Imidazolium based polymeric ionic liquid microgels as an alternative catalyst to metal catalysts for H-2 generation from methanolysis of NaBH4

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(C(6)VImBr) microgels are in 20-50 mu m range with the zeta potential values, measured between 15-21 mV. The prepared PIL microgels, p(C(4)VImBr), p(C(6)VImBr) and p(G(10)VImBr) were used as catalyst for H-2 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 H-2 generation rates were investigated. The hydrogen generation rate (HGR) of the methanolysis of NaBH4 reaction catalyzed by p(C(6)VImBr) microgels using 20 mL 500 mM (2.38 wt%) NaBH4 at 25 degrees C was calculated as 5871 100 mL H-2 g(-1) min(-1). Also, the activation energy (Ea) value was found as 343 0.8 kJ mol(-1) for H-2 generation from methanolysis of NaBH4 catalyzed by p(C(6)VImBr). (C) 2016 Elsevier B.V. All rights reserved.