The adsorption and desorption of CO 2 and SO 2 on an amine-grafted SBA-15 sorbent has been studied by in situ infrared spectroscopy coupled with mass spectrometry. CO 2 adsorbed on an amine-grafted sorbent as carbonates and bicarbonates, while SO 2 adsorbed as sulfates and sulfites. The CO 2 adsorption capacity of the amine-grafted sorbent was almost twice as much as that of a commercial sorbent. The adsorption of CO 2 in the presence of H 2 O and D 2 O shows an isotopic shift in the IR frequency of adsorbed carbonate and bicarbonate bands, revealing that water plays a role in the CO 2 adsorption on amine-grafted sorbents. Although the rate of adsorption of SO 2 was slower than that of CO 2 , the adsorbed S surface species is capable of blocking the active amine sites for CO 2 adsorption. A temperature-programmed degradation study of the amine-grafted sorbent showed that the surface amine species are stable up to 250°C in air.

CO2 adsorption/desorption on SBA-15 grafted with γ-(aminopropyl)triethoxysilane (APTS) has been studied by infrared spectroscopy coupled with temperature-programmed desorption. SBA-15, a mesoporous silica material with a uniform pore size of 21 nm and a surface area of 200−230 m2/g, provides an OH functional group for grafting of γ-(aminopropyl)triethoxysilane. The amine-grafted SBA-15 adsorbed CO2 as carbonates and bicarbonates with a total capacity of 200−400 μmol/g. The heat of CO2 desorption was determined to be 3.2−4.5 kJ/mol in the presence of H2O and 6.6−11.0 kJ/mol in the absence of H2O during temperature-programmed desorption. Repeated CO2 adsorption/desorption CO2 cycles shifted the desorption peak temperature downward and decreased the heat of CO2 adsorption.

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.

No abstract

No abstract

a b s t r a c tLong term containment of stored CO 2 in deep geological reservoirs will depend on the performance of the caprock to prevent the buoyant CO 2 from escaping to shallow drinking water aquifers or the ground surface. Here we report new laboratory experiments on CO 2 -brine-caprock interactions and a review of the relevant literature.The Eau Claire Formation is the caprock overlying the Mount Simon sandstone formation, one of the target geological CO 2 storage reservoirs in the Midwest USA region. Batch experiments of Eau Claire shale dissolution in brine were conducted at 200• C and 300 bars to test the extent of fluid-rock reactions. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis indicate minor dissolution of K-feldspar and anhydrite, and precipitation of pore-filling and pore-bridging illite and/or smectite, and siderite in the vicinity of pyrite.We also reviewed relevant reactivity experiments, modeling work, and field observations in the literature in an attempt to help define the framework for future studies on the geochemical systems of the caprock overlain on geological CO 2 storage formations. Reactivity of the caprock is generally shown to be low and limited to the vicinity of the CO 2 -caprock interface, and is related to the original caprock mineralogical and petrophysical properties. Stable isotope studies indicate that CO 2 exists in both free phase and dissolved phase within the caprock. Carbonate and feldspar dissolution is reported in most studies, along with clay and secondary carbonate precipitation. Currently, research is mainly focused on the micro-fracture scale geochemistry of the shaly caprock. More attention is required on the potential pore scale reactions that may become significant given the long time scale associated with geological carbon storage.

No abstract

Research on carbon capture and storage has been focused on CO 2 storage in geologic formations, with many potential risks. An alternative to conventional geologic storage is carbon mineralization, where CO 2 is reacted with metal cations to form carbonate minerals. Mineralization methods can be broadly divided into two categories: in situ and ex situ. In situ mineralization, or mineral trapping, is a component of underground geologic sequestration, in which a portion of the injected CO 2 reacts with alkaline rock present in the target formation to form solid carbonate species. In ex situ mineralization, the carbonation reaction occurs above ground, within a separate reactor or industrial process. This literature review is meant to provide an update on the current status of research on CO 2 mineralization.