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Lime mud, a kind of industrial waste that produced in paper mill, was proposed as CO2 sorbent in calcium looping process. The carbonation performance of the lime mud was investigated in a dual‐fixed bed reactor (DFR) and a thermogravimetric analyzer (TGA). The carbonation kinetics of the lime mud in the chemical reaction controlled stage was analyzed by a surface reaction‐controlled kinetic model. The results show that the lime mud presents much poorer carbonation performance during the chemical reaction controlled stage compared with the limestone, mainly due to the high content of chlorine in the lime mud. A prewash treatment process was used to decrease the chlorine content to mitigate the sintering of the lime mud when calcined at high temperature. After prewash treatment, the prewashed lime mud shows much higher CO2 capture capacity during the chemical reaction controlled stage compared with the lime mud. A prolonged carbonation process successfully further enhances the microstructure and improves the carbonation performance of the prewashed lime mud in the chemical reaction controlled stage. The lime mud can be effectively used as CO2 sorbent in calcium looping process after prewash treatment and the following prolonged carbonation treatment.

The rapidly rising level of carbon dioxide in the atmosphere resulting from human activity is one of the greatest environmental problems facing our civilization today. Most technologies are not yet sufficiently developed to move existing infrastructure to cleaner alternatives. Therefore, techniques for capturing carbon dioxide from emission sources may play a key role at the moment. The structure of the UiO‐66 material not only meets the requirement of high stability in contact with water vapor but through the water pre‐adsorbed in the pores, the selectivity of carbon dioxide adsorption is increased. We successfully applied the recently developed methodology for water adsorption modelling. It allowed to elucidate the influence of water on CO2 adsorption and study the mechanism of this effect. We showed that water is adsorbed in octahedral cage and stands for promotor for CO2 adsorption in less favorable space than tetrahedral cages. Water plays a role of a mediator of adsorption, what is a general idea of improving affinity of adsorbate. On the basis of pre‐adsorption of methanol as another polar solvent, we have shown that the adsorption sites play a key role here, and not, as previously thought, only the interaction between the solvent and quadrupole carbon dioxide. Overall, we explained the mechanism of increased CO2 adsorption in the presence of water and methanol, as polar solvents, in the UiO‐66 pores for a potential post‐combustion carbon dioxide capture application., MOF trap: We successfully applied a recently developed methodology for water adsorption modelling that allows to elucidate the influence of water on CO2 adsorption and study the mechanism of this effect. We show that water is adsorbed in octahedral cage and stands for promotor for CO2 adsorption in less favorable space than tetrahedral cages. We explain the mechanism of increased CO2 adsorption in the presence of water and methanol, as polar solvents, in the UiO‐66 pores for a potential post‐combustion carbon dioxide capture application.

Recently, the capture of carbon dioxide (CO2) using alkaline waste and byproducts has garnered considerable interest. Construction sludge may be categorized as alkaline waste, as it often exhibits high alkalinity during its generation or intermediate treatment. Hence, researchers have attempted to accelerate pH neutralization and recycle alkaline construction sludge by curing it under a high CO2 concentration. By exposing concentrated CO2 gas to an alkaline sludge, cement hydrates such as calcium hydroxide and calcium–silicate–hydrate gels form calcium carbonate (CaCO3). Subsequently, the generation of CaCO3 is expected to reduce the pH of the sludge. However, the amount of CO2 captured in sludge has not been investigated extensively, unlike those of other alkaline wastes. Therefore, the amount of CO2 captured in alkaline sludge that is associated with pH neutralization is evaluated in this study. It is demonstrated that accelerated carbonation tests using a CO2 incubator and carbonate content evaluation tests based on the gas pressure method successfully reveal the amount of CO2 captured in the alkaline sludge that is associated with pH neutralization. Additionally, the test results show that the amount of mCO2 (i.e., the amount of CO2 captured per 1 g of dry mass of alkaline sludge) increases with ΔpH (ΔpH is the difference between the initial pH and the pH after the alkaline sludge is neutralized). A maximum of 0.021 g of CO2 is captured per 1 g of dry mass of alkaline sludge when the addition ratio of quicklime AQL = 3% and 0.040 g when AQL = 6%. The CO2 capture ratio mCO2/mCO2max, which represents the ratio of CO2 captured in the sludge to the maximum capturing capacity, increases with ΔpH. CO2 capture ratios of up to 90.0% and 84.9% are recorded when AQL = 3% and AQL = 6%, respectively. It is discovered that a higher AQL results in a higher mCO2. Moreover, the test results indicate that a higher AQL causes a more significant change in the CO2 capture ratio, even when the pH decreases slightly.

We compare the industrial viability of two emerging technologies for CO2 capture from flue gases, i.e., adsorption in porous commercial zeolites and biomass production by microalgae. Our study is organized in two steps: first, the best system is selected (either zeolite type or microalgae strain). Second, their performance is quantified and their advantages at real conditions discussed. For the physicochemical process, we find that commercial zeolite MFI is the best choice for CO2 capture from a typical industrial flue gas emission. Numerical dual PSA cycle simulations at ambient conditions yield 8 kg m−3 bed h−1 and an energy consumption of 0.987 MJ per kg of captured CO2. As regards the biological process, evaluation of several microalgae strains in continuous mode using low-cost resources (waste water, fertilizers, flue gases), results in Scenedesmus almeriensis as the most promising strain. The maximal capacity of CO2 capture at laboratory conditions was 0.1 kg m−3h−1, allowing to produce up to 0.06 of kg m−3h−1 of biomass (3% maximal photosynthetic efficiency). Although this is a significantly lower value, the produced biomass, being composed by carbohydrates, entails an overall economic yield of 0.6 € m−3·day. To demonstrate reliability at large scale, experiments were performed in a 100 m2 pilot raceway reactor under outdoor conditions. We measured 54 g of CO2/m2·day (=197 tn/ha·year) and a biomass productivity of 21 g/m2·day (=75 tn/ha·year). The energy consumption approaches to 0.48 MJ/kgCO2, lower than zeolites adsorption. Still, zeolites can be advantageous as they offer higher productivity, lower energy consumption than amines-based methods, and possibility of producing added-value chemical products, such as methanol, CO or CH4., This study was carried out with the financial support of Junta de Andalucía, grant FQM 1851 and the company, SETEC. We are grateful for the practical assistance kindly given by the staff of the Las Palmerillas Experimental Station, part of the Cajamar Foundation. Financial support from the Ministry of Economy and Competitiveness of Spain through project CTM2017-84033-R is gratefully acknowledged.

Several industrial activities often result in the emissions of greenhouse gases such as carbon dioxide and methane (a principal component of natural gas). In order to mitigate the effects of these greenhouse gases, CO2 can be captured, stored and utilized for the dry reforming of methane. Various CO2 capture techniques have been investigated in the past decades. This study investigated the performance and process modeling of CO2 capture through calcium carbonate looping (CCL) using local (Malaysia) limestone as the sorbent. The original limestone was compared with two types of oxalic acid-treated limestone, with and without aluminum oxide (Al2O3) as supporting material. The comparison was in terms of CO2 uptake capacity and performance in a fluidized bed reactor system. From the results, it was shown that the oxalic acid-treated limestone without Al2O3 had the largest surface area, highest CO2 uptake capacity and highest mass attrition resistance, compared with other sorbents. The sorbent kinetic study was used to design, using an Aspen Plus simulator, a CCL process that was integrated with a 700 MWe coal-fired power plant from Malaysia. The findings showed that, with added capital and operation costs due to the CCL process, the specific CO2 emission of the existing plant was significantly reduced from 909 to 99.7 kg/MWh.

Biogas is a valuable source of renewable energy produced from biodegradable organic materials via anaerobic digestion. The production of H2 by sorption enhanced steam reforming (SESR) of biogas has been studied thermodynamic and experimentally. A Pd/Ni–Co catalyst and dolomite as CO2 sorbent were used. The effect of biogas composition (CH4/CO2 vol.%) on the process was evaluated at 600 and 650 °C in a fluidized bed reactor using biogas CO2 concentrations of 5–50 vol.%. During conventional biogas steam reforming (SR), high CH4 partial pressures in the feed favor the process, producing high H2 concentrations. During biogas SESR, CO2 was effectively removed from the gas phase by the sorbent for all the biogas compositions, and it did not alter the process compared to pure methane. Steam methane reforming (SMR) and water-gas shift (WGS), together with carbonation, were the main reactions occurring during biogas SESR. Dry (or CO2) methane reforming did not occur under the conditions studied due to the relatively low temperature and the presence of steam. High H2 purity (98.4 vol.%) and H2 yield (91%) were experimentally obtained, pointing out the biogas SESR as a promising technology for the efficient production of high-purity, high-yield hydrogen from a renewable source., The authors thank Franefoss Miljøkalk A/S (Norway) for supplying Arctic dolomite. This work was carried out with financial support from the Spanish MICINN (Project ENE2017-83530-R) and from the Gobierno del Principado de Asturias (PCTI, Ref. IDI/2018/000115), both co-financed by the European Regional Development Fund (ERDF). M.V. Gil acknowledges support from a Ramón y Cajal grant (RYC-2017-21937) of the Spanish government, co-financed by the European Social Fund (ESF). A. Capa acknowledges a fellowship awarded by the Spanish MICINN (FPI program, PRE2018-083634), co-financed by the European Social Fund (ESF).

Improved powders for capturing CO2 at high temperatures are required for H2 production using sorption‐enhanced steam reforming. Here, we examine the relationship between particle structure and carbonation rate for two types of Na2ZrO3 powders. Hollow spray‐dried microgranules with a wall thickness of 100–300 nm corresponding to the dimensions of the primary acetate‐derived particles gave about 75 wt % theoretical CO2 conversion after a process‐relevant 5 min exposure to 15 vol % CO2. A conventional powder prepared by solid‐state reaction carbonated more slowly, achieving only 50 % conversion owing to a greater proportion of the reaction requiring bulk diffusion through the densely agglomerated particles. The hollow granular structure of the spray‐dried powder was retained postcarbonation but chemical segregation resulted in islands of an amorphous Na‐rich phase (Na2CO3) within a crystalline ZrO2 particle matrix. Despite this phase separation, the reverse reaction to re‐form Na2ZrO3 could be achieved by heating each powder to 900 °C in N2 (no dwell time). This resulted in a very stable multicycle performance in 40 cycle tests using thermogravimetric analysis for both powders. Kinetic analysis of thermogravimetric data showed the carbonation process fits an Avrami–Erofeyev 2 D nucleation and nuclei growth model, consistent with microstructural evidence of a surface‐driven transformation. Thus, we demonstrate that spray drying is a viable processing route to enhance the carbon capture performance of Na2ZrO3 powder.

Metal-organic frameworks (MOFs) are emerging materials for luminescent and photochemical applications. Armed with femto to millisecond spectroscopies, and fluorescence microscopy, the photobehaviors of two Ce-based MOFs are unravelled: Ce-NU-1000 and Ce-CAU-24-TBAPy. It is observed that both MOFs show ligand-to-cluster charge transfer reactions in ≈100 and ≈70 fs for Ce-NU-1000 and Ce-CAU-24-TBAPy, respectively. The formed charge separated states, resulting in electron and hole generation, recombine in different times for each MOF, being longer in Ce-CAU-24-TBAPy: 1.59 and 13.43 µs than in Ce-NU-1000: 0.64 and 4.91 µs. The linkers in both MOFs also undergo a very fast intramolecular charge transfer reaction in ≈160 fs. Furthermore, the Ce-NU-1000 MOF reveals excimer formation in 50 ps, and lifetime of ≈14 ns. The lack of this interlinkers event in Ce-CAU-24-TBAPy arises from topological restriction and demonstrates the structural differences between the two frameworks. Single-crystal fluorescence microscopy of Ce-CAU-24-TBAPy shows the presence of a random distribution of defects along the whole crystal, and their impact on the observed photobehavior. These findings reflect the effect of linkers topology and metal clusters orientations on the outcome of electronic excitation of reticular structure, key to their applicability in different fields of science and technology, such as photocatalysis and photonics. ispartof: ADVANCED SCIENCE vol:6 issue:19 ispartof: location:Germany status: published

In this work, a novel hydrogen production process (Integrated Chemical Looping Water Splitting “ICLWS”) has been developed. The modelled process has been optimised via heat integration between the main process units. The effects of the key process variables (i.e. the oxygen carrier-to-fuel ratio, steam flow rate and discharged gas temperature) on the behaviour of the reducer and oxidiser reactors were investigated. The thermal and exergy efficiencies of the process were studied and compared against a conventional steam-methane reforming (SMR) process. Finally, the economic feasibility of the process was evaluated based on the corresponding CAPEX, OPEX and first-year plant cost per kg of the hydrogen produced. The thermal efficiency of the ICLWS process was improved by 31.1% compared to the baseline (Chemical Looping Water Splitting without heat integration) process. The hydrogen efficiency and the effective efficiencies were also higher by 11.7% and 11.9%, respectively compared to the SMR process. The sensitivity analysis showed that the oxygen carrier–to-methane and -steam ratios enhanced the discharged gas and solid conversions from both the reducer and oxidiser. Unlike for the oxidiser, the temperature of the discharged gas and solids from the reducer had an impact on the gas and solid conversion. The economic evaluation of the process indicated hydrogen production costs of $1.41 and $1.62 per kilogram of hydrogen produced for Fe-based oxygen carriers supported by ZrO2 and MgAl2O4, respectively - 14% and 1.2% lower for the SMR process H2 production costs respectively.

Autothermal Chemical-Looping Reforming (a-CLR) is a process which allows hydrogen production avoiding the environmental penalty of CO2 emission typically produced in other processes. The major advantage of this technology is that the heat needed for syngas production is generated by the process itself. This heat necessary for the endothermic reactions is supplied by a Ni-based oxygen-carrier (OC) circulating between two reactors: the air reactor (AR), where the OC is oxidized by air, and the fuel reactor (FR), where the fuel is converted to syngas. Other important advantage is that this process also allows the production of pure N2 in the AR outlet stream. A renewable fuel such as bioethanol was chosen in this work due to their increasing worldwide production and the current excess of this fuel presented by different countries. In this work, mass and heat balances were done to determine the auto-thermal conditions that maximize H2 production, assuming that the product gas was in thermodynamic equilibrium. Three different types of bioethanol has been considered according to their ethanol purity; Dehydrated ethanol (≈100 vol.%), hydrated ethanol (≈96 vol.%), and diluted ethanol (≈52 vol.%). It has been observed that the higher H2 production (4.62 mol of H2 per mol of EtOH) has been obtained with the use of diluted ethanol and the surplus energy needed could be compensated by the energy save achieved during the purification of ethanol in the production process., This work is partially supported by the Spanish Ministry for Science and Innovation (MICINN project ENE2011-26354), by European Regional Development Fund (ERDF), by the Government of Aragón (Spain, DGA ref. T06) and by CTGAS-ER (project OTT20130989).

Microalgae have drawn the attention of several researchers as an alternative to the traditional physicochemical CO2 capture methods, since they can convert CO2 and water into organic matter and release oxygen into the atmosphere. Microalgal growth can be improved by changing light supply, such as light intensity, wavelength, and photoperiod. In this study, the effect of different light wavelengths on CO2 capture, nutrient removal from a synthetic effluent and biomass production of Chlorella vulgaris, Tetradesmus obliquus and Neochloris oleoabundans was studied. The experiments were conducted with light-emitting diodes (LEDs) with different wavelengths: 380−750 nm (white), 620−750 nm (red) and 450−495 nm (blue). The maximum specific growth rate was obtained by N. oleoabundans with white LEDs (0.264 ± 0.005 d−1), whereas the maximum biomass productivity (14 ± 4 mgdw L−1 d−1) and CO2 fixation rate (11.4 mgCO2 L−1 d−1) were obtained by C. vulgaris (also with white LEDs). Nitrogen and phosphorus removal efficiencies obtained under white light conditions were also the highest for the three studied microalgae.

An electrochemical cell comprising a novel dual‐component graphite and Earth‐crust abundant metal anode, a hydrogen producing cathode and an aqueous sodium chloride electrolyte was constructed and used for carbon dioxide mineralisation. Under an atmosphere of 5 % carbon dioxide in nitrogen, the cell exhibited both capacitive and oxidative electrochemistry at the anode. The graphite acted as a supercapacitive reagent concentrator, pumping carbon dioxide into aqueous solution as hydrogen carbonate. Simultaneous oxidation of the anodic metal generated cations, which reacted with the hydrogen carbonate to give mineralised carbon dioxide. Whilst conventional electrochemical carbon dioxide reduction requires hydrogen, this cell generates hydrogen at the cathode. Carbon capture can be achieved in a highly sustainable manner using scrap metal within the anode, seawater as the electrolyte, an industrially relevant gas stream and a solar panel as an effective zero‐carbon energy source.

The main drawbacks of developing carbon adsorbents from pine sawdust, an abundant biomass feedstock, are the low carbon yield of the process and the poor mechanical properties of the resulting carbons. In an attempt to overcome these limitations, the effect of the addition of coal tar pitch was assessed. Adsorbent pellets were produced from pine sawdust and coal tar pitch by activation with CO2. The preparation process was optimized by using as decision variables the carbon yield and the adsorption performance of the adsorbents in conditions representative of post-combustion capture applications (10% CO2 at atmospheric pressure and at 50 °C). Subjecting the composite pellets to a pre-oxidation treatment with air increased the carbon yield of the production process, and also improved the adsorption kinetics and capacity of the final adsorbents. The prepared adsorbents present a high carbon yield, a superior mechanical resistance and a competitive adsorption performance., This work was carried out with financial support from the Spanish MINECO (Project ENE2011-23467), co-financed by the European Regional Development Fund (ERDF). M.G.P. acknowledges funding from the CSIC (JAE-Doc program), co-financed by the European Social Fund, and I.D. acknowledges funding from the Government of the Principado de Asturias. The authors are grateful to Industrial Química del Nalón S.A. for supplying the coal tar pitch sample.

Recently, the capture and storage of CO2 have attracted research interest as a strategy to reduce the global emissions of greenhouse gases. It is crucial to find suitable materials to achieve an efficient CO2 capture. Here we report our study of CO2 adsorption on boron-doped C60 fullerene in the neutral state and in the 1e−-charged state. We use first principle density functional calculations to simulate the CO2 adsorption. The results show that CO2 can form weak interactions with the BC59 cage in its neutral state and the interactions can be enhanced significantly by introducing an extra electron to the system.

Anaerobic digestion model No.1 (ADM1) was applied and expanded in this study to model and simulate anaerobic digestion (AD) of an industrial carbon capture reclaimer MEA (monoethanolamine) waste (MEAw) together with easily degradable organics. The general structure of ADM1 was not changed except for introducing state variables of MEA and complex organics (CO) in the waste and biochemical reactions of MEA uptake and CO hydrolysis in the model ADM1_MEAw. Experimental batch test results were used for calibrating kinetics variables. The obtained kinetics were employed in the ADM1_MEAw to simulate semi-continuously fed experimental test for 486 days at room temperature (22 +/- 2oC). The validation results show that the ADM1_MEAw was able to predict the process performance with reasonable accuracy, including process pH, biogas generation and inorganic nitrogen concentrations, for a wide range of feed scenarios. Free ammonia inhibition, was observed to be the main inhibitory effects on acetoclastic methanogenesis, leading to volatile fatty acids (VFA) accumulation at high loads. Inhibition assumed to be caused by potentially toxic constituents of MEAw appears to be much less important than ammonia, suggesting that such constituents were broken down by AD.

The overall objective of the test program at CO2 Technology Centre Mongstad (TCM DA) is to verify Aker Solutions’ Advanced Carbon CaptureTM process including two proprietary advanced amine solvents, ACCTM-solvents S21 and S26. Also a short benchmark campaign is conducted with 30% MEA solvent in order to establish a reference. Key performance results are presented for MEA, S21 and S26. Close to 10 000 hours of operation of the TCM DA amine plant was obtained in the three campaigns, with high availability, showing that there are no operational issues related to the S21 and S26 solvents. Optimum SRD for 30 wt% MEA was found to be 3.8 MJ/kg CO2 when capturing CO2 from CHP gas with CO2 concentration 3.4-4.0% and CO2 capture rate of 87%. SRD was found to be approximately 10% lower for ACCTM advanced solvents S21 and S26. SRD values down to 3.4 MJ/kg CO2 was obtained for CHP flue gas with CO2 concentrations below 4 vol% and 87% capture without heat integration or use of ACCTM Energy Saver. Emissions to atmosphere using ACCTM emission control system were shown to be very low for solvent amines and alkyl amines, with measured levels below 0.1 mg/Nm3 in total. Emission of nitrosamines and nitramines were all below analytical detection limits typically around 0.1 μg/Nm3. Solvent amine losses have been quantified to approximately 2.6 kg amine/ton CO2 captured for MEA, 0.5-0.6 kg amine/ton CO2 captured for ACCTM advanced solvent S21, and 0.2-0.3 kg amine/ton CO2 captured for ACCTM advanced solvent S26. Successful reclaiming of ACCTM advanced solvents S21 and S26 was performed towards the end of the campaigns. Reclaiming was performed for validation purposes and not due to any indications of critical loss of solvent performance, high emissions, high viscosity or other operational problems that could be an indication of excessive degradation. No operational problems such as precipitation or fouling were encountered during reclaiming. HSS and most impurities and degradation products were removed from the solvent by more than 80%.

Mineral carbonation is one of the alternatives considered for CO2 sequestration. This consists of inducing the artificial weathering of alkaline minerals to produce stable carbonate solids. This work presents the wet carbonation of lime-rich ashes from the fluidized bed combustion of two different fuels: a Spanish sulfur-rich lignite, with calcium carbonate and quartz as main mineral constituents, and the waste produced during the extraction of the coal. The novelty of the work is its experimental approach, which explores all the variables (pH, temperature, time, liquid to solid ratio, NaCl ratio) from a statistical survey centered on finding optimized conditions that maximize the degree of carbonation. CO2 uptake is determined by direct thermogravimetric tests. The results indicate that high carbonation efficiency (78% efficiency) is achieved for both solids at basic pH and moderate treatment times. Those conditions cause anhydrite to dissolve, increasing the availability of Ca2+ for reprecipitation as carbonate and hydroxide. At neutral pH, 72% conversion efficiency is equivalent to a capture of 8% of the CO2 theoretically emitted in the combustion of coal wastes. The proposed conditions for fly ash carbonation enables rapid CO2 capture that is applicable for upscaling and industrial use., The authors would like to express their gratitude to the Government of Aragon and La Caixa for their financial support of the work through the project DGA-LC-025/2010, and to Carboníferas del Ebro for supplying the fuels used in this work. M.P. Gimeno acknowledges support from the Spanish National Research Council (CSIC) through their JAE-Doc program.

In this work, a high limestone content waste was evaluated as a potential material for CO2 capture. The influence of calcination conditions on the CO2 capture capacity was evaluated using 5 cycles of calcination-hydration-carbonation reactions. A Central Composite Design of Experiments was set using calcination temperatures and time as variables. The response evaluated was the CO2 capture measured by thermogravimetric analysis. The results indicate that both calcination temperature and time influence the CO2 capture capacities in the initial cycles but, after a large number of cycles, the effect becomes less relevant. The optimum calcination temperature did not change significantly between cycles - about 893 °C in the first and 850 °C in the fourth cycle. However, the optimum calcination time decreased from 40.1 min in the first to 22.5 min in the fourth cycle. The maximum CO2 capture capacity declines over the reaction cycles due to the sorbent sintering, which becomes more noticeable. Moreover, the waste used in this work is suitable for separating CO2 from flue gas, achieving more than 0.2 g/g of capture capacity after five cycles.

A process that utilized CO2 recovered from thermal power plant flue gas for methanol production was simulated using Aspen HYSYS V8.4 software. Exergy and economic analyses approaches were used to determine the optimum number of trays in the distillation column for economic operation of the process. The results from both approaches showed that the optimum numbers of trays were 20 and further increase in the number of trays did not yield any significant improvement in the process efficiency and quality of methanol produced. The profitability analysis of the plant showed a payback period of 3 years. The study concluded that locating such plant close to the thermal power plant will mitigate the emission of CO2 by providing onsite utilization for the CO2 emitted and captured from the thermal power plant.Keywords: CO2 capture; methanol production; exergy analysis; economic analysis

The biological production of H2 by dark fermentation is being extensively investigated due to the great potential of the two-phase hydrogen/methane fermentation process for recovering energy from carbohydrate-rich wastes. However, the purification of the bio-hydrogen and biogas obtained is needed to produce high-purity H2 and CH4 streams appropriate for industrial application. In this study, the performance of three activated carbons (No1KCla-600, No1KClb-1000 and No2OS-1000), synthesized from phenol–formaldehyde resins, as potential adsorbents for CO2 capture from bio-hydrogen and biogas streams has been evaluated under dynamic conditions. Adsorption–desorption cycles by means of temperature swings were conducted at ambient temperature and atmospheric pressure with CO2/H2 (40/60 and 70/30 vol.%) and CO2/CH4 (50/50 vol.%) binary gas mixtures in a purpose-built fixed-bed set-up. The performance of the resin-derived carbons to separate CO2 was superior to that of reference commercial carbons in terms of CO2 uptake, breakthrough time and column efficiency. These adsorbents presented high CO2/H2 and CO2/CH4 selectivity values, were easily completely regenerated and did not show capacity decay after multiple cycling. Breakthrough capacities reached 2.11 and 2.03 mmol g−1 at 25 °C for 70/30 CO2/H2 and 50/50 CO2/CH4, respectively. The No2OS-1000 adsorbent, produced from phenol–formaldehyde resin and olive stones (20:80 wt.), gave the greatest values of CO2 capture capacity on a volumetric basis and CO2/CH4 selectivity, which may be advantageous to biogas purification applications because it reduces the size of the necessary equipment., This work was carried out with financial support from the Spanish MINECO (Project ENE2011-23467), co-financed by the European Regional Development Fund (ERDF). N.A.-G. acknowledges a FPI Predoctoral fellowship from the Spanish MINECO, co-financed by the European Social Fund.

Laboratory-scale anaerobic degradation of monoethanolamine waste (MEAw) with co-substrate organics was conducted at room temperature and organic loading rates from 0.19 to 5.03 kg COD/m3 day for 486 days in a hybrid digester. 90 % feed COD conversion to methane was obtained at the lower loads and only 45 % at the highest MEA waste/COD ratio (MEAwr) of 0.62 due to inhibition of methanogenesis. Inhibition at comparable loads decreased with time, implying that the culture adapted to the challenging feed. Methane yield was negatively correlated to MEAwr applied and inhibition avoided at MEAwr

Acknowledgements This paper has received funds from the project PID2019.108826RB. I00 financied by MCIN/ AEI /10.13039/501100011033. Funding for open access charge: Universidad de Granada / CBUA. Our gratitute to Prof. Fernando Gonz ́alez-Caballero for his support and fruitful com- ments during the preparation of the manuscript., In circular economy, useful plastic materials are kept in circulation as opposed to being landfilled, incinerated, or leaked into the natural environment. Pyrolysis is a chemical recycling technique useful for unrecyclable plastic wastes that produce gas, liquid (oil), and solid (char) products. Although the pyrolysis technique has been extensively studied and there are several installations applying it on the industrial scale, no commercial applications for the solid product have been found yet. In this scenario, the use of plastic-based char for the biogas upgrading may be a sustainable way to transform the solid product of pyrolysis into a particularly beneficial material. This paper reviews the preparation and main parameters of the processes affecting the final textural properties of the plastic-based activated carbons. Moreover, the application of those materials for the CO2 capture in the processes of biogas upgrading is largely discussed., This paper has received funds from the project PID2019.108826RB.I00 financied by MCIN/ AEI /10.13039/501100011033., Funding for open access charge: Universidad de Granada / CBUA

[EN] Postcombustion CO2 capture by calcium looping (CaL) is being rapidly developed for coal combustion applications. This work discusses the impact of the accumulation of CaSO4 and other inert solids on CO2 capture efficiency and the overall CaL process performance. Several process configurations are considered, and the mass and energy balances and an updated carbonator reactor model are solved for each configuration. The minimum fresh sorbent requirements for sustaining a certain level of CO2 capture efficiency are quantified as well as the effects of an increase in the make-up flow. It was found that the main effect on the CaL process is produced by the sulfur present in the coal fed to the calciner and in the flue gas entering the carbonator. For a typical set of operating conditions it was calculated that the deactivating effect caused by an increase of 0.5% in the sulfur content with respect to a reference coal (low ash content) fed to the calciner is similar to the effect caused by the accumulation of inerts when using a coal with 15% more ash., M.E. Diego acknowledges a fellowship Grant under the CSIC JAE Programme, co-funded by the European Social Fund. The financial support given by the RECaL project (RFCR-2012-RECaL) is also acknowledged.

Carbon Capture and Storage (CCS) technology has attracted increasing attention as global climate change accelerates. Carbon dioxide removal processes under development include pressure swing adsorption (PSA) and chemical absorption using amine solvents. In this paper, an ammonia solvent, which is relatively inexpensive and has good material properties, was used instead of amines in the carbon dioxide removal process simulation as a chemical absorption method. This simulation used the eNRTL thermodynamics model which has the advantage of predicting ions in the liquid phase in Aspen Plus. A case study (Case Study 1) was conducted to verify the validity of the thermodynamic model. The purpose of this research was to find the operating conditions to eliminate more than 90% of the carbon dioxide contained in the flue gas from coal-fired power stations, and to lower heat duty and operating cost conditions. A second case study (Case Study 2) was conducted to find the operating conditions by comparing various process operating conditions. Additionally, this paper determined lower operating cost conditions by manipulating the amount of steam and cooling water. The results showed that the heater’s outlet temperature should be set at under 80 ℃ to lower the operating costs. As a result of changing the flow rate of the side stream of the split flow process, energy consumption was reduced when compared to the conventional flow process. It was shown that the split flow is a superior process with 10.24% less energy use than the conventional flow. In this study, the split flow process achieved an energy saving advantage when compared to the conventional flow process, and a carbon dioxide removal rate of 95% was achieved.

With fossil fuel being the major source of energy, CO2 emission levels need to be reduced to a minimal amount namely from anthropogenic sources. Energy consumption is expected to rise by 48% in the next 30 years, and global warming is becoming an alarming issue which needs to be addressed on a thorough technical basis. Nonetheless, exploring CO2 capture using membrane contactor technology has shown great potential to be applied and utilised by industry to deal with post- and pre-combustion of CO2. A systematic review of the literature has been conducted to analyse and assess CO2 removal using membrane contactors for capturing techniques in industrial processes. The review began with a total of 2650 papers, which were obtained from three major databases, and then were excluded down to a final number of 525 papers following a defined set of criteria. The results showed that the use of hollow fibre membranes have demonstrated popularity, as well as the use of amine solvents for CO2 removal. This current systematic review in CO2 removal and capture is an important milestone in the synthesis of up to date research with the potential to serve as a benchmark databank for further research in similar areas of work. This study provides the first systematic enquiry in the evidence to research further sustainable methods to capture and separate CO2.

The deployment of Carbon Capture and Storage technologies in the waste management sector can make municipal and industrial waste a strategic resource for climate change mitigation. The generation of energy, in the form of electricity and heat, via the processing and incineration of waste already avoids methane emissions from landfill. The addition of CCS to Waste-to-Energy plants with CO2 capture levels close to 99% can reduce their CO2 emissions to the atmosphere close to zero. With CCS, biogenic carbon in waste becomes a domestic source of negative emissions with a supply chain that would complement other negative emission technologies, such as Bio-Energy with CCS (BECCS).The NEWEST-CCUS project is an ongoing €2.5M multidisciplinary (2019-2022) project involving academics and researchers from six organisations and four European countries. It seeks to improve understanding of technologies and opportunities for negative emissions in the waste-to-energy sector. This paper outlines the broad range of activities undertaken by the consortium in response to key challenges facing the sector.

CO2 Technology Centre Mongstad (TCM) houses a demonstration-scale test facility for CO2 capture solvents termed the “amine plant,” where multiple test campaigns have been performed on numerous solvents that the owners of TCM, TCM DA, have conducted since its inauguration in 2012. The large number of public, industrial, research, and academic participants involved in these campaigns have enriched the projects and ensured that the significant results serve a broad audience. The main objective of these campaigns was to produce knowledge that can be used to reduce the cost as well as the technical, environmental, and financial risks for the commercial-scale deployment of postcombustion CO2 capture (PCC). This includes demonstration of a model-based control system, dynamic operation of the amine plant, investigation of amine aerosol emissions, and establishment of the baseline performance with monoethanolamine for residual fluid catalytic cracker (RFCC) and combined-cycle gas turbine (CCGT)-based combined-heat-and-power plant (CHP) flue gases. The RFCC flue gas is sourced from a nearby Equinor refinery that emulates coal flue gas in composition with 13%–14% vol CO2 content and the CHP flue gas represents flue gas from CCGT power plants with a 3.5% vol CO2 content. In addition to baseline testing, specific tests targeted at reducing CO2 avoided cost have also been conducted utilizing both flue gas sources. This paper focuses on the testing of the CESAR-1 solvent, a blend of 2-amino-2-methyl-1-propanol and piperazine. The Electric Power Research Institute, Inc. (EPRI) assessed the performance of the process using an independent verification protocol (IVP) developed previously. The IVP provides a structured testing procedure for assessing the thermal and environmental performance of PCC processes under normal operating conditions. Throughout the CESAR-1 testing, TCM manually collected extractive samples from the depleted flue gas and product CO2 outlets sequentially. As part of the IVP, EPRI also assessed critical plant instrumentation at TCM for accuracy and precision error based on a comparative analysis done during testing operations and against calibration checks. The CESAR-1 process was evaluated during 16 individual test periods over four days in June 2020. During the tests, extractive samples were taken to measure process contaminants such as aldehydes, ketones, amines, and ammonia. Sulfur oxides and nitrogen oxides were continuously monitored using Fourier-transform infrared (FTIR) analysers on the depleted flue gas and product CO2 streams. TCM has installed multiple measurements (FTIR, non-dispersive infrared sensor, and gas chromatography) of the CO2 concentration allowing comparative confirmation during the test periods. The capture rate was calculated via four methods along with evaluation of the CO2 recovery, which is indicative of the overall mass balance. The overall thermal performance (energy consumption) was assessed based on measured data taken during each of the sampling periods. The CO2 capture rate achieved during the CESAR-1 testing was 97–99%, with steam reboiler duties of 3.41–3.54 GJ/tonne-CO2, and the CO2 gas mass balance closures were close to 100%. These data and the associated assessments, along with the results of TCM sampling during these tests, are presented in this paper.

Storing CO2 in geological formations is an important component of reducing greenhouse gases emissions. The Carbon Capture and Storage (CCS) industry is now in its establishing phase, and if successful, massive storage volumes would be needed. It will hence be important to utilize each storage site to its maximum, without challenging the formation integrity. For different reasons, supply of CO2 to the injection sites may be periodical or unstable, often considered as a risk element reducing the overall efficiency and economics of CCS projects. In this paper we present outcomes of investigations focusing on a variety of positive aspects of periodic CO2 injection, including pressure management and storage capacity, also highlighting reservoir monitoring opportunities. A feasibility study of periodic injection into an infinite saline aquifer using a mechanistic reservoir model has indicated significant improvement in storage capacity compared to continuous injection. The reservoir pressure and CO2 plume behavior were further studied revealing a ‘CO2 expansion squeeze’ effect that governs the improved storage capacity observed in the feasibility study. Finally, the improved pressure measurement and storage capacity by periodic injection was confirmed by field-scale simulations based on a real geological set-up. The field-scale simulations have confirmed that ‘CO2 expansion squeeze’ governs the positive effect, which is also influenced by well location in the geological structure and aquifer size, while CO2 dissolution in water showed minor influence. Additional reservoir effects and risks not covered in this paper are then highlighted as a scope for further studies. The value of the periodic injection with intermittent CO2 supply is finally discussed in the context of deployment and integration of this technology in the establishing CCS industry.

The cycloaddition of CO2 into epoxides to form cyclic carbonates is a highly sought-after reaction for its potential to both reduce and use CO2, which is a greenhouse gas. In this paper, we present experimental and theoretical studies and a mechanistic approach for three catalytic systems. First, as Lewis base catalysts, imidazole and its derivatives, then as a Lewis acid catalyst, ZnI2 alone, and after that, the combined system of ZnI2 and imidazole. In the former, we aimed to discover the reasons for the varied reactivities of five Lewis base catalysts. Furthermore, we succeeded in reproducing the experimental results and trends using DFT. To add, we emphasized the importance of non-covalent interactions and their role in reactivity. In our case, the presence of a hydrogen bond was a key factor in decreasing the reactivity of some catalysts, thus leading to lower conversion rates. Finally, mechanistically understanding this 100% atom economy reaction can aid experimental chemists in designing better and more efficient catalytic systems.

Methanol is considered a sustainable alternative energy source due to its ease of storage and high-octane rating. However, the conventional methanol production process is accompanied by resource consumption and significant greenhouse gas emissions. The electrochemical reaction of electrochemically reacted hydrogen (H2) with captured carbon dioxide (CO2) offers an alternative route to methanol production. This paper presents a new green poly-generation system consisting of a parabolic trough solar collector (PTC) unit, an organic Rankine cycle (ORC) unit, a CO2 capture unit, an alkaline electrolysis unit, a green methanol synthesis and distillation unit, and a double-effect lithium bromide absorption refrigeration (ARC) unit. The system mainly produced 147.4 kmol/h of methanol at 99.9% purity, 283,500 kmol/h of domestic hot water, and a cooling load of 1341 kW. A total 361.34 MW of thermal energy was supplied to the ORC by the PTC. The alkaline electrolysis unit generated 464.2 kmol/h of H2 and 230.6 kmol/h of oxygen (O2) while providing H2 for methanol synthesis. Thermodynamic and economic analysis of the system was carried out. The energy and exergy efficiency of the whole system could reach 76% and 22.8%, respectively. The internal rate of return (IRR) for the system without subsidies was 11.394%. The analysis for the methanol price showed that the system was economically viable when the methanol price exceedsed$363.34/ton. This new proposed poly-generation system offers more options for efficiently green methanol production.

Recycling reinjection of CO2 captured and purified from the produced gas of CO2 flooding can not only enhance oil recovery, but also realize the geological storage of CO2, so as to provide good social and economic benefit. With the operation and advancement of CO2 flooding development mode, one single CO2 capture and purification process can hardly deal with the yearly increase and large-scale variation of CO2 content in the produced gas. In order to provide support for the promotion of CO2-EOR technology oil and gas fields, to this end, this paper puts forward four schemes of multi-method CO2 capture and purification process. It includes two-stage hydramine method, one-stage membrane separation + one-stage hydramine method, two-stage membrane separation + one-stage hydramine method, one-stage membrane separation + two-stage hydramine method. And based on the working condition data of CO2 flooding in one certain oilfield, simulation was carried out by using HYSYS software. In addition, the enrichment degree of the CO2 captured and purified by means of different schemes and its energy consumption and economy were analyzed mainly. And the following research results were obtained. First, when the CO2 concentration of the produced gas is low, it is necessary to put the two-stage alcohol amine circulation process into production firstly to realize the deacidification of natural gas while purchasing some pure CO2 to mix at a certain proportion, so as to reach the required CO2 purity of reinjected gas. Second, as the CO2 concentration of the produced gas increases, it is better to use the membrane separation technology before the two-stage alcohol amine circulation process, so that the enriched and purified gas can reach the required CO2 purity of direction reinjection. In conclusion, the research results can provide engineering practical guidance for the formulation of the scheme to enrich and purify CO2 from the produced gas of CO2 flooding.

This paper is included in the Proceedings of the 16th Greenhouse Gas Control Technologies Conference (GHGT-16), organized 23-27 October 2022 in Lyon, France This work introduces a systematic design procedure for CO2 absorption-based processes using as solvent the mixture of AMP-PZ. We propose to minimize the total CO2 avoided cost. We make the assumption that the capture plant is retrofitted to an existing industrial plant whose operation and production are not changed. Under this assumption, we can define the total CO2 avoided cost by using a method which considers the discounted cash flow resulted from implementing the capture unit. We consider a standard absorber-desorber process configuration, and we model the process in AspenPlus®. We systematically identify the degrees of freedom available for design, and we divided these into degrees of freedom used internally in the simulation in a Design-Specification block (e.g., solvent flowrate and reboiler duty), and degrees of freedom available to an external derivative-free optimizer (e.g., absorber packing height, AMP and PZ composition, and lean solvent loading). As a case study we consider a Waste-to-Energy plant.

6 figures, 2 tables.-- ATI Annual Congress (ATI 2022) 11/09/2022 - 14/09/2022 Bari, Italy., Bioenergy combustion with Carbon Capture and Storage (BECCS) is a key technology to achieve carbon negative emissions power generation. This can be achieved by coupling the biofuels combustion with CO2 capture and storage (CCS). The lowest cost for CCS corresponds at the moment to the Chemical Looping Combustion (CLC) process. This can use biofuels which can be gaseous (biomethane, biogas or syngas etc.), liquid (biodiesel, bioethanol, biobutanol and pyrolysis oils etc.) or solids (wood dust, charcoal dust, wood chips, wood pellets etc.) While plant design with gaseous and liquid biofuels would be simpler, plants using solid biofuels and based on two couple fluidisd beds would need the use of a third reactor named carbon stripper. In the specific case if we plan to couple a CLC plant with a turbo expander (to achieve the high efficiencies of a combined cycle power plant) we have to work with pressurized reactors. However, there are some technical barriers to the coupling of a chemical looping combustor with a turbo expander, such as: the operation of the combustor in pressurised conditions; the inventory balance among reactors; elutriated particles reaching the turbo expander. This explaind why there is no commercial plant at the moment capable to do this. The aim of this paper is to present a model for the dimensioning of an air reactor to be coupled to a turbo expander of the power of about 12 MWe. Based on this, the air mass flow can be obtained and the geometric parameters can be calculated, to have an air velocity which is needed to achieve the fast fluidization regime and to ensure a high conversion rate as well as particles and heat exchage among air and fuel reactor., This work has been funded by the GTCLC-NEG project that has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodow-ska-Curie grant agreement No. 101018756.

The high cost of CO2 capture using amine solvents from combustion sources such as natural gas-fired power plants remains a barrier to the adoption of CO2 Capture and Storage (CCS) as a climate change mitigation measure. The objective of the work reported in this paper was to carry out a preliminary assessment of the potential of five alternative technologies suitable for post-combustion CO2 capture from natural gas derived exhaust gases: • CO2 permeable membranes • Molten Carbonate Fuel Cells • High-pressure solvent absorption from high-pressure exhaust gas from pressurised combustion / power generation • High-pressure solvent absorption supported by exhaust gas compression • Supersonic flow driven CO2 deposition The results of the performance and cost evaluation for each technology are explained and the prospects for significant cost reduction compared to a state-of-the-art CO2 capture process are discussed. Recommendations for further technology development activity are summarised in the conclusion of the paper.

In the past, several research programs were undertaken at European Carbon Capture (CC) pilot plants. The results of these individual MEA based campaigns are brought together in order to better understand the solvent degradation at CC pilot plants. The data correlation analysis shows that nickel catalyzes significantly the formation of some degradation products (e.g. HEPO) at low concentrations of 2 mg/l. The iron impact was less clear than determined for nickel. All pilot plants show HEGly and HEPO as the main degradation products, followed by HEF. Within the group of carboxylic acids, formate is the major degradation product.

Many methanol plants utilize steam-methane reforming (SMR) to produce syngas that is fed into a synthesis loop for producing methanol. As is typical for SMR-based methanol plants, the stoichiometry of the reactants is not at a value that is optimum for the most efficient reactor loop. In order to increase the methanol production capacity, the stoichiometry of the make-up gas can be corrected by injecting CO2 into the process. A case study is presented in which Fluor's Econamine FG PlusSM technology is used for recovering sufficient carbon dioxide from the SMR flue gas to expand the plant capacity by approximately 20%.

Renewable energy sources can contribute to the increasing energy demand as well as reduction of greenhouse gas emissions and pollutants. It is desirable to find the optimum mix between renewable and non-renewable energy sources, based on carbon emissions or cost of electricity constraints. In this paper, a Pinch Analysis based method for allocating different energy sources to different demands of a region is proposed. The proposed approach determines the cost optimum mix of various energy sources. Applicability of the method is demonstrated through an illustrative case study of Lakshadweep Islands, India. These islands are too remote to have inter-connections with the mainland and depend on imports of oil for electrical, process, and transport energy requirements. The locally available renewable energy sources can be used to solve problems of energy security, higher energy cost, and environmental pollution. Additionally, the Government of India provides a significant amount of subsidy to supply electricity in Lakshadweep Islands. The proposed method helps in reducing the burden of subsidy significantly by appropriately utilizing locally available renewable energy sources. The proposed Pinch Analysis formulation consider energy as flow, cost of energy as quality, and minimizes subsidized diesel based power generation (formulated as resource). Based on the current acceptable price of electricity, the use of renewable energy sources leads to saving in the subsidy of 317.08 x 10(6) Rs./y and reduction in emissions from diesel generator set by about 58%. The policy implications for subsidy are also discussed in this paper and therefore, the work is useful to guide policy makers. (C) 2016 Elsevier Ltd. All rights reserved.

Ca-Looping technology has experienced a substantial development in the technical readiness level in the last years, especially in its application as post-combustion CO 2 capture technology in power plants. Experimental results from MW-scale power plants worldwide have confirmed post-combustion Ca-Looping process using interconnected circulating fluidised bed reactors as a promising technology for CO 2 capture. Among the different fields of research having contributed to this breakthrough, modelling activity aiming at assessing sorbent properties, interpreting results from experimental reactors or assessing technology scale-up through large-scale reactors and process integration have played a crucial role. This paper aims at reviewing and discussing findings obtained by different research groups worldwide about post-combustion Ca-Looping process modelling. Assumptions made with respect to sorbent performance, reactor operating conditions and process integration between different components are crucial when evaluating the performance of the Ca-Looping process as a post-combustion technology for CO 2 capture. With the aim of understanding the importance of these assumptions, this paper covers particle reaction and reactor models for carbonation and calcination steps, assessing the impact of the conditions used for their determination into their reactivity predictions, as well as process modelling works that assess performance obtained when integrating a Ca-Looping process into a power plant. Indications on the research needs detected among the reviewed works have also been highlighted in this work to contribute to the advancement of the knowledge on the Ca-Looping technology.

The energy transition is one of the main challenges of our society and therefore a major driver for the scientific community. To ensure a smart transition to a sustainable future energy scenario different technologies such as energy harvesting using solar cells or windmills and chemical storage in batteries, super-capacitors or hydrogen have to be developed and ultimately deployed. New fabrication approaches based on additive manufacturing and the digitalization of the industrial processes increase the potential to achieve highly efficient and smart technologies required to increase the competitiveness of clean energy technologies against fossil fuels. In this frame, the present roadmap highlights the tremendous potential of 3D printing as a new route to fully automate the manufacturing of energy devices designed as digital files. This article gives numerous guidelines to maximize the performance and efficiency of the next generation of 3D printed devices for the energy transition while reducing the waste of critical raw materials. In particular, the paper is focused on the current status, present challenges and the expected and required advances of 3D printing for the fabrication of the most relevant energy technologies such as fuel cells and electrolysers, batteries, solar cells, super-capacitors, thermoelectric generators, chemical reactors and turbomachinery.

Oxy-fuel combustion technology is an effective way to reduce CO2 emissions. An ionic liquid [emim][Tf2N] was used to capture the CO2 in flue gas from oxy-fuel combustion plant. The process of the CO2 capture was simulated using Aspen Plus. The results show that when the liquid–gas ratio is 1.55, the volume fraction of CO2 in the exhaust gas is controlled to about 2%. When the desorption pressure is 0.01 MPa, desorption efficiency is 98.2%. Additionally, based on the designability of ionic liquids, a hypothesis on the physical properties of ionic liquids is proposed to evaluate their influence on the absorption process and heat exchanger design. The process evaluation results show that an ionic liquid having a large density, a large thermal conductivity, and a high heat capacity at constant pressure is advantageous. This paper shows that from capture energy consumption and lean circulation, oxy-fuel combustion is a more economical method. Furthermore, it provides a feasible path for the treatment of CO2 in the waste gas of oxy-fuel combustion. Meanwhile, Aspen simulation helps speed up the application of ionic liquids and oxy-fuel combustion. Process evaluation helps in equipment design and selection.

8 figures.-- Supporting information available., The presence of heteroatoms, such as nitrogen or oxygen, on the surface of nanoporous activated carbons (ACs) promotes CO2 uptake due to the stronger specific interactions with these heteroatoms. However, heteroatom doping post-treatments often decrease the surface area and pore volume of ACs, and it is difficult to separate heteroatom doping from textural effects. The objective of this paper was to investigate when the control of adsorption shifts from surface chemistry to textural characteristics. For this purpose, three different types of commercial ACs were doped with nitrogen and/or oxygen by an easy and cheap method and then subjected to CO2 adsorption experiments up to 32 bar at 273 K. We evaluated the effect of the surface chemistry and texture, considering the whole range of porosity on CO2 adsorption as a function of pressure. Below atmospheric pressure, CO2 adsorption is mainly controlled by surface chemistry, increasing with O + N content, and the narrowest pores are responsible for more than 60% of CO2 adsorption at pressures below 0.01 bar. Above atmospheric pressure, from 1 to about 5 bar, the textural properties become more significant to finally take control of the adsorption phenomena at pressures above 5 bar. We have undoubtedly shown that the adsorption capacity is only a function of the total pore volume and that the adsorbed density is even higher than that of liquid CO2 in ultramicropores (pore diameter less than 0.7 nm) at pressures of 15 bar and above., This study was partly supported by ANR-15-IDEX-04-LUE and ERDF-funded project TALiSMAN (2019-000214).

Rising carbon dioxide (CO2) levels in the atmosphere from anthropogenic sources have led to the development of carbon capture, utilisation and storage (CCUS) technologies. In order to decarbonise chemical synthesis, a process intensification approach can be employed, wherein CO2 capture is coupled to a chemical reaction in a way that improves energy efficiency and product yields. In this review paper, we present advances in CO2 adsorbent development for process intensification, focusing on applications that have achieved a synergistic effect between CO2 adsorption and catalytic reactions that either consume or generate CO2. Firstly, we present a range of solid CO2 adsorbents of varying capability to capture CO2. Then we present a short introduction to the importance of developing CO2 adsorbents for process intensification. In order to improve the direction of research in the future, we emphasise the importance of developing compatible adsorbents and catalysts that operate synergistically and discuss the importance of cross cutting themes in process intensification and research opportunities for the future.

Due to the penetration of renewable intermittent energy, there is a need for coal and natural gas power plants to operate flexibly with variable load. This has resulted in an increasing interest in flexible and operational issues in the capture plant as well. In the present paper a nonlinear model predictive control (NMPC) system was tested at the Tiller pilot plant in Norway. The most important part of the NMPC software is the dynamic model representing the absorber/desorber plant. A previous first principle (mechanistic) dynamic model of the plant using MEA was modified for a solvent of AMP and piperazine, and then successfully verified by step response tests. The NMPC, which was set up to minimize the deviation from the capture rate setpoint and minimize the specific reboiler duty was then tested in a closed loop with large changes in flue gas flow and CO2 composition. Even for gas rate variations of more than 300% (110–340 m3/h) and CO2 concentration changes of 30%, the dynamic response was satisfactory. A test with frequently occurring constraints on the reboiler duty revealed a need for an extension to include direct control of the lean loading. Test of setpoint changes in total CO2 recovery showed that the control system managed to rapidly change from one capture rate to another with a time constant of typically 10 min. This might be used in a second layer of optimization, a dynamic real-time optimizer, that minimizes the capture costs during a longer horizon considering varying energy prices. Demonstration of non-linear model predictive control for optimal flexible operation of a CO2 capture plant

With regards to oil-based diesel fuel, the adoption of bio-derived diesel fuel was estimated to reduce CO2 emissions by approximately 75%, considering the whole life cycle. In this paper, we present a novel continuous-flow process able to transfer an equimolar amount of CO2 (through urea) to glycerol, producing glycerol carbonate. This represents a convenient tool, able to both improve the efficiency of the biodiesel production through the conversion of waste streams into added-value chemicals and to beneficially contribute to the whole carbon cycle. By means of a Design of Experiments approach, the influence of key operating variables on the product yield was studied and statistically modeled.

Tropical forests are a source of several high-value products that provide livelihood to small communities in different regions. Exotic fruits such as annatto are feedstock sources containing bioactive compounds with important applications in the food industry. Nevertheless, the integral use of annatto for community improvement and the crop’s contribution to carbon sequestration in tropical forests have not been analyzed. This paper aims to demonstrate the economic and environmental performance of small-scale alternatives to obtain natural colorants using annatto seed. The extraction of natural colorants (bixin and norbixin) was analyzed using ethanol and NaOH as solvents. The experimental results were used to simulate two scenarios. Scenario one involved bixin production, and scenario two comprised bixin and norbixin production. The economic and environmental assessments were performed considering the life cycle assessment (LCA) methodology based on a Colombian context. The best extraction yield was 72.65 mg g−1 for bixin and 193.82 mg g−1 for norbixin. From a simulation perspective, scenario two showed the best economic performance since a payback period of 3.1 years was obtained. The LCA showed a high CO2 sequestration potential (6.5 kg CO2 eq kg−1 seed) of the annatto crop. Moreover, the solvents used during the colorant extraction proved to be the most environmentally representative. Nevertheless, the CO2 sequestration of the crop continues to exceed the emissions generated by the process. This work demonstrates that the annatto is an alternative for small communities to reach equilibrium between the economic and environmental of the tropical forest.

This paper aims to evaluate different design configurations of a combined heat and power (CHP) plant with post-combustion CO2 capture. Three cases are involved in this study: case 1 consists of three trains and each train has a configuration of one gas turbine with a heat recovery steam generator (HRSG); case 2 consists of three trains and one steam turbine; and case 3 consists of only two trains. The third case presented the highest CHP efficiency of 72.86% with 511.8 MW net power generation. After selecting the optimum configuration, a parabolic-trough collector (PTC) was incorporated to generate additional saturated steam at 3.5 bar for the capture plant, adding greater flexibility to the CHP because more steam was available. In addition, the efficiency of the cycle increased from 72.86% to 80.18%. Although case 2 presented lower efficiency than case 3, it has a steam turbine which brings the possibility of increasing the amount of electricity instead of steam production. When the PTC was incorporated in case 2, the power generated in the steam turbine increased from 23.22 MW to 52.6 MW, and the net efficiency of the cycle from 65.4% to 68.21%.

N-(2-Hydroxyethyl) piperazine (HEPZ) has a chemical structure similar to PZ and has less volatility. It is not easy to volatilize in a continuous operation device. It is studied to replace PZ as a promotor to increase the CO2 capture rate. This paper researches the lowest energy consumption and absorbent loss of HEPZ/H2O in the absorption-regeneration process, and compares it with another five amines, including PZ, MEA, 1-MPZ, AMP and DMEA. Based on the thermodynamic model, this work establishes a process simulation based on the equilibrium stage, assuming that all stages of the absorption and desorption towers reach thermodynamic equilibrium and CO2 recovery in the absorption tower is 90%. By optimizing the process parameters, the lowest thermodynamic energy consumption and absorbent loss of process operation are obtained. Our results show that HEPZ as a promotor to replace PZ and MEA has significant economic value. The lowest reboiler energy consumption of HEPZ with the optimal process parameters is 3.018 GJ/tCO2, which is about 35.2% lower than that of PZ and about 11.6% lower than that of MEA, and HEPZ has the lowest solvent loss. The cyclic capacity is 64.7% higher than PZ and 21.6% lower than primary amine MEA.

In this paper, a feasibility study was carried out to evaluate cyclic adsorption processes for capturing CO2 from either shifted synthesis gas or H2 PSA tail gas of an industrial-scale SMR-based hydrogen plant. It is expected that hydrogen is to be widely used in place of natural gas in various industrial sectors where electrification would be rather challenging. A SMR-based hydrogen plant is currently dominant in the market, as it can produce hydrogen at scale in the most economical way. Its CO2 emission must be curtailed significantly by its integration with CCUS. Two Vacuum Pressure Swing Adsorption (VPSA) systems including a rinse step were designed to capture CO2 from an industrial-scale SMR-based hydrogen plant: one for the shifted synthesis gas and the other for the H2 PSA tail gas. Given the shapes of adsorption isotherms, zeolite 13X and activated carbon were selected for tail gas and syngas capture options, respectively. A simple Equilibrium Theory model developed for the limiting case of complete regeneration was taken to analyse the VPSA systems in this feasibility study. The process performances were compared to each other with respect to product recovery, bed productivity and power consumption. It was found that CO2 could be captured more cost-effectively from the syngas than the tail gas, unless the desorption pressure was too low. The energy consumption of the VPSA was comparable to those of the conventional MDEA processes.

This paper, which is part of a special issue of the International Journal of Greenhouse Gas Control, gives an overview of the latest achievements in the pre-combustion decarbonisation route for the production of electricity with CO 2 capture. Pre-combustion technologies applied to two different fuels are considered, natural gas and coal, since they cover most of electricity production from fossil fuels worldwide. The work first discusses in detail the different sections in which a power plant with pre-combustion CO 2 capture can be divided. For each section, the available technologies with corresponding advantages and disadvantages are presented. Next, the plant lay-outs for natural gas and coal proposed in literature, including heat & mass balances and the economic assessment, are discussed. In general, research activity in pre-combustion decarbonisation for power production focused more on coal than on natural gas-based plant since in the latter case the plant complexity and costs are not competitive with post-combustion CO 2 capture, which is a technology on the verge of commercialization. Finally the paper briefly discusses pre-combustion CO 2 capture in industry especially those projects where CO 2 is captured and stored or used for EOR.

Despite the many technologies for CO2 capture (e.g., chemical or physical absorption or adsorption), researchers are looking to develop other technologies that can reduce CAPEX and OPEX costs as well as the energy requirements associated with their integration into thermal power plants. The aim of this paper was to analyze the technical and economic integration of spiral wound membranes in a coal-fired power plant with an installed capacity of 330 MW (the case of the Rovinari power plant—in Romania). The study modeled energy processes using CHEMCAD version 8.1 software and polymer membranes developed in the CO2 Hybrid research project. Thus, different configurations such as a single membrane step with and without the use of a vacuum pump and two membrane steps placed in series were analyzed. In all cases, a compressor placed before the membrane system was considered. The use of two serialized stages allows for both high efficiency (minimum 90%) and CO2 purity of a minimum of 95%. However, the overall plant efficiency decreased from 45.78 to 23.96% and the LCOE increased from 75.6 to 170 €/kWh. The energy consumption required to capture 1 kg of CO2 is 2.46 MJel and 4.52 MJth.