No.2-24 Effects of mechanical pressure on the char yield during carbonization of biomass

抄録

Biomass waste is a renewable sources and its effective utilization is indispensable, particularly in Thailand, where massive amounts of biomass wastes are generated. Moreover, charcoal from biomass wastes is regarded as candidates for low priced raw materials for activated carbons. However, the yield of charcoal from biomass wastes is low in general. So, it is essential to develop a method to increase the yield of charcoal during the carbonization of biomass wastes. In this study, Leucaena, which is a woody biomass, was pressurized at around 500 MPa at room temperature, called cold press in this work, to prepare biomass pellet. Leucaena was also pre-carbonized under the mechanical pressure of around 10 MPa at the temperature range of 25 °C to around 250 °C, called hot press in this work, to prepare densified semi-chars. Then, both cold press pellets and hot press semi-chars were subjected to carbonization at around 900 °C. It was found that the char yield of cold press pellets prepared from leucaena was 21.9 wt%, while the char yield of powder leucaena was only 17.0 wt%. On the other hand, the char yield of hot press semi-char prepared from leucaena was surprisingly increased to 27.7 wt%. From the detail analyses of gas formation during the carbonization, it was found that the dehydration reaction was accelerated by hot press carbonization and the mechanical pressure suppresses the evolution of tar components. Therefore, the mechanical pressure is judged to be effective to increase the char yield through the carbonization of biomass.