*4.5. Catalytic Tests*

Catalytic screening was carried out in 4 mL batch reactors at 393 K or 413 K. 3 mL of 10 wt. % glucose solution (in DMSO) was heated to the desired temperature together with the MOF catalyst and a magnetic stirring bar (either 10 or 40 mg, corresponding to a 30 or 7.5 substrate:catalyst ratio, respectively) for 3 hours. Blank experiments were also carried out without catalyst. The products were analysed by high performance liquid chromatography (HPLC) equipped with a Bio-Rad HPX 87P column; a photo diode array detector and evaporative light scattering detector (ELSD) were used to monitor 5-HMF and sugars, respectively. The mobile phase was water with 0.6 mL min−<sup>1</sup> flow rate. The products and the reactant (glucose) were quantified by calibration with external standard solutions. Recycle reactions were conducted in a 25 mL reactor with PTFE lining (Berghof, BR-25). In a typical reaction, 200 mg of catalyst and a magnetic stirring bar was placed into the reactor. 15 mL of a solution of 10 wt. % glucose in DMSO was then added. The reactor was sealed and pressurized to 10 bar with helium. The reactor was brought to reaction temperature (120 ◦C) by placing it into a preheated aluminium block heated via a heating/stirring plate. At the end of the reaction (3 hours), the reactor was removed from the heating block and quenched in an ice bath at 0 ◦C to stop the reaction. The reactor was then depressurised and opened. The solid catalyst was recovered from the reaction solution using a centrifuge and washed with DMSO. The reaction solution was filtered and analysed using a Shimadzu HPLC (Shimadzu UK Ltd, Milton Keynes, United Kingdom), as described above. In the subsequent reaction tests, the recovered catalyst was added back into the 25 mL reactor along with fresh stock solution. The reaction procedure was then repeated under the same conditions in order to test the recyclability of the catalyst, and products were analysed as described above.
