Phase-change solvents (PCS) are a promising alternative for reducing the high energy requirements of post-combustion CO2 capture processes. This work presents the pilot-scale evaluation of the novel PCS N-cyclo-hexyl-1,3-propanediamine (S1N)/N,N-dimethylcyclohexylamine (DMCA) for CO2 absorption/desorption in the presence of sulfuric and nitric anions that are found in industrial flue gases. The testing is performed by dissolving a total of 1.7 wt% of sulfuric and nitric acid in the solvent bulk, which corresponds to a large concentration of pollutants that may accumulate in the solvent after long operation. Absorption and regeneration efficiency, cyclic capacity, reboiler duty, and regeneration energy requirements are investigated as key performance indicators (KPI) for the capture process. The performance of S1N/DMCA is investigated with and without the anions for 5, 9 and 12 vol% CO2 concentrations in the flue gas and is compared with the benchmark aqueous monoethanolamine (MEA) 30 wt% in the presence of anions. The results indicate that the anion pollutants induced a 7.5 % reduction of absorption efficiency, 23 % reduction of cyclic capacity, up to 35 % increased reboiler duty, and up to 20 % increased regeneration energy requirements. However, the PCS still achieved 70 % higher cyclic capacity and 60 % lower energetic demands compared to MEA.

Corrosion in CO2 capture units significantly impacts safety and costs. This study evaluates S275 carbon steel in CO2-loaded monoethanolamine (MEA) as a cost-effective alternative to 316 L stainless steel, testing various inhibitors: methionine, imidazole, sodium sulfite, sodium metavanadate (NaVO3), and copper(II) sulfate (CuSO4). Corrosion performance is assessed using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), while SEM and confocal microscopy analyze surface mechanisms. Results show that NaVO3 and CuSO4 provide the highest protection, reaching inhibition efficiencies of 94% (750 ppm) and 98% (1000 ppm), respectively. Polarization curves indicate that both inhibitors act as anodic inhibitors by forming protective layers. SEM confirm iron-based oxides in NaVO3-treated samples and mixed copper-iron oxides in CuSO4-treated ones. Overall, S275 steel shows high potential for CO2 capture systems when paired with effective inhibitors.

This study focuses on investigating the corrosion performance of SS 304 L and SS 316 L stainless steels when exposed to the APBS-CDRMax (R) solvent, under various conditions, including CO2 and presence of SOX/NOX contaminants. Electrochemical techniques, including potentiodynamic and cyclic polarization are employed, along with Inductively Coupled Plasma (ICP) analysis to evaluate both the short-term corrosion rate and the pitting tendency. Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-Ray (EDX) analysis provide insights into the underlying corrosion mechanism. Long term exposure tests are also carried out at temperatures up to 90 degrees C to assess the long-term corrosion behavior of the stainless steels and stability of the solvent. Findings indicate that APBS-CDRMax (R) presents extremely low corrosion rates, even in the presence of high concentrations of sulfuric and nitric acid used to simulate the effects of SOX and NOX dissolution. The observed corrosion rates are multiple times lower than those of the benchmark monoethanolamine (MEA) solvent. Microscopic observation and EDX analysis identify the presence of black layers associated with amine byproducts and different types of corrosion precipitates, many of which are linked to the inherent properties of the solvent. Long-term exposure tests indicate a tendency for the stainless steels to form corrosion precipitates, confirming the solvent's exceptional low corrosivity over time and reveal a stabilization of the corrosion process after 7-10 days of exposure to the solvent. Following extended exposure of the solvent to conditions causing thermal degradation, only minor signs of degradation are observed. The solvent's CO2 loading capacity remains virtually unaffected, whereas both density and viscosity remain stable.

We investigate the presence and effects of impurities in the carbon capture, transportation and sequestration (CCS) technology chain. We start from the composition of flue gases and investigate the subsequent treatment methods, the technical and operating characteristics of solvent-based CO2 capture pilot plants, the compositions of the absorber and desorber outlet streams and the CO2 stream specifications for downstream compression, transportation and storage processes. We present public data from 40 campaigns in large capture pilot plants and 20 sets of specifications for CO2 transportation and underground storage from national agencies, companies and projects worldwide. We identify and categorize the impurities depending on the flue gas source and the solvent type. The most commonly identified emissions in the treated gas are ammonia (NH3) and the solvent used in each plant. Monoethanolamine (MEA) emissions are higher compared to those of the other amine solvents. Sulfur and nitrogen oxides (SOx, NOx) are the most investigated impurities, whereas oxalate and formate are the most reported degradation products. Regardless of the solvent used, NOx, NH3 and aldehydes are reported in the CO2 gas product stream of most campaigns. The specifications for transportation and sequestration have similarities, with those of Northern Lights being stricter.

This work is devoted to evaluating the corrosion behaviors of SS 304L and SS 316L in monoethanolamine solutions (MEA) containing SOX and NOX pollutants, examining both lean and CO2-loaded conditions at 25 °C and 40 °C. Electrochemical techniques (potentiodynamic and cyclic polarization) were used along with Scanning Electron Microscopy, Confocal Microscopy and weight loss measurements. The results reveal that the introduction of SOX and NOX pollutants increased the corrosion rate, whereas CO2 loading primarily reduced the corrosion resistance in the lean MEA solution, while its impact on solutions with SOX and NOX was less pronounced. This suggests that SOX and NOX play primary roles in the metal’s dissolution. Also, SS 316L demonstrated superior corrosion resistance compared to 304L in nearly all of the cases examined. Elevated temperatures were also found to intensify the corrosion rate, indicating a correlation between the corrosion rate and temperature. A microscopic observation and EDX analysis revealed that corrosion products are characterized by high concentrations of iron (Fe) and oxygen (O) as well as carbon (C). There is also an indication of the possible formation of amine complexes, suggesting a potential for amine degradation. No pitting corrosion was observed in SS 304L and SS 316L across any tested solution. Finally, the immersion results expose a tendency for passivity in all amine solutions and at both temperatures after several days of exposure. Moreover, they confirm the very low corrosion rate calculated from potentiodynamic curves due to minimal weight loss after 24 days of immersion.

The corrosion behavior of two stainless steels (316L and 304L) was evaluated using a CO2-loaded aqueous solution of 30 wt.% monoethanolamine (MEA) with a view to simulating corrosion related mechanisms in amine treatment procedures. Corrosion behavior was experimentally evaluated as a function of CO2 loading and solution temperature, using electrochemical techniques (polarization curves, cyclic polarization, and EIS measurement). The results reveal that the aqueous MEA solution containing CO2 creates a favorable environment for the corrosion of both stainless steels. The rate of corrosion is accelerated when the temperature of the loaded MEA solution rises, which was attributed to the thermal degradation of the loaded MEA, thus causing higher kinetics of the cathodic reactions at higher temperatures. More specifically, for the SS 304L the corrosion rate is almost doubled when the solution temperature is increased from 25 °C to 40 °C and is quadrupled when the solution temperature rises to 80 °C. For the SS 316L, the corrosion rate becomes almost threefold and sixfold upon increasing temperature of the load amine solution to 40 °C and 80 °C, respectively. The overall corrosion rate of SS 316L is lower with respect to the SS 304L for the same temperature and loading conditions. The essential dependency of corrosion rate on solution type (unloaded and loaded MEA solution) demonstrates that the corrosion process and reactions are controlled by a diffusion mechanism.

The proliferation of industrial-scale CO2 capture technologies requires improvements in existing systems. Absorption/desorption capture processes that employ phase-change solvents (PCS) are promising for energy and cost reduction. Several PCSs have been investigated at bench scale, but very few have been tested in pilot-scale plants. The novel PCS mixture S1N (N1-cyclohexylpropane-1,3-diamine)/DMCA (Dimethylcyclohexylamine) has previously exhibited desirable performance in equilibrium experiments, economic and sustainability studies. This work presents the pilot-scale evaluation of S1N/DMCA for the first time, at two different concentrations and various liquid-to-gas ratios. Experimental evidence on key performance indicators is brought forward, including absorption efficiency, cyclic capacity, distance from equilibrium and regeneration energy in comparison to benchmark solvent MEA (monoethanolamine). S1N/DMCA enables robust operation as it maintains a cyclic capacity of 0.63 mol/kg at different liquid-to-gas ratios, which is about two times higher than that of MEA. It achieves operating loadings close to equilibrium, reaching 1.6 mol/kg, and a regeneration energy of 2.3 GJ/tn CO2, representing 45% reduction compared to MEA.

In this work a pilot plant with a rotating packed bed (RPB) reactor for nanoparticle production is demonstrated. The overall process is explained and the preliminary experimental outcomes are interpreted. The experiments are performed with slacked lime suspensions and CO2 gas. Three crucial process parameters, namely rotating speed, slurry flow and gas flow rate, were studied for their impact on the process key performance indicators (KPIs) of reaction time (trxn), particle size ( ?? ) and capture efficiency (?CO2). A factorial design with three factors and two levels was employed in order to attain a generalized view of the process behavioral trends. The reaction time was derived from pH measurements. Products were characterized by X-ray diffraction, scanning electron microscopy and particle size distribution measurement methods. Capture efficiency was estimated through gas flow rate measurements. The results indicated the successful production of nano-sized calcite particles with diameters down to 34 nm.

Phase-change solvents promise reduced energetic and environmental footprints for separation systems, including absorption-based CO2 abatement technologies. The search for efficient phase-change solvents is limited by challenges in vapour-liquid-liquid equilibrium (VLLE) prediction and in sustainability assessment. We overcome these with a digital approach to screen billions of structures and design the novel phase-change solvent S1N (N1-cyclohexylpropane-1,3-diamine) and mixture S1N/DMCA (N,N-dimethylcyclohexylamine). Screening criteria include thermodynamic and process-related properties, reactivity and sustainability of solvent production and use. VLLE phase envelopes are predicted using the SAFT-gamma Mie (Statistical Associating Fluid Theory) equation of state thanks to its transferability to any structure and the implicit modelling of ionic species. Experimental validation confirms the suitability of S1N/DMCA for scaling-up, with a cyclic capacity of 1.19 mol CO2/ kg-solvent, a regeneration energy of 2.3 GJ/ton-CO2, and vapour losses and viscosity lower by 10% and 70% than those of other solvents. S1N is also safer for plant operation and working personnel.

Large-scale CO2 abatement is key to avoid the detrimental environmental impacts of increased CO2 emissions worldwide. Solvent-based absorption is a mature post-combustion capture technology for short- to medium-term implementation. However, high energetic requirements, capture costs and technical challenges have been prohibiting its wide industrial deployment. Extensive research efforts have enabled significant improvements that resulted in scaling-up of pilot plants to industrial-level systems and commercial installations. This work provides a detailed review of these activities for plants of different capacities in 37 locations worldwide. The presented information pertains to: a) baseline, packed bed, absorption/desorption flowsheets, originally developed for alkanolamines, b) flowsheets with significant structural modifications that increase the operating driving forces, c) flowsheets including modifications for phase-change solvents and d) flowsheets that incorporate rotating packed beds (RPB). Technical details are presented regarding tested solvents, energetic performance, operating conditions, types and capacity of equipment, emissions, degradation and corrosion. It is observed that energy recovery in the stripper enables significant regeneration energy reduction, as proven in a commercial-scale plant. Equivalent performance has also been achieved with the chilled ammonia process in large-scale pilots. Liquid-liquid phase-change solvents and RPBs exhibit high potential for operating and capital expenditure reductions, but require significant scaling-up effort. Research in RPBs includes mainly lab-scale, mass transfer investigations. Several large-scale plants are being developed in China.