Gas and tar formation characteristics in gasification for biomass materials

Abstract

Gas and tar formation characteristics from the gasification of woody biomass were investigated by experimentation to obtain detailed and specific insights into the proper operation of the gasification process. We focused on the determination of the relationship between the gasification operation parameters and the composition of the resulting gases and catalyst application on tar formation and suppression. The generation of combustible gases, including hydrogen (H₂), by biomass gasification increased with increasing temperature and the addition of water vapor. A sufficiently high temperature (850 °C or higher) was required to effectively suppress tar production without the use of a catalyst. However, the choice of higher temperatures should be carefully considered in terms of energy loss. The nickel (Ni) mesoporous catalyst exhibited the highest catalytic effect on gasification and the catalyst application resulted in more than 50 %(V/V) H₂ composition in the product gas. The application of combustion ash and dolomite resulted in the second highest H₂ production effect after Ni catalyst. The reduction of tar formation by Ni catalyst reached 84 % at 750 °C. The relationships between various factors such as temperature and the proportion of polycyclic aromatic hydrocarbon (PAH) compounds in tar were examined. The PAH ratio in tar was shown to be a simple and clear indicator of the effect of temperature and catalyst application on tar reduction.