Physically mixed black liquor as a catalytic additive for pressurised steam gasification of different rank bituminous coals

Abstract

Increasing prices and limited availability of oil and natural gas resulted in the popularity of gasification-based coal chemical production. However, the problems with low fuel conversion and high CO2 emission are hindering its competitiveness with other fossil fuels. Blending black liquor from the pulp and paper industry with coal could potentially mitigate the problem due to its carbon neutrality and high catalyst content, but their performance needs extensive analysis. Therefore, three bituminous coals with variable petrographic composition and ash content were physically mixed with various loadings of black liquor (5–20%wt) and gasified under pressurised steam at 800–1000 °C. The parameters such as syngas production and carbon conversion were measured and kinetic parameters were calculated with Random Pore Model, Grain Model and Isoconversional Model. The results have shown that the presence of black liquor has equally increased the gasification performance of each coal despite their different reactivity. For most reactive samples with an addition of 10%wt. Black liquor, the syngas yield had grown by up to 61%, carbon conversion increased by up to 23% and energies of activation reached as low as 39 kJ⋅mol-1, which makes the approach highly competitive against other catalytic impregnation methods.