Carbon Dioxide Sorption Research Articles

Studying the Sorption of Carbon Dioxide by Modified Silica Gel with 2-Hydroxyethylcarbamate

The main cause of global warming is the steady increase in greenhouse gases in the atmosphere. The largest share of greenhouse gases is carbon dioxide CO2. Therefore, it is important to efficiently separate it in different gas systems. The article examines the sorption of carbon dioxide from polysilicic acid—silica gels modified with hydroxyethyl carbamate (HEC). It is shown that the modification is optimal in 30% HEC solutions. The fact of modification is confirmed by the presence of amino, hydroxyl, and carbonyl groups in the sorbents. Thermal stability is studied by the thermogravimetric method. Sorption at high pressures is studied by the gravimetric method and sorption at atmospheric pressure is studied by the thermogravimetric method. It is found that the presence of amino groups contributes to the sorption of carbon dioxide by silica gel more than doubling. The highest sorption rates are found to be 8.8% of the mass of the sorbent at 30°C. After five cycles of sorption/desorption processes in sorbents, the maximum sorption capacity decreased by 10%. The sorption rate increases at high pressures of up to 3 atm. Sorbents modified with a 30% HEC solution at 3 atm sorb up to 9.96 mol CO2/g. The relatively fast growth of the sorption rate at high pressures and its relatively slow growth at low pressures prove that the process corresponds to type-2 sorption. Such sorption systems are promising for use in various technological systems containing CO2.

Polar Acylamide Functionalized Porous Cu-MOFs for Sustainable and Selective Carbon Dioxide Sorption and Separation at Ambient and High Pressure

Metal–organic frameworks with suitable voids and polar functional group are expectant candidates for their excellent carbon dioxide uptake. Herein, two new polar acylamide-functionalized three-dimensional Cu(II)-MOFs have been synthesized, namely, {[Cu2(4-pmi)(glut)2]·(H2O)8}n (1) and {[Cu(4-pmi)(2-ntp)]·(H2O)4}n (2) (4-pmi = pyridine-4-yl-methylene-isonicotinohydrazide, glut = glutarate, and 2-ntp = 2-nitroterephthalate). The dehydrated framework of these two materials demonstrates a moderately high carbon dioxide uptake at ambient pressure (1 bar and 195 K) and high pressure (20 bar and 273 K) for both compounds, 1 and 2. Excitingly, high pressure carbon dioxide sorption of these two compounds, 1 and 2, shows high uptake of 187 and 233 cc/g, respectively. Here, the favorable pore-centric orientation of the acylamide functional group and interaction with the quadruplolar carbon dioxide molecule make such unprecedented results of carbon dioxide sorption. These compounds will be an appropriate commander for their potential application of selective and sustainable carbon dioxide scavenging from industrial flue gas and natural gas.

Synthesis, structures, and CO2 sorption of a Cu(II) and Zn(II) two-fold interpenetrated pyridyl diimide metal–organic frameworks

Herein we report synthesis, structures and CO2 sorption studies of two 2-fold interpenetrated three dimensional (3D) metal–organic frameworks (MOFs) namely; {[Cu(2,6-NDC)(L1)0.5]·3DMF}n (1) and {[Zn0.5(2,6-NDC)0.5(L2)0.5]·2DMF}n (2) where L1 is 5,5′-carbonylbis(2-(pyridin-3-ylmethyl)isoindoline-1,3-dione, L2 is 2,2′-bis(pyridin-4-ylmethyl)-[5,5′-biisoindoline]-1,1′–3,3′-tetraone, DMF is N,N’-dimethylformamide, and 2,6-NDC is 2,6-naphthalenedicarboxylic acid. The MOFs were synthesized solvothermally and characterized using single-crystal X-ray diffraction (SCXRD), thermogravimetric analysis (TGA), and powder X-ray diffraction (PXRD). SCXRD revealed that 1 and 2 are 3D and possess 33% and 27% of solvent-accessible volumes. Carbon dioxide sorption experiments were conducted at 195 K and 273 K on the desolvated phases of 1 (1-d) and 2 (2-d). 1-d adsorbs 11 cm3 g−1 (STP) at 273 K and 30 cm3 g−1 (STP) at 195 K, while 2-d adsorbs 35 cm3 g−1 (STP) at 273 K and 80 cm3 g−1 (STP) at 195 K.

Experimental and modelling studies of carbon dioxide capture onto pristine, nitrogen-doped, and activated ordered mesoporous carbons.

The search for suitable materials for carbon dioxide capture and storage has attracted the attention of the scientific community in view of the increased global CO2 levels and its after-effects. Among the different materials under research, porous carbons and their doped analogues are extensively debated for their ability to store carbon dioxide at high pressures. The present paper examined high-pressure carbon dioxide storage studies of 1-D hexagonal and 3-D cubic ordered mesoporous pristine and N-doped carbons prepared using the nano-casting method. Excess carbon dioxide sorption isotherms were obtained using the volumetric technique and were fitted using the Toth model. Various parameters that influence CO2 storage on metal-free ordered mesoporous carbons, such as the effect of pore size, pore dimension, pyrolysis temperature, the impact of nitrogen substitution, and the effect of ammonia activation are discussed. It was observed that the carbon dioxide storage capacity has an inverse relation to the total nitrogen doped, the amount of pyridinic nitrogen functionality, and the pyrolysis temperature, whereas the pore size seems to have a linear relationship. On the other hand, the presence of oxygen has a positive effect on the sorption capacity. Among the prepared ordered mesoporous carbons, the ammonia-treated one has shown the highest adsorption capacity of 37.8 mmol g-1 at 34 bar and 0 °C.

Molecular Dynamics and Nuclear Magnetic Resonance Studies of Supercritical CO2 Sorption in Poly(Methyl Methacrylate).

The study of supercritical carbon dioxide sorption processes is an important and urgent task in the field of "green" chemistry and for the selection of conditions for new polymer material formation. However, at the moment, the research of these processes is very limited, and it is necessary to select the methodology for each polymer material separately. In this paper, the principal possibility to study the powder sorption processes using 13C nuclear magnetic resonance spectroscopy, relaxation-relaxation correlation spectroscopy and molecular dynamic modeling methods will be demonstrated based on the example of polymethylmethacrylate and supercritical carbon dioxide. It was found that in the first nanoseconds and seconds during the sorption process, most of the carbon dioxide, about 75%, is sorbed into polymethylmethacrylate, while on the clock scale the remaining 25% is sorbed. The methodology presented in this paper makes it possible to select optimal conditions for technological processes associated with the production of new polymer materials based on supercritical fluids.

Correlating the Macrostructural Variations of an Ion Gel with Its Carbon Dioxide Sorption Capacity

We report on a direct correlation between the macroscale structural variations and the gas sorption capacities of an ion gel. Here, we chose 1-ethyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide ([Emim][TF2N]) and poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP) as the ionic liquid and host polymer, respectively. The CO2 sorption in the thin films of the IL-polymer was measured using the gravimetric method. The results of our experiment showed that the trend in CO2 uptake of these mixtures was nonlinearly correlated with the content of IL. Here, we highlight that the variations in the molecular structure of the polymers were the main reason behind the observed trend. The presented data suggested the possibility of using the composition of mixtures containing IL and polymers to realize a synergistic gain for gas sorption in these mixtures.

Ecologo-economic assessment of burial technologies for greenhouse gas emissions in underground geological spaces

In view of the available essential storage resources and capacities to reduce carbon footprint, Russia considers prospects for application of projects and technologies connected with burial of greenhouse gas emissions in underground geological spaces as low-carbon economy develops. The scope of the analysis embraces approaches and technologies on reduction in greenhouse gas emissions, including enhancement of energy efficiency of economy, use of renewable energy sources, utilization of solid domestic waste in power generation and arrangement of carbon fields for carbon dioxide sorption by forests and landscapes. The prerequisites and constraints of using the CCUS technologies are identified. Regarding burial of greenhouse gas emissions, the constraints include high expenses and the absence of the effective maintenance and control. For the assessment of the attractiveness and efficiency of carbon emission management projects, the article discusses benefits of increased oil recovery due to reservoir performance stimulation by carbon dioxide injection, greenhouse emission quotas and imposition of carbon tax. The ecological and economic efficiency of carbon emission management and burial project is illustrated in the context of climate change and energy transition. It is suggested to measure carbon footprint per economy sectors connected with greenhouse gas emissions (power generation, metallurgy, mining, etc.) with a view to promoting carbon neutrality of production on the basis of specific cost of reduction and management of greenhouse gas emissions, as well as from calculation of possible loss and damage because of greenhouse gas emissions and climate changes.  The study was supported by the Russian Science Foundation, Project No. 21-18-00500 Institutional Engineering of Monotowns in the Arctic—Modernization and Sustainable Development.

Molecular-level investigation of plasticization of polyethylene terephthalate (PET) in supercritical carbon dioxide via molecular dynamics simulation.

The current study aims to use the molecular dynamics (MD) simulation method to discuss the glass transition behaviour and fractional free volume (FFV) of the pure polyethylene terephthalate (PET) and the plasticized PET induced by supercritical carbon dioxide (SC-CO2) sorption. The adsorption concentration reproduced through sorption relaxation cycles (SRC) was firstly estimated and in an order of magnitude with the known experimental results available in the reported literature. The FFV induced by SC-CO2 in PET polymer changes regularly, which is proportional to the capacity of SC-CO2 adsorption with the changes in temperature and pressure. The glass transition temperature (Tg) was further estimated to be almost identical to the known experimental values and shows a gradually decreasing tendency with the increase of pressure. Meanwhile, the plasticization of PET polymer studied by radial distribution functions showed that CO2 molecules occupying the sorption sites on the PET backbone promoted plasticization by increasing the fluidity of the PET backbone chain.

Dependence of the foaming window of poly(ethylene terephthalate-co-ethylene 2,5-furandicarboxylate) copolyesters on FDCA content

The objective of the present work was to study the dependence of the foaming temperature window of poly(ethylene terephthalate-co-ethylene 2,5-furandicarboxylate) (PEFT) copolyesters on 2,5-furandicarboxylic acid (FDCA) content after different saturation pressures. First, the chemical structure of PEFT copolyesters was characterized, and the effect of FDCA content on the sorption of carbon dioxide (CO2) and the crystallization behavior of PEFT copolyesters was studied. Second, the foaming of PEFT copolyesters was carried out using a batch foaming process. Third, the foaming temperature window was defined for PEFT copolyesters through identifying the lower and the upper foaming temperature boundaries. It was found that with the increase of FDCA content, the sorption of CO2 decreased, and the melting temperature and the crystallinity of PEFT decreased. This led to the increase of the lower foaming temperature while the decrease of the upper one, thus making the foaming temperature window gradually narrowed. It is considered that the lower foaming temperature was determined by the rigidity of the macromolecular chains as well as the CO2 sorption, while the upper one by the crystals formed in PEFT with copolymerization of FDCA units. In addition, with the increase of the saturation pressure, the lower foaming temperature of all PEFT samples decreased, and the upper foaming temperature of PEFT15%, PEFT20% and PEFT30% decreased as well, attributed to the plasticization effect of CO2. However, the upper foaming temperature of PET, PEFT5% and PEFT10% unexpectedly increased with the saturation pressure due to the CO2-induced crystallization. The findings in this study are very important for guiding the foaming and cell structure control, not only for PEFT copolyesters, but also for other semicrystalline copolymers.

Base-type nitrogen doping in zeolite-templated carbon for enhancement of carbon dioxide sorption

Nitrogen-doped microporous carbons were synthesized via pyrolytic carbonization of pyrrole in a FAU zeolite template, using a carbonization temperature of either 600 or 700 °C. The carbon products, which were freed by dissolution of the template, all possessed a zeolite-like ordered pore arrangement with a high specific surface area of 2300–2500 m2 g−1 and a sharp distribution of pore diameters centered at 0.9 nm. The N content was similarly 5 wt%, but X-ray photoelectron spectroscopy analysis indicated that the 600 °C-pyrolized carbon had a relatively higher content of base-type N atoms (i.e., pyridinic and pyrrolic) than non-basic N (graphenic and oxidic), compared to the case at 700 °C. The 600 °C-pyrolized carbon exhibited an outstandingly high CO2 uptake. A breakthrough test with a CO2-H2O-N2 mixture at 1 bar indicated that the 600 °C-pyrolized carbon could capture CO2 effectively under humid conditions. This result suggests that it is important for CO2 capture, to achieve a high N content when doping with pyridinic or pyrrolic N as the major species. The high adsorption performance of zeolite-template carbon was attributable to the higher content of pyridinic N and pyrrolic N over graphitic N in the carbon, which provided basicity resulting in a strong chemisorption interaction with CO2.

Chiral Lanthanum Metal–Organic Framework with Gated CO2 Sorption and Concerted Framework Flexibility

A metal–organic framework (MOF) CTH-17 based on lanthanum(III) and the conformationally chiral linker 1,2,3,4,5,6-hexakis(4-carboxyphenyl)benzene, cpb6–: [La2(cpb)]·1.5dmf was prepared by the solvothermal method in dimethylformamide (dmf) and characterized by variable-temperature X-ray powder diffraction (VTPXRD), variable-temperature X-ray single-crystal diffraction (SCXRD), and thermogravimetric analysis (TGA). CTH-17 is a rod-MOF with new topology och. It has high-temperature stability with Sohncke space groups P6122/P6522 at 90 K and P622 at 300 and 500 K, all phases characterized with SCXRD and at 293 K also with three-dimensional (3D) electron diffraction. VTPXRD indicates a third phase appearing after 620 K and stable up to 770 K. Gas sorption isotherms with N2 indicate a modest surface area of 231 m2 g–1 for CTH-17, roughly in agreement with the crystal structure. Carbon dioxide sorption reveals a gate-opening effect of CTH-17 where the structure opens up when the loading of CO2 reaches approximately ∼0.45 mmol g–1 or 1 molecule per unit cell. Based on the SCXRD data, this is interpreted as flexibility based on the concerted movements of the propeller-like hexatopic cpb linkers, the movement intramolecularly transmitted by the π–π stacking of the cpb linkers and helped by the fluidity of the LaO6 coordination sphere. This was corroborated by density functional theory (DFT) calculations yielding the chiral phase (P622) as the energy minimum and a completely racemic phase (P6/mmm), with symmetric cpb linkers representing a saddle point in a racemization process.

Combining FTIR spectroscopy and pressure-decay techniques to analyze sorption isotherms and sorption kinetics of pure gases and their mixtures in polymers: The case of CO2 and CH4 sorption in polydimethylsiloxane

A hyphenated technique combining FTIR Spectroscopy and Barometry is implemented to study transport properties of pure and mixed gases in rubbery polymers. FTIR spectroscopy is operated in situ and in the transmission mode. The specific case of transport of pure CO2 and CH4 in polydimethylsiloxane (PDMS) was addressed by performing the experimental investigation at ambient temperature and pressure values up to 9 bar, analyzing quantitatively both the gas phase and the solid polymer phase. The IR signals of each species in the gaseous phase were first calibrated against density data of each pure gas. Then, sorption experiments from a unary gas phase were conducted increasing the pressure stepwise and the amount of gas sorbed at each pressure within the polymer was quantitatively determined by measuring the absorbance decay within the gas phase. From these measurements, equilibrium sorption isotherms and sorption kinetics of both pure gases in PDMS have been evaluated. At the same time, FTIR spectra of pure CO2 absorbed within the polymer phase were collected and calibrated. The spectroscopic contrast in the gas and the polymer phase allowed us to apply the same approaches to sorption of gas mixtures, a very difficult task with the techniques currently available. Preliminary results for the sorption of carbon dioxide from CO2/CH4 gas mixtures are presented.

Effect of pore structure on competitive sorption and diffusion of mixed methane and carbon dioxide in anthracite, South Qinshui Basin, China

A deep understanding of the competitive adsorption and diffusion of methane (CH4) and carbon dioxide (CO2) in coal is significant for implementing the CO2-ECBM project. For three high-rank coal samples, industrial analysis, coal maceral, and vitrinite reflectance (RO) determination, mercury injection test, and low-temperature nitrogen/carbon dioxide specific surface test were carried out, and the composition and pore structure of coal samples were studied systematically. Meanwhile, through the three mixed gases (75%CH4 + 25%CO2, 50%CH4 + 50%CO2, 25%CH4 + 75%CO2) adsorption and desorption test, the absolute adsorption amount, free phase and adsorption phase of CH4 and CO2 under different equilibrium pressures, and the equivalent diffusion coefficients of gas migration in the process of adsorption/desorption equilibrium were calculated. Finally, the relationship among the coal composition, pore structure, and the competitive adsorption and diffusion characteristics of methane and carbon dioxide mixture in coal were studied. The results show that: (1) the composition of coal has an important influence on the development of coal pore structure and the adsorption and transport of gas in coal. Supermicropore (<2 nm in size) is the prominent adsorption place. Furthermore, its development, which essentially determines the adsorption capacity of coal samples, is positively correlated with fixed carbon content, vitrinite content, and vitrinite reflectance. (2) When the pores >100 nm in size relatively developed, the coal samples have higher porosity, lower micropore diffusion, and a smaller desorption hysteresis index. Because the pore's connectivity is limit, its content has no apparent correlation with the permeability of coal samples and most of the adsorption and diffusion parameters. (3) The desorption hysteresis is mainly caused by the opposite migration direction of gas in the process of adsorption and desorption and the resulting dislocation of coal matrix swelling and shrinkage. The competitive adsorption of CH4 or CO2 and their separation index (SCO2/CH4) in coal samples decreases with the increase of adsorption equilibrium pressure. Also, the desorption process often shows a higher SCO2/CH4 value than that of the adsorption process. (4) During the adsorption process, the equivalent macro-diffusivities of the coal sample decrease as a power function with increasing pressure and increase with the carbon dioxide content increasing in the mixed gas. However, the equivalent micro-diffusivities change little with the different CH4 and CO2 mixtures migration in different coal samples. The equivalent diffusion coefficient of coal is positively correlated with macropore, mesopore, transitional and micropore content in coal samples.

Ligated Solvent Influence on Interpenetration and Carbon Dioxide and Water Sorption Hysteresis in a System of 2D Isoreticular MOFs.

Four two-dimensional (2D), fluorinated metal-organic frameworks (MOFs), [Cu(hfipbb)(DMF)]n·0.5(DMF)n (1), [Cu(hfipbb)(DEF)]n (2), [Cu3(hfipbb)3(DMA)3]n·6(DMA)n·2(H2O)n (3), and [Cu2(hfipbb)2(DEA)2]n·2(DEA)n·2(H2O)n (4), have been synthesized where hfipbb = 4,4'-(hexafluoroisopropylidene)bis(benzoate), DMF = N,N'-dimethylformamide, DEF = N,N'-diethylformamide, DMA = N,N'-dimethylacetamide, and DEA = N,N'-diethylacetamide. The choice of either a formamide or acetamide solvent ligand leads to a 2D, doubly interpenetrated (1 and 2) or noninterpenetrated (3 and 4) MOF structure. Despite their lower potential void spaces, the doubly interpenetrated structures have superior carbon dioxide and hydrogen sorption properties. Their 195 K CO2 sorption isotherms display inflection points, followed by ∼3-fold increases in their sorption capacities and very large extents of hysteretic behavior. This shows that small changes in the identity of the ligated solvent ligand can affect whether the resulting MOF is interpenetrated or noninterpenetrated and so drastically affect the sorption properties. In addition, the activated phase of a fifth MOF, synthesized through DMF ligand exchange with water in 1 (1W), does not display an inflection point and subsequent increased CO2 sorption at 195 K, despite having the same degree of interpenetration, showing that even more subtle differences in the desolvated phases can lead to marked differences in their sorption behavior.

Sorption-enhanced propane partial oxidation hydrogen production for solid oxide fuel cell (SOFC) applications

Solid oxide fuel cells (SOFC), as high-temperature fuel supply systems, are regarded as one of the most adaptable technologies in terms of efficiency, flexibility, and environmental friendliness. Catalytic propane partial oxidation is recognized as an efficient gas supply method for SOFC applications. However, incombustible by-product CO2 would decrease the purity of hydrogen, thereby reducing the power of fuel cells. Sorption-enhanced propane partial oxidation is an efficient way to adapt to SOFC operating conditions while improving hydrogen production and reducing carbon dioxide emissions. This paper introduces a cage-like porous Ce1-xCaxMO3-λ (M = Co, Fe and Cu) sorbent for providing high carbon dioxide sorption capacity and improving hydrogen purity over the Ni/Al2O3 catalyst. As obtained, Ce1-xCaxFeO3-λ and Ni/Al2O3 sorbent-catalyst performed the best, with the highest hydrogen yield up to 1654 μmol/gcat·s which was 1055 μmol/gcat·s higher than that of pure Ni/Al2O3. The produced reforming gas is served as a fuel in the proposed SOFC system. A maximum output power density of 581 mW/cm2 was reached. This work offered a simple and viable way of combining inexpensive and robust catalyst-sorbent for sorption-enhanced propane partial oxidation in terms of efficient indirect hydrogen supply toward SOFC power generation.

Porous Organic Polymers Derived from Ferrocene and Tetrahedral Silicon-Centered Monomers for Carbon Dioxide Sorption.

Herein, we present two novel ferrocene-containing porous organic polymers, FPOP-1 and FPOP-2, by the Heck reactions of 1,1′-divinylferrocene with two tetrahedral silicon-centered units, i.e., tetrakis(4-bromophenyl)silane and tetrakis(4′-bromo-[1,1′-biphenyl]-4-yl)silane. The resulting materials possess high thermal stability and moderate porosity with the Brunauer–Emmer–Teller (BET) surface areas of 499 m2 g−1 (FPOP-1) and 354 m2 g−1 (FPOP-2) and total pore volumes of 0.43 cm3 g−1 (FPOP-1) and 0.49 cm3 g−1 (FPOP-2). The porosity is comparable to previously reported ferrocene-containing porous polymers. These materials possess comparable CO2 capacities of 1.16 mmol g−1 (5.10 wt%) at 273 K and 1.0 bar, and 0.54 mmol g−1 (2.38 wt%) at 298 K and 1.0 bar (FPOP-1). The found capacities are comparable to, or higher than many porous polymers having similar or higher surface areas. They have high isosteric heats of up to 32.9 kJ mol−1, proving that the affinity between the polymer network and CO2 is high, which can be explained by the presence of ferrocene units in the porous networks. These results indicate that these materials can be promisingly utilized as candidates for the storage or capture of CO2. More ferrocene-containing porous polymers can be designed and synthesized by combining ferrocene units with various aromatic monomers under this strategy and their applications could be explored.

Significance of extra-framework monovalent and divalent cation motion upon CO2 and N2 sorption in zeolite X

Experimental observations and the GCMC (Grand Canonical Monte Carlo) simulations with fixed and mobile cations in their cavities have been used to study nitrogen and carbon dioxide sorption in divalent cation (Ca, Sr, and Ba) exchanged Zeolite X. Simulations of carbon dioxide and nitrogen adsorption isotherms and the heat of adsorption in divalent cation exchanged zeolite X produced results that were similar to those found in experimental results. Both experimental and simulated isotherms showed that carbon dioxide adsorption capacity is saturated at lower pressure with high adsorption capacity than the nitrogen isotherm in all zeolite samples. In the order of electronegativity of the extra-framework cations, the isosteric heat of sorption results show that carbon dioxide as well as nitrogen molecules interact more with divalent metal ion exchanged zeolites. Simulations of carbon dioxide and the nitrogen sorption in zeolite -X revealed that the mobile extra-framework cations in the cages of zeolite X had a significant advantage over zeolite molecular sieves in the separation process. The simulation with mobile cations can be a good tool for developing selective and purposeful zeolite-based adsorbents by knowing the cation position and its migration upon the adsorption of various gases.

Identification of swelling/shrinking coefficients under CO2 on an FKM O-ring – Comparison with HNBR and influence of reinforcements on the matrices

A better understanding of elastomers’ behavior during Rapid Gas Decompression (RGD) requires advanced knowledge of what is happening during gas sorption and desorption. This will offer to improve numerical simulation phenomena to consider a real environmental use of an O-ring, as for thermal applications. A previous experimental study developed testing protocols to investigate the performance of elastomeric O-rings. The non-contact measurement technique has been validated to identify the swelling and shrinking coefficients during sorption and desorption of carbon dioxide (CO2) from a Hydrogenated Nitrile Butadiene Rubber (HNBR) O-ring. The present work describes the effect of CO2 pressures on Fluorocarbon rubber (FKM) seals behavior coupled with temperature. To evaluate the effect of reinforcing the HNBR and FKM matrices with nanofillers, experimental tests were carried out and compared with those of the two elastomers without fillers. The four materials’ CO2 sorption and desorption coefficients are identified, and their swelling upon decompression is measured. It appears that HNBR is the best candidate under the applied service conditions. On the other hand, the nanofillers introduced in the elastomers may cause some early damages under RGD conditions.

Hydrothermal Carbonisation of Biomass Wastes as a Tool for Carbon Capture

Abstract Replacing fossil resources with bioresources is one of the promising directions for more environmentally friendly energy production, but the production and processing of biomass generates a large amount of waste with limited use and recycling possibilities. In this respect Hydrothermal Carbonisation (HTC) offers a sustainable and cost-effective solution for disposal and creation of new products from biomass through resource recovery and through climate-neutral process. In this study the impact of biomass type and HTC conditions on the yield and properties of artificial humic substances and hydrochar to achieve carbon capture aim has investigated. A major impact on the yield of HTC products do have the duration and temperature of the treatment, as well as catalyst used (pH of the reaction) and changing the carbonisation conditions it is possible to design the desirable composition of obtained products. During HTC process significant changes of the biomass composition happens resulting in the removal of most labile components. Although the carbon dioxide sorption capacity of hydrochar is relatively low, after activation efficient sorbent (activated carbon) can be obtained, prospective for carbon capture aims.

Interlayer Cation-Controlled Adsorption of Carbon Dioxide in Anhydrous Montmorillonite Clay

Widely available natural layered expandable clay minerals (smectites) can sorb carbon dioxide in their interlayer space under specific conditions and hence may show potential for gas separation or carbon sequestration processes. This work presents experimental adsorption and desorption measurements of gaseous, sub-critical carbon dioxide (p = 0.1 bar up to 20 bar, T = −20 °C up to 300 °C) on well-characterized anhydrous smectite (Wyoming montmorillonite) and focuses on the effect of the interlayer cation (size). Using seven alkali and alkaline-earth metal cations and three quaternary ammonium cations, a wide range of ionic radii are studied. Physisorption of CO2 in the interlayer space is confirmed via infrared spectroscopy measurements. The results show that optimally sized interlayer cations─comparable to the thickness of a carbon dioxide monolayer─open the interlayer space to make it easily accessible for CO2 up to 1.7 mmol g–1. In particular, Cs-exchanged and tetramethylammonium-exchanged montmorillonite facilitate the rapid sorption of carbon dioxide even at ambient pressure and temperature. These results provide valuable insights into the applicability of widely available natural adsorbent clays for carbon capture and sequestration for the mitigation of climate change.