Energy & Fuels, Vol.18, No.1, 251-256, 2004
Thermochemical generation of hydrogen from switchgrass
Thermochemical production of hydrogen is anticipated to be one of the most cost-effective means of producing hydrogen fuel. Switchgrass, a warm-season, perennial grass that is native to many areas of the United States, is an attractive feedstock for this purpose. The goal of this study is to convert switchgrass into hydrogen by the sequential processes of thermal gasification in a fluidized bed reactor, catalytic steam reforming of tars, and the use of water-gas shift catalysts to enhance the concentration of hydrogen. Air-blown gasification of switchgrass produced relatively low concentrations of hydrogen (about 8.5 vol-%). Steam reforming of tars and light hydrocarbons and reacting steam with carbon monoxide via the water-gas shift reaction increased the hydrogen content in the producer gas to 27.1 vol-%. The catalysts used in the steam reformer and water-gas shift reactors were examined at the end of the trials using X-ray photoelectron spectroscopy and BET analysis. These analyses showed changes in pore size and pore size distribution. Although not evident during the tests, eventual degradation of the catalysts can be expected as the result of deposition of coke, sulfur, and chlorine on the catalysts.