Catalytic effects of industrial waste alkali liquor in pressurized steam gasification of coal char

The catalytic activity of an industrial waste alkali liquor for coal gasification was identified, and the WJT coal impregnated of black liquor (BL) was gasified with steam under the temperatures 700−750 ℃ at high pressure. The effects of major process variables such as catalyst loading and temperature were investigated, which was also in comparison with Na₂CO₃ (SC). The results show that with an increase in the catalyst loading the gasification rate and the carbon conversion rise first and then drop, having the highest values at a 3% of Na loading and being higher than that with SC. Meanwhile, the catalytic activity increases with increasing the gasification temperature. The influence of BL addition on the BET surface area and pore volume was studied by an isothermal N₂ adsorption-desorption experiment. It is indicated that the BET surface area and pore volume increase at first and then decrease with an increase in the BL loading. The increase of surface area and pore volume provide more gasification active sites and thus promote the reactivity of char gasification. However, the blocking of pores in coal char caused by excess catalyst loading can result in a decrease in the surface area and pore volume and thus the declining of the gasification rate.