
Department of Chemical & Environmental Engineering & Nanoscience Institute of Aragon (INA), University of Zaragoza, Mariano Esquillor edif. I+D, 50018 Zaragoza, Spain.
Dalton Trans. 2018 Jan 30;47(5):1693-1702. doi: 10.1039/c7dt03360e.
The continuous production of Pt-based heterogeneous catalysts based on ultra-small (<2 nm) noble metal nanoparticles deposited on mesoporous ordered silica and their catalytic activity in VOC abatement are here reported. Microfluidic reactors can be used not only to enable the fast and controlled production of ultra-small Pt nanoparticles (NPs), but also alloyed NPs including PtPd, PtRu and PtRh can be formed in short residence times (between 60 s and 5 min). A novel continuous and homogeneous loading of these catalytic NPs on SBA-15 used as a mesoporous support is also here reported. This procedure eases the NP loading and minimizes washing post-treatments. A 12-fold decrease in the synthesis time was obtained when using this microfluidic reactor compared to the traditional batch production of Pt NPs. Microflow and batch type reactors yielded a Pt precursor conversion to generate Pt NPs with a 90% and 85% yield, respectively. Under the same conditions, the productivity of the microfluidic system (27 mg Pt NPs per h) was twice the one achieved in the conventional batch type reactor. The catalytic performance of the supported catalysts separately prepared by microfluidics and by conventional impregnation under the same conditions and with the same noble metal loading was also compared in the n-hexane abatement as a model of VOCs. Both catalysts were active in the VOC oxidation reaction but a 95% reduction in the catalyst synthesis time was obtained when using the catalysts produced in the microfluidic platform. For this reaction a long-term activity test was successfully carried out at 175 °C during 30 h on stream using the heterogeneous catalyst prepared by using the flow reactor.
本文报道了基于沉积在介孔有序二氧化硅上的超小（<2 nm）贵金属纳米颗粒的铂基多相催化剂的连续生产及其在挥发性有机化合物（VOC）减排中的催化活性。微流控反应器不仅可用于快速、可控地生产超小铂纳米颗粒（NPs），还能在短停留时间（60秒至5分钟）内形成包括PtPd、PtRu和PtRh在内的合金纳米颗粒。本文还报道了一种将这些催化纳米颗粒新颖地连续且均匀负载在用作介孔载体的SBA-15上的方法。该方法简化了纳米颗粒的负载过程，并将洗涤后处理降至最低。与传统间歇式生产铂纳米颗粒相比，使用这种微流控反应器时合成时间减少了12倍。微流控反应器和间歇式反应器产生铂前驱体转化以生成铂纳米颗粒的产率分别为90%和85%。在相同条件下，微流控系统的生产率（每小时27毫克铂纳米颗粒）是传统间歇式反应器的两倍。在正己烷减排作为挥发性有机化合物模型的实验中，还比较了在相同条件下且具有相同贵金属负载量时，通过微流控和传统浸渍法分别制备的负载型催化剂的催化性能。两种催化剂在挥发性有机化合物氧化反应中均具有活性，但使用微流控平台生产的催化剂时，催化剂合成时间减少了95%。对于该反应，使用流动反应器制备的多相催化剂在175°C下成功进行了30小时的长期活性测试。
