Hydrogen Production from Aqueous Solutions of Urea with Ruthenium-based Catalysts.
An efficient catalytic system for hydrogen production from aqueous solution of urea was developed using ruthenium-based catalysts as an alternative for existing systems based on several H2 carriers. Ru/SiO2 showed the highest H2 yield among various SiO2 -supported transition-metal catalysts. Optimization of the catalyst support revealed that Ru/Al2 O3 exhibited the best catalytic performance, with a minimum amount of CO formed as a by-product (1.8 mol %). A mechanistic study suggested that the reaction proceeds mainly via two steps: urea hydrolysis (H2 NCONH2 +H2 O→2 NH3 +CO2 ) followed by NH3 decomposition (2 NH3 →3 H2 +N2 ).