Abstract

Sequestration of carbon dioxide in commercial calciumoxide packings with inclusions of nano-sized calciumoxide near ambient temperatures

Author(s): W.J.N.Fernando, A.L.Ahamad, Y.S.Neo

Calcium Oxide which has high sorption capacity for carbon dioxide and therefore has been used as a sorbent for carbon dioxide. In this study the effect of inclusion of nano calcium oxide in beds of micro-sized calcium oxide is studied.Nano calciumoxide of average pore size of 100nmismixed withmicro-sized calciumoxide (20 µm) and the mixture of calcium oxide was reacted with carbon dioxide at 30oC (near ambient temperature). It was observed that the rates of reaction decreased when particle size was reduced frommicro to nano. It was also observed that themicro particles had a steep drop in the rate with concentration of Carbon dioxide which could be attributed to surface reactions inmicro particles thus limiting approach of carbon dioxide to interior pores. The rates of absorption of 33.33%and 66.7%nano mixes were observed to be lower than 100%nano packings which could be attributed to filling up ofmicro pores of themicro-particle packings by nano particles requiring carbon dioxide to penetrate by diffusion through nano pores. These compositions were observed to represent approximately the voidage fraction (42%) of the micro-sized calciumcarbonate indicating low effectiveness factors and involvement of Knudsen diffusional effects.