U. P. M. Ashik

This study aimed to investigate the effect of carbon derived from glucose (C) on the physicochemical characteristics and catalytic activity of Ni, supported over SiO₂, ZSM-5, and TiO₂ in methane dry reforming. Among the Ni catalysts without C, Ni/SiO₂ exhibited the highest CH₄-CO₂ conversion and stability at all experimented temperatures. On the other hand, the C-incorporated catalysts prepared by glucose impregnation, followed by pyrolysis, showed dissimilar performances. C improved the stability of Ni/SiO₂ in the reforming at 650 °C and 750 °C and increased the CH₄ and CO₂ conversion to the level close to the thermodynamic equilibrium at 850 °C. However, this element did not substantially affect the activity of Ni/ZSM-5 and exerted a retarding effect on Ni/TiO₂. Characterizations with H₂-TPD, XRD, EXAFS, and STEM-EDS revealed that the different influences of C by the supports were attributed to the extent of metal dispersion and metal-support interaction.

Sequential coal briquetting and carbonization was applied to preparation of cokes from 9 non- or slightly caking coals with carbon contents (fC) of 67–85 wt%-daf. Coal pulverization to sizes of <106 µm and briquetting at 40°C enabled to prepare cokes with tensile strength (σ) over 10 MPa from 4 coals with fC of 82–85 or 67 wt%-daf. Then, by introducing fine pulverization to sizes of < 10 µm before the briquetting, 7 coals were converted successfully into cokes with σ = 11–25 MPa. Increasing the briquetting temperature to 240°C further increased σ to 19–35 MPa for all the 9 coals. It was thus demonstrated that the hot briquetting of finely pulverized coal was a method to prepare high strength coke regardless of the rank of parent coal. Cokes were also prepared from 14 binary coal blends. All the cokes prepared by applying the fine pulverization and hot briquetting had σ of 20–35 MPa, which agreed well with that calculated by weighted average of those from the component coals. On the other hand, positive and also negative synergistic effects of blending occurred when blends were briquetted at 40°C. Characteristics of bonding/coalescence among particles of different types of coals were responsible for such synergies.