High-throughput activity screening and sorting of single catalyst particles with a droplet microreactor using dielectrophoresis

Solid catalysts are complex, multi-component materials with large interparticle heterogeneities that hamper statistically relevant in-depth catalyst characterization. Here we introduce an automated high-throughput screening and sorting method for catalyst particles. A droplet microreactor was developed for fluorescence-activated sorting of catalyst particles using dielectrophoresis. Fluid catalytic cracking (FCC) particles stained with styrene derivatives were analysed with the analytical platform developed and sorted based on catalytic activity. Highly active and low-to-moderately active catalyst particles were sorted using 4-fluorostyrene or 4-methoxystyrene as probe, respectively. FCC particles were encapsulated in liquid droplets, where fluorescent FCC particles activated the dielectrophoretic sorter and were sorted within 200 ms. Post-sorting analysis of 4-fluorostyrene-stained and sorted catalyst particles was done using fluorescence microscopy and micro-X-ray fluorescence. This confirmed that the sorted particles were the least deactivated and showed the highest acidity, while non-sorted particles contained more metal poisons.