Hokkaido University · Engineering
Professor Naoto Tsubouchi's research lab specializes in coal pyrolysis chemistry, with a focus on understanding the fundamental mechanisms of volatile release, carbon structure development, and the roles of inherent and added catalysts—particularly calcium and iron-based minerals—in influencing nitrogen, chlorine, and oxygen species evolution during thermal conversion. The lab employs advanced analytical techniques such as XPS, online gas monitoring, and XRD to investigate the behavior of heteroatoms (N, Cl, O) and catalytic effects in low-rank coals and carbonized materials. Their work also extends to applications in clean coal technology, including hot gas cleanup for IGCC systems and the development of catalytic materials for ammonia decomposition.
Figures are computed from collected data and may differ slightly.
Pyrolysis of five coals has been carried out at 1000−1350 °C and different heating rates with fixed-bed and free-fall reactors to examine carbon structures in devolatilized chars. The X-ray diffraction measurements show the formation of crystallized carbon with turbostratic structures, depending strongly on coal type and severity of pyrolysis. The proportion of the carbon with low rank coals decreases by demineralization with acid washing but contrarily increases by subsequent addition of Ca2+ i
The effects of Ca catalysts on nitrogen release during heat treatment of polyacrylonitrile-derived carbon and pyrolysis of low rank coals have been studied with a fixed bed quartz reactor in a stream of high purity He. In the temperature-programmed treatment at 10 °C/min of the carbon with 3 wt % Ca, the Ca promotes N2 formation at 850−1000 °C and the catalytic effect is larger at a higher temperature. When a low rank coal, after demineralization and subsequent addition of 3 wt % Ca, is pyrolyze
In order to understand chlorine chemistry in coal pyrolysis, the dynamics of HCl evolution and changes in chlorine functional forms during temperature-programmed pyrolysis of eight Argonne premium coal samples have been examined with an online HCl-monitoring technique and by the Cl 2p X-ray photoelectron spectroscopy (XPS) method. The rate profiles of HCl evolved show at least three distinct peaks at 390, 520, and 600 °C, and the presence of these peaks depends strongly on the type of coal. The
The evolution of HCl during pyrolysis of 16 coals with different ranks at a heating rate of 10 °C/min has been studied with an online monitoring method. Approximately 50%−95% of total chlorine is converted to HCl up to 800 °C, and the remainder is mostly retained in the char, which leads to a strong reverse correlation between the two. As the sum of Na and Ca naturally present in coal increases, the amount of HCl tends to decrease. The temperature dependence of the rate of HCl evolved differs wi
Catalytic decomposition of 2000 ppm NH 3 in different atmospheres with an Australian α-FeOOH-rich limonite ore at 750–950 °C under a high space velocity of 45000 h −1 has been studied with a cylindrical quartz reactor to develop a novel hot gas cleanup method of removing NH 3 from fuel gas produced in an air-blown coal gasification process for an integrated gasification combined cycle (IGCC) technology. The limonite shows very high catalytic activity for the decomposition of NH 3 diluted with in
The evolution of gaseous oxygen-containing species (CO, CO2, and H2O) during carbonization of 10 types of caking coals has been investigated mainly using a fixed-bed quartz reactor to reveal the influence of inherent oxygen species on the Gieseler fluidity of the coal particles. The heating rate and temperature were 3 °C/min and 1000 °C, respectively. CO evolution apparently started after 350 °C, and the rate profile for CO evolved showed the main or shoulder peak at about 650 °C in many cases.
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