Enhanced Tolerance to Flue Gas Contaminants on Carbon Dioxide Capture Using Amine-Functionalized Multiwalled Carbon Nanotubes

Abstract

The adsorption behavior of adsorbents for carbon dioxide can be significantly affected by flue gas contaminants. In this work, we examined the performance of tetraethylenepentamine (TEPA) impregnated industrial grade multiwalled carbon nanotubes (IG-MWCNTs) in trace amounts of flue gas contaminants such as H2O, NO, and SO2. It was observed that H2O and NO had a minimal impact on CO2 adsorption capacity, while the effect of SO2 on CO2 adsorption was influenced by adsorption temperature and SO2 concentration. Compared with silica-based adsorbents, i.e., TEPA-impregnated MCM-41, amine-functionalized IG-MWCNTs show significantly better tolerance to H2O and SO2. In addition, we examined the variation of CO2 adsorption with and without SO2 with various experimental methods (N2 adsorption/desorption isotherms, X-ray diffraction, and differential scanning calorimetry analysis) and molecular simulation. Experimental results show that irreversible sulfate/sulphite species deposited into the adsorbent contributes to the decrease on CO2 adsorption, while the results from simulation studies reveal that the enthalpy difference between the isolated TEPA with SO2 and TEPA···SO2 (ΔH(TEPA···SO2)) is larger than that of CO2 (ΔH(TEPA···CO2)), indicating that SO2 has a stronger reaction activity with TEPA than CO2. The increase of the ratio of ΔH(TEPA···SO2)/ΔH(TEPA···CO2) with increasing temperature illustrates that the difference of CO2 adsorption capacity with and without SO2 increases with elevated temperatures.

SOx/NOx Removal from Flue Gas Streams by Solid Adsorbents: A Review of Current Challenges and Future Directions

“…76 The adsorbents exhibited a dramatic CO 2 capacity loss at 60 °C in the presence of 1000 ppm SO 2 . The reduction of CO 2 capacity is likely due to accumulation of stable sulfite/sulfate compounds on the adsorbent surface, which occupied the active adsorption sites and likely blocked the diffusion path of CO 2 .…”

Effect of Hg on CO2 capture by solid sorbents in the presence of acid gases

“…It has been reported before that secondary amines adsorb more SO 2 than primary and tertiary amines with comparable amine loading [49,50]. In other words, the strong reaction activity of SO 2 with TEPA [51] and the possible formation of sulphates and/or sulphites on the surface of the adsorbents may compete for the same adsorption sites as CO 2 [19][20][21]48,49], decreasing adsorbents adsorption capacity. Some authors have also demonstrated a higher HCl adsorption on sorbents treated with ammonia over untreated materials [52].…”

A review of N-functionalized solid adsorbents for post-combustion CO2 capture

“…Carbon-based materials vary from the cheap, widely used activated carbon (AC) to the state-of-the-art carbon nanotube (CNT), and can all be used for gas adsorption and separation due to their immense surface areas (Table 3). Amine-loaded mesoporous carbons [144], carbon nanotubes [149,158], and some ACs [147] all show similar properties to amine-loaded silica adsorbents due to their mesoporous nature.…”