**4. Conclusions**

This study demonstrated the application of flow microreactors packed with catalysts derived from **UiO-66** MOF for the hydrolysis of ethyl paraoxone. Through the tableting and sieving procedure, catalysts with a particle size between 125 and 250 μm were found to be most suitable for kinetic testing of this application. Catalysts with a smaller particle size demonstrated a significant pressure drop that resulted in the segregation and channeling of the packed catalyst bed. Catalysts derived from MOFs with smaller crystal sizes proved more effective than catalysts derived from MOFs with larger crystal sizes. The catalyst displayed an excellent long-term stability of more than 18 h of continuous operation. The presence of –NH2 functionality greatly enhanced catalyst activity in agreemen<sup>t</sup> with previous reports. The flow microreactor setup also allowed us to conduct easy kinetic investigations to deduce the first-order reaction kinetics and the apparent activation energy for the reaction.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2073-4344/10/10/1159/s1: detailed synthesis methods of **1**–**4**, ethyl-paraoxon, and complete analysis data from Figures S1–S19, Table S1.

**Author Contributions:** Conceptualization, S.T.M., and M.A.-R.; funding acquisition, S.T.M., and M.A.-R.; methodology, P.E, S.T.M., and M.A.-R.; project execution, P.E., N.E., and W.C.; Supervision, S.T.M. and M.A.-R.; writing—original draft, P.E., S.T.M., and M.A.-R. writing—review and editing, P.E., S.T.M., and M.A.-R. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by TAMUQ seed and startup research funding and the Qatar National Research Fund, National Priority Research Program gran<sup>t</sup> NPRP9-377-1-080.

**Conflicts of Interest:** The authors declare no conflict of interest.
