The removal of CO2 and N2 from natural gas: A review of conventional and emerging process technologies

Despite the large number of metal–organic frameworks that have been studied in the context of post-combustion carbon capture, adsorption equilibria of gas mixtures including CO2, N2, and H2O, which are the three biggest components of the flue gas emanating from a coal- or natural gas-fired power plant, have never been reported. Here, we disclose the design and validation of a high-throughput multicomponent adsorption instrument that can measure equilibrium adsorption isotherms for mixtures of gases at conditions that are representative of an actual flue gas from a power plant. This instrument is used to study 15 different metal–organic frameworks, zeolites, mesoporous silicas, and activated carbons representative of the broad range of solid adsorbents that have received attention for CO2 capture. While the multicomponent results presented in this work provide many interesting fundamental insights, only adsorbents functionalized with alkylamines are shown to have any significant CO2 capacity in the presenc...

/pdf/application-of-a-high-throughput-analyzer-in-evaluating-3bpan2ztvp.pdf

Application of a high-throughput analyzer in evaluating solid adsorbents for post-combustion carbon capture via multicomponent adsorption of CO2, N2, and H2O.

Separation of CO2 and N2 from CH4 is significantly important in natural gas upgrading, and capture/removal of CO2, CH4 from air (N2) is essential to greenhouse gas emission control. Adsorption equilibrium and kinetics of CO2, CH4, and N2 on an ordered mesoporous carbon (OMC) sample were systematically investigated to evaluate its capability in the above two applications. The OMC was synthesized and characterized with TEM, TGA, small-angle XRD, and nitrogen adsorption/desorption measurements. Pure component adsorption isotherms of CO2, CH4, and N2 were measured at 278, 298, and 318 K and pressures up to 100 kPa, and correlated with the Langmuir model. These data were used to estimate the separation selectivities for CO2/CH4, CH4/N2, and CO2/N2 binary mixtures at different compositions and pressures according to the ideal adsorbed solution theory (IAST) model. At 278 K and 100 kPa, the predicted selectivities for equimolar CO2/CH4, CH4/N2, and CO2/N2 are 3.4, 3.7, and 12.8, respectively; and the adsorption ...

Adsorption of CO2, CH4, and N2 on Ordered mesoporous carbon: Approach for greenhouse gases capture and biogas upgrading

Adsorbents with small pores are especially relevant for capturing carbon dioxide at large emission sources. Such sorbents could be used potentially to reduce the energy demands for separating carbon dioxide from flue gas as compared with today's technologies. Here, we review the literature for crystalline, inorganic, and potentially inexpensive adsorbents. A number of different adsorbents with narrow pore openings are compared.

/pdf/zeolites-and-related-sorbents-with-narrow-pores-for-co2-2xrvbsjuo4.pdf

Zeolites and related sorbents with narrow pores for CO2 separation from flue gas

As a major greenhouse gas, methane, which is directly vented from the coal-mine to the atmosphere, has not yet drawn sufficient attention. To address this problem, we report a methane nano-trap that features oppositely adjacent open metal sites and dense alkyl groups in a metal-organic framework (MOF). The alkyl MOF-based methane nano-trap exhibits a record-high methane uptake and CH4 /N2 selectivity at 298 K and 1 bar. The methane molecules trapped within the alkyl MOF were crystalographically identified by single-crystal X-ray diffraction experiments, which in combination with molecular simulation studies unveiled the methane adsorption mechanism within the MOF-based nano-trap. The IAST calculations and the breakthrough experiments revealed that the alkyl MOF-based methane nano-trap is a new benchmark for CH4 /N2 separation, thereby providing a new perspective for capturing methane from coal-mine methane to recover fuel and reduce greenhouse gas emissions.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ange.201907248

A Metal–Organic Framework Based Methane Nano‐trap for the Capture of Coal‐Mine Methane

An experimental evaluation of the kinetics and equilibrium capacities of pure fluids as a fast and effective means to screen an adsorbent's gas separation potential is described. Equilibrium adsorption capacities for pure N2, CH4, and CO2 have been determined using a Micromeritics ASAP2020 sorption analyzer, for three commercially available zeolites: natural chabazite, H+ mordenite, and Linde 4A molecular sieve over the temperature range from (248 to 302) K and pressure range from (0.001 to 120) kPa. Toth models were regressed to the equilibrium data for each gas and used to generate inferred equilibrium selectivity maps over a wider range of temperature and pressure for the purpose of targeting any future mixture measurements. For each gas, the rate of adsorption at 100 kPa was measured as a function of temperature and used with a linear driving force model to calculate mass transfer coefficients. In most cases the ratio of the mass transfer coefficients for each pair of gases was close to unity and did ...

Screening Zeolites for Gas Separation Applications Involving Methane, Nitrogen, and Carbon Dioxide

Helium is a unique gas with a wide range of important medical, scientific and industrial applications based on helium's extremely low boiling temperature, inert and non-flammable nature and small molecular size. The only practical sources of helium are from certain natural gas (NG) fields. As world demand for helium rapidly increases, the value of NG fields that contain it even in very small amounts is likely to rise significantly if the helium can be recovered efficiently. However, recovering the helium from the NG using conventional cryogenic distillation processes is expensive and energy intensive. We review the scope for improving the efficiency of the conventional helium recovery and upgrade processes, and evaluate the potential of emerging technologies based on adsorption or membrane separations for helium upgrade and purification. Helium recovery and purification processes are comparable in many ways with systems designed for hydrogen purification and thus, many of recent technological advances for...

https://journals.sagepub.com/doi/pdf/10.1260/0263-6174.32.1.49

A review of conventional and emerging process technologies for the recovery of helium from natural gas

https://research-repository.uwa.edu.au/files/10859479/Saleman_et_al_2015_Capture_of_low_grade_methane.pdf

Capture of low grade methane from nitrogen gas using dual-reflux pressure swing adsorption

We report here measured adsorption capacities for a natural chabazite zeolite at pressures ranging from (5 to 3000) kPa, at temperatures of (244 and 305) K, for pure N2, CH4, and CO2, and for gas mixtures of CH4 + CO2. The pure gas data sets from this work and from the literature were in good agreement (10 %) and were regressed to Toth models over a wide range of pressure and temperature. We show that extrapolation of models that were fit only to low pressure data (below 120 kPa) can lead to a 30 % deviation in adsorption capacities predicted at high pressures. Similarly, models fit only to high pressure pure fluid data resulted in unreliable predictions for mixture adsorption capacities particularly when the component's partial pressure was low. The experimental results indicate that, while the chabazite is unlikely to be useful for N2/CH4 separation, it may have potential for removing bulk CO2 from natural gas, particularly at low temperatures. A feed gas mixture of 0.95CH4 + 0.05CO2 placed in contact w...

Volumetric Adsorption Measurements of N2, CO2, CH4, and a CO2 + CH4 Mixture on a Natural Chabazite from (5 to 3000) kPa

A dynamic column breakthrough (DCB) apparatus was used to measure the capacity and kinetics of CH4 and N2 adsorption on zeolite H+-mordenite at temperatures in the range 243.8–302.9 K and pressures up to 903 kPa. Equilibrium adsorption capacities of pure CH4 and pure N2 were determined by these dynamic experiments and Langmuir isotherm models were regressed to these pure fluid data over the ranges of temperature and pressure measured. A linear driving force-based model of adsorption in a fixed bed was developed to extract the mass transfer coefficients (MTCs) for CH4 and N2 from the pure gas experimental data. The MTCs determined from single adsorbate experiments were used to successfully predict the component breakthroughs for experiments with equimolar CH4 + N2 gas mixtures in the DCB apparatus. The MTC of CH4 on H+-mordenite at 902 kPa was 0.013 s−1 at 302.9 K and 0.004 s−1 at 243.6 K. The MTC of N2 on H+-mordenite at 902 kPa was 0.011 s−1 at 302.9 K and 0.005 s−1 at 243.5 K. The values of the MTCs measured for each gas at a constant feed gas flow rate were observed to increase in a linear trend with the inverse of pressure. However, the apparent MTCs obtained at the lowest pressures studied (≈105 kPa) were systematically below this linear trend, because of the slightly longer residence time of helium in the mass spectrometer used to monitor effluent composition. Nevertheless, the pure fluid dynamic breakthrough data at these lowest pressures could still be reasonably well described using MTC values estimated from the linear trend. Furthermore, the results of dynamic breakthrough experiments with mixtures were all reliably predicted using the capacity and MTC correlations developed for the pure fluids.

Capacity and kinetic measurements of methane and nitrogen adsorption on H+-mordenite at 243-303 K and pressures to 900 kPa using a dynamic column breakthrough apparatus

K. Ida Chan

Papers

Screening Zeolites for Gas Separation Applications Involving Methane, Nitrogen, and Carbon Dioxide

A review of conventional and emerging process technologies for the recovery of helium from natural gas

Capture of low grade methane from nitrogen gas using dual-reflux pressure swing adsorption

Volumetric Adsorption Measurements of N2, CO2, CH4, and a CO2 + CH4 Mixture on a Natural Chabazite from (5 to 3000) kPa

Capacity and kinetic measurements of methane and nitrogen adsorption on H+-mordenite at 243-303 K and pressures to 900 kPa using a dynamic column breakthrough apparatus