Imidazolium based polymeric ionic liquid microgels as an alternative catalyst to metal catalysts for H2 generation from methanolysis of NaBH4

•Poylmeric ionic liquid (PIL) catalyst for H2 production from methanolysis of NaBH4.•PILs as green catalyst for green energy carrier of H2 production from NaBH4.•Fast H2 production via PILs catalyzed NaBH4 methanolysis.•PIL catalysts as an alternative to toxic metal nanoparticles for H2 production.

Ionic liquid monomers (ILMs), 1,n-dialkyl-3,3′-bis-1-vinyl imidazolium bromides, ([C1,n(Vim)2]Br n = 4, 6 and 10) were prepared from vinyl imidazole (VI) and dibromo alkanes, dibromobuthane (DBB), dibromohexane (DBH) and dibromodecane (DBD). Then, polymeric ionic liquid (PIL) microgels were synthesized by photo-initiated inverse suspension polymerization technique using these prepared ILMs. The SEM images revealed that the sizes of p(C6VImBr) microgels are in 20–50 μm range with the zeta potential values, measured between 15–21 mV. The prepared PIL microgels, p(C4VImBr), p(C6VImBr) and p(C10VImBr) were used as catalyst for H2 generation from the methanolysis and hydrolysis of NaBH4. PIL microgels as catalyst were shown great catalytic activity in the methanolysis of NaBH4. Therefore, various parameters such as the type of PIL microgels, the amount of PIL microgels, the concentration of NaBH4, methanolysis temperature of NaBH4 reactions, and the reusability of PIL microgel effecting the H2 generation rates were investigated. The hydrogen generation rate (HGR) of the methanolysis of NaBH4 reaction catalyzed by p(C6VImBr) microgels using 20 mL 500 mM (2.38 wt%) NaBH4 at 25 °C was calculated as 5871 ± 100 mL H2 g− 1 min− 1. Also, the activation energy (Ea) value was found as 34.3 ± 0.8 kJ mol− 1 for H2 generation from methanolysis of NaBH4 catalyzed by p(C6VImBr).

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