CO2 Adsorption Analysis Research Articles

Investigating Discrepancies in Adsorption Enthalpy Predictions: An Analysis of CO2 Adsorption on HKUSTs

The pressing need to mitigate the presence of harmful gases in the atmosphere motivates scientific and engineering endeavors to devise effective adsorption solutions. Achieving practical and specific adsorption is essential for improving capture processes, with CO2 being a prominent target due to its significant environmental repercussions. Metal-organic frameworks (MOFs), distinguished by their high porosity and adaptable structure, have emerged as promising candidates for CO2 adsorption. Especially noteworthy are functionalized MOFs, which augment adsorption capacity, selectivity, and heat of adsorption. This research investigates CO2 adsorption on HKUST-1 modified with three amines of varying strengths, evaluating adsorption capacity and thermal impacts using direct adsorption calorimetry and Van't Hoff thermodynamic models.

Enhancing carbon dioxide uptake in biochar derived from husk biomasses: Optimizing biomass particle size and steam activation conditions

This research focuses on developing activated biochars for CO2 adsorption, evaluating the impact of particle size and steam activation conditions on almond shells (AS), pistachio shells (PS), and nut shells (NS), three crops that are grown worldwide. A literature review was carried out on the characteristic parameters that a biomass must have to produce a biochar of an acceptable quality to capture CO2. Initially, a physicochemical characterization of the selected biomasses was conducted, revealing high levels of volatiles (78–84 wt%), carbon (41–53 wt%), and inherent metals (Ca, K, Mg and Na). This process involved pyrolysis and activation under pre-established conditions, followed by CO2 adsorption analysis using thermogravimetry. Interestingly, intermediate-sized biochars (ranging from 2 to 1.4 mm) exhibited higher CO2 uptake. Once the optimal particle size was determined, steam activation conditions were further optimized by varying temperature. In this regard, these conditions were established at 900 °C for 30 min, at a steam flow rate of 0.15 mL/min and a pressure of 1 bar. This study highlighted biomass heterogeneity, resulting in distinct biochar morphologies (microporous PS activated biochars, and mesoporous NS and AS biochars) and higher carbon content compared to raw materials. However, the O/C and H/C ratios fell as severity rose. On researching steam activation holding times at a constant temperature of 900 °C, similar trends were observed, with high carbon content in the biochars. Finally, based on CO2 adsorption results, 2.81, 2.12 and 1.76 mmol/g for PS, AS and NS activated biochars, respectively, optimal shorter activation times (15 min) were selected for AS and NS biochars.

Breathing Behavior and Superprotonic Conductivity of Two-Dimensional Flexible Metal-Organic Frameworks Tuned with Alkoxy Groups.

Flexible metal-organic frameworks (FMOFs) exhibit reversible structural transitions ("breathing" behaviors), which can regulate the proton transport passageway effectively. This property offers remarkable advantages for improving the proton conductivity. Our objective of this work is to design a single-variable flexibility synergistic strategy for the fabrication of FMOFs with high conductivity. Herein, four two-dimensional FMOFs, {[Co(4-bpdb)(R-ip)]·xsolvents}n (x = rich, 1-4), have been successfully designed and assembled (4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene and R-ip = MeO/EtO/n-PrO/n-BuO-isophthalate). Upon the release and/or absorption of different solvent molecules, they display reversible breathing behaviors, thereby resulting in the formation of the partial and complete solvent-free compounds {[Co(4-bpdb)(R-ip)]·ysolvents}n (y = free or poor, 1A-4A). This breathing behavior involves the synergistic self-adaption of the dynamic torsion of alkoxy groups and reversible structural transformation, leading to remarkable changes in cell parameters and void space, as evidenced by single-crystal X-ray diffraction, powder X-ray diffraction, and N2 and CO2 adsorption analyses. At 363 K and 98% relative humidity, 2A exhibits the best proton conductivity among the FMOFs. Its conductivity reaches 4.08 × 10-2 S cm-1 and is one of the highest conductivities shown by reported unmodified MOF-based proton conductors.

The potential application of cellulose acetate membrane for CO2 adsorbent

ABSTRACT Numerous countries have deployed significant efforts to reduce the amount of CO2 released into the atmosphere. Carbon capture and storage is widely regarded as a mitigation technique that can significantly reduce CO2 emissions. A crucial stage in carbon capture and storage is CO2 adsorption using a membrane. Cellulose acetate has demonstrated excellent properties as a membrane material. In this study, we examined the potential of cellulose acetate membrane (CAM) for CO2 gas capture. Two forms of CAM were developed for this study, with and without the addition of glycerol. Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), and CO2 adsorption analyses were used to characterise CAM in numerous ways. The analysis revealed that the addition of glycerol improved the gas adsorption properties of the material. The incorporation of glycerol into the cellulose acetate matrix resulted in an observed augmentation in both the diameter and pore size. The adsorption properties of CO2 are significantly influenced by the microscopic structure of the cellulose acetate membrane. The CAM can be viewed as a possible material for CO2 adsorbers.

Bimetallic Metal Organic Framework Composites for Carbondioxide Capture

Maintaining breathable air in human space flight missions is a challenge since there will be a gradual increase in the concentration of CO2 due to the exhalation of the spacecraft crew. Modern air revitalization technology for space missions uses temperature swing adsorption with zeolite-based materials as the adsorbent. However, the major drawbacks of zeolites are difficulty in regenerating used adsorbent and low selectivity towards CO2. Besides, frequent replacement of adsorption beds is necessary because of their low adsorption capacity towards CO2. This requires carrying a few spare beds in the spacecraft, which is not preferred because of the low-weight requirements for space missions. Hence, shifting to alternate materials with more selectivity and adsorption capacity toward CO2 becomes essential. Metal-organic frameworks (MOFs) are a class of crystalline materials found to be potential adsorbents for CO2 capture. Due to their ultra-high porosity, tunable pore characteristics, selective capture, and synergistic performance, they could replace the existing zeolite-based adsorbents. Further enhancement in the adsorption capacity could be achieved by introducing a secondary metal into the framework. This will bring heterogeneity in the structure, creation of defects, and open metal sites, thus enhancing the adsorption behavior. Incorporating a secondary metal into the framework and an additional filler material like activated carbon, making a BMOF composite, would lead to an exemplary improvement in the adsorption activity. The addition of filler material will lead to an increase in pore volume, which will enhance the adsorption capacity. In the current work, activated carbon was synthesized from sawdust via chemical activation method using KOH as the activating agent. It was carried out at low temperatures to boost the porous structure formation. Then the composite of Cu-Ni bimetallic MOF with activated carbon was prepared through one-pot solvothermal synthesis. The incorporation of activated carbon created an additional number of pores in the system leading to enhanced adsorption. N2 adsorption-desorption analysis was carried out to find the surface area. The results showed that the surface area of activated carbon and Cu-Ni-Activated carbon BMOF composite was found to be 576 m2/g and 1321 m2/g, respectively. The analysis also revealed the presence of microporous system in the material. Several characterization techniques, such as IR, SEM, XRD etc., were used to study morphology and characteristic features. The SEM shows that the incorporation of nickel and activated carbon have made a profound modification on the octahedral morphology of copper.CO2 adsorption studies were carried out at 1 bar, 25°C. The BMOF composite adsorbent was found to adsorb ~4.52 mmol/g of CO2 whereas the as-synthesized activated carbon and ZSM-5 were found to adsorb ~2.71 mmol/g and ~1.68 mmol/g respectively. To understand the level of microporosity in the supermicropores range, CO2 adsorption analysis at 1 bar and 0°C was carried out since N2 adsorption at -196°C have limitations due to kinetic diffusion related problems at low temperatures. It revealed a micropore volume (<1.066nm) of 0.252 cm3 /g and a pore size range of 4-10 angstroms, which is ideal for selective CO2 adsorption. Also, the BMOF composite was found to adsorb ~8.27 mmol/g at 0°C, which showed that adsorption capacity increases with a decrease in temperature. Hence, the BMOF composites could serve as a promising adsorbent for selective CO2 capture. Figure 1

The Control of Shale Composition on the Pore Structure Characteristics of Lacustrine Shales: A Case Study of the Chang 7 Member of the Triassic Yanchang Formation, Ordos Basin, North China

The pore structure characteristics of shales are controlled by their mineral and organic matter compositions. However, the contributions of different components to the pore structure characteristics of lacustrine shales remain poorly understood. In this study, fifteen Chang 7 Member shales of the Yanchang Formation, Ordos Basin, were investigated through total organic carbon (TOC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and low-pressure N2 and CO2 adsorption analyses to study the control of shale composition on the pore structure characteristics of lacustrine shales. The results show that the average TOC content of the Chang 7 Member shales is 9.63 wt.%. XRD analysis shows that minerals in the Chang 7 Member shales consist of quartz, feldspars, clay minerals, and pyrite. The clay minerals were dominated by illite, chlorite, and interstratified illite/smectite. The mesopore characteristics of the Chang 7 Member shales and micropore characteristics of organic-lean shales are mainly controlled by clay minerals, whereas the micropore characteristics of organic-rich samples are controlled by both clay minerals and organic matter. SEM observations show that the phyllosilicate framework pores are the main pore type in the Chang 7 Member shales. The results of this study provide important insights into compositional control on the pore structure characteristics of lacustrine shales.

Thermodynamic characteristics of CO2 adsorption on β-cyclodextrin based porous materials: Equilibrium capacity function with four variables

This work focuses on establishing a kind of extended adsorption model equation including four variables relevant to preparation conditions (activation temperature and heating rate) except adsorption situations (adsorption temperature and adsorption pressure). And the equation is used for thermodynamic analysis of CO2 adsorption on a promising cyclodextrin based porous material. Novelty, those isotherms of CO2 adsorption on the porous materials prepared at different activation temperatures and heating rates are experimentally obtained to investigate the effects of activation temperature and heating rate on CO2 adsorption. Then the parameters of the model equation are quantified based on 589 data points from the isotherms by the least squares regression method combined with the steepest descent mode. Research results indicate that high performance for CO2 uptake appears on the porous material prepared at high activation temperature and low heating rate. Differently with the previous studies, the adsorption site energy distribution is found to exhibit an asymmetrical peak and the peak site energy increases with an increase of activation temperature but the decrease of heating rate. Moreover, a series of interesting phenomena of those thermodynamic state parameters via adsorption temperature and pressure are verified based on both extended Slip model and D-R model, which have not been reported before.

Metal–Organic Frameworks (MOFs) Containing Adsorbents for Carbon Capture

In this study, new composite materials of montmorillonite, biochar, or aerosil, containing metal–organic frameworks (MOF) were synthesized in situ. Overall, three different MOFs—CuBTC, UTSA-16, and UiO-66-BTEC—were used. Obtained adsorbents were characterized using powder X-ray diffraction, thermogravimetric analysis, nitrogen adsorption porosimetry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectrophotometry. Additionally, the content of metallic and nonmetallic elements was determined to investigate the crystalline structure, surface morphology, thermal stability of the obtained MOF-composites, etc. Cyclic CO2 adsorption analysis was performed using the thermogravimetric approach, modeling adsorption from flue gasses. In our study, the addition of aerosil to CuBTC (CuBTC-A-15) enhanced the sorbed CO2 amount by 90.2% and the addition of biochar (CuBTC-BC-5) increased adsorbed the CO2 amount by 75.5% in comparison to pristine CuBTC obtained in this study. Moreover, the addition of montmorillonite (CuBTC-Mt-15) increased the adsorbed amount of CO2 by 27%. CuBTC-A-15 and CuBTC-BC-5 are considered to be the most perspective adsorbents, capturing 3.7 mmol/g CO2 and showing good stability after 20 adsorption-desorption cycles.

Behavior of organic matter-hosted pores within shale gas reservoirs in response to differential tectonic deformation: Potential mechanisms and innovative conceptual models

Remarkable breakthroughs have been achieved in exploration of marine shale gas, acting as important cleaner energy resources in complex tectonic regions, encouraging us to accurately estimate different reservoir capacity of tectonically deformed gas shales. In particular, organic matter (OM) pore system, acting as the most important storage space for high-over-mature marine gas-shale reservoirs in South China has not yet been specifically targeted and comparatively studied in a regional and differential tectonic deformation regime. A set of shale drilling core samples from the Upper Silurian to Lower Ordovician Wufeng-Longmaxi Formations in the Sichuan Basin and its periphery were targeted by a multi-methodical approach utilizing organic geochemistry and mineralogical investigations, FE-SEM observation and digital image processing and extraction, and combined fluid intrusion (N2 and CO2 adsorption analysis). From undeformed shales (UDS) through slightly deformed shales (SDS) to intensely deformed shales (IDS), an obviously and progressively “Triple Jump” reduction in multi-scale pore volume and specific surface areas, and characteristic parameters for OM pores including the plane porosity (Phi) (the average dropped from 23.14% to 10.33%), the equivalent circle diameter (ECD) (the average dropped from 28.38 nm to 10.09 nm), the perimeter over area (PoA) (the average rose from 0.1126 to 0.2718), and the dominant pore diameter (DOM size) (the average dropped from 113.80 nm to 20.78 nm). The reactivation of seepage channels and intrusion of brittle minerals are proposed as two main microscopic forcing mechanisms, updated and innovative conceptual models are proposed to reconstruct an OM pore response processes under a differential tectonic deformation regime in panoramic view for Lower Paleozoic marine gas shale reservoirs of China. Thus, an evolution of spatial resolution spanning a total of three different scales respectively as structural styles, shale reservoir architectures, and microscopic petrological compositions are together portrayed.

Determination of the Fractal Dimension of CO2 Adsorption Isotherms on Shale Samples

The fractal theory has been widely applied to the analysis of gas adsorption isotherms, which are used for the pore structure characterization in unconventional reservoirs. Fractal dimension is a key parameter that can indicate the complexity of the pore structures. So far, most fractal models for gas adsorption are for N2 adsorption, while fractal models for CO2 adsorption are rarely reported. In this paper, we built a fractal model for CO2 adsorption by combining a thermodynamic model and the Dubinin–Astakhov model. We then applied the new model to three CO2 adsorption isotherms measured on shale samples. The results show that the fractal dimension from the new model lies between 2 and 3, which agrees with the fractal geometry. The new model presented in this paper can be used for the CO2 adsorption analysis, which allows characterizing micropore structures in shales.

Kinetics and mechanism analysis of CO2 adsorption on LiX@ZIF-8 with core shell structure

LiX@ZIF-8 is a kind of core-shell nanomaterial with high CO2 adsorption capacity applied to CO2 capture in highly humid flue gas. CO2/N2 separation performance and adsorption kinetics are another two critical indicators for a new adsorbent. Except for significant CO2/N2 separation capacity. The breakthrough curves of LiX@ZIF-8 under different adsorption temperatures were investigated by three kinetic models, namely pseudo-first order, pseudo-second order, and Avrami's kinetic model. It is proved that the pseudo-first order could successfully predict the adsorption behavior of LiX@ZIF-8. The normalized standard deviation of pseudo- first order model is only 2.8% at 25 °C. Furthermore, Boyd's film-diffusion model, interparticle diffusion model, and intraparticle diffusion model are selected to explore the mass transfer resistance of LiX@ZIF-8. It is found that film diffusion controls the adsorption rate in the initial stage and intense intraparticle diffusion is the rate-limiting reason in subsequent adsorption stage due to abundant micropores in LiX and ZIF-8.

Fractal characteristics of pulverized high volatile bituminous coals with different particle size using gas adsorption

To better understand the effect of particle size on fractal characteristics of pores in coal, three high volatile bituminous coals with mean maximum vitrinite reflectance of 0.82–0.90% collected from the Naryksko-Ostashinskaya coalbed methane field in Kuznetskiy Basin in Russia were crushed and sieved to five progressivelydecreasing particle size fractions: 1.0–0.5 mm, 0.50–0.25 mm, 0.250–0.125 mm, 0.125–0.063 mm and 0.063–0.032 mm. For all particle size fractions, particle size distribution measurement, proximate analysis, maceral analysis and low-pressure N2 adsorption and CO2 adsorption analyses were conducted. Fractal dimensions D1 (pore surface roughness) and D2 (pore structural irregularity) were determined from relative pressure intervals of 0–0.45 and 0.45–1 of N2 adsorption isotherm with the application of the fractal Frenkel-Halsey-Hill theory, respectively. The results demonstrate significant differences in fractal dimensions in different particle size fractions. As particle size of coal samples decreases, D1 decreases, while D2 increases. Some constricted mesopores are transformed into non-constricted mesopores during crushing. The non-constricted mesopores increasingly concentrate in smaller pore sizes, which results in smoother pore surface (decreasing D1) and more heterogeneous pore structure (increasing D2). Mesopores with pore width between 2 nm and 5 nm are the key to fractal dimensions. Individual mesopore structure parameters closely associated with particle size have universal correlations with fractal dimensions. The increasing mesopore specific surface area and volume and decreasing average mesopore width lead to a decrease in D1 and an increase in D2, which further confirms the effect of particle size on fractal dimensions.

Reservoir Characteristics of the Lower Permian Marine-Continental Transitional Shales: Example from the Shanxi Formation and Taiyuan Formation in the Ordos Basin

The pore types and pore structure parameters of the heterogenetic shale will affect the percolation and reservoir properties of shale; therefore, the research on these parameters is very important for shale reservoir evaluation. We used X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), low-pressure CO2 adsorption analysis, mercury injection capillary pressure (MICP), and high-pressure methane adsorption analysis to analyze the characteristics of different pore types and their parameters of the Lower Permian Shanxi Formation and Taiyuan Formation in the Ordos Basin. The influence of different mineral contents on the porosity and pore size is also investigated. The Shanxi Formation (SF) is composed of quartz (average of 38.4%), plagioclase, siderite, Fe-dolomite, calcite, pyrite, and clay minerals (average of 50.1%), while the Taiyuan Formation (TF) is composed of calcite (average of 37%), siderite, Fe-dolomite, quartz, pyrite, and clay minerals (average of 32.3%). The most common types of pores observed in this formation are interparticle pores (InterP pores), intraparticle pores (IntraP pores), interclay pores, intercrystalline pores (InterC pores), organic matter pores (OM pores), and microfractures. CO2 adsorption analysis demonstrates the type I physisorption isotherms, showing microporous solids having comparatively small external surfaces. The similar types of isothermal shapes of the Shanxi Formation (SF) and Taiyuan Formation (TF) suggest that both types have similar pore size distribution (PSD) within the measured pore range by the low-pressure CO2 adsorption experiment. The micropore pore size of the TF is larger than that of the SF. MICP shows the larger pores (&gt;50 nm), and most of the volume was adsorbed by macropores. Methane gas sorption capacity increases with increasing pressure. Clay minerals and quartz played an important role in providing adsorption sites for methane gas. The overall analysis of both formations shows that TF has good reservoir properties than SF.

Top-Down’ Contextualized Processing of Stimuli Modulates Auditory Mismatch Responses in the Rat

Carbon dioxide (CO2) can be effectively captured from gas mixtures by adsorption on zeolite pellets in fixed-bed columns. In this paper we start from an experimental analysis of CO2 adsorption on a sample of few pellets, to end up with a simulation model for an adsorption column filled with a large number of pellets. The initial experimental analysis is based on dedicated isothermal tests carried out with a gas adsorption analyzer. For the relation between the measured amount of adsorbed CO2 per unit sorbent mass and the input adsorption pressure and temperature, an equilibrium Three-Site Langmuir (TSL) equation is here adopted. Its unknown parameters, namely the saturation capacities, the affinities and the adsorption energies, are estimated by minimizing the error between the equation and the measures. Then, for a whole adsorption column, a simple dynamic model is worked out, based on one-dimensional partial differential equations along the column axial direction: these account basically for mass and energy conservation, for the bulk gas flow and for the porous sorbent. The overall description obtained by combining the TSL equation with the rest of the model is validated against experimental tests, consisting of inlet CO2 molar fraction steps, on a laboratory-scale column.

PdZn bimetallic nanoparticles for CO2 hydrogenation to methanol: Performance and mechanism

By means of density functional theory calculation, an exploration is conducted into the catalytic performance and reaction mechanism of CO2 hydrogenation to methanol on Pd32Zn6 (alloy), Pd32Zn6 (shell/core), and Pd38 nanoparticles. The potential preferred adsorption sites and adsorption energies of all the reaction species are determined. In particular, the electronic structure analysis of CO2 adsorption reveals the significant orbital hybridization occurring between the adsorbed CO2 molecule and Pd atoms, indicating that CO2 molecule is desirably activated and fully prepared for further hydrogenation. Furthermore, the reaction energies and activation barriers to the elementary reactions involved in the HCOO pathway are calculated precisely for the three nanoparticles. Compared with Pd38, the kinetically preferred pathway of methanol synthesis has shown changes after the introduction of Zn, and the activation barrier to the rate-determining step of the reaction route is also reduced on Pd32Zn6 (alloy) and Pd32Zn6 (shell/core) nanoparticles. It is suspected that the PdZn nanoparticle with an alloy structure exhibits higher activity of CO2 hydrogenation to methanol than that with a shell/core structure, which is attributed to the former having a lower activation barrier to the rate-determining step.

Compositional Control on Shale Pore Structure Characteristics across a Maturation Gradient: Insights from the Devonian New Albany Shale and Marcellus Shale in the Eastern United States

The pore structure characteristics of shales are controlled by their mineralogical and organic matter (OM) compositions. However, the contributions by different components in shales at varying thermal maturities remain poorly understood. In this study, Devonian New Albany Shale and Marcellus Shale samples spanning a thermal maturity from marginally mature (vitrinite reflectance Ro 0.55%) to post-mature (Ro 2.41%) were selected to study the control of the composition on the pore structure properties of shales at different stages of thermal maturation. Scanning electron microscopy (SEM) imaging was used to examine the pore types in shales, and low-pressure N2 and CO2 adsorption analyses were used to quantitatively characterize the mesopore and micropore characteristics of bulk shales and major components in shales. The results show that matrix-associated pores including interparticle pores between silt-sized mineral grains, phyllosilicate framework pores, and intraparticle pores within mineral grains exist in all samples but become less common with increasing maturity, which is likely caused by the elevated compaction, cementation, and occlusion with bitumen. Secondary organic pores were not observed by SEM at marginal maturity but were detected in the condensate-wet gas and dry gas windows, with more organic pores in the dry gas window. At marginal maturity, OM has large amounts of mesopores and micropores, as demonstrated by low-pressure N2 and CO2 adsorption analyses of OM isolated from shales, even though no OM-hosted pores were observed by SEM. With increasing thermal maturity, the mesopore and micropore specific surface areas (SSAs) of OM increase and make greater contributions to the pore structure properties of bulk shales. The mesopore and micropore properties of shales are controlled by the OM content and maturity as well as by the clay mineral type and content, and they can be estimated from the contribution of each component at different stages of thermal maturation. Accurate evaluation of the pore volume and SSA of shales will have important implications for assessing gas adsorption and transport in shales.

Laboratory investigation on pore characteristics of coals with consideration of various tectonic deformations

Coal structure is highly related to paleo-stress variation and the pore structure of coals can be modified through tectonic activities. This study characterizes the pore structure variations for various coal samples with different tectonic deformation intensities. The low temperature N2 and pressure CO2 adsorption analyses were conducted to quantify the pore structures, and high pressure CH4 adsorption measurements were carried out for the sorption analysis. The pores were classified into ultramicropores (<2 nm), micropores (2–10 nm), mesopores (10–100 nm) and macropores (>100 nm). The results show that with the increase of coal deformation intensity, the proportion of pore size of 50–300 nm decreased, showing that more macropores and mesopores were deformed to the smaller pores (<50 nm). Micropores (2–10 nm) in granulated and mylonitic coals obviously increased. The predominant ultramicropore in four kinds of coal structures were distributed at the range of 0.45–0.6 nm and 0.80–1.0 nm. Tectonic coals formed more ultramicropores lower than 0.65 nm. The adsorption of CH4, N2 and CO2 increased as the coal deformation degree increased, following the order: mylonitic coal > granulated coal > cataclastic coal > intact coal. Fractal dimensions show that tectonic coals characterized the rougher pore surface (higher D1) and more homogeneous pore structures (lower D2), which led to the higher adsorption capacity. The development of micropores was positive with Langmuir VL, but the ultramicropore SSAs were significantly larger than the contribution to SSAs of micropores and mesopores. Thus, ultramicropore provided the main adsorption sites for CH4. The variations of adsorption potential increased with the coal deformation intensity increased, and the smaller the adsorption space volume was, the larger adsorption potential would be, illustrating that adsorption in micropores was higher than mesopores and macropores. Tectonic coals have the higher reduced rate of cumulative surface free energy, which shows that tectonic damages promote the adsorption potential and surface free energy in coals.

Suitability of Steel Making Slag as a Construction Material Resource

One of the largest problems facing the steelmaking industry is the high amount of waste currently produced and the low amount of waste that is currently recycled. This study aims to look at the suitability of 3 different samples of basic oxygen steelmaking (BOS) slag as a construction material, in concert with their carbon capture capacity. Characterization by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma spectroscopy (ICP), X-ray fluorescence (XRF), CO2 adsorption analysis, and thermogravimetric analysis (TGA) demonstrated that these BOS slags were found to have several favorable characteristics making them suitable for reuse as construction material.

SnS Nanoparticles Grown on Sn-Atom-Modified N,S-Codoped Mesoporous Carbon Nanosheets as Electrocatalysts for CO2 Reduction to Formate

Electrochemical conversion of carbon dioxide (CO2) to formate provides a method for the synthesis of valuable fuels and chemical products. Herein, SnS nanoparticles were grown in situ on Sn-atom-modified N,S-codoped mesoporous carbon nanosheets. As a result, a novel nanohybrid (NH) catalyst named SnS/Sn-NSC NH was obtained for CO2 electroreduction for formate production. In the obtained NHs, the synergistic effect of SnS nanoparticles (∼2.2 nm) with Sn atoms in the carbon matrix and the 3D hierarchical porous structure could provide more active sites and shorten the diffusion pathway, thereby improving the performance of CO2 reduction. The SnS/Sn-NSC NH showed a high Faradaic efficiency (FE) of formate of 91% at a low potential of −0.7 V (vs reversible hydrogen electrode, RHE). In particular, the SnS/Sn-NSC NH demonstrated a favorable FEformate value of over 80% over a wide potential range. On the basis of spectroscopic characterizations, electrochemical tests, and CO2 adsorption analyses, the origin of the enhanced catalytic performance was suggested. This work offers an efficient strategy to construct 3D hierarchical SnS/Sn-NSC NHs for enhancing formate productivity through CO2 electrocatalytic reduction.

The CO2 adsorption performance of aminosilane-modified mesoporous silicas

Aminosilane-modified MCM-41 and SBA-15 mesoporous silicas were synthesized using sodium silicate extracted from gold mine tailings slurry in this study. Pure silica source was used in the synthesis of mesoporous silica in order to compare differences in textural properties and amine loading with differences in CO2 adsorption performance. CO2 adsorption analysis of the synthesized samples was carried out at 25, 75 and 100 °C. The results showed that the aminosilane-modified MCM-41 from slurry and aminosilane-modified SBA-15 from pure silica have the highest adsorption capacities of 1.55 and 1.37 mmol g−1, respectively. As a result, it was found that the CO2 adsorption capacities of the aminosilane-modified samples were increased by increasing the amine contents and the specific surface area. From three kinetic models (pseudo-first-order, pseudo-second-order model and Avrami’s equation), Avrami model well represented the adsorption kinetic data for all adsorbents and revealed that multiple reaction pathway occurred in the CO2 adsorption. In addition, aminosilane-modified samples presented good regenerability after four adsorption–desorption cycles.