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• Amine emissions and their volatile degradation products from carbon capture pilot plant. • Long-term measurement of purity of the CO 2 produced from the desorber. • Process parameters for treating 200 m3/h of flue gas from coal-fired boiler. • Gas analysis from different sections of the absorber using FTIR analyzer. • Evaluation of the pretreatment section, which cleans the flue gas entering the CO 2 absorber. Carbon dioxide reduction by amine absorption is considered the most technologically advanced method. This method is particularly recommended for gases with low CO 2 concentrations, such as flue gases. On the other hand, the use of amine absorption solutions can contribute to the emission of harmful chemicals into the atmosphere. This paper presents the emission of amines and their degradation products from a CO 2 capture pilot plant treating a slipstream (approximately 200 m3 N /h) of flue gas from a pulverized coal-fired boiler. The studies were conducted during a 2-week research campaign at the Łaziska Power Plant in Poland. An aqueous blend of 2-amino-2-methyl-1-propanol (25 % AMP) with piperazine (9 % PZ) was used as the absorption liquid. Among others, ammonia (12 ppmv), acetone (1 ppmv) and AMP (20 ppmv) were found to be the main contaminants in the clean gas (from the absorber). However, it should be noted that only single water wash section was used. The composition of the CO 2 produced (from the desorber) was also measured. It was shown that the main pollutants were water vapor (3–4 % vol.), ammonia (2–6 ppmv), nitrogen oxide, formaldehyde, and formic acid (sum, up to 10 ppmv). Traces of acetone were also detected. The composition of this gas is of practical importance for the planned management of the captured CO 2 stream. During the studies, the CO 2 capture efficiency was in the range of 86.6 %-94.6 %. The average specific reboiler heat duty (gross) was 3.24 MJ/kg of removed CO 2. [ABSTRACT FROM AUTHOR]

Stenotrophomonas maltophilia has been demonstrated herein to reduce CO 2 without any cofactor, photon or hydrogen (H 2) addition during reaction. S. maltophilia reduces 13CO 2 into 13C-labeled formate in batch mode. Two intracellular enzymes are curently being considered for their ability to catalyze the CO 2 reduction reaction: a Fe-nitrogenase and a formate dehydrogenase (FeS-FDH). The reaction was intensified by implementing the bacteria in an electrolysis cell continuously fed with CO 2. In this configuration, CO 2 removal reached up to 25% v/v at 30°C and atmospheric pressure. [Display omitted] • An isolated S. maltophilia bacterium was demonstrated to reduce CO 2 without H 2. • A commercial strain whose genome matches at 99.9% has similar CO 2 -reducing activity. • Fed-batch electrolysis allowed increasing CO 2 removals by at least 20-times. • The strain was active for at least 46 days and CO 2 removals up to 25% v/v were got. • The bacterial strain S. maltophilia was also demonstrated to reduce N 2. [ABSTRACT FROM AUTHOR]

• Separation of H 2 and CO 2 is necessary for various individual applications. • Membrane-based technologies for separation of CO 2 and bioH 2 have been reviewed. • Alternatives for the biologically-mediated conversion of carbon dioxide into value-added products were tabulated. • Membrane-assisted biohydrogen downstream technology has been proposed. In the course of dark fermentative hydrogen production, a complex gaseous mixture with significant quantity of CO 2 is formed. Hence, proper separation of H 2 and CO 2 is required for adequate utilization of hydrogen gas in fuel cell applications. Technological solutions for the removal of CO 2 can be designed by using gas separation membranes. Nevertheless, contemporary systems should be concerned with the consecutive valorization of carbon dioxide, as well. In this review article, the membrane-based technologies aiming at the effective separation of CO 2 and biohydrogen (bioH 2) will be evaluated, along with concise discussion and perspectives of integrative schemes offering alternatives for the biologically-mediated (fermentative, bioelectrochemical and algal) conversion of carbon dioxide into value-added substances, such as methane, hydrocarbons, etc. With this analysis, the objective was to bring the most important aspects of membrane-assisted biohydrogen downstream technology under one cover and give insights to recent advancement and possible future research directions. [ABSTRACT FROM AUTHOR]

Some deep-water offshore fields produce oil with high gas/oil ratios and ultra-high %CO 2 (>60%mol) with the onus of processing low-grade gas simultaneously handling huge CO 2 dispatch goals. Thus, processing solutions are needed to make feasible such high-capacity gas rigs hundreds of kilometers offshore. Feasibility relies on the choices for CO 2 capture and adjustment of water and hydrocarbon dew-points of such high flow rate gas. This problem was approached adopting supersonic separators for dew-point adjustments and for CO 2 capture on a floating-hub processing 50 MMsm ³/d of CO 2 ultra-rich gas, reinjecting 96% of treated CO 2 -rich gas for enhanced oil recovery, while reserving 4% as fuel-gas after CO 2 abatement to 20%mol for power production. Process alternatives were assessed in terms of power demand and profitability comparing supersonic separator with membrane-permeation for CO 2 removal. Results show that 1st supersonic separator for dew-point adjustments of raw gas recycling condensate to the oil-gas-water separator and 2nd supersonic separator for CO 2 removal avoiding CO 2 freeze-out, give optimum net present value and minimum CO 2 emissions. On one hand, these facts are consequences of less compressor investment as 2nd supersonic separator ejects pressurized CO 2 condensate requiring 5% less compression power for enhanced oil recovery relatively to the power required by the low-pressure CO 2 -rich permeate from the membrane-permeation alternative. On the other hand, the best net value of supersonic separator alternative also reflects its highest revenues derived from recycling condensate from 1st supersonic separator entailing 18% higher oil production. Image 1 • Offshore gas-hub for high-scale processing of 68% CO 2 natural gas is investigated. • Two serial supersonic separator units are the best economic option for gas-hub. • 1st supersonic separator unit adjusts water and hydrocarbon dew-points ejecting C3+. • 2nd supersonic separator unit removes CO 2 without freeze-out ejecting liquid CO 2. • 2nd supersonic separator economically outperforms membranes for limited CO 2 capture. [ABSTRACT FROM AUTHOR]

• Industrial by-products show variable promise for geochemical carbon dioxide removal. • Reactions with CO 2 vary with different physical, chemical and mineral properties. • Different samples have been tested here for their reactivities with CO 2 and water. • Ca- and Mg-bearing samples were key cation sources at favourable dissolution rates. • Reaction accelerants such as heat and enriched CO 2 gas can increase CDR potential. Industrial solid waste by-products are being increasingly employed for geochemical carbon dioxide removal (CDR) strategies due to their fine grain size, accessibility, and large annual production tonnages. Here, a range of such by-products has been tested experimentally for their reactivities with CO 2 and water. Sample solutions were monitored for 100 h for changes in chemistry, and solid samples were characterised pre- and post-experiment. Samples rich in Ca- and Mg-bearing minerals, such as dunite, kimberlite, and ilmenite mine tailings, as well as marble quarry cuttings, were key cation sources. Ni sulphide, fluorite and borax tailings, coal-fired power plant fly ashes, and red mud samples showed high dissolution rates. The highest reaction rates were often observed during the initial few hours, and compared well to rates determined for rocks typically targeted for CDR purposes, such as basalt and gabbro. Several samples also showed secondary carbonate precipitation, suggesting opportunities for the development of single-step CDR technologies. Overall, the results of this study indicate that several industrial by-products can provide sufficient cations at favourable dissolution rates for geochemical CDR purposes. Any on-site or near-site conditions for reaction acceleration such as heat, concentrated CO 2 or microbes, could further increase favourability for geochemical CDR opportunities. [Display omitted] [ABSTRACT FROM AUTHOR]

Porous membranes as gas-liquid contactors are widely used in carbon dioxide (CO2) absorption systems. It provides larger mass transfer area and excellent operational flexibility. Membrane contactors have been considered as alternative to conventional approaches in removing CO2. In spite of its advantages over conventional technologies, membrane wetting is a major problem which reduces performance of CO2 absorption. This paper explains the concept of membrane wetting phenomenon and its influence on the CO2 mass transfer through the membrane and absorption performance. The factors that cause membrane wetting were presented including hydrophobicity of membranes surfaces, membrane pore size, liquid entry pressure and properties of absorbent liquid. Current proposed methods to alleviate the membrane wetting were reviewed and discussed. Development of mathematical model was presented for all types of membrane wetting modes, as well as its validity for CO2 physical and chemical absorption. [ABSTRACT FROM AUTHOR]

Sulfur dioxide (SO 2) is one of the acidic components found in the flue gas that can harm industrial facilities and the environment. SO 2 adsorption by metal-organic frameworks (MOFs) is an emerging method to effectively remove SO 2 in low concentrations from the gas mixtures. In this study, amino-functionalized MIL-53(Al), i.e., NH 2 -MIL-53(Al), was synthesized through the solvothermal method and examined for SO 2 adsorption at relatively moderate pressure and temperature (up to 2 bar, 25–80 ℃). According to the results of XRD, FT-IR, TGA, and DSC analysis, NH 2 -MIL-53(Al) demonstrated appropriate water, acid, and thermal stability. The SO 2 adsorption capacity of NH 2 -MIL-53(Al) was 5.21 mmol.g−1 at T = 25 °C and P = 0.92 bar, significantly higher than its CO 2 adsorption capacity under similar conditions, demonstrating its high selectivity for adsorption of SO 2 relative to CO 2. Though the crystal structure of the tested MOF slightly changed after five adsorption/desorption cycles, its SO 2 adsorption capacity decreased only 6.64%, signifying its proper durability and regenerability under humid and acidic conditions. These features are promising to use NH 2 -MIL-53(Al) as a suitable adsorbent to selectively remove SO 2 from flue gas. [Display omitted] • A functionalized MOF (NH 2 -MIL-53(Al)) was examined for SO 2 adsorption. • NH 2 -MIL-53(Al) demonstrated appropriate water, acid, and thermal stability. • NH 2 -MIL-53(Al) showed excellent adsorption capacity at low SO 2 concentration. • NH 2 -MIL-53(Al) showed high selectivity to adsorb SO 2 over CO 2 at moderate P and T. • The MOF almost preserved its SO 2 adsorption capacity after 5 adsorption/desorption cycles. [ABSTRACT FROM AUTHOR]

Abstract: RATE was recently awarded a contract to license a new grass roots sulphur recovery project including design of the Acid Gas Removal and the Sulphur Recovery Unit, Tail Gas Treating, water dew point control unit, Thermal Oxidizer (incineration system) and the Liquid Sulphur Degassing Units for a Sour Gas Field Development (SGFD) in Asia. The challenge in this project was to deal with a wide range of feed gas compositions of H2S and CO2 while also dealing with a lot of impurities such as carbonyl sulfide (COS), heavy hydrocarbons, mercaptans, and benzene, toluene, xylene (known as BTEX) where the operation of the SRU's with the lean gas and impurities are difficult. The Feed Gas Composition to the Acid Gas Removal Unit (AGRU) consists of number of cases. The design had to be able to operate in all of these cases while achieving a stable operation and meeting the performance guarantees and environmental regulations. The H2S concentration to the AGRU varies from 2.3% to 5%, the CO2 concentration varies from 3% to 6%, benzene from 40 ppmv to 90 ppmv, toluene from 45 ppmv to 220 ppmv, xylene from 20 ppmv to 150 ppmv, carbonyl sulfide (COS) from 25 ppmv to 70 ppmv, and heavy hydrocarbons up to C50+, mercaptans from 15 ppmv to 50 ppmv plus many pseudo components according to the gas analysis from more than 100 wells. The H2S concentration to the sulphur Recovery unit varies from 30% to 47% and CO2 ranges varies from 58% to 43% respectively. The gas pressure was around 100 barg at 50 °C. The sales gas has to meet the following performance guarantees. [•] H2S, 4 ppmv [•] CO2 less than 1.7% max [•] COS 4 ppm wt maximum, [•] Organic sulphur 50 ppm- wt maximum, total sulphur 60 ppm wt maximum [•] H2S, 4 ppmv [•] CO2 less than 1.7% max [•] COS 4 ppm wt maximum, [•] Organic sulphur 50 ppm- wt maximum, total sulphur 60 ppm wt maximum The Sulphur Recovery, Tail Gas Treating, Thermal Oxidizer, and Liquid Sulphur Degassing have to meet the following performance guarantees. [•] Sulphur Recovery minimum 96%, [•] Overall SRU + TGU less than 50 ppmv of SO2 at stack [•] Liquid sulphur Degassing, less than 10 ppmw of H2S [•] Sulphur Recovery minimum 96%, [•] Overall SRU + TGU less than 50 ppmv of SO2 at stack [•] Liquid sulphur Degassing, less than 10 ppmw of H2S In this paper, we will discuss the design features of the units and reasons why they were selected. We will discuss the options that we considered to design this unit, including the solvent evaluation & selection, the impact of H2S/CO2 ratio on the AGRU and the SRU design, and the selected optimum scheme of the Sulphur Recovery Units, and the TGU to meet the performance guarantees for all 10 cases including the operating and the capital costs comparison. [Copyright &y& Elsevier]

Highlights: [•] New methods of producing plasticization resistant membrane materials for CO2 removal. [•] CO2-induced plasticization phenomenon is discussed. [•] Plasticization property is evolving into a conventional trade-off pattern. [•] Glassy and rubbery polymeric membranes were reviewed. [•] Glassy polymers exhibit better antiplasticization property. [ABSTRACT FROM AUTHOR]

Abstract: Biomass in combination with carbon capture and storage (CCS) is one of few options that make a reduction of global CO2 concentration in the atmosphere possible. This option is likely to be required to meet climate targets. This study shows the global potential for combining bio-energy conversion with CCS (BE-CCS) up to 2050. The assessment focuses on two BE-CCS routes for the production of biomethane, based on gasification and anaerobic digestion. Routes for the production of power and liquid fuels have been addressed in an earlier study by IEAGHG. For the two routes the technical and economic potential was analysed. The results show that deployment of the global technical potential can result in negative greenhouse gas emissions (GHG) up to 3.5 Gt CO2-eq. on an annual basis in 2050. Including avoided emissions by replacing natural gas, the annual greenhouse gas emission savings could add up to almost 8 Gt of CO2-eq in 2050. The economic potential reaches up to 0.8 Gt of negative GHG emissions when assuming a CO2 price of 50 €/tonne. [Copyright &y& Elsevier]

Abstract: As an alternative to chemical and physical solvents, membrane technologies and PSA, process principles for CO2 removal from natural gas by low-temperature distillation are presented. A low-temperature process reducing the CO2 concentration from an initial50.6 vol-% to LNG specification (50ppm) has been simulated in Aspen HYSYS. Main results such as product streams, power consumption for auxiliary refrigeration and steam requirements have been estimated. The process delivers the natural gas product for liquefaction at approximately 40bar pressure and a temperature of -88°C and should be well suited for further cooling and liquefaction. [Copyright &y& Elsevier]

Abstract: The objective of this study is to investigate the potential process for the removal of carbon dioxide (CO2) from flue gas using fundamental membrane contactor, which is a membrane gas absorption (MGA) system. The experiments consisted of microporous polyvinylidenefluoride (PVDF) flat sheet membrane with 0.1μm (as module I) and 0.45μm (as module II) pore size. 2-Amino-2-methyl-1-propanol (AMP) solution was employed as the liquid absorbent. The effect of AMP concentration was studied with variation in the range 1–5M. In addition, the experiments were carried out with 10%, 20%, 30% and 40% gas ratio of CO2 to N2 and pure CO2 as well. Through contact angle measurement, membranes for module I and module II were obtained with CA values of around 130.25° and 127.77°, respectively. The mass transfer coefficients for module II are lower than those of module I for 1–5M of AMP. Furthermore, the increase in CO2 concentration in the feed gas stream enhanced the CO2 flux as the driving force of the system was increased in sequence from 1M to 5M of AMP. However, after the particular percentage (40%) of CO2 inlet concentration, the CO2 fluxes seem saturated. The combination of AMP as liquid absorbent and PVDF microporous membrane in MGA system has shown the potential to remove the CO2 from flue gas. In addition, the higher AMP concentration gave higher mass transfer coefficient at low liquid flow rates. [Copyright &y& Elsevier]

Anthropogenic CO2 emissions have a significant effect on climate, which is the cause for serious concern. Conventional solvents such as alkanolamine used for carbon dioxide capture suffer from corrosiveness and require high regeneration energy. Recently, deep eutectic solvents (DESs), widely regarded as green solvents, have emerged as better alternatives to the existing solvents. Therefore, in this work, three different DESs with common Hydrogen Bond Acceptor (methyltriphenylphosphonium bromide) and different Hydrogen Bond Donors (glycerol, ethylene glycol, and diethylene glycol) were synthesized, and the prospect for CO2 absorption was investigated experimentally. The CO2 uptake in DESs was measured using the pressure drop method at different temperatures and pressures up to 12 bar. Experimentally obtained vapor-liquid equilibria were correlated well using the Peng–Robinson model. Experiments concluded that diethylene glycol-based DESs have the highest CO2 solubility. The results were used to simulate the flue gas decarbonization process, further depicting that the synthesized DESs have shown the potential to capture CO2 from flue gas. [Display omitted] • The comparative study of phosphonium-based DESs for their effectiveness in capturing CO2 is experimentally analyzed. • Peng–Robinson equation of state has been used to thermodynamically model the experimentally obtained results. • Process modeling and simulation of CO2 capture from the flue gas stream was investigated using aspen plus simulator. • The double-stage and three-stage process was used for flue gas decarbonization. [ABSTRACT FROM AUTHOR]

Gasification has been increasingly seen as a method to convert solid fuel into combustible syngas. However, these applications require syngas with strict requirements and raw syngas often does not meet these requirements. Therefore, a form of syngas upgrading needs to be applied. One of the most common form of syngas upgrading is removal of CO 2 , which is often present in large concentrations in raw syngas. The currently existing CO 2 removal technologies were either designed not with syngas in mind or for large scale industries, which makes them somewhat inefficient for application with gasification syngas. This calls for more research into efficient removal of CO 2 , from syngas. In this review, the application of deep eutectic solvent (DES) as one of the potential new absorbent for CO 2 removal from gas streams and more specifically from syngas are discussed. DES has garnered attention due to its high CO 2 absorption performance, process friendliness, and environmental friendliness. At present, most studies on DES are still limited to basic absorption behavior of the absorbent. This review aims to provide not just a clear picture of the current research situation for DES as CO 2 removal absorbent, but also detail the possible research directions that might be taken for the development of DES as CO 2 absorbent from syngas. To that end, this paper shall discuss the specific situation of gasification development, syngas utilization, and the current DES research situation including: its advantages compared to conventional absorbents, its current research situation, challenges, and possible future research directions. [Display omitted] • Comprehensive review on the recent development, potential, and challenges in the application of DES as CO 2 absorbent. • Critical review that provides analysis on potential advantages and issues on DES for CO 2 absorbent. • Solutions suggested based on studies from other areas that could potentially be suitable. [ABSTRACT FROM AUTHOR]

• MWCNTs were functionalized using MDI (4,4'-Methylene diphenyl diisocyanate). • PU/MWCNT (NCO&COOH) MMMs were prepared for CO 2 /N 2 and CO 2 /CH 4 separation. • Morphological and spectral analysis was carried out. • PU membrane containing 0.3 wt.% modified MWCNT (-NCO) has shown superior gas separation properties. Carbon dioxide, an important heat-trapping (greenhouse) gas, was eliminated using polyurethane (PU) mixed-matrix membranes (MMMs) prepared with different loadings (0.1, 0.2, 0.3, 0.5, 1.0 wt.%) of functionalized filler (multi-walled carbon nanotubes). The functional groups (–COOH and –NCO) on MWCNTs were used to overcome the aggregation of filler in the membrane matrix. FTIR, XRD, and SEM were used to characterize the functionalized MWCNTs. Furthermore, AFM, FESEM, FTIR, and XRD were used to characterize the morphological and structural properties of membranes. In order to investigate CO 2 removal, all the fabricated membranes were evaluated operationally by performing permeation tests of CO 2 , N 2 , and CH 4. The prepared MMMs showed an increase in gas permeabilities for all gases with an increase in filler loading from 0.1 wt.% up to 0.3 wt.%, while further increase up to 1.0 wt.% reduced the permeabilities. CO 2 removal performance of the MWCNT-filled membranes was improved while the permeability of CO 2 , ideal selectivity of CO 2 /N 2 , and CO 2 /CH 4 of MMM with 0.3 wt.% loading of MWCNT-NCO showed an increase about 5%, 51%, and 14%, respectively, in comparison to neat PU membrane. This membrane surpassed Robeson's upper bound. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) removal is an important process in natural gas processing. For offshore natural gas, due to the space limitations of offshore platforms, the volume requirement of CO 2 removal equipment is very strict. Therefore, high-efficient CO 2 removal equipment is needed to meet the processing requirements of natural gas. As a new type of process intensification technology, the rotating packed bed (RPB) is a desirable candidate for removing CO 2 from offshore natural gas due to its good mass transfer performance and considerable size savings. In this paper, the research progress of RPBs is reviewed from the aspects of hydrodynamic characteristics and mass transfer performance. Different research methods have been discussed, and their advantages and disadvantages have been pointed out. The factors that affect the efficiency of CO 2 removal have been analyzed, and operational recommendations have been given. Suggestions for future research are put forward to promote the application of RPBs on offshore platforms for CO 2 removal from offshore natural gas. • RPB has potential to play an important role on offshore platform for CO 2 removal. • Inadequate research of hydrodynamics of RPB limits performance predictions. • The simulation and modeling methods of RPB need to be further studied. • Impacts of special condition of offshore platform on RPB require consideration. [ABSTRACT FROM AUTHOR]

The continuously increasing of sour natural gas reservoirs worldwide necessitate a highly efficient CO 2 removal technology for offshore application. Therefore, the intensification technology for absorption attaches research interest to address this issue. This review covers the intensification factor, operating feasibility and perspective for each potential technology. Microchannel reactor offers the highest ideal intensification factor but suffers from offshore operation difficulties. Even-though high frequency ultrasonic reactor and rotating packed bed demonstrate high flexibility for long-term operation, yet both technologies require high energy consumption. Combination of hollow fibre membrane contactor and rotating packed bed is suggested to optimize the overall absorption process. • A comprehensive review on the intensified technologies for absorption process. • Review of the advantages and disadvantages for each technology. • Review of feasibility and perspective for each technology at offshore condition. [ABSTRACT FROM AUTHOR]