โ Scribed by Tsutomu Suzuki; Junichi Iwasaki; Hidetaka Konno; Tetsuo Yamada
No coin nor oath required. For personal study only.
Iron-loaded raw and demineralized birch chars were hydrogasified in a thermobalance to examine the influence of ash removal on their reactivities at 700 and 800ยฐC. Demineralization was so effective in enhancing the reactivity in the low-temperature region that 4 wt% iron loading gave a conversion of 90 wt% at 700ยฐC. The increased catalytic effect of iron in the absence of wood ash can be explained by the formation of finer metallic iron particles during the gasification. The loss in the catalytic activity of iron due to calcium and silica as the main ash components was investigated by X-ray diffraction and X-ray photoelectron spectroscopy. It is proposed that calcium and silica form calcium iron oxides and iron silicates during carbonization, inhibiting the reduction of iron oxide to metal with catalytic activity at low temperatures. However, the ash plays quite a different role at higher temperatures. Its presence was beneficial for the formation of catalytically active metallic iron, whereas demineralized char rapidly lost reactivity in this region, owing to accelerated sintering of metallic iron particles.
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