Carbon Dioxide Capture by Diamine-Grafted SBA-15:  A Combined Fourier Transform Infrared and Mass Spectrometry Study

Abstract

The adsorption and desorption of CO 2 on diamine-grafted SBA-15 have been studied by infrared spectroscopy coupled with mass spectrometry. Diamine was grafted onto the SBA-15 surface by the reaction of [N-(2-aminoethyl)-3-aminopropyl]trimethoxysilane with the surface OH. CO 2 is adsorbed on the diamine-grafted SBA-15 as bidentate carbonate and bidentate and monodentate bicarbonates at 25 °C. Bidentate carbonate and monodentate bicarbonates are the major surface species formed and decomposed during the concentration-swing adsorption/desorption process at 25 °C. Temperature-programmed desorption revealed that the monodentate and bidentate bicarbonates bound stronger to the diamine-grafted SBA-15 surface than the bidentate carbonate. The amount of CO 2 desorbed from the carbonate and bicarbonate between 30 and 120 °C is 2 times more than that of CO 2 adsorbed/desorbed during each cycle of the concentration-swing adsorption/desorption. Desorption at 120 °C removes the majority of the captured CO 2 and regenerates the sorbent for CO 2 capture at low temperature. Regeneration of the sorbent with temperature-swing adsorption gives a significantly higher CO 2 capture capacity than concentration-swing adsorption. The use of a diamine-grafted sorbent, with an adsorption capacity of more than 1000 µmol/g of sorbent and a temperature-swing adsorption process, could be a cost-effective alternative to capture CO 2 from power plant flue gases.

A Review of CO2 Capture by Absorption and Adsorption

“…Though the rate-limiting step for adsorption as the diffusion of CO 2 from flue gas to the inside pore of a mesoporous adsorbent is about 3 orders of magnitude higher than that for aqueous amine absorption as the CO 2 mass transfer across the gas-liquid interface (Khatri et al, 2005), some existing problems including low CO 2 adsorption capacities at low pressures and influenced by water vapor and gases other than CO 2 still hinder the practical application of adsorption to capture CO 2 .…”

“…The differences were caused by the extent of surface grafting that was influenced by diffusion of amines in pores, amount of silanol groups on surface, and porosity of the support. Chuang's group synthesized the APS-and 2N-APS-grafted SBA-15 for CO 2 capture and reported all the CO 2 adsorption capacities less than 1 mmol/g, mainly due to the supports with low surface area, around 200 m 2 /g (Chang et al, 2003;Khatri et al, 2005Khatri et al, , 2006. They also used in situ infrared spectroscopy coupled with mass spectrometry to further study the effects of amine nature, adsorbed CO 2 species, and SO 2 on CO 2 adsorption capacity.…”

Fabrication of Mesostructured Silica Materials through Co-Structure-Directing Route

“…15,20,21 On the contrary, when anionic surfactants are used, mesoporous silica materials can be synthesized under acidic conditions (the S ¹ I + pathway), 15 or through a mediator ion M + in basic conditions (the S ¹ M + I ¹ pathway). 15,22 Nevertheless, due to the significant protonation of anionic surfactants, the interactions between anionic surfactants and silica species are too weak, so that the mesopores formed by the S ¹ I + and S ¹ M + I ¹ pathways result in lamellar or disordered structures, and have a wide pore size distribution. Besides of the electrostatic interactions, mesoporous silica materials can also be mediated through hydrogen bonds when nonionic surfactants are used (the S 0 I 0 and S 0 (XI) 0 pathways; S 0 : nonionic surfactants; I 0 : uncharged silica species; (XI) 0 : ion pairs).…”

Interactive CO2Adsorption on the BaO (100) Surface: A Density Functional Theory (DFT) Study

“…2 For highly efficient CO2 separation processes, CO 2 adsorption on a solid sorbent can be a method with a good potential because of its low operating costs and low energy demands. [3][4][5][6] Among various adsorption methods that use different adsorbents, mineral carbonation has the potential for CO2 separation because it leads to the formation of stable carbonates, minimizing the leakage of CO2 into the atmosphere after capture. Because mineral carbonation is the reaction between CO2 and metal oxides to form carbonates, quantum chemical calculations can be performed to evaluate the adsorption mechanism of CO2 on the surface of a solid sorbent.…”