A hybrid membrane-absorption process for carbon dioxide capture: Effect of different alkanolamine on energy consumption

The potential of direct air capture using adsorbents in cold climates.

Performance evaluation of PACT Pilot-plant for CO2 capture from gas turbines with Exhaust Gas Recycle

Post-combustion CO2 capture with membrane process: Practical membrane performance and appropriate pressure

Reducing the efficiency penalty of carbon dioxide capture and compression process in a natural gas combined cycle power plant by process modification and liquefied natural gas cold energy integration

This paper assesses two possible acid gas removal processes for CO2 removal onboard a floating LNG facility: (1) the well-established amine absorption process, and (2) a membrane/amine absorption hybrid process. The assessment considers process and economic aspects as well as sizing due to the on-board application. Process simulation models of each of the systems were developed in the Aspen Hysys (V8.6) software package. Two different gas fields are assumed with Feed1 containing 10%/0% CO2/H2S and with Feed2 50%/1% CO2/H2S. The feed rate in each scenario was 590,000 Nm3/h and the sweet gas specification was 50 ppm CO2 and 4 ppm H2S. The amine absorption process modelled as the base case was a 50% MDEA solution. The hybrid membrane/amine process featured a polymeric membrane unit implemented as a sub-flowsheet and then the amine unit. Our results suggest that for a very sour gas feed there may be advantages with a hybrid membrane/amine process that allows the plant weight to be reduced by 80%, volume by 50%, investment costs by 70% and annual operation costs by 40%. The most important disadvantage concerning the hybrid process is the high methane slip which can be reduced by further development of membrane properties and process design. The participation of the membrane unit increases generally with the percentage of acid gas in the feed. If the boundary conditions are comparable to those used in this paper, it can be stated that the CO2 concentration should be at least 10% for a proficient application of a hybrid process. This study presents models to evaluate novel acid gas removal processes and describes suitable process metrics that could be considered for floating LNG production facilities.

The reduction in CO~2~ emissions from anthropogenic sources has become a topic of widespread interest over the past number of years. As the power generation sector is by far the largest stationary-point-source of CO~2~, being responsible for approximately 35% of total global CO~2~ emissions^1^ this question has special relevance for this industry. As the inclusion of carbon capture facilities incurs a significant energy penalty on the efficiency coal-fired power-stations, there is a strong requirement for the improvement of these systems in terms of the minimisation of operation and maintenance costs, capital costs and the maximisation of efficiency and flexibility. This last issue has relevance for start-up times and ramp-rates. Post-combustion capture methods based on the chemisorption of CO~2~ in aqueous amine solutions are among the most mature and accepted technologies for CO2 capture from power plants^2^. However, amines are complex, associating solvents requiring a sophisticated thermodynamic model, capable of modelling the hydrogen bonding interactions that occur in these systems. One such model is provided by the statistical associating fluid theory (SAFT^3^). This is a molecular approach, specifically suited to hydrogen-bonding, chain-like fluids. In this contribution we use the SAFT approach for potentials of variable range (SAFT-VR^4^) to model the thermodynamics and phase equilibria of a number of amines including ammonia and monoethanolamine. The molecules are modelled as homonuclear chains of tangentially bonded square-well segments of variable range, and a number of short-ranged off-centre attractive square-well sites are used to mediate the anisotropic effects due to association in the fluids. We also determine values of the binary parameters for mixtures and then use these parameters to predict the phase equilibria of amine+water, amine+carbon dioxide as well as water+carbon dioxide mixtures. We then consider the phase equilibria of the ternary mixtures of amine+water+carbon dioxide and finally that of quaternary mixtures of amine+water+carbon dioxide+nitrogen. A good quantitative understanding of the phase behaviour of these quaternary mixtures is essential for accurate modelling of absorption processes for carbon dioxide capture. 1. Steeneveldt, R., Berger, B. & Torp, T.A., ChERD, 84(A9): 739-763, 20062. Rao, A.B.; Rubin, E.S., 2002. A Technical, Economic, and Environmental Assessment of Amine-Based CO2 Capture Technology for Power Plant Greenhouse Gas Control. Environ. Sci. Technol. 36, 4467-44753. Chapman, W.G., Gubbins, K.E., Jackson, G. & Radosz, M., Ind. Eng. Chem. Res., 1990. 29, 1709-17213. Gil-Villegas, A., Galindo, A., Whitehead, P. J., Mills, S. J. & Jackson, G., J. Chem. Phys. 106 (10), 8 March 1997

Typical case of carbon capture and utilization in Chinese iron and steel enterprises: CO2 emission analysis

Emergy analysis of three alternative carbon dioxide capture processes

A partir da revolução industrial, houve um aumento da emissão de gases de efeito estufa na atmosfera terrestre, como o dióxido de carbono (CO2), o que poderá levar a um aumento na temperatura global até o final do século XXI. O efeito direto do incremento na concentração de CO2 nas plantas é a possibilidade de aumento da taxa de crescimento das plantas e produtividade das culturas, uma vez que o CO2 é o substrato para fotossíntese. Se o aumento da concentração de CO2 for acompanhado de aumento da temperatura do ar, poderá haver encurtamento do ciclo e aumento da respiração do tecido vegetal, reduzindo ou anulando os efeitos benéficos do CO2. No entanto, a resposta aos aumentos na concentração de CO2 e temperatura do ar varia de acordo com a cultura considerada. Assim, o objetivo desta revisão foi reunir informações da resposta ecofisiológica da cultura do arroz, um dos três cereais mais produzidos e consumidos pela população mundial, à mudança climática. Plantas com metabolismo C3, como o arroz, são mais beneficiadas pelo aumento da concentração de CO2 atmosférico do que plantas com metabolismo C4. Altas temperaturas diurnas e noturnas podem reduzir drasticamente o potencial produtivo da cultura do arroz devido ao encurtamento do ciclo da cultura e à esterilidade de espiguetas. Essa tendência pode ser mitigada com a seleção de genótipos mais resistentes às condições de alta temperatura do ar durante o florescimento, bem como a alteração da época de semeadura.

Integration of carbon capture with utilization technologies can lead the way to a net-zero carbon economy. Nevertheless, direct chemical conversion of chemically captured CO2 remains challenging due to its thermodynamic stability. Here, we demonstrate CO2 capture from flue gas/air and its direct conversion into syngas under solar irradiation without any externally applied voltage. The system captures CO2 with an amine/hydroxide solution and photoelectrochemically converts it into syngas (CO:H2 1:2 (concentrated CO2), 1:4 (simulated flue gas), and 1:30 (air)) using a perovskite-based photocathode with an immobilized molecular Co-phthalocyanine catalyst. At the anode, plastic-derived ethylene glycol is oxidized into glycolic acid over a Cu26Pd74 alloy catalyst. The overall process uses flue gas/air as carbon source and discarded plastic waste as electron donor, opening avenues for integrated carbon-neutral/negative solar fuel and waste upcycling technologies.

Advanced post combustion CO2 capture process – A systematic approach to minimize thermal energy requirement

Process design and optimization of MEA-based CO2 capture processes for non-power industries

Limestone-based dual-loop wet flue gas desulfurization under oxygen-enriched combustion

CO2-EOR (CO2-enhanced oil recovery) is an effective method to increase oil recovery. With more and more exploitation of oilfields, a large amount of CO2 will spill out the surface, which can cause serious environmental problems. At present, high energy consumption, low CO2 purity and recovery are still the main challenges of single CO2 capture technology. Therefore, the combination of different CO2 capture technology is a reasonable choice to overcome these bottlenecks. In this work, a cryogenic-membrane hybrid process for the CO2 capture from extraction gas was proposed. In detail, the main parameters of cryogenic-membrane hybrid process (i.e., CO2 content in feed gas, compression pressure, membrane area, liquefaction temperature) which effect on CO2 properties were investigated. The simulation results indicated that the CO2 purity and recovery rate of cryogenic-membrane hybrid process can achieve 99% and 96%, respectively, and the energy consumption of the whole system was less than 850 MJ t–1 CO2. Compared with membrane and cryogenic process, cryogenic-membrane hybrid process can save about 10% energy consumption. The results of this work indicate that cryogenic-membrane hybrid process has great potential for practical application.

Introduction To achieve carbon neutrality, it is necessary to apply practical CO2 reduction and effective utilization technologies. Recently, there has been an expectation for the electrochemical reduction of CO2 (CO2 Reduction Reaction: CO2RR) using electricity derived from renewable energy. CO2RR with low overvoltage using a polymer electrolyte membrane is an actively researched next-generation technology. It is important to improve Faraday efficiency and analyze CO2RR mechanisms. Cu electrode catalysts are commonly used for CO2RR due to their high Faraday efficiency. However, a challenge remains in reducing the overvoltage of CO2RR to the level of hydrogen generation in normal PEM water electrolysis. Although Pt electrode catalysts have a significantly lower Faraday efficiency for CO2RR than Cu electrode catalysts, they have been reported to have low overvoltage1. Recent research has shown that the presence of water in the supplied CO2 and the alloy composition enhances Faraday efficiency2,3. To reduce CO2RR overvoltage, this study utilized a Pt electrode. Successful CO2RR requires the electrode catalyst surface to have coexisting surface-adsorbed hydrogen (Had) and CO2RR intermediate (COad). This study investigates the effect of electrolyte pH (perchloric acid concentration) and CO2 concentration on the COad and Had, utilizing a Pt polycrystalline electrode. Experimental Electrochemical measurements were carried out using a three-electrode cell. The counter electrode was a Pt mesh, and the reference electrode was a reversible hydrogen electrode (RHE). The working electrode was a φ3 mm Pt polycrystalline disk electrode that was mirror-polished with a 0.05 μm alumina suspension. Cyclic voltammetry (CV) measurements were performed with a sweep range of 0.05-1.0 V vs. RHE and a sweep rate of 50 mV/s or 10 mV/s. The results of the CV measurements are presented after IR correction. To evaluate CO2RR, the concentration of HClO4 was adjusted to 0.01-0.5 M as the electrolyte. The CO2 concentration was varied from 0-100 vol% and bubbled for 30 minutes before the CV measurements. For the electrochemical evaluation of CO2RR, the initial potential was kept at 0.05-0.4 V for 5 minutes before the CV measurements, and then the CV measurement was performed. Results and Discussion 1. CO2RR potential in HClO4 electrolyte saturated with 100% CO2 Figure 2 shows the results of CV measurements performed after holding the initial potentials at 0.05-0.4 V for 5 minutes before starting the CV measurements. The bubbling CO2 concentration during the measurements was 100%, and the HClO4 concentration was 0.1 M. In comparison to the CV peaks observed in the N2 atmosphere, peaks where the CO2RR reduction intermediate (COad) are reoxidized are observed at 0.6-0.7 V in the 100% CO2 atmosphere. The charge of these COad peaks remain constant at low initial holding potentials. However, it decreases significantly as the initial holding potential approaches 0.4 V. Under the measurement conditions of 100% CO2 atmosphere and 0.1 M HClO4 concentration, it can be seen that CO2 is reduced on the Pt electrode at a potential positive of 0 V vs. RHE because the COad peaks are seen between 0.05-0.3 V of the initial holding potentials. 2. Dependence of COad peak on bubbling CO2 concentration CV measurements were performed by changing the CO2 concentration bubbled in 0.1 M HClO4. Figure 3 shows the results of CV measurements at an initial potential hold of 0.05 V, where the CO2 concentration was changed from 0% to 100%. In the Hupd region, the amount of charge decreases in the CO2 atmosphere because CO2 is already surface-adsorbed as COad at 0.05 V, and the decrease is larger as the CO2 concentration increases. It is evident that the peaks of COad increase as the concentration of CO2 increases. Additionally, when the CO2 concentration is low, the peaks of COad are divided into at least two peaks, indicating the generation of COad with different adsorption structures during CO2RR. As the CO2 concentration increases, the peaks of COad appearing on the low potential side also increase. Additionally, the ratio of COad with different adsorption structures might change depending on the CO2 concentration bubbled. Acknowledgements This work was supported by JSPS KAKENHI Grant Number JP23K13835 and TEPCO Memorial Foundation.