CATALYTIC GASIFICATION OF LIGNITE WITH KOH IN SUPERCRITICAL WATER

摘要

Supercritical water gasification of lignite with KOH was investigated in a batch autoclave on a wide range of conditions, that is residence time (5-30 min), mass ratio of H2O to lignite (0.5-10), temperature (400-600°C) and mass ratio of KOH to lignite (0-20%). Although lignite is difficult to be gasified in supercritical water, the results indicated that gasification efficiency about 47% was achieved at 30 min, 550°C with 10% KOH. Higher mass ratio of H2O to lignite and temperature can lead to higher gas yields and GE. It is also observed that the solid residue was dispersed at low feed concentration and consolidated at high concentration. Besides KOH's improvement of water-gas shift reaction, in this case, it is also observed that KOH also enhances the gasification of aromatics of lignite in supercritical water, which leads to higher gasification efficiency of lignite.