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Carbon dioxide (CO2) emission reduction is a current hotspot for researchers and innovators owing to an abrupt increase in CO2 concentration in the ecosystem. The current focus of environmental eng...

Li4SiO4-based adsorbent is considered as a promising choice for the CO2 removal from power plants’ flue gases. However, the relatively high raw materials cost still limits its industrial applications. In this work, aiming to reduce the cost of Si-source, three novel natural occurring minerals including the pumicestone, the montmorillonite and the attapulgite were employed as Si-sources for the production of Li4SiO4-based adsorbents. The phase composition, surface morphology as well as the cyclic CO2 ad-desorption performance of obtained adsorbents were experimentally and kinetically investigated. It is found that the Si content of minerals directly determines the adsorption capacity of adsorbents, resulting in a relatively high and stable capacity of nearly 0.1 g/g within 22 cycles for the pumicestone derived adsorbent compared with other adsorbents obtained from minerals. Moreover, the excess Ca inside the minerals is found forming CaO, which is harmful to the desorption performance of adsorbent owing to the occurrence of Li–Ca–CO2 interactions. As a consequence, Si-source with high Ca content was proven inadaptable for the synthesis of Li4SiO4-based adsorbent, which provides guidance for the future selection of mineral Si-sources in this field.

Efficient capture and storage of carbon dioxide can avoid the global warming crisis. Gas hydrate, as a novel gas in separation technique, has an excellent potential for separation of CO2 from power...

Ionic liquids (ILs) are a promising class of absorbents for next-generation carbon-capture processes. In particular, aprotic heterocyclic anion ILs (AHAs) have received significant attention due to...

Adsorption of CO2 from post-combustion flue gas is one of the leading candidates for globally impactful carbon capture systems. This work focused on understanding the opportunities and limitations of sub-ambient CO2 capture processes utilizing a multistage separation process. A hybrid process design using a combination of pres- sure-driven separation of CO2 from flue gas (e.g., adsorption- or membrane-based separation) followed by CO2-rich product liquefaction to produce high-purity (>99%) CO2 at pipeline conditions is considered. The operating pressure of the separation unit is a key cost parameter and also an important process variable that regulates the available heat removal necessary to reach the sub-ambient operating conditions. The economic viability of applying pressure swing adsorption (PSA) processes using fiber sorbent contactors with internal heat management was found to be most influenced by the productivity of the adsorption system, with productivities as high as 0.015 molCO2 /kgsorb -1 sec -1 being required to reduce costs of capture below $60/ ton CO2 captured. This analysis was carried out using a simplified two-bed process, and thus there is opportunity for further cost reduction with exploration of more complex cycle designs. Three exemplar fiber sorbents (MIL-101(Cr), UiO-66, and zeo- lite 13X) were considered for application in the sub-ambient process of PSA unit. Among the considered sorbents, zeolite 13X fiber composites were found to perform better at ambient temperatures as compared to sub-ambient. MIL-101(Cr) and UiO- 66 fiber composites had improved purity, recovery, and productivity at colder tem- peratures reducing costs of capture as low as $61/ton CO2. Future economic improvement could be achieved by reducing the required operating pressure of the PSA unit and pushing the Pareto frontier closer to the final pipeline requirement via a combination of PSA cycle design and material selection. KEYWORDS CO2 capture, fiber sorbents, heat management, pressure swing adsorption, sub-ambient process

This paper examines the synthesis of the ZnO/carbon spheres composites using resorcinol—formaldehyde resin as a carbon source and zinc nitrate as a zinc oxide source in a solvothermal reactor heated with microwaves. The influence of activation with potassium oxalate and modification with zinc nitrate on the physicochemical properties of the obtained materials and CO2 adsorption capacity was investigated. It was found that in the case of nonactivated material as well as activated materials, the presence of zinc oxide in the carbon matrix had no effect or slightly increased the values of CO2 adsorption capacity. Only for the material where the weight ratio of carbon:zinc was 2:1, the decrease of CO2 adsorption capacity was reported. Additionally, CO2 adsorption experiments on nonactivated carbon spheres and those activated with potassium oxalate with different amounts of zinc nitrate were carried out at 40 °C using thermobalance. The highest CO2 adsorption capacity at temperature 40 °C (2.08 mmol/g adsorbent) was achieved for the material after activation with potassium oxalate with the highest zinc nitrate content as ZnO precursor. Moreover, repeated adsorption/desorption cycle experiments revealed that the as-prepared carbon spheres were very good CO2 adsorbents, exhibiting excellent cyclic stability with a performance decay of less than 10% over up to 25 adsorption-desorption cycles.

The development of new amine solvents without the major drawbacks of conventional amines is crucial to industrial applications of CO2 capture. This paper presents a water-lean CO2 capture solvent having a low regeneration energy and low degradation. The water-lean solvent, K2Sol, is a sterically hindered diamine; because of the hindered amine site, K2Sol easily forms bicarbonate, resulting in a high absorption capacity. The minimum solvent regeneration energy is obtained using Gaussian process Bayesian optimization (GPBO) and bench-scale pilot plant experiments. GPBO finds the optimal solution using the input and output relationship of experiments; thus, expensive first-principle model construction can be avoided. According to the pilot plant experiment, the optimal regeneration energies of monoethanolamine (MEA) and K2Sol are 4.3 and 2.8 GJ/t CO2, respectively, indicating that K2Sol requires only 65% of the regeneration energy of MEA. Fewer than 30 experiments are required to find the optimal pilot plant operation for both the MEA and K2Sol experiments. We also describe the superior properties of K2Sol in terms of the CO2 loading, cyclic capacity, regeneration temperature, and degradation.

To reach the short-term targets of the carbon dioxide limit, measures such as carbon capture and storage are necessary. The objective of this paper is to assess some low-temperature post-combustion...

Tetraethylenepentamine (TEPA) and its derivatives were used to functionalize mesocellular silica foam (MSU-F) supports by wet impregnation for utilization as solid sorbents for CO2 capture. TEPA de...

In this work, a comparative study on water-stable microporous adsorbents is conducted computationally in the quest of a suitable adsorbent for post-combustion CO2 capture. In this regard, three met...

Five different diamine-appended metal-organic frameworks (MOFs) that show a S-shaped CO2 isotherm are evaluated for post-combustion CO2 capture from dry flue gas using a vacuum swing adsorption process. A comprehensive simulation and optimization study using a multi-objective genetic algorithm is performed. The optimization to maximize CO2 purity and recovery showed a key link between the feed temperature, evacuation pressure and process performance. The MOFs that achieve a target CO2 purity ⩾95% and recovery ⩾90%, namely, mmen-Mn2(dobpdc) and mmen-Mg2(dobpdc) were optimized to reduce parasitic energy and increase productivity. The adsorbents, mmen-Mn2(dobpdc), mmen-Mg2(dobpdc) and Zeolite 13X showed minimum parasitic energies of 142, 152 and 167 kWh e / tonne CO 2 cap , respectively and maximum productivities of 0.4, 0.45 and 0.65 mol CO 2 m - 3 ads s - 1 , respectively while achieving CO2 purity ⩾ 95 % and recovery ⩾ 90 % . The possible low N2 affinity and the unique shape of the CO2 isotherm were found to be key reasons for a lower energy consumption.

SummaryWe present a simulation study of a mature reservoir for carbon dioxide (CO2) enhanced-oil-recovery (EOR) development. This project is currently recognized as the world's largest project using post-combustion CO2 from power-generation flue gases. With a fluvial formation geology and sharp hydraulic-conductivity contrasts, this is a challenging and novel application of CO2 EOR. The objective of this study is to obtain a reliable predictive reservoir model by integrating multidecadal production data at different temporal resolutions into the available geologic model. This will be useful for understanding flow units along with heterogeneity features and their effect on subsurface flow mechanisms, to guide the optimization of the injection scheme and maximize CO2 sweep and oil recovery from the reservoir.Our strategy consists of a hierarchical approach for geologic-model calibration incorporating available pressure and multiphase production data. The model calibration is performed using regional multipliers, and the regions are defined using a novel adjacency-based transform accounting for the underlying geologic heterogeneity. The genetic algorithm (GA) is first used to match 70-year pressure and cumulative production by adjusting pore volume (PV) and aquifer strength. Water-injection data for reservoir pressurization before CO2 injection is then integrated into the model to calibrate the formation permeability. The fine-scale permeability distribution consisting of more than 7 million cells is reparameterized using a set of linear-basis functions defined by a spectral decomposition of the grid-connectivity matrix (Laplacian grid). The parameterization represents the permeability distribution using a few basis-function coefficients that are then updated during history matching. This leads to an efficient and robust work flow for field-scale history matching.The history-matched model provided important information about reservoir volumes, flow zones, and aquifer support that led to additional insight compared with previous geological and simulation studies. The history-matched field-scale model is used to define and initialize a detailed fine-scale model for a CO2 pilot area that will be used to study the effect of fine-scale heterogeneity on CO2 sweep and oil recovery. The uniqueness of this work is the application of a novel geologic-model parameterization and history-matching work flow for modeling of a mature oil field with decades of production history, and which is currently being developed with CO2 EOR.

In the present work, steady-state simulations of the natural gas combined cycle (NGCC) and the post-combustion CO2 capture (PCC) processes have been modelled in Aspen Plus® environment. The capture plan model was validated with data from the Colombian power plant "Termocentro" at 300MWe. A techno-economical evaluation study has been performed for both a combined cycle (gas and steam) and the PCC process. The PCC process was based on the solvent 30% (w/w) MEA-H2O and on the solvent H2O-30% (w/w)-MEA-5% (w/w))-[Bmim][Bf4]. Sensitivity analysis was carried out, giving as a result an optimum concentration of 5% (w/w) for the 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid ([Bmim] [BF4]) solvent. The study indicates how with efficient operation conditions of solvent regeneration, [Bmim][Bf4] may be used for CO2 capture plans on the future.

Heat consumption is a major concern for the development of the post-combustion CO2 capture in thermal power plants. In this work, a mathematical model is implemented to minimize the heat duty for a conventional post-combustion CO2 capture process. An explicit three-parameter vapor-liquid equilibrium (VLE) model is developed. In the VLE model, the solvent is characterized by the absorption heat, indexes for cyclic capacity and absorption capacity. The configuration of these properties is based on typical commercially available solvents. The minimal heat consumption of the optimal solvent is 2.44 MJ/kmol CO2, which is 70 percent of the conventional MEA solvent. Besides, the match relationship between the absorption heat and lean solvent loading is investigated from the view of balance between absorption and regeneration processes.

Aqueous ammonia (NH3) is a promising alternative solvent for the capture of industrial CO2 emissions, given its high chemical stability and CO2 removal capacity, and low material costs and regeneration energy. NH3 also has potential for capturing multiple flue gas components, including NOx, SOx and CO2, and producing value-added chemicals. However, its high volatility and low reactivity towards CO2 limit its economic viability. Considerable efforts have been made to advance aqueous NH3-based post-combustion capture technologies in the last few years: in particular, General Electric's chilled NH3 process, CSIRO's mild-temperature aqueous NH3 process and SRI International's mixed-salts (NH3 and potassium carbonate) technology. Here, we review these research activities and other developments in the field, and outline future research needed to further improve aqueous NH3-based CO2 capture technologies.

An adsorbent for post-combustion carbon dioxide capture was prepared using low-cost and sustainable natural zeolite coated with chitosan. An optimum adsorbent was identified from 3 levels of particle size of natural zeolite and 10 levels of chitosan loading. The optimum adsorbent was characterized using infrared spectroscopy, scanning electron microscopy, thermal gravimetric analysis and differential scanning calorimetry. The chemical and thermal properties of the adsorbent indicated successful coating of chitosan on natural zeolite. The adsorbent registered competitive dynamic adsorption capacity of 0.81 mmol g-1 with good retention, at least, up to 5 adsorption-desorption cycles.

This study investigated the effect of particle size and chitosan loading on the performance of chitosan-coated natural zeolite adsorbent in post-combustion carbon dioxide capture. The adsorbents were prepared in 3 levels of average particle size (0.75 mm, 1.5 mm and 2 mm) of natural zeolite and 4 levels of chitosan loading (0, 15, 30 and 45 wt% of natural zeolite) using a simple coating procedure. The adsorbents were characterized using infrared spectroscopy, scanning electron microscopy, thermal gravimetric analysis, and differential scanning calorimetry. The capture performance of the adsorbent was measured in terms of breakthrough time. The change in chemical properties, surface morphology and thermal characteristics of natural zeolite confirms the successful coating of chitosan. The mean breakthrough time increases with decreasing particle size and increasing chitosan loading up to 15 wt% of natural zeolite.

A new and robust generation-2 light-responsive MOF with UiO-66 topology applicable for post combustion CO2 capture has been successfully synthesized and is described in this article. Azo-UiO-66 shows a satisfactory performance for CO2/N2 separation as observed through high CO2/N2 selectivity. Furthermore, due to the presence of azobenzene groups, Azo-UiO-66 also exhibits a very efficient CO2 photoswitching uptake, a characteristic that has never been observed in any generation-2 light-responsive MOF. Combined together with its robust character, this makes Azo-UiO-66 a promising candidate for highly selective and low energy CO2 capture applications. To further apply this material, Azo-UiO-66 was incorporated in Matrimid to form mixed matrix membranes (MMM). Composites with up to 20 wt% of Azo-UiO-66 were fabricated and tested. The resulting MMM showed increased performance in terms of CO2 permeability and CO2/N2 selectivity compared with the similar MOF-based MMM composites. This then shows another promising application of Azo-UiO-66 as a filler to enhance polymeric membrane performance for CO2 separation.

Solid-state synthesis ensures a high loading and well-dispersed growth of a large collection of metal–organic framework (MOF) nanostructures within a series of commercially available mesoporous silica. This approach provides a general, highly efficient, scalable, environmentally friendly, and inexpensive strategy for shaping MOFs into a fluidized form, thereby allowing their application in fluidized-bed reactors for diverse applications, such as CO2 capture from post-combustion flue gas. A collection of polyamine-impregnated MOF/SiO2 hybrid sorbents were evaluated for CO2 capture under simulated flue gas conditions in a packed-bed reactor. Hybrid sorbents containing a moderate loading of (Zn)ZIF-8 are the most promising sorbents in terms of CO2 adsorption capacity and long-term stability (up to 250 cycles in the presence of contaminants: SO2, NOx and H2S) and were successfully prepared at the kilogram scale. These hybrid sorbents demonstrated excellent fluidizability and performance under the relevant process conditions in a visual fluidized-bed reactor. Moreover, a biochemically inspired strategy for covalently linking polyamines to MOF/SiO2 through strong phosphine bonds has been first introduced in this work as a powerful and highly versatile post-synthesis modification for MOF chemistry, thus providing a novel alternative towards more stable CO2 solid sorbents.

Amine-functionalized solid adsorbents have significant application potential in post-combustion CO2 capture due to the advantages of high capacity, low regeneration cost and long-term stability. Although the powdery adsorbents exhibit higher CO2 uptake capacity, the poor strength and large pressure drop limit their practicability. Monolithic adsorbent is considered as a good choice to solve these problems, but still facing the bottle-neck of insufficient CO2 capacity. In this work, a facile and feasible gel-casting method was proposed to fabricate monolithic adsorbents with high CO2 capacity, excellent mechanical strength, and good cycling stability. MCM-41 with rich mesoporous structure was immobilized by polymerization of organic polymer to construct monolithic adsorbents supports with high specific surface area (~1088 m2 g−1) and mechanical strength. The 70T-MM-550 monolithic adsorbent impregnated with TEPA achieved high adsorption capacity of 151.1 mg g−1 at 75 ℃ under 1 atm pure CO2. The monolithic adsorbents also showed good reversibility of CO2 adsorption under mild conditions, where the adsorption capacity decreased only by 2.8% after five regeneration cycles. In addition, the radial and axial compressive strength of 70T-MM-550 is over 200 N cm−1 and 4.5 MPa, respectively. In consideration of the high CO2 capture performance and mechanical properties of the monolithic adsorbents, the findings here open a new avenue for designing efficient monolithic CO2 adsorbents with industrially potential.

The research conducted in the last five years can potentially paint a picture of the next generation’s research related to solvent development for post-combustion carbon dioxide capture. This paper presents a comprehensive summary of the research work in this field conducted in the period from 2015 to 2020. The work includes research efforts in the areas of: (i) solvent chemistry, which refers to the work conducted on solubility, reaction kinetics, nuclear magnetic resonance or NMR analysis for ion speciation, and alternative solvents, (ii) development of amine solvents, which includes development of catalyst and enhancement of current solvents with the aid of catalysts, (iii) a novel regeneration process called Electrochemically Mediated Amine Regeneration, and (iv) applications of artificial intelligence technologies to the carbon dioxide capture process. The paper can be considered an update discussion and summary of the research work conducted in diverse areas related to solvent development for post-combustion carbon dioxide capture since our review of the research area published in 2015.

The absorption/desorption performance of carbon dioxide (CO2) in aqueous 5 M monoethanolamine (MEA) solutions in the presence of various solution regeneration promoters was comprehensively investig...

The energy consumption associated with absorbent regeneration remains the most critical challenge for the industrial implementation of chemisorption based CO 2 capture processes. Aimed at reducing the energy consumption, this paper proposes a promising process modification of the ammonia (NH 3 ) based CO 2 capture process that involves an advanced flash stripper with a cold rich split. We investigated the techno-economic performance of the advanced NH 3 process integrated with a 650 MW coal-fired power plant, and evaluated it technical and energy performance using a rigorous, rate-based model in Aspen Plus. A sensitivity study was also performed to optimise the modelling parameters, i.e. the stripper pressure and the absorbent NH 3 concentration, and minimize the regeneration duty. A very competitive regeneration duty of 1.86 MJ/kg CO 2 was achieved for an optimised stripper pressure of 12 bar and an NH 3 concentration of 10.2 wt%, with a total equivalent work of 0.164 MW h/t CO 2 for absorbent pumping, NH 3 regeneration and CO 2 compression. We also used a validated economic model to estimate the capital investment of the advanced NH 3 process and its corresponding economic performance. With its significant reduction in energy consumption, the proposed process was economically competitive with CO 2 avoided cost was as low as US$40.7/t CO 2 . This was 34% and 44% less than the reference NH 3 and monoethanolamine (MEA) processes, respectively. The advanced NH 3 based flash stripper also had technical and economic advantages over other amine absorbents, such as MEA and piperazine (PZ), as well as other advanced stripper modifications, such as inter-heating process, revealing its process viability in commercial application.

Gas-fired industrial furnaces are used for heat-treatment of semi-finished steel products. The required energy is provided by gas-fired burners, which are supplied by fuel and air. The combustion is often realized fuel rich to avoid scale formation at the product surface. Thus, the flue gas contains unburnt products, which are oxidized in a post combustion chamber by adding fresh air. The control of the volume flow of air to the post combustion chamber is a crucial task because the flue gas leaving the furnace must not contain unburnt products. For this control task, a two-degrees-of-freedom control strategy based on differential flatness in combination with a MIMO-PI controller is proposed. The basis for the control design is a first-principles mathematical model of the air supply circuit and the combustion of flammable products. The model is validated by means of measurement data from a real plant.

Comparison of ProTreat ® simulations to data obtained from testing ION's advanced solvent at the NCCC facility demonstrated excellent agreement between process simulations and process telemetry. ProTreat ® simulations created and executed to resemble test conditions during ION's testing campaign at NCCC converged with good accuracy. The models predicted temperature profiles for absorption and stripping columns the were directly compared with real data and served to evaluate the accuracy of the simulations. Lean and rich solvent loading predictions using ProTreat ® were within 6% (mass/mass) of measured results. The software-generated temperature profiles in the absorber and stripper yielded variances of less than 5 °F (2 °C) at any height of the packing across all periods of evaluation with real data. Comparing ProTreat ® simulations with actual process data has provided confidence in using ProTreat ® as a viable method for predicting ION's proprietary solvent's gas treating capabilities.

Siloxanes present in small concentrations in biogas interfere with the operation of biogas-to-energy facilities. During biogas combustion, siloxanes form white deposits on engine components (engine heads, spark plugs, valves) in crystals or amorphous forms depending on the temperature. The purpose of this study was to evaluate the economic feasibility of biogas-to-energy systems for managing the operational challenges due to siloxanes in biogas. The facility maintenance cost data were compiled by a survey of biogas-to-energy facilities in the United States. Economic analyses were performed to compare the operational costs due to increased maintenance for removing the white deposits forming on the engine components and the installation of a pretreatment system (carbon adsorption) to remove siloxanes prior to combustion. Numerical analyses showed that for the facilities with operating capacities less than 1300 m3/h (750 scfm), the costs for installation and operation of the carbon adsorption system exceeded the maintenance costs for removal of deposits from the engine components. The maintenance costs correlated well with the reported maintenance needs which were between 120 and 800 man hours per year. On the basis of siloxane removal costs alone, it is not economically feasible to install a carbon adsorption system for siloxane removal prior to combustion for small facilities processing less than 1300 m3/h (750 scfm) of biogas. However, using a process for siloxane removal prior to gas engines (e.g., carbon adsorption) would be improve the overall performance of the gas engines and reduce maintenance need at all facilities.

In the current work five different solvent blends are experimentally studied and the reboiler duties are calculated using the so-called short-cut method. Tertiary amines, 2-(diethylamino)ethanol (DEEA), 3-(Diethylamino)-1,2-propanediol (DEA-12PD), 2-[2-(Diethylamino)ethoxy]ethanol (DEA-EO), 1-(2-Hydroxyethyl)piperidine (12HE-PP) are blended with 3-(Methylamino)propylamine (MAPA) and ethanolamine (MEA). The first results from simple solvent screening are given and the cyclic capacities are calculated based data at 40 °C and 80 °C. Then, five solvent systems are chosen for vapor–liquid equilibrium characterization. The vapor–liquid equilibrium data are then used to estimate cyclic capacities at more realistic temperatures, between 40 °C and 120 °C and by using a short-cut method proposed in the literature the reboiler duties of the characterized solvents are estimated. Finally, the potential of the studied systems is discussed. Several of the characterized blends showed reboiler duties around 2.5 . © 2019, Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license.

Many studies have been carried out to understand the mechanism of solvents degradation. For MEA, different kinds of degradation have been identified: MEA oxidative degradation related to the presence of oxygen in flue gas, thermal degradation due to high temperature in the stripper and a third mechanism of degradation due to the presence of contaminant (NOx, SOx, etc) in the combustion flue gas. The goal of this study is to identify the impact of the presence of SO2 on MEA oxidative degradation.

In order to study the effect of CO2 loading on the physical properties of non-aqueous organic solvents, the secondary amine diethanolamine (DEA) was studied in 1-Propanol. The effect was reported in terms of viscosity, density and CO2 loading; their trends were obtained based on timely basis. Three different concentrations of DEA in 1-Propanol were tested to show the effect of amine concentration on the measured properties. The considered concentrations were of 2, 3.5 and 5M at room conditions. All three concentrations showed solid formation beyond their maximum CO2 capacity where a biphasic behaviour was observed for 3.5 M and 5 M. Furthermore, the trend for the measured properties were of increasing pattern for all concentrations until the solid formation point, where after this point the readings fluctuated. All of the investigated concentrations showed losses that were ~11 w.t% of 1-Propanol. For comparison reasons, also 30 w.t% of aqueous DEA was studied in the same manner and better CO2 loadings were obtained for all the studied non-aqueous systems. The aqueous secondary amine showed a maximum loading of 31 (mg CO2/g sample) where the 2 M DEA in 1-Proponol showed a comparable maximum capacity of 35 (mg CO2/g sample) with the viscosity and density of 9.28 cP and 0.91 g/mL, respectively. It is noteworthy that this loading in the non-aqueous medium was obtained using a lower amount of DEA than in aqueous solution. Out of the three studied concentrations, the secondary amine DEA in 1-Propanol, showed leading results with the 3.5 M concentration, in which its viscosity was 35.68 cP for 74 (mg CO2/g sample) as a loading and 0.93 g/mL of density. It was observed that flowing CO2 beyond this point leads to solid formation within the 3.5 M solvent system; biphasic behaviour. With this, the 3.5 M system can be advised to be further studied for post-combustion CO2 capture.

A blend of 2-Amino-2-methyl-1-propanol (AMP)/ Piperazine (Pz), known as the CESAR 1 solvent, has been widely studied in different aspects like physical, transport and thermal properties; kinetic, mass transfer properties and equilibrium properties. The solvent has shown a potential to be better than the benchmarking solvent 30 mass% MEA. In this work, we report on an e-NRTL model for the system and compare with experimental data. Further, results from an aerosol growth model are presented. This is important to understand the performance of the solvent with regard to emissions.

Aqueous ammonia (NH3)-based capture process has the potential to simultaneously remove NOx/SO2/CO2 pollutants at low cost, but conventional NH3-based process suffers high NH3 slip, high energy consumption and high capital investment. The present study aims to advance the NH3-based scrubbing technology to overcome these technical issues. We used inter-cooled CO2 absorber to mitigate the NH3 emission and enhance CO2 absorption, while employed advanced flash stripper configuration to significantly decrease the absorbent regeneration duty. We also proposed an effective NOx/SO2 removal process by utilizing the slipped NH3 for multi-pollutant emission control. A validated model was used to gain insight into the techno-economic performance of this advanced NH3-based NOx/SO2/CO2 removal process, and important process parameters such as absorption temperature, NH3 concentration and flue gas NOx/SO2 concentrations were investigated in detail. The results indicate that the advanced NH3 process enabled great capital saving by 23% and energy saving by 42%, resulting in a low CO2-avoided cost of US$44.3/t CO2, which is 42.8% lower than the baseline NH3 process.

This paper presented a comparative study of monoethanolamine (MEA) and diethanolamine (DEA) for post-combustion CO2 capture (PCC) process with different process configurations to study the interaction effect between solvent and process. The steady state process model of the conventional MEA-based PCC process was developed in Pro/II® and was validated with the experimental data. Then ten different process configurations were simulated for both MEA and DEA. Their performances in energy consumption were compared in terms of reboiler duty and total equivalent work. The results show that DEA generally has better thermal performances than MEA for all these ten process configurations. Seven process configurations provide 0.38%–4.61% total energy saving compared with the conventional PCC process for MEA, and other two configurations are not favourable. For DEA, except one configuration, other process configurations have 0.27%–4.50% total energy saving. This work also analyzed the sensitivities of three key parameters (amine concentration, stripper pressure and lean solvent loading) in conventional process and five process modifications to show optimization strategy.

Potassium carbonate supported on alumina is used as a solid sorbent for CO2 capture at low temperatures. However, its CO2 capture capacity decreases immediately after the first cycle. This regeneration problem is due to the formation of the by-product [KAl(CO3)(OH)2] during CO2 sorption. To overcome this problem, a new regenerable potassium-based sorbent was fabricated by CO2 thermal treatment of sorbents prepared by the impregnation of δ-alumina with K2CO3 in the presence of 10 vol% CO2 and 10 vol% H2O. The CO2 capture capacities of the new regenerable sorbents were maintained over multiple CO2 sorption tests. These results can be explained by the fact that the sorbent prepared by CO2 thermal treatment did not form any by-product during CO2 sorption. Based on these results, we suggest that the regeneration properties of potassium-based sorbents using δ-alumina could be significantly improved by the use of the CO2 thermal treatment developed in this study.

Thiourea was selected as representative of combined S- and N-inhibitors and injected after the post-combustion zone of two full-scale municipal solid waste incinerators (MSWIs) using a dedicated feeder. Firstly, the operating conditions were scrutinised by monitoring the concentrations of SO2, NH3 and HCl in the clean flue gas. The suppression experiment showed that in MSWI A thiourea could reduce the total I-TEQ value in flue gas by 73.4% from 1.41 ng I-TEQ/Nm3 to 0.37 I-TEQ/Nm3, those in fly ash by 87.1% from 14.3 ng I-TEQ/g to 1.84 I-TEQ/g and the total dioxins emission factor by 87.0 wt.%, with a (S + N)/Cl molar ratio of 9.4. The suppression efficiencies of PCDD/Fs in flue gas and fly ash in MSWI B could be up to 69.2% and 83.0% when the (S + N)/Cl molar ratio attained 7.51. Furthermore, the congener distributions of dioxins were also analysed in the flue gas and fly ash, before and after addition of thiourea, to find cues to some suppression mechanism. In addition, the filtered fly ash was explored by the Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) analysis of fly ash. These results suggest that poisoning the metal catalyst and blocking the chlorination are most probably responsible for suppression.

The market of solar-assisted post-combustion CO2 capture (SPCC) is emerging globally in recent years. It is considered as a promising technology to apply the ammonia as the absorbent to implement the SPCC technology in view of its low regeneration temperature and low regeneration heat duty. However, few literatures indicate which type of solar thermal collectors (STCs) involved in the ammonia-based SPCC power plant is more applicable. Therefore, in this paper, the maximum theoretical potential price of STCs which make the value of the levelized costs of electricity (LCOE) and the cost of CO2 removed (COR) lower than that of the reference post-combustion CO2 capture (PCC) power plant is estimated. The potential of ammonia-based SPCC technology in the selected locations is also estimated, based on the detailed solar radiation resource assessment (i.e. DNI, sunshine time) and the STCs performance. It would be more attractive to adopt the vacuum tube (VT) as the STC involved into the ammonia-based PCC power plant to capture CO2 than parabolic trough collector (PTC). In order to achieve lower LCOE and COR than that of the reference PCC system, the price of the vacuum tube (VT) has to be reduced to 131.02 $/m2, 91.76 $/m2 and 57.10 $/m2 for the location of M1(Lhasa), M2(Tianjin) and M3(Xi’an), respectively. And the price of the parabolic trough collector (PTC) has to be reduced to 139.09 $/m2, 89.83 $/m2 and 50.84 $/m2, respectively.

In an effort to reduce the overall energy penalty and capital expenditure associated with carbon capture technologies, a variety of porous solid adsorbents have been developed. The limitations of solid sorbent in large-scale process are related to its CO2 uptake, physicochemical stability, lifecycle, regenerability and operation condition. In this paper, siliceous foam materials were synthesized via a modified microemulsion templating method and functionalized with branched polyethylenimine (PEI). The physical characteristics of synthesized silica adsorbents under different aging conditions were analysed via N2 sorption analysis and Scanned Electron Microscopy (SEM) morphological analysis. CO2 uptake was evaluated by thermogravimetric analyser (TGA). The results show that CO2 uptake is desirable even under low CO2 partial pressure and is predictable with multiple linear regression (MLR) model in the range of examined materials.

Post-combustion CO2 capture (PCC) is considered the most feasible and viable process for CO2 abatement in the power sector. Aqueous monoethanolamine (MEA) solvent, traditionally used in this process, brings along challenges, namely, huge energy requirement for solvent regeneration, huge solvent flow rate leading to large equipment sizes, and chemical and thermal degradability, among others. In this study, the prospects of replacing aqueous MEA solvent with a blend of ionic liquid (IL) and MEA are explored. IL is generally chemically and thermally stable among other encouraging properties but is however expensive. A blend of IL and MEA is predicted to have shared qualities of MEA and IL and therefore could hypothetically contribute to meaningful reduction in overall cost of the process.

Capturing CO2 from post-combustion flue gas is one of the major solutions to CO2 abatement in global warming and climate change. Potassium-based solid sorbents are confirmed as promising means for this purpose. To dispose of the substantive flue gas, the CO2 capture process should be cost-effective. In this work, a novel K2CO3/PF sorbent was prepared by impregnation of potassium carbonate (K2CO3) on potassium feldspar (PF). The synthesized sample was characterized by X-ray fluorescence (XRF), field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). The CO2 sorption behaviors of K2CO3/PF were evaluated in a fixed-bed reactor in simulated flue gas composition of 60 °C, 5% CO2, and 10% H2O. The sorbent regeneration behaviors were also investigated in a N2 atmosphere at 550 °C with a ramping rate of 10 °C/min. Further insights were focused on the reaction pathway and multiple cycle behaviors of the sorbent in 10 CO2 sorption–desorption tests. The CO2 sorption capacity of K2CO3/PF is c...

This work evaluates the viability of a two-stage process using combined nitrogen (N2)-selective and carbon dioxide (CO2)-selective membranes for post-combustion CO2 capture. A novel type of cellulose acetate (CA) hybrid membrane is used here as a N2-selective membrane. The silica functionalized with p-tetranitrocalix[4]arene (Si–CL) was incorporated into the CA matrix, thereby resulting in a CA/Si–CL hybrid membrane. Moreover, the published permeation data of a CO2-selective fixed-site-carrier (FSC) membrane, i.e., polyvinylamine (PVAm) casted on porous polysulfone (PSf), is used here in a simulation study to serve as a second stage membrane. Although experimental work on the CA/Si–CL hybrid membrane is in progress based on the assumptions of initial appreciable results, a two-stage membrane process is proposed in which a N2-selective membrane is placed in the first stage, while a CO2-selective membrane is placed in the second stage. Subsequently, the techno-economic analysis of a two-stage membrane proce...

International audience; Aqueous ammonia is well known to be a substitute of MEA solvent for absorbing CO2 in post-combustion process. However, aqueous ammonia is highly volatile it can become gaseous and leaves the absorption column with the treated gas. Several processes that use ammonia solution as solvent deal with this problem. The use of membrane contactor could limit ammonia loss and could widen the operative ranges of temperature, pressure and ammonia concentration. This paper aims at evaluating and comparing different methods to capture CO2 by ammoniac. The evaluation of all process has demonstrated a high CO2 removal efficiency.

In recent decades, the accelerating economic and social developments have led to exponentially increasing emissions of carbon dioxide (CO2) into the atmosphere. As a result, much research efforts have been directed toward more effective measures for the carbon capture and storage (CCS). In this review, we first briefly described the general background on the various techniques available for the abatement of CO2 emissions worldwide. Then, we provided an in-depth discussion regarding the two comparable control technologies, i.e., the amine- vs. ammonia-based capture approaches; ammonia has lower energy costs than monoethanolamine (MEA). The applicability of each method was described further with an emphasis on their advantages and disadvantages. We also briefly discussed the available options for post-absorption processing such as recovery of absorbed CO2, compression, and storage. Many immobilized amines as adsorbents can only be regenerated a few times or are a ‘once-through process’. This may deplete the global supply of those materials if CCS is scaled up in excess of Mton CO2 captured per year. Ideally, the captured CO2 should be isolated from the atmosphere indefinitely and/or photochemically reduced (either biologically or industrially). Finally, we explored future challenges in this field of study to envision and suggest more optimized solutions.

An important process consideration in ammonia-based, post-combustion CO2 capture is the volatility of ammonia. Consequently, there is a need to adopt control measures to minimize the emission (the slip) of ammonia from such processes. This work evaluates techno-economic aspects of methods to reduce the ammonia slip. The emission of ammonia is required to be below 10 ppm while the ammonia slip from the absorber in an ammonia-based process may exceed 10%. The ammonia control methods that are evaluated in this work are staged absorption, ammonia abatement cycle, chilled absorption and acid wash. The control methods are also evaluated with respect to local conditions, such as cooling water temperature and flue gas CO2 concentration. Rate- and equilibrium-based thermodynamic modelling forms the basis for the evaluation process. A simplified economic estimation method is used to evaluate the utility cost of ammonia control designs under different operating conditions. The economic estimation shows that for the best case conditions the utility cost are as low as 1.5(sic)/tCO(2). However, the cost of the ammonia control may be more than tenfold when the available cooling water temperature is increased (>5 degrees) or when the flue gas CO2 concentration is decreased (