Simultaneous CO2/HCl removal using carbide slag in repetitive adsorption/desorption cycles

In this work, a method to simultaneously remove CO2/HCl of carbide slag in adsorption/desorption cycles was proposed. The effects of cycle number, adsorption temperature, desorption temperature, HCl fraction and sorbent particle size on cyclic CO2/HCl adsorption behavior of carbide slag in the adsorption/desorption cycles were investigated. The main products after CO2/HCl adsorption by carbide slag were CaCO3 and CaClOH in the first 10 adsorption/desorption cycles. After the desorption process, CaCO3 was completely decomposed into CaO and CO2, while CaClOH was stable. The presence of HCl increased the CO2 adsorption capacity of carbide slag in the first few cycles, because HCl could break the compact CaCO3 product layer and it then enhanced CO2 diffusion through the layer. However, this stimulative effect gradually disappeared as the cycles proceed. The presence of 0.01-0.03% HCl showed positive effect during the first 10 cycles and a decreased CO2 capacity was observed with HCl fraction above 0.03%. At the same time, both adsorption and desorption temperatures exhibited significant influence on CO2/HCl adsorption capacity of carbide slag. The carbide slag with smaller particles leads to higher cyclic CO2 adsorption capacity in the presence of HCl. (C) 2014 Elsevier Ltd. All rights reserved.