HYDROGASIFICATION OF WOOD FOR HIGH HEATING-VALUE GAS-PRODUCTION .9. HNO3-OXIDATION PRETREATMENT OF LARCH BARK FOR IRON-CATALYZED HYDROGASIFICATION

Larch bark was pretreated with HNO3 for subsequent iron-catalyzed hydr ogasification of the char. The oxidation pretreatment had the followin g effects: (1) Decrease of catalyst poisons; (2) Increase of oxygenate d sites; (3) Improved dispersion of iron loaded by wet impregnation; ( 4) Increase of carboxyl groups for loading with ion-exchange iron. The influence of these factors and their mutual effects were discussed by comparing the reactivities among raw, HCl-demineralized, O-3-oxidized , and HNO3-oxidized chars with impregnated iron and ion-exchanged iron . Of these four factors, (4) was the most important for great gasifica tion reactivity of HNO3-oxidized char because a complete conversion at 800 degrees C could be achieved by a smaller loading of ion-exchanged iron than that of wet-impregnated iron. This confirmed that a high di spersion of the catalyst is critical for the successful gasification o f bark char.