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• Novel theory on non-ideal mixed solvent electrolyte diffusion. • New concepts for generic ionic diffusion schemes. • Fick's law, Maxwell-Stefan, and Nernst-Planck multicomponent diffusion equations. • Predictions of thermodynamic correction factors using extended UNIQUAC. • A CO 2 capture, reservoir simulation, and corrosion case study. Thermodynamic ideality is often assumed in diffusion calculation, implying concentrations are assumed equal to the activities with activity coefficients of one. A general set of diffusion flux and molar flux equations are developed, incorporating equilibrium thermodynamic models for non-ideal conditions in well-known non-equilibrium diffusion theory. Derivations are based on the Maxwell-Stefan friction theory with the chemical potential as the driving force. Isothermal and isobaric conditions are assumed, and the theory does not include the Soret coefficient or the Onsager formalism. In this work, Fick's law is derived from the general diffusion theory, also as a function of activity gradients. The results illustrate that concentration cannot just be substituted by activity. Using a similar approach demonstrates that the Nernst-Planck (NP) equation may be derived from the general theory incorporating terms for migration and convection. An extended NP equation is derived including the thermodynamic correction factors (TCF) to account for the non-ideality of the liquid. The derived equation shows the improvement of the self-diffusion terms and friction coefficients in the NP equation and that the TCF enhances the observed effective diffusivities. Examples of TCF are presented using the extended UNIQUAC thermodynamic model. This is done for the CO 2 -NaOH-monoethyleneglycol-water system, which is typically found in wet natural gas pipeline CO 2 corrosion systems. pH-stabilization is classically used in the prevention of corrosion, but the results show that glycol has a noticeable effect of the diffusion on key components in the corrosion mechanism. A TCF of 0.4 to 1.3 may be expected. This indicates that the flux calculation deviates up to 60 % from the real-life scenario if ideality is assumed. The thermodynamic model may therefore improve the diffusion calculations considerably. [Display omitted] [ABSTRACT FROM AUTHOR]

This study models the phase equilibria of the sulphur compounds – SO 2 , H 2 S, and COS – in mixtures relevant to carbon capture and storage (CCS). The modelling tool used in this investigation is the cubic plus association (CPA) equation of state. Modelling of binary and multicomponent mixtures of these sulphur compounds with CO 2 , water, glycols, methane, and other inert compounds is performed. Different approaches are considered in the modelling of these mixtures. Sulphur compounds are treated as non-associating or self-associating with multiple association sites, culminating in the proposal of new association schemes. Throughout the study, the predictive and correlative performance of CPA is assessed. It has been found that the allocating of association sites for the sulphur compounds leads to improved modelling of phase equilibria behaviour. Further analysis against multicomponent systems will need to be performed to conclude on the appropriate association schemes for these compounds. [ABSTRACT FROM AUTHOR]

Reactive absorption is a key process for gas separation and purification and it is the main technology for CO 2 capture. Thus, reliable and simple mathematical models for mass transfer rate calculation are essential. Models which apply to parallel interacting and non-interacting reactions, for all industrially relevant reaction regimes must be developed and validated against experimental measurements. In a previous work, we presented the general model (GM) enhancement factor model for (m+n)-th order reversible reactions and validated it against the numerical solution of the two-film model for absorption, desorption and pinch conditions. In this work, we apply the GM model to multiple parallel reactions. We deduce the model for piperazine (PZ) CO 2 capture and we validate it against wetted-wall column measurements using 2, 5 and 8 molal PZ for temperatures between 40 °C and 100 °C and CO 2 loadings between 0.23 and 0.41 mol CO 2 /2 mol PZ. We show that overall second order kinetics describes well the reaction between CO 2 and PZ accounting for the carbamate and bicarbamate reactions. Here we prove the GM model for piperazine and MEA but we expect that this practical approach is applicable for various amines, blends of amines and promoted amines with similar kinetics. We believe that this practical implementation of mass transfer rate calculation will be in the accuracy range of a wetted wall column experiment for other parallel reaction systems. This is in line with our observation from other similar solvents studied, not shown here. Furthermore, we compare the GM model and the numerical solution of the complete two-film model predictions to MEA wetted-wall data and we prove that it is safe to assume that GM and the two-film model give practically identical results. We demonstrate that the expected predictability of CO 2 mass transfer rates using off-the-shelf correlations generally is ±20%. [ABSTRACT FROM AUTHOR]

This study derives a general method (GM) for reactive absorption and desorption calculation. It connects the Onda's approximation for reversible reactions with the van Krevelen's approach for instantaneous irreversible reactions. It is set-up for a reversible ( m + n )-th order, forward reaction kinetics and applied for the CO 2 –MEA–H 2 O second order reversible system. The results show that the GM predicts the two-film theory within 2% accuracy and the surface renewal model within 10% accuracy, both at absorber and desorber conditions and for high driving force and pinch conditions. GM is compared to the ideas of van Krevelen, and Astarita and Savage. An analysis demonstrates how the GM model eliminates many of the limitations of previous approaches. It has a noticeable potential to enhance the accuracy of process simulators without sacrificing the simulation time. It could eliminate the need for conservative and uncertain design and therefore it will lead to more realistic cost estimations. [ABSTRACT FROM AUTHOR]

Freezing point depressions (FPD)in phase change solvents containing2-(diethylamino)ethanol (DEEA) and 3-(methylamino)propylamine (MAPA)were measured using a modified Beckmann apparatus. The measurementswere performed for the binary aqueous DEEA and MAPA solutions, respectively,in the concentration ranges of (0 to 55) mass percent and (0 to 32.5)mass percent of amine. For the ternary aqueous DEEA–MAPA solutions,freezing points were measured for 5:1, 3:1, 1:1, 1:3, and 1:5 molarratios of DEEA/MAPA. The FPD method was extended for easy and accuratemeasurement of freezing points in the CO2loaded systems.It is based on saturation of the solution by CO2and thendilution by using a batch of the original unloaded solution in orderto get the solutions with different CO2loadings. Freezingpoint measurements were then carried out for (12, 20, 30, and 33)mass percent DEEA solutions and (10, 20, and 27) mass percent MAPAsolutions at different CO2loadings. The apparatus andthe experimental method used showed good repeatability and accuracy.The measured freezing point data were compared with monoethanolamine(MEA) and methyl diethanolamine (MDEA) found in the literature. Theexperimental values indicate that the DEEA–water interactionis almost similar to that of MEA–water interaction. MAPA hasshown a stronger nonideal behavior compared to DEEA. A correlationfor the freezing points as a function of solution composition wasformulated for the unloaded binary and ternary systems. [ABSTRACT FROM AUTHOR]

In this work, CO2 conditioning processes for ship-based CCS sequestration are modelled using the software APSEN HYSYS V11. This study uses the captured CO2 gas from the 3D project as the feed. The feed stream contains water, H2S, and CO as contaminants. The purification processes for dehydration, desulfurization, and CO removal are reviewed. Two liquefaction approaches, the open-cycle and the closed-cycle liquefaction, are modelled and compared for transport pressures 7 and 15 bar. It is found that the energy requirement of the open-cycle process is higher than that of the closed-cycle liquefaction process. For the closed-cycle design, two refrigerants, ammonia and propane, are considered. Results show that the energy requirement of the process using ammonia is lower than that of propane. When comparing the two transport pressures, it is found that liquefaction at 15 bar requires less energy than 7 bar. On top of that, both refrigerants are unsuited for the liquefaction of CO2 at 7 bar, as their operating pressures are below 1 atm. Several optimization concepts are tested on the closed-cycle liquefaction design. The net power consumption of the closed-cycle liquefaction is reduced when CO2 is precooled using the intermediate pressure ammonia streams and the cold from the CO stripper. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide is essentially removed from the raw natural gas to meet the process, health, safety and environmental standards. Alkanolamine based absorption process remains the prevalent technique for hydrogen sulfide removal due to ease of operation and economic considerations. The design of such gas separation systems is a critical factor in meeting the stringent process requirements and optimizing operations. To achieve precise design, determination of vapor–liqid equilibrium for the system is indispensable while maintaining efficacy and simplicity. This study presents a simple model for estimating hydrogen sulfide solubility in aqueous alkanolamines and their blends in the high pressure-high gas loading region. The model equation is developed by considering and combining amine protonation and bi-sulfide formation reactions, assuming ideal liquid properties. Satisfactory correlated values of hydrogen sulfide loadings (0.21–3.15 mol gas/mole solvent) are obtained over a wide range of temperature (298.15–393.15 K), pressure (60–7027 kPa) and alkanolamine concentration (1.12–14.27 molal). Parameters are given for the hydrogen sulfide solubility in aqueous solutions of monoethanolamine, diethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol, piperazine, diglycolamine, di-isopropylamine, 1-amino-2-propanol and their selected blends. The model shall be useful for the design of alkanolamine based natural gas sweetening systems, operating at high pressure and high hydrogen sulfide gas loadings. [ABSTRACT FROM AUTHOR]

The development of advanced processes for carbon dioxide capture requires reliable thermodynamic models to ensure accurate process design. This work presents an optimized parameter set of the Extended UNIQUAC model for advanced mixed solvent solutions containing CO 2 -MDEA-NH 3 -K 2 CO 3 in water. The model was parameterized using vapor–liquid equilibrium, pure component saturation pressure, excess enthalpy, heat of absorption, molar heat capacity, apparent molar heat capacity, and solid–liquid equilibrium. These thermal and equilibrium properties cover temperatures between 253.6 K to 600 K and pressures up to 75.6 bar. The current model represents an extension of previous versions that were suitable for modeling aqueous NH 3 and K 2 CO 3 solutions. This parametrization accounts for molecular interactions between MDEA and these two components, which allows for the design of advanced capture processes. This paper demonstrates that the new model parameters are valid within the range of operational conditions typically found in CO 2 capture processes. [Display omitted] • New parametrization of the Extended UNIQUAC model for mixed solvents for CO 2 capture. • Analysis of different experimental and benchmark between similar measurements. • Calculation of several physical properties and phase equilibrium diagrams. [ABSTRACT FROM AUTHOR]

Post-combustion carbon capture is a well-established technology to limit CO 2 from industrial emissions. However, challenges such as high energy requirements for solvent regeneration persist. Research is still being conducted to improve the energy efficiency of the process. This study aims to present the results of process intensification in a pilot-scale CO 2 capture plant. The pilot-scale investigations were carried out at Amager Bakke, a Waste-to-Energy facility in Copenhagen, Denmark. The tests were conducted by implementing the split flow configuration as a method of process intensification. The CO 2 rich stream was split before flowing through the rich/lean heat exchanger. One of the split streams was fed to the stripper top, and the other was sent through the heat exchanger and then fed to the stripper. The cold split stream at the stripper top is heated by the overhead vapours which would otherwise escape the stripper. The current work discusses the split flow configuration results of the pilot plant by employing 30 wt % MEA as the solvent and compares it to the base-case performance of the pilot. Experiments were conducted by splitting 22 % of the rich solvent and feeding it to the stripper top. The performance of the split flow configuration was analysed at different reboiler duties. A minimum specific reboiler duty of 3.45 GJ/tonne CO 2 is obtained for the split flow configuration, which is less than the base case by 7.8 %. Additionally, a reduction in the condenser duty by at least 68 % was achieved by the implementation of the split flow configuration. • Pilot-scale heat integration methods such as split flow are seldom demonstrated experimentally. • Split flow configuration experiments were conducted at a WtE facility. • The pilot's performance improved by 7.8 % compared to the base case. • The SRD of the system could be lowered to 3.45 GJ/tonne CO2. • The total cooling duty of the pilot remains unchanged from base case. [ABSTRACT FROM AUTHOR]

[Display omitted] • A PtX technology capable of removing methyl mercaptan from gas has been developed. • Electrochemically regenerated chlorine oxidizes methyl mercaptan and removes it. • The technology can purify gas to a high degree and is adaptable and scalable. • No Chlorine is released into the cleaned exhaust gas. • The final product of the oxidation is sulfate which is dissolved in the solvent. A new electroscrubbing technology has been developed. This Power-to-X process utilizes active chlorine, which oxidizes impurities and is continuously regenerated in an electrochemical cell. The process is primarily intended for hydrogen sulfide capture, but has shown potential in removing other sulfur components as well. In this paper the capability of the process for removing methyl mercaptan has been examined. The electroscrubbing process was able to remove mercaptan to undetectable levels. The capture rate of mercaptan was primarily determined by the applied electrical current. Gas flow and concentration had a negligible effect on the capture while liquid flow had only a minor impact. The primary product of the mercaptan oxidation was found to be sulfate ions. [ABSTRACT FROM AUTHOR]

Fouling processes present significant challenges in many industries; understanding these processes is crucial for accurate prediction and planning effective mitigation protocols. Composite fouling is prevalent in many industrial applications, however, studies of these systems are scarce. We present, for the first time, new insights on the interaction between two common crystallization foulants: BaSO 4 and CaCO 3. We conducted a series of crystal growth experiments in a plug flow reactor. We used high resolution X-ray micro-computed tomography to visualize the crystal formation. In the first set of experiments, crystals (either BaSO 4 or CaCO 3) were grown on pristine steel surfaces; these pre-fouled surfaces were then used as substrates for the composite fouling studies. The chemical compositions of the substrates were different from that of the foulant, i.e., either BaSO 4 on CaCO 3 or CaCO 3 on BaSO 4. Growth rates were obtained through gravimetric analysis. We characterized surface properties, such as the crystal size distribution, surface coverage, and texture parameters through advanced image analysis. Our results reveal that deposition behaviour depends on complex substrate-foulant interactions. Whereas the net deposition of CaCO 3 on a BaSO 4 substrate increased with time, significant detachment processes were observed for the reverse case. The increased detachment of BaSO 4 on a CaCO 3 substrate can be attributed to either the weak interaction within the CaCO 3 crystal structure or the CaCO 3 /steel interface. We also show how substrate properties govern crystal cluster sizes and distribution. The results from this work provide a basis for the development of more comprehensive prediction models. [Display omitted] • Composite fouling systems were investigated • BaSO 4 substrates nearly doubled the growth rate of CaCO 3. • CaCO 3 substrates promote BaSO 4 detachment. • BaSO 4 preferentially grew on top of CaCO 3 resulting in smaller clusters. [ABSTRACT FROM AUTHOR]

Equilibriumtotal pressures were measured and equilibrium CO2partialpressures were calculated from the measured total pressure data inbinary and ternary aqueous solutions of 2-(diethylamino)ethanol (DEEA)and 3-(methylamino)propylamine (MAPA). The measurements were carriedout in a commercially available calorimeter used as an equilibriumcell. The examined systems were the binary aqueous solutions of 5M DEEA, 2 M MAPA, and 1 M MAPA and the ternary aqueous mixtures of5 M DEEA + 2 M MAPA (5D2M) and 5 M DEEA + 1 M MAPA (5D1M), which gaveliquid–liquid phase split upon CO2absorption. Thetotal pressures were measured and the CO2partial pressureswere calculated as a function of CO2loading at three differenttemperatures 40 °C, 80 °C, and 120 °C. All experimentswere reproduced with good repeatability. The measurements were carriedout for 30 mass % MEA solutions to validate the experimental method.All the measured data were also compared with the results of 30 mass %MEA as a reference case. 5 M DEEA has shown high cyclic capacity.Both 2 M and 1 M MAPA showed high loading capacities at 40 °Cand 120 °C. The aqueous amine mixtures, 5D2M and 5D1M, gave fairlygood cyclic capacities and their results depend on the concentrationof the promoter (MAPA) in the mixture. Approximate enthalpies of absorptionof CO2in all the tested aqueous amine systems were estimatedfrom the CO2solubility data. The measured total pressureand the estimated CO2solubility data can be useful inthermodynamic modeling of the capture systems when aqueous DEEA–MAPAsolutions are used as capture solvents. [ABSTRACT FROM AUTHOR]

• Biomethane quality is demonstrated with water-lean 30 wt% MEA + 15 wt% monoethyleneglycol (MEG) solvent. • Water-lean 30 wt% MEA + 15 wt% MEG increases specific reboiler duty by 6 % at base case. • Rich solvent recycle with cooling increases the rich loading to 0.49 from 0.46 mol/mol. • The lowest specific reboiler duty was 3.48 MJ/kg CO 2 with 30 wt% MEA + 15 wt% MEG. • The water-lean solvent forms 2-methyl-dioxolane resulting in increased emissions. This study investigates the potential of a water-lean 30 wt% monoethanolamine (MEA) solvent for biogas upgrading. The solvent consists of 30 wt% MEA, 15 wt% monoethyleneglycol (MEG), and 55 wt% water at zero loading. The solvent is investigated using a mobile pilot scale amine scrubbing unit, with a capacity of 1 ton CO 2 per day, with the option to utilize a rich solvent recycle (RSR) configuration. Without the RSR configuration, the water-lean solvent obtains a low rich loading of 0.46 mol/mol resulting in a specific reboiler duty (SRD) of 3.92 MJ per kg CO 2 , which is 6 % higher compared to aqueous 30 wt% MEA. Combining the RSR configuration with cooling enables a higher rich loading of 0.49 mol/mol and decreases the SRD to 3.48 MJ per kg CO 2 , which is 6% lower than for aqueous 30 wt% MEA. It is found that 30 wt% MEA + 15 wt% MEG only achieves lower SRD than aqueous 30 wt% MEA if similar rich loading can be achieved. By measuring emissions from the absorber and stripper columns, it was found that MEG and MEA form 2-methyl-dioxolane resulting in increased emissions when utilizing this water-lean solvent. [ABSTRACT FROM AUTHOR]

The heat of absorption is a critical thermodynamic property for establishing new solvents for CO 2 capture. Experimental data for this thermodynamic property in the literature is limited. This study aims to determine the heat of absorption for new solvent compositions, which can potentially reduce energy consumption in solvent regeneration processes. The obtained heat of absorption data for CO 2 in these solvents will contribute to the development of an Extended UNIQUAC model for the corresponding electrolyte system. The heat of absorption of CO 2 was investigated in aqueous solvents containing 30 wt% MEA, 30 wt% MEA with 7.5 wt% MEG, 30 wt% MEA with 30 wt% MEG, and 30 wt% MEA with 7.5 wt% Urea. The measurements were conducted at 40 °C and 120 °C using a Setaram C-80 Calorimeter equipped with a mixing cell. MEG and Urea were included as vapour reduction additives (VRAs) due to their ability to lower the vapour pressure of the solvents. The results show that the solvents containing 7.5 wt% and 30 wt% MEG exhibit higher heat of absorption compared to the aqueous 30 wt% MEA at 40 °C, with increases of 3.7% and 2.4%, respectively. However, at 120 °C, the heat of absorption is lower by 4.2% and 8.3% for the solvents with 7.5 wt% and 30 wt% MEG. In contrast, the solvent with 7.5 wt% Urea has a lower heat of absorption than the aqueous 30 wt% MEA, with reductions of 8.5% and 7.3% at 40 °C and 120 °C, respectively. • Heat of absorption measured for MEA and VRAs, assessing energy reduction potential. • Accurate measurements performed, providing loading and temperature dependent data. • Solvents with MEG had higher heat of absorption, indicating better absorption. • Solvent with Urea had lower heat of absorption, suggesting energy advantages. • Findings aid development of Extended UNIQUAC model for these electrolyte systems. [ABSTRACT FROM AUTHOR]

Post-combustion carbon capture is a well-established technology for removing CO 2 from industrial emissions. However, research is still underway to optimise the process and make it more energy efficient. The current work aims to present the results from pilot-scale (with a capacity of 1 tonne CO 2 /day) studies of CO 2 capture conducted at Amager Bakke, a Waste-to-Energy facility in Copenhagen, Denmark. The pilot operation is fully automated, and the process control structure helps achieve multiple steady states at regular intervals. In addition, the pilot is capable of several configurations which can assist in optimising the energy required for solvent regeneration. The current work discusses the base case configuration of the pilot plant by employing 30 wt % MEA as the solvent. Experiments were conducted to analyse the influence of reboiler duty, solvent flow rate, and gas flow rate on the pilot's performance. The influence of these parameters on several aspects is discussed in detail, and recommendations for the optimal operation of such plants are provided. An optimum specific reboiler duty of 3.46 GJ/tonne CO 2 is obtained at a solvent flow rate of 306 kg/h, flue gas flow rate of 113 kg/h, and reboiler duty of 17.5 kW excluding heat loss. [Display omitted] • Pilot-scale CO2 capture is crucial before full-scale implementation. • Parametric analysis helps in identification of optimal performance of the pilot. • The performance of the pilot can be improved by 9% even in base-case operation. • Energy is lost in the system mainly at the stripper top and the heat exchangers. • The process can be optimised by implementing heat integration. [ABSTRACT FROM AUTHOR]

• The performances of a pillow-plate methanol reactor are assessed through CFD. • The CFD model is validated with a two dimensional heterogeneous model. • A sensitivity analysis is carried out on sheet distance for the pillow geometry. • A comparison of the performances of pillow-plate and tubular reactors is reported. This work investigates the performances of a pillow-plate heat exchanger utilized as reactor for small-scale methanol synthesis. When downscaled, multi-tubular packed bed reactors are complicated to use since they undergo rapid losses in catalyst activity. A possible pathway to improve the unit performances is to diminish the tubes diameter and number. As this kind of reactors is governed by convective heat transfer, though, the use of long tubes is required to keep the mixture velocity high. This leads to the use of very long reactors, which cannot be easily realized with traditional designs. In order to tackle this issue, we propose the utilization of an innovative design, the pillow-plate reactor, increasing heat and mass transfer and the unit compactness. The study compares the performances of a packed-bed and a pillow-plate reactor through temperature profiles and methanol productivity at varying reactor lengths (1 – 6 m). It is proved that the pillow-plate unit, unlike the multi-tubular one, well manages scale reduction: when 1 m long reactors are employed, the outlet methanol fraction is close to equilibrium (5.8% vs. 4.9% for packed beds) and the hot-spots are well controlled (537 K vs. 557 K for tubular reactors). Moreover, it is also shown that the distance of metal layers in the pillow arrangement remarkably influences heat exchange, which is very effective for close layers, with a hot-spot of 518 K with a 3 mm gap, and much worse for the 12 mm design (552 K). [Display omitted] [ABSTRACT FROM AUTHOR]

A new power-to-X desulfurization technology has been examined. The technology uses only electricity to oxidize the hydrogen sulfide (H 2 S) found in biogas to elemental sulfur. The process works by using a scrubber where the biogas comes into contact with a chlorine containing liquid. This process is capable of removing close to 100% of H 2 S in biogas. In this paper a parameter analysis of process parameters has been carried out. In addition a long term test of the process has been performed. It has been found that the liquid flow rate has a small but notable influence on the process' performance on removing H 2 S. The efficiency of the process largely depends on total amount of H 2 S flowing through the scrubber. As the H 2 S concentration increases, the amount of chlorine required for the removal process is also increased. A high amount of chlorine in the solvent may lead to unwanted side reactions. [Display omitted] • A PtX technology capable of removing hydrogen sulfide from gas has been developed. • Electrochemically regenerated chlorine oxidizes hydrogen sulfide to solid sulfur. • The technology can purify gas to a high degree and is quickly adaptable. • The solvent flow has only a small effect on the efficiency of the process. • The process is stable over longer periods of operation. [ABSTRACT FROM AUTHOR]

Crystallisation fouling is a challenge in numerous applications. To mitigate fouling we need to determine the basic mechanisms involved in the process. While ex situ techniques have been widely used in previous studies, they cannot capture complex dynamic effects. We conducted an in situ investigation of the dynamic effects of crystallisation fouling in a steel pipe (length 3 cm, diameter 3 mm) using X-ray micro-computed tomography (μ CT) over more than six days. We employed a custom-developed image reconstruction algorithm, which ensured high spatiotemporal resolution from a laboratory instrument. We quantified the evolving fouling using advanced segmentation techniques of 4D images. To understand how the pipe interface structure impacts reactive transport, the experimental geometries of the flow system were used to perform computational fluid dynamic simulations. These new data allowed us to identify three growth phases: initiation, expansion, and densification. • Three phases of surface crystallisation were identified. • The rate of crystal deposition varied by a factor of 4 over a period of six days. • Reactive transport modelling was coupled with the experimental geometries. • Novel dynamic reconstruction algorithms were developed to treat 4D X-ray CT. • In situ X-ray μ CT was used to examine crystallisation fouling for more than six days. [ABSTRACT FROM AUTHOR]

Direct catalytic methanation of CO2 (from CO2/CH4 biogas mixture) to produce biomethane was conducted in a pilot demonstration plant. In the demonstration project (MeGa-StoRE), a biogas desulfurization process and thermochemical methanation of biogas using hydrogen produced by water electrolysis were carried out at a fully operational biogas plant in Denmark. The main objective of this part of the project was to design and develop a reactor system for catalytic conversion of CO2 in biogas to methane and feed biomethane directly to the existing natural gas grid. A process was developed in a portable container with a 10 Nm3/h of biogas conversion capacity. A test campaign was run at a biogas plant for more than 6 months, and long-time operation revealed a stable steady-state conversion of more than 90% CO2 conversion to methane. A detailed catalytic study was performed to investigate the high activity and stability of the applied catalyst. [ABSTRACT FROM AUTHOR]

Vapour-liquid equilibrium of carbon dioxide loaded potassium and sodium l -lysine salts have been investigated in the region of high-pressure and high loadings. The equilibrium solubility of carbon dioxide was measured in separate aqueous l -lysine alkaline salts for a range of temperature (303.15–363.15 K), solution concentrations (1.0–3.0 M) and pressure (95–4204 kPa). In addition to that, solubility of carbon dioxide in blends of both aforementioned amino acid salts with piperazine were investigated. All the studied solutions exhibited an increase in the carbon dioxide loading values with increase in the pressure and had a negative relationship with increase in the temperature and solvent concentration. Furthermore, the experimental data was correlated by the Kent-Eisenberg model. The correlated values shows a good agreement (AAD% of 5.15%) with experimental values. The regressed parameters of the model allows satisfactory estimation of the loadings of carbon dioxide in all studied solutions, for parametric studies. The study shows that l -lysine salts are potential green solvents for the carbon dioxide capture at high pressure. [ABSTRACT FROM AUTHOR]