Fengsheng Su

Capture of CO2 from flue gas via multiwalled carbon nanotubes

Carbon nanotubes (CNTs) were modified by 3-aminopropyl-triethoxysilane (APTS) solution and were tested for its CO2 adsorption potential at multiple temperatures (20-100 degrees C). The physicochemical properties of CNTs were changed after the modification, which makes CNTs adsorb more CO2 gases. The adsorption capacities of CO2 via CNTs and CNTs(APTS) decreased with temperature indicating the exothermic nature of adsorption process and increased with water content in air at 0-7%. The mechanism of CO2 adsorption on CNTs and CNTs(APTS) appears mainly attributable to physical force regardless of temperature change, which makes regeneration of spent CNTs at a relatively low temperature become feasible. The CNTs(APTS) have good adsorption performance of CO2 at 20 degrees C as compared to many types of modified carbon or silica adsorbents documented in the literature. This suggests that the CNTs(APTS) are promising low-temperature adsorbents for CO2 capture from flue gas.

Adsorption, desorption, and thermodynamic studies of CO2 with high-amine-loaded multiwalled carbon nanotubes.

Commercially available multiwalled carbon nanotubes (CNTs) were functionalized with a high mass load of 3-aminopropyltriethoxysilane (APTS) to study their behaviors in the cyclic CO(2) adsorption as well as the associated thermodynamic properties. The breakthrough curve showed a fast kinetics of CO(2) adsorption resulting in percentage ratios of working capacity to equilibrium capacity greater than 80%. The adsorption capacity of CNT(APTS) was significantly influenced by the presence of water vapor and reached a maximum of 2.45 mmol/g at a water vapor of 2.2%. The adsorption capacities and the physicochemical properties of CNT(APTS) were preserved through 100 adsorption-desorption cycles displaying the stability of CNT(APTS) during a prolonged cyclic operation. The heat input required to regenerate spent CNT(APTS) was determined, and the result suggests that adsorption process with solid CNT(APTS) is possibly a promising CO(2) capture technology.

Adsorption of carbon dioxide from gas streams via mesoporous spherical-silica particles.

Abstract A relatively new mesoporous silica sorbent for environmental protection applications (i.e., mesoporous spherical-silica particles [MSPs]), was modified by N-[3-(trimethoxysilyl)propyl]ethylenediamine (EDA) solution and was tested for its potential in the separation of carbon dioxide (CO2) from flue gas. The CO2 adsorption capacity of MSP and MSP(EDA) increased with temperature from 20 to 60 °C but decreased with temperature from 60 to 100 °C. The mechanism of CO2 adsorption on both samples is mainly attributed to physical interaction regardless of temperature change. The MSP(EDA) have good adsorption performance as compared with EDA-modified zeolite or granular activated carbon conducted in this study and many types of silica sorbents reported in the literature. The cyclic CO2 adsorption showed that spent MSP(EDA) could be effectively regenerated at 120 °C for 25 min and CO2 adsorption capacity of MSP(EDA) was preserved during 16 cycles of adsorption and thermal regeneration. These results suggests that MSP(EDA) are efficient CO2 sorbents and can be stably used in the prolonged cyclic operation.