To design the inline continuous-flow catalyst recycling, detailed knowledge of the OSN performance with the solution collected at the outlet of the flow reactor was key. Therefore, a batch study was performed by collecting and filtering the solution resulting from the model alkylation reaction (Figure ). Encouraging results were obtained when performing singlestage filtration, with catalyst retention in the retentate side approaching total rejection (99.4% recovery) after the initial transient period when membrane compaction and equilibration with the surrounding environment resulted in slowly improving filtration performance that stabilized over a few hours. Despite the high catalyst recovery, limited flux through the membrane resulted in a relatively low permeate volume, which in turn affected the overall product recovery for a single stage (48.1%), since a large fraction of the product remained in the retentate volume. It should be noted that the product transport through the membrane is not selective, resulting in equal concentrations in permeate and retentate. For this reason, the product recovery is only dependent on the permeate-to-retentate volumetric ratio. Therefore, to increase the overall permeate volume and in turn product recovery, a second filtration stage was added to the process, where the retentate solution still containing a relatively large amount of product was filtered through a second OSN unit. Given the smaller input volume, the second filtration had a lower flow rate, which resulted in equilibrium flux values lower than for the first stage, in line with the results of the flow rate screening for filtration of TBADT solutions. For the second stage, catalyst retention exceeded 99%, resulting in a combined catalyst recovery of 98.4% over the two stages paired with a satisfactory product recovery exceeding 80%. The results of these experiments highlighted the trade-off between the catalyst recovery and the product recovery for a membrane with limited flux and high chemical resistance. Nevertheless, the two-stage filtration design enabled overcoming the trade-off and delivered high catalyst recovery coupled with suitable product recovery. Given the promising results of the 19-hours run, a 3-day catalyst recycling experiment was performed (Figure ). Throughout this period, the fraction yield of the model alkylation oscillated in a narrow range of 79 -84%, and a total TON of 6738 (including additional 373