Steam Gasification of Thermally Extracted Ash-Free Coals: Reactivity Effects Due to Parent Raw Coals and Extraction Solvents

Utilization of coal is currently limited to coal-fired power plants and iron smelting, partly because of the incombustible ash in coal and the inability of existing technologies to modify its properties. This work investigates whether the gasification behavior of ash-free coals (AFCs) can be modified. Sixteen different AFCs were prepared using variously ranked coals (Eco, Cyprus, Drayton, and Hail Creek) and extraction solvents with different polarities (N-methyl-2-pyrrolidone, ethylenediamine, 1-methylnaphthalene, and tetralin). Next, the reactivities of the AFCs in steam gasification at 800 °C were tested, and the results are discussed taking into consideration their compositional differences. A combination of low-rank coals and polar solvents produces reactive AFCs that can be catalytically gasified under mild conditions. In contrast, AFCs extracted using nonpolar solvents are less reactive and possibly applicable as a carbon electrode precursor. In short, the properties of AFCs can be changed to some ...