Abstract
Cellulose, one of the important components of biomass, was gasified in supercritical water to produce hydrogen-rich gas in an autoclave which was operated batch-wise under high-pressure. KCO and Ca(OH) were selected as the catalysts (or promoters). The temperature was kept between 450°C and 500°C while pressure was maintained at 24–26 MPa. The reaction time was 20 min. Experimental results showed that the two catalysts had good catalytic effect and optimum amounts were observed for each catalyst. When 0.2 g KCO was added, the hydrogen yield could reach 9.456 molkg which was two times of the H amount produced without catalyst. When 1.6 g Ca(OH) was added, the H yield was 8.265 molkg which is lower than that obtained using KCO as catalyst but is still 1.7 times that achieved without catalyst. Comparing with the results obtained using KCO or Ca(OH) alone, the use of a combination of KCO and Ca(OH) could increase the H yield by up to 2.5 times that without catalyst and 25% and 45% more than that obtained using KCO and Ca(OH) alone, respectively. It was found that methane was the dominant product at relatively low temperature. When the temperature was increased, the methane reacts with water and is converted to hydrogen and carbon dioxide.
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