CO₂ Capture by a K₂CO₃–Carbon Composite under Moist Conditions

Abstract

Potassium carbonate (K2CO3) is recognized as a potential candidate for CO2 capture by flue gas under moist conditions because of its high sorption capacity and low cost. However, undesirable effects and characteristics that are associated with the desorption process, such as the slow reaction rate and the high regeneration temperature, lead to high energy costs and thus hinder its application. To improve the CO2 capture properties of K2CO3 under moist conditions, we investigated in this study the reaction rate and the regeneration temperature of a K2CO3–carbon composite (KC-CC), which was prepared from terephthalic acid and KOH. The successful synthesis of KC-CC was confirmed by the X-ray diffraction and Raman spectrometry results, while the CO2 capture characteristics of KC-CC under moist conditions were examined by thermogravimetric analysis. The CO2 capture experiment was repeated twice. The CO2 capture by KC-CC was faster than that by bulk K2CO3, while after the CO2 capture, the regeneration proceeded at lower temperatures compared to bulk KHCO3. Moreover, after a 10-cycle repetition of the CO2 capture experiment, KC-CC exhibited a stable performance. Thus, compared to bulk K2CO3, KC-CC could efficiently capture CO2 at an increased reaction rate and a lower regeneration temperature. This may be due to the nanostructural properties of KC-CC, which were also indicated by the results of XRD analysis.

Shedding Light on Solid Sorbents: Evaluation of Supported Potassium Carbonate Particle Size and Its Effect on CO2 Capture from Air

“…This means that for K 2 CO 3 with different sizes, diffusion of CO 2 and water into K 2 CO 3 is limited to a certain penetration depth, and further diffusion is not possible. Nasiman and Kanoh reported CO 2 capture from air under TGA conditions by 60 wt % K 2 CO 3 in K 2 CO 3 –carbon nanocomposites. From the XRD peak broadening, they estimated a size of approximately 20 nm for K 2 CO 3 particles.…”

“…This (internal) diffusion limitation was also reported for other sorbents, such as Li 2 CO 3 /K 2 CO 3 and CaO. , Therefore, the size of the K 2 CO 3 particles must be an important factor in determining the capacity and kinetics of the sorbent during CO 2 capture. It was suggested previously that nanoscale K 2 CO 3 particles have a higher capacity for the sorbent; ,− however, the size was not specified. The main reason for the lack of accurate size data is that no technique has been established to analyze K 2 CO 3 nanoparticles, especially when they are supported.…”

Activated carbon‐based composites for capturing CO2: a review

“…Similarly, alkali metal carbonate (K 2 CO 3 , Na 2 CO 3 , or Li 2 CO 3 ) can also be used for CO 2 absorption at low temperature due to the considerable S BET and low cost. 43,44 It has been reported that K 2 CO 3 supported on AC revealed better contact between adsorbent and CO 2 . [45][46][47] Lee et al [48][49][50] found that AC/K 2 CO 3 could be completely regenerated at 150°C.…”

Gas-Particle Flows in a Two-Stage Integrated Bubbling-Transport Fluidized Bed for CO2 Capture

“…Postcombustion CO 2 capture refers to capturing carbon dioxide (CO 2 ) from flue gases generated after combusting carbon-based fuels. It is one of the most promising technologies for carbon capture and storage (CCS). − By comparing with other technical routes of postcombustion CO 2 capture, the chemical adsorption process using low-temperature solid sorbents (i.e., alkali-based sorbents and solid amine sorbents − ) has gained great attention owing to the advantages of the low additional energy demand, lack of corrosion, and low secondary pollution …”