Abstract:
In this research, catalytic effect of char on hydrogasification of biomass derived volatile was studied. Experiments were carried out in a fixed bed reactor. Results showed that an increase in H2 flow rate gave more CO hydrogenation, forwarding CH4 formation. Char was found to have a catalytic effect on tar cracking, resulting in higher carbon conversion into gaseous products. Moreover, volatile hydrogenation and CO hydrogenation were also affected by the presence of char causing more CH4 production. An influence of hydrogasification temperature was also examined in a range of 600 to 800 C. At a higher hydrogasification temperature, gaseous products were increased while tar was decreased. An explanation for this is that tar cracking is progressive at higher temperature since it is endothermic. In addition, condition of char preparation is an important factor affecting char properties. Char prepared from slow pyrolysis at 750 C gave higher carbon conversion and gaseous products (CO, CH4 and CO2) more than the one from fast pyrolysis. Nevertheless high heating value of the gaseous products produced by slow- pyrolyzed char at 750 C was found to have the highest heating value about 14.76 MJ/Nm3. Effect of char to biomass ratio showed that increase of this ratio from 0.5 to 2 gave higher carbon conversion and the composition of CO, CH4 and CO2 in the produced gas was also increased. This can emphasize that char acts as a catalyst for tar cracking, hydrogasification and CO hydrogenation.