Cyclic CO₂ capture of carbide slag modified by pyroligneous acid in calcium looping cycles

Abstract

Carbide slag is a kind of industrial waste obtained in the production of acetylene that is the raw material of polyvinyl chloride in chlor-alkali plants. The carbide slag modified by pyroligneous acid was proposed as a CO 2 sorbent at high temperature. The CO 2 capture capacity of the carbide slag modified by pyroligneous acid in the calcium looping cycles was investigated in a thermogravimetric analyzer and a dual fixed-bed reactor. The modified carbide slag exhibits better CO 2 capture capacity than the carbide slag. The modified carbide slag releases the organic substances whose combustion leads to a drop in CO 2 capture capacity. The pre-calcination treatment of the modified carbide slag at 400°C before the first calcination was employed to avoid the combustion of the organic substances. The pre-calcined modified carbide slag exhibits higher carbonation conversions, compared with the modified carbide slag without pre-calcination treatment. The pre-calcined modified carbide slag achieves higher carbonation conversions at 950°C and shows larger surface area and pore volume than the modified carbide slag in the cycles. It indicates that combining the modification by pyroligneous acid with the pre-calcination treatment apparently improves cyclic CO 2 capture capacity of the carbide slag in the multiple cycles.