Production of COx-Free Hydrogen from Biomass and NaOH Mixture: Effect of Catalysts

Hydrogen without CO and CO 2 was produced through the reactions of cellulose with NaOH and water at 473−773 K according to the following overall stoichiometric reaction: (C 6 H 10 O 5 ) + 12NaOH + H 2 O = 6Na 2 CO 3 + 12H 2 . Cellulose reacted with NaOH and water to produce hydrogen, Na 2 CO 3, and a small amount of methane as the byproduct. The total yield of hydrogen obtained through the reaction at a temperature range 473−773 K was estimated to be 62% on the basis of the stoichiometric equation. The formation of hydrogen was specifically enhanced by the addition of Ni, Co, Rh, or Ru catalyst supported on Al 2 O 3 to the mixture of cellulose and NaOH, and the total yields of hydrogen were dramatically improved to almost 100%. Among the many catalysts tested, Ni/TiO 2 and Ni/Cr 2 O 3 were promising catalysts which maintained catalytic activity during repeated reactions, keeping the hydrogen yield almost 100%.