The catalytic gasification of rice husk with pure CO2 has been carried out at 800 oC and at atmospheric pressure. Five kinds of catalysts (Fe2O3, CoO, NiO, CuO, ZnO) supported on γ-Al2O3 were compared with their activity for the gasification, different preparation methods of the catalyst were employed to compared their activity. The results showed that ZnO/γ-Al2O3 prepared by coprecipitation with ethylamine exhibited the highest activity. The effects of catalyst loading, space velocity and rice husk particle size on the gasification were studied. The suitable gasification conditions were obtained as follows: loading of ZnO 7.5 %, space velocity 4.0 h-1 and particle size of rice husk 0.2-0.3 mm. Under such conditions, CO content was 17.7 %, with a CO2 conversion of 20.7 %, and rice husk conversion of 75.2 %. CO2 gasification kinetics for rice husk was also investigated. The relationship of carbon conversion versus reaction time for rice husk was measured from 762 oC to 837 oC. The shrinking core model (SCM) was used to correlate the relationship between conversion and time and to obtain the reaction rate constants at different temperatures. Then the reaction activation energy (Ea) and the pre-exponential factor (k0) were predicted respectively using the Arrhenius equation. The activation energy values of gasification with ZnO/γ-Al2O3 and without catalyst were 104 kJ/mol and 125 kJ/mol, respectively. The pre-exponential factor values were 4.51×103 min-1 and 2.58×104 min-1.

Catalyst and process parameters for the gasification of rice husk with pure CO2 and the gasification kinetics

249th National Meeting (2015)

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