Effect of compression molding of CaCO powder on the kinetics of CO capture towards sustainable CO capture and sequestration cycle.

Reducing CO emissions from industrial sectors and motor vehicles is currently receiving much attention. There are different strategies for CO capture, one of which is using calcium oxide (CaO). In our proposed carbon dioxide cycle, limestone is first calcined to get CaO, which is then used to capture CO by converting it to CaCO. Next, the released CO could be converted to different organic matter by different sequestration techniques. For this purpose, CaCO discs have been prepared by compression molding to investigate the effect of sintering temperature on the mechanical and chemical properties of CaO carbonation reaction. The aim of this work is to fill the knowledge gap for the effect of the contact profile between CO gas and CaO disc, particularly the effect of reducing the void fraction of CaO on the rate of carbonation reaction. It was found that the flexural strength of the CaO discs was influenced by several factors, such as the calcination temperature, duration of calcination, and pressing pressure. The carbonation step indicated that both CO and HO are reacting with CaO simultaneously and progressively, with the progressive reaction of HO and CO being a favorable route. The carbonation process happens as a surface reaction-controlled process followed by a slower internal diffusion-controlled process. Additionally, a kinetic study of the competing reactions indicated that two factors are controlling the process: diffusion of gases through the pores and then the reaction rate. Furthermore, our data showed that the CO uptake rate was 1352.34 mg/g CaO, indicating that 566.34 mg of CO was adsorbed inside the pores of the CaO disc. Based on these results, we propose a new mechanism of the sequence of the competing reactions. In summary, the CaO discs revealed a significant removal of CO from stack gases, which will be suitable for removing CO from exhaust gases generated by industrial processes and other sources of emissions such as vehicles and ships.