(333e) Room Temperature Co2 Removal over K2co3 on Porous Microfibrous Media

Authors: 
Sathitsuksanoh, N., Auburn University


A large amount of CO2 is generated during the reformation of logistical fuels (i.e. JP8), which has to be reduced prior to entering the PEMFCs due to the possibility of side reactions, such as COS formation and reverse water-gas shift. Thus, the development of a new material for a cost-effective filtration with high CO2 adsorption capacity is needed to ensure the activity maintenance of various processes. Supported K2CO3 sorbents on SiO2, Al2O3, and activated carbon particulates (ACP) of 150-250 micron diameter are prepared by pseudo-incipient wetness impregnation from K2CO3 precursors. The result suggests that the CO2 adsorption capacity depends on the nature of supported materials and the moisture content remained in the sorbents after drying at 100oC. The prepared sorbents were then tested in a packed bed column (1.5 cm ID) at room temperature in the presence of water (87% RH). The CO2 adsorption capacity decreases in a sequence as follows: Al2O3>ACP>SiO2. The K2CO3/SiO2 shows a decrease in CO2 adsorption capacity due to an interaction between SiO2 and K2CO3. The K2CO3/ Al2O3 sorbents yield the highest CO2 adsorption capacity of 0.09 g CO2/ total gram of dry sorbent. The differential scanning calorimetry (DSC) was then used in order to determine the thermal stability and regeneration temperature of the sorbents. The result shows that the K2CO3/Al2O3 sorbent capacity decreases during the first few regeneration cycles due to the formation of inactive phase of potassium aluminum carbonate. In the case of K2CO3/ACP, the regeneration recovers 85% of the initial CO2 adsorption capacity. A microfibrous entrapped K2CO3/ACP sorbents is developed for CO2 removal from wet gases. A microfibrous carrier consisting of 4 and 8 um (dia.) metal fibers is utilized to entrap 150-250 um (dia.) activated carbon particulates (ACP). The nano-dispersed nature of the K2CO3 combined with the use of small support particulates promotes high K2CO3 utilization, high contacting efficiency, and high accessibility of K2CO3. The nano-dispersed nature of K2CO3 combined with the use of small support particulates promotes high K2CO3 utilization, high contacting efficiency, and high accessibility of K2CO3 while minimizing the pressure drop. The use of microfibrous entrapped sorbents provides reduced external mass transfer resistance, enhanced adsorption rate, and reduction of heat required for regeneration. This novel adsorbent allows reduction in overall system weight and volume for continuous removal of trace CO2 from gas streams with high levels of relative humidity, namely a fuel processor stream.