Solid Sorbents

Surface of activated carbon can be functionalized with amine groups to enhance their capacity for CO 2 adsorption. Amine functionalized solid sorbents were prepared by anchoring two types of amine compounds, namely ethylenediamine (EDA) and 2-chloroethylamine hydrochloric acid (CEA) on the surface of palm shell based activated carbon (PSAC). Samples of PSAC were first oxidized by nitric acid using three different available setups to ensure about creation of a significant amount of oxygen containing groups on the surface. At the second stage, the best oxidized sample was modified by anchoring EDA and CEA on the surface to produce a superior CO 2 adsorbent. Several quantitative and qualitative methods were used to characterize the prepared samples: Nitrogen adsorption at 77K, proximate and ultimate analysis and temperature programmed desorption (TPD). Moreover, CO 2 adsorption study was carried out using CO 2 adsorption isothermal profile at 30°C and temperature-programmed (TP) CO 2 adsorption test. All modified samples had a lower surface area than the virgin PSAC. The best modified sample presented an increase of 45% in CO 2 capture capacity at 100°C. On the other hand, on the basis of unit surface area, CO 2 capture capacity of amine modified samples was much higher, compared to the parent sample. Furthermore, the modified samples showed a less dependency of their CO 2 capacity on temperature indicating chemisorption of the adsorbate on the PSAC surface. © 2011 IEEE.

http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6114246&tag=1

An electro balance reactor (thermo gravimetric analyzer) was used to study the reaction rate and achievable sorbent capacity as a function of carbonation temperature, carbonation gas composition, and calcination temperature and atmosphere. The first precursor (calcium carbonate) was calcined to calcium oxide and then converted at temperature ranges (550 m m o C ~ 750 o C) to calcium carbonate (CaCO 3 ) and final absorption capacity of calcium oxide at 700 o C is 65%. The second precursor (caustic soda) at temperature ranges (75 o C ~ 225 o C) was directly carbonated to sodium carbonate and found that 77% sodium carbonate hydrate and sodium carbonate 23% at 150 o C. The final absorption capacity is 25 % and also caustic soda was directly carbonated to sodium carbonate at 225 o C and final absorption capacity is 19.2 %. Lithium orthosilicate at temperature ranges (550 o C ~ 750 o C) was directly carbonated to lithium metasilicate and lithium carbonate and found that the final absorption capacity at 700 o C is 35%. Sorbent reproducibility and durability were studied in multi-cycle tests for calcium oxide and lithium orthosilicate. Electro balance tests show that lithium orthosilicate sample had better performance than calcium oxide sample for multi-cycle tests.