Bar pCO2 Research Articles

Effect of mineral growth rate on Zinc incorporation into calcite and aragonite

The distribution coefficient of Zn2+ (i.e., D⁎Zn2+) between calcite/aragonite and reactive fluids were estimated as a function of mineral growth rate (10–8.6 < rp < 10–7.3 mol/m2/s) at 25 °C and 1 bar pCO2. The obtained results suggest that rate strongly influences D⁎Zn2+ in both minerals and the dependence of D⁎Zn2+ on growth rate can be described as:Log D⁎Zn2+, calcite = −0.331 (±0.048) Log rp – 0.991 (±0.375); R2 = 0.82Log D⁎Zn2+, aragonite = 0.751 (±0.089) Log rp + 5.160 (±0.702); R2 = 0.88These correlations for calcite and aragonite are in agreement with the incorporation of foreign ions in compatible and incompatible host mineral structures, respectively. The use of the surface reaction kinetic model (SRKM) to fit the experimental data provided good results for calcite. In contrast, SRKM was not able to provide a good fit for Zn incorporation in aragonite, underlying the difficulties to model incorporation of foreign elements incompatible with the host mineral structure.Moreover, a linear correlation was found between D⁎Zn2+ and the saturation degree of the reactive fluid with respect to the growing mineral phase that can be described as:Log D⁎Zn2+calcite = −1.280 (±0.221) SIcalcite + 1.864 (±0.053); R2 = 0.77Log D⁎Zn2+aragonite = 2.852 (±0.418) SIaragonite - 1.640 (±0.138); R2 = 0.82Considering that SImineral = 0 reflects chemical equilibrium in the above equations, a Log D⁎Zn2+ at equilibrium was calculated for both calcite (1.9) and aragonite (−1.6). This value is in good agreement with the theoretical models for calcite, whereas in the case of aragonite it is 1.5 to 2.1 orders of magnitude lower than the previously published values. While the incorporation of Zn ions into calcite implies the formation of a dilute solid-solution between calcite and smithsonite (i.e. ZnCO3), the incorporation of Zn ions into aragonite is likely associated to the density of defect sites at the growing mineral surface.

Cyclic carbonate synthesis via cycloaddition of CO2 and epoxides catalysed by beta zeolites containing alkyl imidazolium ionic liquids used as structure-directing agents

Cyclic carbonates were synthesized via CO2 cycloaddition and epoxides, allyl-glycidyl-ether (AGE) and propylene oxide (PO), using hybrid materials formed by beta zeolites and ionic liquids, 1‑butyl‑3-methylimidazolium chloride (BMI.Cl) or 1-decyl-3-methylimidazolium chloride (DMI.Cl), as structure-directing agents which remained in their porosity. The beta zeolites, β-BMI.Cl and β-DMI.Cl, were used to convert AGE to AGC (allyl-glycidyl-carbonate), and β-BMI.Cl was also used to convert PO to PC (propylene carbonate). The optimal condition for β-BMI.Cl in which there was the total CO2 conversion was 50 bar pCO2 at 145 °C using AGE and 30 bar pCO2 at 130 °C using PO, being better than the catalyst β-DMI.Cl. The reuse of β-BMI.Cl led to a 95% yield of AGC after 5 h of reaction at 145 °C, showing the good stability of this catalytic system. The activation energy (Ea) of 97 kJ/mol was obtained through kinetic experiments conducted with AGE and β-BMI.Cl. Comparing experiments performed only with ionic liquids and hybrid materials, the last ones enabled the CO2 conversion with higher efficiency and were thermally more resistant. The results demonstrate that the β-BMI.Cl and β-DMI.Cl hybrid materials are promising catalytic systems to produce cyclic carbonates through CO2 conversion.

Effect of growth rate on nickel and cobalt incorporation in aragonite

The incorporation of Ni and Co in aragonite was experimentally investigated as a function of mineral growth rate using the constant addition technique at 25 °C and 1 bar pCO2. The distribution coefficients of Ni and Co (i.e., DMe=Me/CasolidaMe2+/aCa2+fluid) exhibit a linear correlation with mineral growth rate in the range −9.1 ≤ Log rp ≤ −7.5 mol/m2/s. The obtained results suggest a stronger dependency of DNi to growth rate compared to that observed for DCo. These dependencies can be described as:Log DNi = 1.247 (±0.152) Log rp + 7.448 (±1.212); R2 = 0.82Log DCo = 0.312 (±0.047) Log rp + 1.664 (±0.383); R2 = 0.81The DMe-aragonite values for both Ni and Co are systematically lower than unity and their increase with increasing growth rate is in agreement with the incorporation of elements incompatible with the host mineral structure. Using the dependency of DNi and DCo to the saturation indices (SI) of the reactive solution with respect to aragonite, the DMe under equilibrium were estimated. These estimates yield equilibrium Log DMe values of −3.9 and − 1.0 for Ni and Co, respectively. These experimentally defined Deq values are 1.3 to 4.3 orders of magnitude lower compared to theoretical estimates that were earlier published in the literature. Similar to other incompatible elements, the observed increase of DNi and DCo values with degree of saturation, points towards incorporation related to the density of defect sites on the mineral surface. Finally, the dependencies recorded in this study suggest that DNi and DCo have the potential to be used as a proxy for saturation degree of the reactive solution.

The role of Cl- in the formation of the corrosion products and localised corrosion of 15Cr martensite stainless steel under an CO2-containing extreme oilfield condition

This paper focused on the corrosion behaviour of 15Cr stainless steel in deep/ultra-deep geological environments. The relationship between corrosion products and general/localised corrosion under various Cl- concentrations at 200 °C and 28.5 bar pCO2 were systematically investigated. The results indicate that high Cl- content of 81 000 ppm promoted the general/localised corrosion via precipitation of the chloride-rich products, which retarded the formation of nanocrystalline NiFe2O4 and decreased the corrosion resistance. The corrosion products consisted of outer FeCO3 and inner NiFe2O4/FeCr2O4/Cr(OH)3 in a low Cl- content of 29 503 ppm. The characterisation of the corrosion products is combined with thermodynamics calculations.

Experimental analysis on the carbonation rate of Portland cement at room temperature and CO2 partial pressure from 1 to 51 bar

Considering the range of PCO2 of previous laboratory experimental works, in this study the carbonation rate of class G Portland cement was investigated at room temperature, in the PCO2 interval from 1 to 51 bar, to fill the existing gap of knowledge, through three types of laboratory experiments. Cement hydration (accompanied by limited carbonation) was carried out for 28 days at atmospheric conditions. Cement carbonation was then investigated using a micro-reactor by reacting, in distinct runs, cement powder samples, under stirred conditions, and massive samples, under stagnant conditions, with pure CO2(g) and MilliQ water. After the completion of each experiment, chemical analyses on both the aqueous solution (IC, ICP-OES, acidimetric titration) and the solids (XRD, SEM, TGA/DTA) were performed.In type 1 experiments, cement powder was reacted at 11 bar PCO2, for 1, 3, 6, 21, 67, 97 and 120 h. Portlandite was only present in the hydrated cement paste and was converted to CaCO3 in less than 1 h. In type 2 experiments, cement powder was reacted for 6 h at PCO2 of 1, 11, 31 and 51 bar. The extent of cement carbonation was similar for any PCO2 values.The experiments of type 3 were performed with cement cube samples at 11 bar PCO2 for 6, 24 and 210 h. The average carbonation depth attained was 0.23 mm in 1 day, and resulted to be linearly related to the square root of reaction time indicating that cement carbonation rate was controlled by diffusion (Fickian behavior).

An experimental study of basalt–seawater–CO2 interaction at 130 °C

Over millions of years, the interaction of marine basalt with percolating seawater in low-temperature ocean floor hydrothermal systems leads to the formation of calcite and aragonite. The presence of these minerals in marine basalts provides evidence for substantial CO2 fixation in these rocks. Here, we report on laboratory experiments to study this process under enhanced CO2 partial pressures (pCO2) at 130 °C. Mid-ocean-ridge-basalt (MORB) glass was reacted with North Atlantic Seawater charged with CO2 in batch experiments lasting up to 7 months. For experiments initiated with seawater charged with ~2.5 bar pCO2, calcite and aragonite are the first carbonate minerals to form, later followed by only aragonite (±siderite and ankerite). For experiments initiated with seawater charged with ~16 bar pCO2, magnesite was the only carbonate mineral observed to form. In total, approximately 20% of the initial CO2 in the reactors was mineralized within five months. This carbonation rate is similar to corresponding rates observed in freshwater-basalt-CO2 interaction experiments and during field experiments of the carbonation of basalts in response to CO2-charged freshwater injections in SW-Iceland. Our experiments thus suggest that CO2-charged seawater injected into submarine basalts will lead to rapid CO2 mineralization. Notably, at pCO2 of tens of bars, magnesite will form, limiting the formation of Mg-rich clays, which might otherwise compete for the Mg cation and pore-space in the submarine basaltic crust. This suggests that the injection of CO2-charged seawater into subsurface basalts can be an efficient and effective approach to the long-term safe mineral storage of anthropogenic carbon.

Mineralization potential of water-dissolved CO2 and H2S injected into basalts as function of temperature: Freshwater versus Seawater

Mineralization of freshwater-dissolved gases, such as CO2 and H2S, in subsurface mafic rocks is a successful permanent gas storage strategy. To apply this approach globally, the composition of locally available water must be considered. In this study, reaction path models were run to estimate the rate and extent of gas mineralization reactions during gas-charged freshwater and seawater injection into basalts at temperatures of 260, 170, 100, and 25°C. The calculations were validated by comparison to field observations of gas-charged freshwater injections at the CarbFix2 site (Iceland). The results show that more than 80% of the injected CO2 dissolved in freshwater or seawater mineralizes as Ca and Fe carbonates at temperatures ≤170°C after reaction of 0.2 mol/kgw of basalt, whereas at 260°C much lower carbon mineralization rates are observed in response to the same amount of basalt dissolution. This difference is due to the competition between carbonate versus non-carbonate secondary minerals such as epidote, prehnite, and anhydrite for Ca. In contrast, from 80 to 100% of the injected H2S is predicted to be mineralized as pyrite in all fluid systems at all considered temperatures. Further calculations with fluids having higher CO2 contents (equilibrated with 9 bar pCO2) reveal that i) the pH of gas-charged seawater at temperatures ≤170°C is buffered at ≤6 due to the precipitation of Mg-rich aluminosilicates, which delays CO2 carbonation; and ii) the most efficient carbonation in seawater systems occurs at temperatures <150°C as anhydrite formation is likely significant at higher temperatures.

The evolution and characterisation of the corrosion scales formed on 3Cr steel in CO2-containing conditions relevant to geothermal energy production

The corrosion behaviour of 3Cr steel at CO2 partial pressures (pCO2) of 2.7/28.5 bar and 200 °C was investigated. The evolution of double-layered corrosion scales was analysed by surface analysis to identify physical and chemical nature and results are combined with an analysis of thermodynamic calculations. Both experimental and thermodynamic results show that the corrosion scales comprise a crystalline FeCO3 outer layer and an inner Fe3O4, FeCr2O4, and Cr(OH)3 at 2.7 bar pCO2. At 28.5 bar pCO2, the inner layer evolves to be a mixture of FeCr2O4 and Cr(OH)3 containing concentrated Cl− ions, and this induces an enhancement of localised corrosion.

Influence of a small velocity variation on the evolution of the corrosion products and corrosion behaviour of super 13Cr SS in a geothermal CO2 containing environment

The general and localised corrosion of super 13Cr SS under various CO2 partial pressures (pCO2) in the static conditions and rotated speeds of 188 rpm at 200 °C were evaluated. The results show that super 13Cr SS exhibits lower localised corrosion risk at 188 rpm compared to the static conditions. The small velocity retards the localised corrosion through the formation of uniform corrosion product scales, which mainly comprises nanocrystalline FeCr2O4 at 2.7 bar pCO2. A double-layered film consists of an inner layer of Cr(OH)3/undissolved austenite and an outer crystalline FeCO3 layer was observed at 28.5 bar pCO2.

Experimental determination of calcite solubility and the stability of aqueous Ca– and Na–carbonate and –bicarbonate complexes at 100–160 °C and 1–50 bar pCO2 using in situ pH measurements

The solubility of calcite was measured at 100, 120, 140 and 160 °C at 1–50 bar pCO2 in 10−3–0.1 mol·kg−1 NaCl solutions using a new experimental setup involving in situ pH measurements with high-temperature solid-contact H-selective glass and two types of reference electrodes: (i) Ag/AgCl in 3.5 M KCl, saturated AgCl placed in a Teflon extensible container with liquid junction, and (ii) solid-contact high-T Na-selective glass electrode in the cell without liquid junction. The stability constants of NaHCO3° and NaCO3− aqueous complexes formation were determined in NaCl-Na2CO3/NaHCO3 solutions in CO2-free media and under 10 bar pCO2 from 100 to 160 °C. These values allowed calculation of the pH of the calibration solution in the system NaCl-CO2-H2O used in the cell without liquid junction with Na+-selective electrode as a reference. This highly stable, low-cost electrode system can be recommended for routine pH measurements at 4 < pH < 10 in sodium-bearing solutions up to 160 °C and the critical point of CO2. The values of the stability constants of CaCO3° and CaHCO3+ aqueous complexes and calcite solubility product were generated at 100, 120, 140 and 160 °C allowing a description of the solubility of calcite in a wide range of pH and pCO2.

Experimental study on mafic rock dissolution rates within CO2-seawater-rock systems

Far-from-equilibrium batch experiments have been performed to study the low temperature dissolution potential of crystalline submarine basalts (from Juan de Fuca Plate and Mid-Atlantic Ridges) and of a highly altered gabbro from the Troodos ophiolite (Cyprus) in presence of seawater and carbon dioxide (CO2). The experiments have been carried out at 40 °C for up to 20 days with initial pH of ∼4.8 and under ∼1 bar pCO2 to identify the progressive water-rock interactions. Elemental steady-state release rates from the rock samples have been determined for silicon and calcium, the solution concentrations of which were found to be the most effective monitors of rock dissolution. Mass balance calculations based on dissolved Si and Ca concentrations suggest the operation of reaction mechanisms focussed on the grain surfaces that are characteristic of incongruent dissolution. Also, basic kinetic modelling highlights the role of mass-transport limitations during the experiments. Ca release rates at pH ∼ 5 indicate significant contributions of plagioclase dissolution in all the rocks, with an additional contribution of amphibole dissolution in the altered gabbro. Si release rates of all solids are found to be similar to previously studied reactions between seawater and basaltic glass and crystalline basalt from Iceland, but are higher than rates measured for groundwater-crystalline basalt interaction systems. This comparison with previous experimental results resumes the debate on the role of experimental variables, such initial rock mass and crystallinity, pCO2, and fluid chemistry on dissolution processes. Our new data suggest that CO2-rich saline solutions react with mafic rocks at higher rates than fresh water with low pCO2, at the same pH. Most significantly, both ophiolitic gabbro and Juan de Fuca basalts show Si and Ca release rates similar or higher than unaltered crystalline basalt from Iceland, highlighting the potential substantial role that ophiolitic rocks and offshore mafic reservoirs could play for the geological storage of CO2.

Effect of sulfate on magnesium incorporation in low-magnesium calcite

The incorporation of magnesium and sulfate in calcite is frequently used to characterize and trace the environmental conditions occurring during carbonate mineral formation. Although both ions are simultaneously incorporated in the growing calcite, the effect of sulfate on magnesium incorporation in calcite is still under-explored. In this study, we examine the Mg incorporation in low-Mg calcite as a function of growth rate at 25 °C and 1 bar pCO2 in the presence and absence of aqueous sulfate. The obtained results suggest that high calcite growth rates induce a significant increase in the partitioning coefficient of Mg between the precipitated low-Mg calcite and aqueous solution (i.e. DMg=nMg/nCacalcite[Mg2+]/[Ca2+]solution). Obtained DMg values exhibit similar dependence to mineral growth rate for experiments performed in the presence and absence of sulfate, however a systematic shift to lower DMg values is observed for calcites formed in the presence of sulfate. The lower DMg values of calcites formed in sulfate-bearing solutions are attributed to the incorporated SO4 ions which provoke expansion in the unit cell along the c-axis of the newly formed calcite. A larger unit cell is unfavorable for the substitution of Ca by smaller Mg ions in calcite. The coupled effect of (i) sulfate uptake during calcite growth and (ii) precipitation rate on DMg can be expressed by the equation DMg=0.03726-0.02345×-logrp-7-XSO4×0.004607+0.002109×-logrp-7; (−8 ≤ log(rp) ≤ −7; 0 ≤ Xso4 ≤ 2.6; T = 25 °C) and is valid for 0.01 ≤ DMg ≤ 0.04. In analogy to Mg also SO4 ions are inhibiting calcite growth, thus promoting the formation of aragonite due to adsorption phenomena and blocking of calcite surface sites. These results improve our understanding on physicochemical parameters controlling CaCO3 composition and mineral polymorphism and are discussed in their relevance for the use of magnesium and sulfate environmental proxies in natural surroundings.

The formation of FeCO3 and Fe3O4 on carbon steel and their protective capabilities against CO2 corrosion at elevated temperature and pressure

This study investigates the corrosion performance of X65 carbon steel at elevated temperatures (up to 250 °C) and CO2 partial pressures (up to 28.5 bar pCO2). A detailed appraisal of how the corrosion products can protect against general and localised corrosion is presented. The morphology and chemical composition of corrosion products were determined using various microscopic and spectroscopic techniques, with localised corrosion rates being determined by surface profilometry. An increase in temperature or reduction in CO2 partial pressure favours the formation of a protective magnetite layer. It is thermodynamically more stable and more protective than iron carbonate in these conditions.

Accelerated carbonation by cement kiln dust in aqueous slurries: chemical and mineralogical investigation

AbstractCement kiln dust accelerated carbonation in aqueous slurries at 25°C and 3 bar PCO2 was investigated by X‐ray diffraction analysis, solution chemistry, scanning electron microscopy, and energy dispersive spectroscopy to better understand chemical and mineralogical processes governing CO2 uptake. Dissolution of lime, portlandite, and ettringite occurs primarily in the carbonation process. These provide Ca2+ ions to react with CO32− ions leading to calcite bulk precipitation from solution. Concomitantly, the dissolution of Ca‐(Al)‐silicate grains takes place but it is limited by the formation of a Si‐rich and Ca‐depleted rim which appears onto the grain surfaces due to an initial hydration step. The Si‐rich decalcified rim hinders the diffusion of Ca2+ ions from the core of silicate grains to the bulk solution. The diffusion of Ca ions through the rim is then the rate limiting step for the carbonation of Ca‐(Al)‐silicate, that accounts for up to 4% of the carbonation potential. Achieved results elucidate the processes governing CO2 uptake by cement kiln dust, and are fundamental in the perspective of enhanced CO2 sequestration by cement kiln dust. © 2017 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Experimental Analysis of the Reaction Rate of Hydrated Class G Cement Powder at 11 bar PCO2 and Ambient Temperature

The aim of this work is to study the alteration of class G Cement at ambient temperature under a relatively high CO2 partial pressure through suitably designed laboratory experiments, in which cement hydration and carbonation are taken into account separately. First, the hydration process was carried out for 28 days to identify and quantify the hydrated solid phases formed. After the completion of hydration, accompanied by partial carbonation under atmospheric conditions, the carbonation process was investigated using a stirred micro-reactor by reacting cement powder with pure CO2(g) (PCO2 = 11 bar) and MilliQ water for different reaction times. The reaction time was varied to constrain the reaction kinetics of the carbonation process and to investigate the evolution of primary and secondary solid phases. Mineralogical analyses (X-ray Powder Diffraction and Scanning Electron Microscope) were carried out to this purpose. Water analyses were also performed by ion chromatography at the end of each experimental run to investigate the chemical effects of cement carbonation on the aqueous solution. The carbonation degree was calculated from the results of Thermo-Gravimetric analysis (TGA). The main results of these experiments is the quick conversion of portlandite and Ca1.60SiO3.6·2.58H2O (C-S-H) to calcite. In fact, the carbonation degree attains 80% after 6 hours of reaction time. Experimental outcomes will be simulated by means of the PHREEQC software package to obtain further indications on cement carbonation

Topologically diverse shape-persistent bis-(Zn-salphen) catalysts: efficient cyclic carbonate formation under mild conditions.

By adopting a shape-persistent bimetallic design approach, high initial molecular turnover frequencies (up to 14,800 h(-1)) for coupling of CO2 with epoxides in conjunction with (n)Bu4NI, plus excellent yields under mild conditions (1 bar of CO2, 45 °C) have been achieved for catalysts containing cofacial Zn-salphen units.

The use of high pressure CO2‐facilitated pH swings to enhance in situ product recovery of butyric acid in a two‐phase partitioning bioreactor

Through the use of high partial pressures of CO2 (pCO2 ) to facilitate temporary pH reductions in two-phase partitioning bioreactors (TPPBs), improved pH dependent partitioning of butyric acid was observed which achieved in situ product recovery (ISPR), alleviating end-product inhibition (EPI) during the production of butyric acid by Clostridium tyrobutyricum (ATCC 25755). Through high pressure pCO2 studies, media buffering effects were shown to be substantially overcome at 60 bar pCO2 , resulting in effective extraction of the organic acid by the absorptive polymer Pebax® 2533, yielding a distribution coefficient (D) of 2.4 ± 0.1 after 1 h of contact at this pressure. Importantly, it was also found that C. tyrobutyricum cultures were able to withstand 60 bar pCO2 for 1 h with no decrease in growth ability when returned to atmospheric pressure in batch reactors after several extraction cycles. A fed-batch reactor with cyclic high pCO2 polymer extraction recovered 92 g of butyric acid to produce a total of 213 g compared to 121 g generated in a control reactor. This recovery reduced EPI in the TPPB, resulting in both higher productivity (0.65 vs. 0.33 g L(-1) h(-1) ) and yield (0.54 vs. 0.40). Fortuitously, it was also found that repeated high pCO2 -facilitated polymer extractions of butyric acid during batch growth of C. tyrobutyricum lessened the need for pH control, and reduced base requirements by approximately 50%. Thus, high pCO2 -mediated absorptive polymer extraction presents a novel method for improving process performance in butyric acid fermentation, and this technique could be applied to the bioproduction of other organic acids as well.

Pore-scale controls on calcite dissolution rates from flow-through laboratory and numerical experiments.

A combination of experimental, imaging, and modeling techniques were applied to investigate the pore-scale transport and surface reaction controls on calcite dissolution under elevated pCO2 conditions. The laboratory experiment consisted of the injection of a solution at 4 bar pCO2 into a capillary tube packed with crushed calcite. A high resolution pore-scale numerical model was used to simulate the experiment based on a computational domain consisting of reactive calcite, pore space, and the capillary wall constructed from volumetric X-ray microtomography images. Simulated pore-scale effluent concentrations were higher than those measured by a factor of 1.8, with the largest component of the discrepancy related to uncertainties in the reaction rate model and its parameters. However, part of the discrepancy was apparently due to mass transport limitations to reactive surfaces, which were most pronounced near the inlet where larger diffusive boundary layers formed around grains and in slow-flowing pore spaces that exchanged mass by diffusion with fast flow paths. Although minor, the difference between pore- and continuum-scale results due to transport controls was discernible with the highly accurate methods employed and is expected to be more significant where heterogeneity is greater, as in natural subsurface materials.

Dissolution kinetics of Devonian carbonates at circum-neutral pH, 50 bar pCO2, 105 °C, and 0.4 M: The importance of complex brine chemistry on reaction rates

The dissolution kinetics of carbonate rocks sampled from the Keg River Formation in Northeast British Columbia were measured at 50bar pCO2 and 105°C, in both natural and synthetic brines of 0.4M ionic strength. Natural brines yielded reaction rates of −12.16±0.11molcm−2s−1 for Log RCa, and −12.64±0.05 for Log RMg. Synthetic brine yielded faster rates of reaction than natural brines. Experiments performed on synthetic brines, spiked with 10mmol of either Sr or Zn, suggest that enhanced reaction rates observed in synthetic brines are due to a lack of trace ion interaction with mineral surfaces. Results were interpreted within the surface complexation model framework, allowing for the discrimination of reactive surface sites, most importantly the hydration of the >MgOH surface site. Dissolution rates extrapolated from experiments predict that CO2 injected into the Keg River Formation will dissolve a very minor portion of rock in contact with affected formation waters.

Carbon dioxide adsorption in microwave-synthesized metal organic framework CPM-5: Equilibrium and kinetics study

The adsorption equilibrium and diffusion of CO2 in CPM-5 (crystalline porous materials) were experimentally studied using a volumetric approach at three different temperatures 273, 298, and 318K and gas pressures up to 105kPa. The Freundlich adsorption equilibrium model was applied to correlate the adsorption isotherms, and the classical microspore diffusion model was applied to obtain the adsorption kinetic curves and diffusivity of CO2 in CPM-5. The selectivity of CO2 over N2 was estimated from the single component isotherms at conditions relevant to post combustion applications (0.15bar PCO2 and 0.75bar pN2). It was found that at pressures up to 105kPa, the CPM-5 adsorbent has CO2 adsorption capacity of 3mmol/g, 2.3mmol/g, at 273K and 298K, respectively, which is significantly higher than those of MOF-5 under the same conditions. The selectivity factor was 14.2 and 16.1 at 273 and 298K, respectively. The CO2 diffusivity in CPM-5, estimated from the adsorption kinetic data measured at low pressures, are 1.86×10−12m2/s, 7.04×10−12m2/s, and 7.87×10−12m2/s at 273K, 298K and 318K, respectively. The initial isosteric heat of adsorption of CO2 on the CPM-5 is 36.1kJ/mol. CPM-5 shows attractive adsorption properties as an adsorbent for separation of CO2 from flue gas.