Reaction Kinetics Analysis of Hydrogen
Production by Biomass Gasification in Supercritical Water
Hao Xiaohong,Guo Liejin,Lu Youjun,Zhang Ximin
(State Key Laboratory of Multiphase Flow in Power Engineering,Xi'an Jiaotong
University,Xi'an 710049, China)
Abstract: The reaction kinetics of sodium carboxymethylcellulose (CMC) and sawdust/CMC
gasification in supercritical water was studied. The results indicate that the reaction is
of pseudo¡Mfirst¡Morder kinetics.The activation energy of CMC is 160 kJ/mol at 20 MPa
and 97~81 kJ/mol at 25~35 MPa, respectively.The activation energy decreases with the
increasing pressure.The activation volume can reach the order of magnitude of 10ª¬3 at
near-critical state of water and decrease rapidly away from the critical point of
water.The curves of solubility parameter,dielectric constant,and supercritical water
density versus reaction rate constant have the similar tendency of linear relation.The
reaction rate decreases with the increase of these parameters.The value of activation
volume at the near-critical state of water is larger than that of leaving away from the
critical point of water when sawdust/CMC is gasified in supercritical water at 923 K.The
curves of solubility parameter, dielectric constant,and supercritical water density versus
reaction rate have the similar trends.
Keywords:biomass;supercritical water;gasification;hydrogen production