Characterization of Sodium-Based Sorbents for CO_2 Capture from Flue Gas

摘要

The purpose of this work is to identify potential materials for CO_2 capture sorbent compositions and to make dry regenerable sorbents by spray drying technique to obtain high mechanical strength and chemical reactivity. Much attention has been recently directed towards cost-effective and energy-efficient process - anthropogenic CO_2 sequestration techniques aimed at capturing CO_2 released from fossil fuel-fired power plants. One of the advanced concepts for low-cost capturing CO_2 is an absorption process with dry regenerable sorbents. This report described mechanical strength and CO_2 sorption capacity of spray-dried sodium-based CO_2 sorbents applicable to the flue gas conditions. During the sorbent screening with Na_2CO_3 as active CO_2 sorption components, the five formulations containing 20-50 wt percent active component were spray-dried in the 2-15 kg scale based on solid raw materials. The TGA chemical reactivities of sorbents were also investigated along with pure Na_2CO_3 and NaHCO_3 in the temperature range of 50-70 deg C with simulated flue gas containing 10 vol percent H_2O and 14.4 vol percent CO_2. The CO_2 sorption capacities of sorbents are 9-14 g CO_2/100 g sorbent (or wt percent) with the maximum sorbent utilization of 180 percent. The sorption capacity of some sorbents is comparable to or better than that of pure Na_2CO_3 and NaHCO_3 sorbents. The chemical reactivities of sorbent are very sensitive to calcination temperature of green body, water sorption capacity, and carbonation temperature. The sorbent calcined at 500 deg C showed the best chemical reactivity at 50 deg C. The attrition indices of some sorbents by ASTM D 5757 reached below 60 percent and also depended on the calcination temperature. It is concluded that dry regenerable spray-dried sodium-based sorbent could be a viable option to capture CO_2 from flue gas condition.