chapter  6
40 Pages

Hydrogen Production by Supercritical Water Gasification

ByEmhemmed A.E.A. Youssef, George Nakhla, and Paul Charpentier

A uid heated to above the critical temperature and compressed to above the critical pressure is known as a supercritical uid. The phenomena and behavior of supercritical uids has been the subject of research right from the 1800s (Browne 1987). Two supercritical uids are of particular interest: carbon dioxide and water. Carbon dioxide has a low critical temperature of 31°C and a moderate critical pressure of 7.3 MPa. It is nonammable, nontoxic, and environmentally friendly. It is often used to replace toxic Freons and certain organic solvents. Furthermore, it is miscible with a variety of organic solvents and is readily recovered after processing.