Experimental investigation on hydrogen production by gasification of ligntn in supercritical water

Gasification of lignin in supercritical water was studied using a continuous operation tube flow reactor. At the first stage, the feedstock of lignin was gasified under a pressure range from 15.0 MPa to 27.5 MPa and a tube wall temperature range from 500°C to 650°C and with concentration of solution from 1% to 3% with a reactant flowrate from 4.7 mL/min to 7.5 mL/min. Then, the continuous operation tube flow reactor was reconstructed, the gasification effect of lignin at high wall temperature from 700°C to 775°C with high concentration was examined. The influence of the main parameters (pressure, temperature, mass flowrate and concentration of solution) on lignin gasification was investigated. It shows high temperature favor lignin gasification efficiency and H₂ yield, result in the production of a hydrogen-rich gas; high pressure promote H₂ yield also, and promote medianation. The efficiency of lignin gasification and H₂ yield drop rapidly with increase of concentration of solution. Long residence time favor H₂ yield, but has litde effect on gas fraction. It was also discovered that lignin has low gasification efficiency than cellulose. To get high efficiency of lignin gasification, the tube wall temperature must be set at above 700°C.