Catalytic activity of metal‐free amine‐modified dextran microgels in hydrogen release through methanolysis of NaBH4. (27th March 2020)

• Record Type: Journal Article
• Authors: Inger, Erk; Sunol, Aydin K.; Sahiner, Nurettin
• Is Part Of: International journal of energy research. Volume 44:Number 7(2020)
• Page Start: 5990
• Page End: 6001
• Publication Date: 2020-03-27
• Subjects: dextran microgel/nanogel -- H2 production -- methanolysis -- natural polymeric catalysts -- sustainable catalysts; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Power resources -- Research -- Periodicals; 621.042
• DOI: 10.1002/er.5395
• Languages: English
• ISSNs: 0363-907X

Abstract

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 NaBH4 to produce H2 . 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 NaBH4 to produce H2 . The effects of reaction temperature and NaBH4 concentration on H2 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 NaBH4 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. Abstract : Preparation of microgel in a single step from a natural polymer, dextran and its' chemical modification to be used as metal free catalyst for H2 production from NaBH4 methanolysis is reported. The modified dextran microgels were found as efficient catalysts with readily re‐generable and reusable with high hydrogen generation rates. The E a of NaBH4 methanolysis catalyzed by modified dextran microgel is 32.87 kJ/mol, much better than most of the metal‐based catalysts reported in the literature for the same purpose.