Catalytic activity of amine functionalized titanium dioxide nanoparticles in methanolysis of sodium borohydride for hydrogen generation

Abstract

Titanium dioxide (TiO2) nanoparticles, Anatase (A-TiO2), Rutile (R-TiO2), and Rutile-Anatase (RA-TiO2) mixture were modified chemically with ethylene-diamine, diethylene-tri-amine, tri-ethylene-tetra-amine, and polyethyleneimine (PEI) to functionalize their surface to catalyze sodium borohydride methanolysis to generate hydrogen. PEI modified TiO2 particles catalyzed the methanolysis reaction more effectively than amines with lesser number of amine groups for all the forms of modified TiO2 catalysts. The Hydrogen Generation Rate (HGR) values for A-TiO2, R-TiO2, and RA-TiO2 are 3121, 3525, and 2920 mL H2/(g catalystXmin), respectively and are further increased by 25.6, 30.6, and 36.7%, respectively when protonated. The protonated catalyst, A-TiO2-PEI+, R-TiO2-PEI+, and RA-TiO2-PEI+, are effective at low temperatures, 253–313 K, with activation energies of 35.2, 36.3, and 36 kJ/mol for methanolysis, respectively. These catalysts retain over sixty percent of the original HGR at the end of fifth consecutive reuse. All the forms of the catalysts are completely regenerateable through hydrochloric acid treatment.