Vollenbroek Jeroen C, Nieuwelink Anne-Eva, Bomer Johan G, Tiggelaar Roald M, van den Berg Albert, Weckhuysen Bert M, Odijk Mathieu
BIOS Lab on a Chip Group, MESA+ Institute, University of Twente, Hallenweg 15, 7522 NH Enschede, The Netherlands.
Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.
Microsyst Nanoeng. 2023 Mar 30;9:39. doi: 10.1038/s41378-023-00495-2. eCollection 2023.
The particles of heterogeneous catalysts differ greatly in size, morphology, and most importantly, in activity. Studying these catalyst particles in batch typically results in ensemble averages, without any information at the level of individual catalyst particles. To date, the study of individual catalyst particles has been rewarding but is still rather slow and often cumbersome. Furthermore, these valuable in-depth studies at the single particle level lack statistical relevance. Here, we report the development of a droplet microreactor for high-throughput fluorescence-based measurements of the acidities of individual particles in fluid catalytic cracking (FCC) equilibrium catalysts (ECAT). This method combines systematic screening of single catalyst particles with statistical relevance. An oligomerization reaction of 4-methoxystyrene, catalyzed by the Brønsted acid sites inside the zeolite domains of the ECAT particles, was performed on-chip at 95 °C. The fluorescence signal generated by the reaction products inside the ECAT particles was detected near the outlet of the microreactor. The high-throughput acidity screening platform was capable of detecting ~1000 catalyst particles at a rate of 1 catalyst particle every 2.4 s. The number of detected catalyst particles was representative of the overall catalyst particle population with a confidence level of 95%. The measured fluorescence intensities showed a clear acidity distribution among the catalyst particles, with the majority (96.1%) showing acidity levels belonging to old, deactivated catalyst particles and a minority (3.9%) exhibiting high acidity levels. The latter are potentially of high interest, as they reveal interesting new physicochemical properties indicating why the particles were still highly acidic and reactive.
多相催化剂的颗粒在尺寸、形态上有很大差异，最重要的是在活性方面。批量研究这些催化剂颗粒通常会得到总体平均值，而没有任何关于单个催化剂颗粒层面的信息。迄今为止，对单个催化剂颗粒的研究虽有收获，但仍然相当缓慢且常常很麻烦。此外，这些在单颗粒水平上有价值的深入研究缺乏统计相关性。在此，我们报告了一种用于高通量基于荧光测量流化催化裂化（FCC）平衡催化剂（ECAT）中单个颗粒酸度的液滴微反应器的开发。该方法将对单个催化剂颗粒的系统筛选与统计相关性相结合。在95°C下于芯片上进行了由ECAT颗粒沸石域内的布朗斯特酸位点催化的4-甲氧基苯乙烯的齐聚反应。在微反应器出口附近检测到ECAT颗粒内反应产物产生的荧光信号。该高通量酸度筛选平台能够以每2.4秒检测1个催化剂颗粒的速率检测约1000个催化剂颗粒。检测到的催化剂颗粒数量代表了总体催化剂颗粒群体，置信水平为95%。测得的荧光强度在催化剂颗粒之间显示出明显的酸度分布，大多数（96.1%）显示出属于老化、失活催化剂颗粒的酸度水平，少数（3.9%）表现出高酸度水平。后者可能具有很高的研究价值，因为它们揭示了有趣的新物理化学性质，表明了这些颗粒为何仍然具有高酸性和高反应性。
