Catalytic activity of metal‐free amine‐modified dextran microgels in hydrogen release through methanolysis of NaBH 4

Summary Polymeric microgels were prepared from dextran (Dex) by crosslinking linear natural polymer dextran with divinyl sulfone (DVS) with a surfactant‐free emulsion technique resulting in high gravimetric yield of 78.5 ± 5.3% with wide size distribution. Dex microgels were chemically modified, and then used as catalyst in the methanolysis of NaBH 4 to produce H 2 . The chemical modification of Dex microgel was done on epichlorohydrin (ECH)‐reacted Dex microgels with ethylenediamine (EDA), diethylenetriamine (DETA), and triethylenetetraamine (TETA) in dimethylformamide (DMF) at 90°C for 12 hours. The modified dextran‐TETA microgels were protonated using treatment with hydrochloric acid (HCl) and m‐Dex microgels‐TETA‐HCl was found to be a very efficient catalyst for methanolysis of NaBH 4 to produce H 2 . The effects of reaction temperature and NaBH 4 concentration on H 2 generation rates were investigated and m‐Dex microgels‐TETA‐HCl catalyst possessed excellent catalytic performances with 100% conversion and 80% activity at end of 10 consecutive uses and was highly re‐generatable with simple HCl treatment. Interestingly, m‐Dex microgels‐TETA‐HCl catalyst can catalyze NaBH 4 methanolysis reaction in a mild temperature range 0 to 35°C with E a value of 30.72 kJ/mol and in subzero temperature range, −20 to 0°C with E a value of 32.87 kJ/mol, which is comparable with many catalysts reported in the literature.