Hydrogen and synthesis gas production from activated carbon and steam via reusing carbon dioxide

A method of producing hydrogen and syngas from the interaction of activated carbon, steam and carbon dioxide is conducted in the present study, where the interaction combines the solution loss reaction and steam gasification reaction. Two important parameters of reaction temperature and steam/CO₂ molar ratio (i.e. S/C ratio) in the ranges of 850-950°C and 0-1 are taken into account. The experiments indicate that the CO₂ conversion from the reaction in the absence of steam is around 50% at 950°C. Increasing S/C ratio increases the H₂ yield, but the CO₂ conversion decreases, revealing the competing roles played by steam and CO₂ with the reaction of activated carbon. With the conditions of S/C=0.5 and 950°C, the CO₂ conversion drops to around 30% and the H₂ yield is around 0.45mol (mol H₂O)^-1. Furthermore, from the analyses of SEM and BET, the results indicate that an increase in S/C ratio intensifies the number of pores on the surface of the activated carbon, and its surface area is increased from 833.13m²g^-1 in the raw material to 1100-1450m²g^-1 in the reacted activated carbon. It follows that the porous structure of the activated carbon has a significant influence on syngas formation. In summary, the novel method simultaneously possesses the merits of low cost of raw material, reusing CO₂ and generating hydrogen and syngas.