Energy Sources Part A-recovery Utilization and Environmental Effects, Vol.35, No.22, 2149-2155, 2013
The Hydrothermal Liquefaction of Rice Husk to Bio-crude Using Metallic Oxide Catalysts
Hydrothermal liquefaction of rice husk was investigated in a 10-ml stainless steel micro-reactor. Without catalyst, the bio-crude yields are in the range of 11.8-23.8 wt%, depending on temperature, reaction time, and water/rice husk mass ratio. With catalysts, the bio-crude yields are obviously increased and the highest bio-crude yield of 32.5 wt% is obtained with La2O3 catalyst at 300 degrees C for 10 min and a water/rice husk mass ratio of 5. The elemental analysis shows that the oxygen contents of bio-crude are significantly decreased by La2O3 and Dy2O3 catalysts, respectively. The highest higher heating value (31.78 MJ/kg) of bio-crude is obtained with La2O3 catalyst, which is obviously higher than that of the raw material (16.19 MJ/kg). Energy balance results show that La2O3 and Dy2O3 catalysts have a beneficial effect on energy recovery and energy consumption ratio. Gas chromatography-mass spectrometry and Fourier transform-infrared analysis show that La2O3 and Dy2O3 decrease the contents of phenols and acids and promote the formation of hydrocarbon (alkenes and alkynes) and esters.