Breakthrough experiments of CO2 capture using SAPO-35

https://doi.org/10.1039/D2SC00702A

“The breakthrough experiments of SAPO-35_0.14 were performed by utilizing binary CO₂/N₂ (20 : 80 v/v) gas mixtures at 298 K and atmospheric pressure in a fixed bed continuous separation system (Fig. S10†), imitating the industrial process conditions of flue gas.^1b,22 The corresponding breakthrough curves are displayed in Fig. 4. As shown in Fig. 4a, when the CO₂/N₂ mixture at a rate of 3.0 mL min⁻¹ was fed into 5.80 g of SAPO-35_0.14 adsorbent, N₂ eluted first through the column without CO₂ breakthrough. However, the outlet concentration of CO₂ was below the detection limit of the FID until 800 seconds because CO₂ adsorbed on SAPO-35_0.14. When the pores of SAPO-35_0.14 progressively filled with CO₂, CO₂ began to break through the column and diluted the N₂. Hence, dynamic gas separation was achieved by selective CO₂ adsorption to SAPO-35_0.14. In line with equilibrium isotherms, the higher affinity of SAPO-35_0.14 for CO₂ over N₂ led to adequately long differences in breakthrough times. SAPO-35_0.14 is highly selective under dynamic conditions, hence we carried out multiple consecutive tests (Fig. 4b), and the results showed that the adsorption capacity of SAPO-35_0.14 fully recovered to its initial capacity, proving that SAPO-35_0.14 has excellent regeneration. In addition, for CO₂ capture from flue gas, it is important to evaluate the capacity and selectivity of adsorbents in the presence of water. We performed multiple consecutive breakthrough experiments of SAPO-35_0.14 with a relative humidity of ∼40% by using a vapor generator at 298 K and 1 bar. The corresponding breakthrough curves are displayed in Fig. S11.† SAPO-35_0.14 well maintains its adsorption and separation abilities and regeneration in the presence of water, indicating the potential of the adsorbent for selective CO₂ adsorption in practical application.”

“Fig. 4 (a) Experimental binary breakthrough curves for a gas mixture of CO₂/N₂ (20 : 80 v/v) on SAPO-35_0.14 at 298 K and 100 kPa with a total gas flow rate of 3 mL min⁻¹. C_t and C₀ denote outlet and inlet concentrations, respectively. (b) Multiple consecutive cycles of breakthrough curves for SAPO-35_0.14 with an adsorption/desorption gas flow rate of 3 mL min⁻¹ (CO₂/N₂ 20 : 80 v/v for adsorption and He for desorption) at 298 K and 100 kPa.”