Distribution of product gases from hydrogen generation of straw/CMC gasification in supercritical water

In order to look for a new technology for upgrading agriculture waste, hydrogen production from straw/carboxymethylcellulose (CMC) gasification in supercritical water (SCW) was investigated by minimum Gibbs free energy theory and experimental methods. The results show that the main product gases are hydrogen, carbon dioxide, and methane. There is very large difference in product gases distribution in different temperature range. In the undercritical water district (330~374°C), low supercriti cal water district (375~430°C) and high supercritical water district (≥430°C), hydrogen mole fraction increases from the lowest to the highest in the product gases. High temperature favors hydrogen generation, but the composition of product gases keeps constant when the temperature reaches a high value. Simultaneously, temperature and concentration of feedstock have larger effects than pressure on product gases. High heating value increases with concentration of feedstock, and decreases with temperature. It is proposed that the optimal temperature for hydrogen production from the mixture of 2% straw and 2% CMC gasification in SCW is 450~600°C.