Fe-doped carbon catalysts were prepared from Shenmu sub-bituminous coal with addition of Fe­(NO3)3 by KOH activation, and used for catalytic methane decomposition. The effects of Fe amount and carbonization/activation temperature on the structure and catalytic performance of resultant catalysts were investigated. The results showed that ferric nitrate mixed with coal could be directly reduced to Fe metal during the carbonization/activation process without a hydrogen reduction process. Methane conversion over Fe-doped carbon catalysts significantly increases as the amount of added Fe increases. When the amount of Fe added is 30 wt %, the resultant Fe-doped carbon has the highest catalytic activity and methane conversion increases from initial 20% to 58% at the reaction time of 9 h. Low carbonization temperature leads to high initial conversion. The active sites of the Fe-doped carbon catalysts prepared at higher temperature mainly come from metal Fe particles, thus leading to lower initial catalytic activity but better stability.

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Ash fusion temperatures (AFTs) are important parameters influencing the stable operation of industrial entrained-flow gasifier. It is well known that the separate addition of CaO and MgO can ameliorate the ash fusibility. However, the synergistic effect of CaO and MgO on the ash melting characteristics is still unclear. For this sake, the ash fusion temperature analyzer (AFTA), X-ray diffraction (XRD), Raman spectrum, and FactSage thermodynamics software were applied to investigate the ash fusion behavior with various CaO/MgO mass ratios in this work. It showed that as the CaO/MgO mass ratio increased, the AFTs decreased first and then increased slightly with reaching the minimum at the CaO/MgO mass ratio of 8:2. When the CaO/MgO mass ratio was low, the formation of spinel with stable lattice was the main reason for the high AFTs. As the CaO/MgO mass ratio increased, the formation of low-melting-point feldspar minerals such as anorthite and melilite resulted in the AFT reduction. As well, when the mass ratio of CaO/MgO reached 8:2, the relatively high amorphous content led to the lowest AFTs. Additionally, the variation of the liquid slag content with the increase in temperature was analyzed, and the melting process was divided into the primary fusion stage and the free-liquid stage.

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