Hydrogen from Biomass via Air-Steam Gasification

The air-steam gasification would be one of the practical conversion technologies among biomass gasification (Li et al., 2004). In general, the gasification tempera- 

Partial oxidation of hydrocarbons is the exothermic reaction with oxygen and steam. The amonnts of oxygen and water vapor are controlled so that the reaction proceeds without the need for external energy. An example reaction for this process is  

The carbon dioxide from the gas mixture is removed by washing with water and the carbon monoxide is removed by absorption or membrane separation. 

The percentage of hydrogen in gaseous products from the samples of hazelnut shell, tea waste and spruce wood increased from 43.3 to 56.9%, 41.0 to 53.9% and 40.0 to 51.5% by volume, respectively, while the final air-steam gasification temperature was increased from 900 to 1250 K (Figs. 6.14 to 6.16). 

Comparison of pyrolysis and air-steam gasification shows that the yield of hydrogen from biomass is generally higher by air-steam gasification than that by pyrolysis, because with interaction of water and char from decomposition of biomass intermediate products are formed, which leads to more hydrogen-rich gas yield by the steam reforming. 

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