Cellulose, the most abundant renewable
biopolymer, exists in many
forms, such as microgranular cellulose (MGCell), sigmacell cellulose
(SCell), cellulose fibers (FCell), and α-cellulose (AlfaCell).
Several of these cellulose forms were protonated with an amine-containing
agent polyethyleneimine (PEI), and the modified celluloses (XCell-PEI+) were studied as catalysts in methanolysis of NaBH4 for hydrogen (H2) generation. It was found that the SCell-PEI+-catalyzed reaction is the fastest one among the modified
celluloses with a hydrogen generation rate of 5520 ± 119 mL H2/(g of catalyst × min). The activation energies of MGCell-PEI+, SCell-PEI+, FCell-PEI+, and AlfaCell-PEI+ were determined as +21.7, +23.4, +24.8, and + 21.8 kJ/mol,
respectively. Reusability of catalysts was investigated, and regeneration
of cellulose based catalysts after the fifth cycle could be readily
achieved by HCl treatment to completely recover its activity. Therefore,
PEI-modified-protonated cellulose forms constitute sustainable, re-generable,
and renewable catalysts for production of H2, an environmentally
benign green energy carrier.