Cyclic CO2 Research Articles

CO2 adsorption the numerical simulations and the controlling factors to low rank coal

Carbon Capture Sequestration (CCS) in unmineable coal seams questionably gives benefits for the commercial success through potential release of additional methane during the injection of CO2 adsorbs into the coal seams, the process known as enhanced coalbed methane (ECBM) recovery. However, a significant concern lies in the loss of injectivity due to reduction in permeability by coal matrix swelling occurences with CO2 adsorption although this effect can be partially be offset with ‘huff and puff’ scheme of cyclic CO2 injection followed by extraction of the released methane. The paper discusses the results of a numerical simulation study carried out with GEM compositional reservoir simulator to evaluate the effects of uncertainties in various reservoir parameters on the overall volume of CO2 storage and additional methane recovery of low rank coalfield. A 12-15m thick seam at shallow depth, 50-75 m was considered for fluid flow simulation study. While some information on the reservoir setting was obtained through literature and personal communication with the CBM operators, the rest of the information was derived through laboratory studies. The reservoir parameters considered for the study are injection pressure, adsorption capacity, cleat permeability and porosity, and initial gas saturation. A 100-acre drainage area with 5-spot vertical well pattern was considered with one central injector and four producers on four corners of the study area. The maximum allowable injection pressure was estimated to be 7500 kPa at the reservoir setting. The injection pressure was varied from 1000 kPa to 7500 kPa in the simulation. A number of adsorption isotherms were established in the laboratory. The variations in the adsorption parameters observed through the isotherms were considered as uncertainty in the storage capacities. Significant variations were observed due to the variation in adsorption isotherms both for CO2 storage and additional methane recovery. Fracture permeability was varied from 3 md to 200 md, which is the range of permeability observed in the coalfield is around 100-200 mD. The results of simulation indicate a strong influence of porosity on the CO2 storage and ECBM recovery. Fluid flow simulation study shows that variation in sorption time has no significant effect for a low permeability situation while some marginal effect in high permeability situation. Cleat porosity was varied from 1 % to 10 %. Within this range of porosities, enhanced methane recovery varied from 1 % to 10 % relative to the primary recovery but the volume of stored CO2 did not vary significantly. Lastly, the pore pressure, adsorption and gas saturation of CO2 sequestered volume and additional methane recovery were found to increase substantially.

Experimental investigation on the operation parameters of carbon dioxide huff-n-puff process in ultra low permeability oil reservoirs

For oil reservoirs featured with ultra low permeability, CO2 huff-n-puff can be a promising approach for enhanced oil recovery. To understand its production performance and the effects of different factors in field operation, a series of CO2 huff-n-puff experiments under various conditions were conducted using a 1D sandpack model, and the extraction effect of CO2 and its influence on oil production have been analyzed. The experimental results show that, as cyclic CO2 injection quantity increases, the cyclic oil recovery factor is improved, but the CO2 utilization factor is reduced, and there will be an optimum cyclic injection quantity from economic point of view. Both cyclic oil recovery factor and CO2 utilization factor are improved with the increasing reservoir temperature, while injection of low temperature CO2 may impose an adverse influence on oil recovery performance. In addition, the cyclic oil recovery factor and CO2 utilization factor firstly rise and then fall with the increasing soaking period. The results presented in this study are expected to provide some guidance to the field implementation of CO2 huff-n-puff technique in ultra low permeability oil reservoirs.

Evaluation of high-temperature CO2 capture performance of cellulose-templated CaO-based pellets

The addition of biomass-based pore-forming templates is an effective approach to improve CO2 capture performance of CaO-based pellets. In this work, cellulose-templated CaO-based pellets were prepared via an extrusion-spherization method. The cyclic CO2 uptake capacity of cellulose-templated pellets was investigated with the variation of pellet size, particle size of cellulose and pre-calcination conditions. It is found that the smaller pellets possess the faster CO2 capture rate during chemical reaction-controlled stage, while the pellet size scarcely affects the ultima CO2 capture capacities of cellulose-templated pellets in 30 min carbonation. Although the addition of cellulose template contributes to enhance CO2 uptake of CaO-based sorbent pellets (over 0.32 g CO2/g sorbent after 25 cycles), the particle size of cellulose plays a limited role on the CO2 capture performance enhancement effectiveness. Additionally, the cellulose-templated pellets pre-calcined under severe conditions (air calcination and coal combustion) exhibit the inferior, initial CO2 capture capacities due to the excessive sintering as a result of heat release of cellulose and coal combustion. However, severe pretreatments are rewarding to improve the CO2 sorption stability of cellulose-templated sorbent pellets because of the generation of large amounts of micro-sized cavities which are less sensitive to sintering.

Cyclic CO2 – H2O injection and residual trapping: Implications for CO2 injection efficiency and storage security

To meet the Paris Agreement target of limiting global warming to 2 °C or below it is widely accepted that Carbon Capture and Storage (CCS) will have to be deployed at scale. For the first time, experiments have been undertaken over six cycles of water and supercritical CO2 injection using a state of the art high flow rig recreating in-situ conditions of near wellbore injection into analogue storage reservoir rocks. The results show that differential pressure continuously increases over multiple injection cycles. Our interpretation is that multiple cycles of injection result in a reduced effective permeability due to increased residual trapping acting as a barrier to flow resulting in reduced injectivity. This is supported by numerical modelling and field observations that show CO2 injectivity and its variation over time will be affected by multiple cycles of injection. These results suggest that loss of injectivity must be incorporated into the injection strategy and that careful management of cyclic injection will create the opportunity to increase residual trapping.

Influence of water vapor on cyclic CO2 capture performance in both carbonation and decarbonation stages for Ca-Al mixed oxide

Little research was carried out to study the effect of water vapor with different contents on the CO2 adsorption performance during extending cycles in both carbonation and decarbonation stages. This study described the CO2 adsorption performance of Ca-Al mixed oxides under different water vapor concentrations. The results revealed that the reactivity and durability of both fresh and spent sorbents were remarkably enhanced by adding water vapor. The initial CO2 carbonation capacity increased from 56 wt% without water to 70.7 wt% with 1.6% water vapor at the adsorption temperature of 600 °C. The stability of Ca-Al mixed oxides was also investigated during 220 cycles with 1% steam vapor. The CO2 adsorption capacity retained 55.6 wt% after 220 cycles, indicating an excellent long-term durability. The excellent CO2 adsorption capacity and stability of the mixed oxides in the existence of water vapor may be attributed to the following reasons: water vapor facilitated CO2 diffusion in the CaCO3 product layer during the carbonation stage as well as the decomposition rate of CaCO3 during the calcination stage; water vapor facilated the formation of the loose porous structure, which was favorable for the subsequent carbonation of CaO.

CO2 capture and attrition performance of competitive eco‐friendly calcium‐based pellets in fluidized bed

AbstractA system incorporating spent bleaching clay (SBC) into the calcium looping (CaL) process has been proposed. In this paper, prepared sorbents doped with regenerated SBC and cement were tested in a bubbling fluidized bed (BFB) to examine in detail their cyclic CO2 capture capacity and attrition properties. The results revealed that the cyclic CO2 capture capacity of pellets modified by pyrolyzed SBC and/or cement showed significantly better performance than limestone, which is consistent with the thermogravimetric analyzer (TGA) results. This is due to the improvement of pore structure and enhanced sintering resistance created by adding support materials to the sorbent. The elutriation rates of the composites prepared with pyrolyzed SBC and/or cement were consistently lower than for crushed limestone. Scanning electron microscopy (SEM) images indicated that the pellets possessed higher sphericity than limestone particles, thus reducing surface abrasion. Limestone exhibited a high attrition rate (diameter reduction rate) of 10.7 μm/cycle, which could be eliminated effectively by adding regenerated SBC and/or cement. ‘L‐5PC‐10CA’ (85% lime/5% pyrolyzed SBC/10% cement) exhibited an attrition rate of only 7.9 μm/cycle. Based on the analysis of breakage and probability density function (PDF) for particle size distribution, it appeared that pellets without cement experienced breakage (mostly chipping and disintegration) and surface abrasion, whereas ‘L‐10CA’ (90% lime/10% cement) and ‘L‐5PC‐10CA’ mainly suffered surface abrasion, combined with some chipping. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

A study of structure-activity relationships of aqueous diamine solutions with low heat of regeneration for post-combustion CO2 capture

The structure-activity relationship of eleven diamines and MEA was investigated in order to provide guidance for the selection of the potential CO2 capture absorbent. The effects of methyl, ethyl, hydroxyl groups, and distance between N groups in molecular structures were evaluated experimentally by using the rapid fast screening method and computed by Gaussian 09. Experimental results revealed that the proper number of methyl groups and ethyl groups on N atom could improve the absorption rate as well as the cyclic CO2 capacity, and the addition of a hydroxyl group actually achieved a lower energy requirement (i.e. cyclic CO2 capacity) for solvent regeneration with the decreasing stability of carbamate. In addition, the diamine with a hydroxyl group is more favorable for good stability in regeneration process, which addresses the problem of solvent loss in the application of diamines. Chain length extension from C2 to C3 can result in the poorer stability of the carbamate and lower energy requirement for amine regeneration. Thus, the lowest energy consumption (i.e. CO2 cyclic capacity) was then achieved by aqueous 2-((2-aminoethyl)amino)ethanol (AEEA) solution, presenting it can be considered as an alternative or a potential absorbent for post-combustion CO2 capture. Furthermore, the relative free energies of the tested diamines were computed by the Gaussian software for validating the stability of the carbamate formation, the order of which is in accordance with the order of the cyclic CO2 capacity for all tested amines, indicating the experimental conclusion can be reliable.

Microwave regeneration of monoethanolamine aqueous solutions used for CO2 capture

Aqueous amine absorbents are widely used in post-combustion CO2 capture processes. To strip the CO2, the solutions are usually heated around 110–140 °C using a steam reboiler located at the bottom of the regeneration column. In this work, microwave irradiation was studied as a new alternative to heat and regenerate CO2-rich monoethanolamine (MEA) aqueous solutions. Various parameters like the amine concentration, the regeneration temperature and the initial microwave power were modified to assess regeneration efficiencies by microwave heating and to find optimal experimental conditions in term of recovered CO2 amount and energy consumption.The heating rate of solutions by microwave was found to be mostly influenced by their heat capacity, viscosity and CO2 loading. The optimal heating rate was found for the 50 wt% MEA solution and regeneration performance parameters, based on the CO2 stripped quantity and microwave energy absorbed by the solution, were also found to be optimal at this concentration. Using a 50 wt% MEA solution instead of the well-known 30 wt% gave a 13% increase in the CO2 cyclic capacity while the regeneration energy consumption decreased by 15% under the optimal conditions tested in this work. These results indicate that the 50 wt% MEA solution seems to offer great potential in a cyclic CO2 absorption-microwave regeneration process.

Mass transfer performance for CO2 absorption into aqueous blended DMEA/MEA solution with optimized molar ratio in a hollow fiber membrane contactor

Combination N,N-dimethylethanolamine(DMEA) and monoethanolamine (MEA) may represent a potential absorbent for CO2 capture due to the high absorption rate, high cyclic CO2 capacity and low energy requirement for solvent regeneration. Both the absorption and regeneration performances for 2 kmol/m3 DMEA/MEA with molar ratios of 2.0:0.0, 1.5:0.5, 1.0:1.0, 0.5:1.5, and 0.0:2.0 were estimated in terms of the absorption rate, regeneration rate and cyclic CO2 capacity using an improved rapid screening method. The experimental results showed that the highest cyclic CO2 capacities (i.e. low energy requirement) for the cyclic reaction time of 30 min and 60 min were obtained both by 1.0 M DMEA + 1.0 M MEA solution, indicating the synergistic effects existing in CO2 absorption into DMEA/MEA solution. Additionally, the mass transfer performance of CO2 absorption into 1.0 M DMEA + 1.0 M MEA solution was investigated in a hollow fiber membrane contactor. The effects of key operational parameters such as liquid velocity, inlet gas flow rate, CO2 partial pressure, feed temperature range, CO2 lean loading, amine concentration and membrane contactor height on the CO2 flux and overall gas phase mass transfer coefficient were investigated. Furthermore, a developed correlation was successfully applied for the prediction of overall gas phase mass transfer coefficient (KG) for CO2 absorption into DMEA/MEA solution, with an average absolute relative deviation (AARD) of 8.31%. Thus, a potential absorbent (i.e. DMEA/MEA) for CO2 capture was proposed in this work.

Numerical modelling of cyclic CO2 injection in unconventional tight oil resources; trivial effects of heterogeneity and hysteresis in Bakken formation

The impact of rock heterogeneity on the performance of cyclic gas injection is a key element in tight oil reservoir modeling. Dependency of relative permeability on saturation history during cyclic CO2 injection (CCI) in various operational constraints affects the oil recovery in different ways. Numerous studies exist on the hydraulically fractured horizontal wells in unconventional resources, especially on cyclic gas injection performance. However, because of simplifications, the uncertainty due to permeability heterogeneity and dependency of reservoir gas extent on saturation history has not been considered in simulation models. A poor understanding of the variables affecting CO2 injection efficiency might result in unsuccessful treatments and project failures. The aim of the present work is to numerically model the physical properties of matrix heterogeneity and relative permeability hysteresis, which are influential in reservoir performance and should not be ignored during CCI. In this work, a compositional simulation model is built based on the Bakken formation geological settings, well production and crude oil PVT data. To embody heterogeneity, matrix and natural fracture effective permeability fields are log-normally populated. Four permeability maps based on Dykstra-Parsons (DP) coefficients are generated and applied in a sector model. A relative permeability hysteresis model is incorporated within the simulator using the Killough’s method. Hence, the effect of hysteresis-induced gas retardation on oil recovery and CO2 retention can be studied during CCI in which strong flow reversals happens. A compositional field-scale simulation of CCI is conducted and recovery performance is investigated as well as retained CO2 saturation. The simulation results revealed that production is greatly affected by heterogeneity at early stages of reservoir life. Uneven flow in the presence of heterogeneity leads to lower recovery during primary depletion. This effect is more highlighted after implementing CCI since injected gas is prevented from uniform distribution further and deep into the reservoir. Dissolution gas trapping is also modeled with inclusion of relative permeability hysteresis. Recovered oil from the hysteretic model illustrates a minor effect on CO2 trapping at near-miscible conditions. However, CO2 retention improves oil recovery at immiscible injection. In this model shortcomings of uncertainties associated with the simplified reservoir models in terms of uniformity in absolute permeability and relative permeability are reduced. Our results highlight the underlying mechanisms of lower recovery induced by heterogeneity and of improved efficiency due to hysteresis.

Porous extruded-spheronized Li4SiO4 pellets for cyclic CO2 capture

In this work, spherical Li4SiO4 pellets were produced via an extrusion–spheronization technique. This pelletization process caused the destruction of the original porous structure, a reduction of the specific surface area and, thus, a decrease in the CO2 sorption performance. Therefore, a typical pore-forming material of microcrystalline cellulose was employed to modify the inner microstructures of the pellets and thus enhanced the cyclic CO2 sorption capacity. The pellets modified with 20 wt% microcrystalline cellulose exhibited a high capacity of 0.282 g CO2/g sorbent at the 70th cycle, which is even comparable with that of the Li4SiO4 powder. It has been indicated that the performance enhancement is attributed to the increased surface area and enriched porosity. In addition, the sorbent pellets are required to possess excellent mechanical performance for the practical application in the circulating fluidized-bed reactors; therefore, the mechanical properties, i.e., compression strength and anti-attrition performance, were also tested. The results indicated that the Li4SiO4 pellets maintained quite outstanding mechanical performance. The good physicochemical properties of the pellets show that the developed Li4SiO4-based sorbents have promising prospects for high temperature CO2 capture in fluidized-bed systems.

Characterization and evaluation of synthetic Dawsonites as CO2 sorbents

The sorbent enhanced water-gas shift (SEWGS) process has great potential for CO2 capture and is thereby a realistic alternative to conventional post-combustion capture by gas emission scrubbing. Nevertheless, better performing materials are required to make SEWGS competitive against state-of-the-art scrubbing technologies. Dawsonite, NaAl(OH)2CO3, has a high carbonate content and forms in situ during CO2 capture on alkali metal promoted alumina, thereby showing potential in variable temperature capture processes. For the isothermal SEWGS process the performance in pressure swing absorption is essential. We evaluate here synthetic Dawsonites [MAl(OH)2CO3, M = K, Na] as CO2 sorbents for the SEWGS process based on data from in situ X-ray diffraction, combined thermogravimetric analysis and mass spectrometry, magic-angle spinning nuclear magnetic resonance spectroscopy, as well as high pressure fixed bed reactor tests at isothermal conditions. The results show that synthetic Dawsonites are promising sorbents for the SEWGS process, however, with moderate cyclic CO2 capacities (∼0.3–0.7 mmol CO2/g sorbent) in comparison to alkali-metal promoted hydrotalcites. On the other hand, the materials exhibit relatively fast sorption rates at low temperatures (280–310 °C), favoring the water-gas shift reaction in the SEWGS process.

Adsorption breakthrough and cycling stability of carbon dioxide separation from CO2/N2/H2O mixture under ambient conditions using 13X and Mg-MOF-74

Carbon dioxide and storage is an efficient method to reduce the emitted CO2 from the burning of fossil fuels. Zeolite-based materials are conventional adsorbents used to adsorb some gasses involving carbon dioxide. Mg-MOF-74 is an eminent reticular material among adsorbents due to its good CO2 capacity at low pressures (10–20 kPa). In this study, an experimentally validated model is used to report the H2O effect on CO2 separation using 13X and Mg-MOF-74 under ambient conditions. A computational model has been developed using ANSYS Fluent program linked by user-define-function (written in C). The adsorption breakthrough results show that a humid CO2/N2 mixture, under 300 K, 86% RH, 101.3 kPa, could slightly reduce the CO2 adsorption capacity by about 0.05% and 6% for 13X and Mg-MOF-74, respectively (at CO2 adsorption breakthrough saturation). Regardless of these reductions, Mg-MOF-74 has better adsorption capacity, even under humid ambient conditions, by about 5.77 mmol/g in a comparison to 2.27 mmol/g for 13X, respectively.Cycling stability over more than 90 cycles is also simulated; and shows that, a dehydration process is recommended to be carried out before the CO2 separation process for efficient energy consumption and sustainable adsorbents. The total recyclable amounts of adsorbed CO2 are about 0.94 and 3.07 mmol/g for 13X and Mg-MOF-74, respectively, under 101.3 kPa adsorption, 2 kPa desorption, 86% relative humidity, and 298 K. The cyclic CO2 separation is found to be a robust method more than the breakthrough separation to evaluate the real adsorption capacities.

CO2 capture using mesocellular siliceous foam (MCF)-supported CaO

CaO is a promising material as an alternative CO2 capture material which can be used at high temperature. However, CaO sinters to form large particles under long-term high temperature conditions, resulting in a rapid decrease of its surface area and the capacity of CO2 capture. Incorporating CaO into inert materials is a promising strategy to enhance the performance of CO2 capture. This work investigated a novel composite material called mesocellular siliceous foam (MCF)-supported CaO to enhance the stability and capacity of CaO-based materials for CO2 capture. The crystal structure, surface morphology and porosity property of the developed composite materials were investigated. Thermogravimetric measurements were carried out to study the cyclic CO2 capture performance of the MCF-supported CaO composites. The results showed that a part of CaO reacted with the silica wall, and the formation of Ca2SiO4 within the MCF framework limited the presence of CaO in the mesopores, thus inhibited the sintering of CaO. The sample of MCF-3CaO exhibited a better performance of CO2 capture and long-term stability, compared with the materials prepared with lower CaO loading. This work contributes to the development of high temperature CO2 capture adsorbents, which can be applied for decarbonizing major industrials e.g. power plant.

Selective formation of a zwitterion adduct and bicarbonate salt in the efficient CO2 fixation by N-benzyl cyclic guanidine under dry and wet conditions.

The efficient CO2 fixation by N-benzyl cyclic guanidine 1 was achieved by bubbling dry CO2 through CH3CN at 25 °C for 2 h. In addition, the zwitterion adduct 2 and bicarbonate salt 3 were selectively prepared from 1 under dry (in anhydrous CH3CN) and wet (in CH3CN containing an equimolar amount of water for 1) conditions, respectively. Both compounds 2 and 3 were isolated as white solids and their structures were characterized in detail by elemental analysis, FTIR-ATR, solid-state NMR, TGA, and DFT calculation. These analytical results obviously revealed the formation of a zwitterion adduct and bicarbonate salt from N-benzyl cyclic guanidine and CO2. Especially, the zwitterion adduct of the monocyclic guanidine derivative and CO2 was isolated and characterized for the first time.

Introduction of chemically bonded zirconium oxide in CaO-based high-temperature CO2 sorbents for enhanced cyclic sorption

In this study, ZrO2 is introduced in a new form to reduce sintering and enhance the cyclic stability of CaO-based sorbents. Such a material has potential for high-temperature CO2 capture applications. Two Zr-modified CaO materials having a Ca/Zr molar ratio of 30 are prepared using the solid-state and citrate sol-gel methods. The solid-state method yields a physical mixture of CaO and ZrO2, while the citrate sol-gel method induces chemical bonding between ZrO2 and the CaO surface to form CaZrO3. The CO2 sorption uptake was significantly increased in both unmodified CaO and ZrO2-containing CaO [77.3 wt% (17.6 mol kg−1) and 73.2 wt% (16.6 mol kg−1), respectively, at 650 °C and 1 bar] when the citrate sol-gel method was used. The CaO having the chemically bonded ZrO2 reveals significantly enhanced cyclic stabilities, with an extremely high CO2 sorption uptake of 70.5 wt% (16.0 mol kg−1) on average during 10 cycles. On the other hand, the CaO containing the physically mixed ZrO2 reveals an average cyclic CO2 sorption uptake of only 37.2 wt% (8.5 mol kg−1). The chemically bonded ZrO2 is expected to be well scattered on the CaO surface and effectively cover the sorbent, resulting in the reduction of thermal sintering. In addition to cyclic stability, CO2 sorption kinetics of CaO-based sorbents can be enhanced through the citrate sol-gel method, which is resulted from the significantly reduced size of CaO particles.

CaO-based sorbent derived from lime mud and bauxite tailings for cyclic CO2 capture.

Using aluminum nitrate (AlN) and bauxite tailings (BTs) as different dopants, and lime mud (LM) as calcium source, a series of CaO-based sorbents were prepared for CO2 capture by dry mixing method; then, the carbonation conversions of multiple carbonation/calcination cycles were detected in a thermogravimetric analyzer (TGA). Effects of different dopants, dopant contents, precalcination conditions, and a long series of cycles on CO2 absorption properties were scrutinized, and the phase composition and morphologies were tested by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Durability studies show that the sample doped with AlN remains a higher absorption conversion (30.88%) after 30 carbonation/calcination cycles. In the meantime, the sorbent doped with BTs showed a lower conversion, which is probably resulted from the impurities from waste BTs. However, the sample BT has a better cyclic absorption stability. In addition, the incorporation of BTs, as a kind of solid waste, not only decreases the preparation cost but also is good for environment. The occurrence of Ca12Al14O33 phase is considered to provide a stable framework inhibiting inactivation of CaO, and improve the CO2 adsorption stability. Graphical abstract ᅟ.

Bromide Adsorption on Pt(111) over a Wide Range of pH: Cyclic Voltammetry and CO Displacement Experiments

Bromide adsorption on Pt(111) is investigated by means of cyclic voltammetry and CO displacement experiments at different pH values. In acidic pH, bromide adsorption is strongly overlapped with hyd...

Catalyst-TiO(OH)2 could drastically reduce the energy consumption of CO2 capture

Implementing Paris Climate Accord is inhibited by the high energy consumption of the state-of-the-art CO2 capture technologies due to the notoriously slow kinetics in CO2 desorption step of CO2 capture. To address the challenge, here we report that nanostructured TiO(OH)2 as a catalyst is capable of drastically increasing the rates of CO2 desorption from spent monoethanolamine (MEA) by over 4500%. This discovery makes CO2 capture successful at much lower temperatures, which not only dramatically reduces energy consumption but also amine losses and prevents emission of carcinogenic amine-decomposition byproducts. The catalytic effect of TiO(OH)2 is observed with Raman characterization. The stabilities of the catalyst and MEA are confirmed with 50 cyclic CO2 sorption and sorption. A possible mechanism is proposed for the TiO(OH)2-catalyzed CO2 capture. TiO(OH)2 could be a key to the future success of Paris Climat e Accord.

One-step synthesis of porous Li4SiO4-based adsorbent pellets via graphite moulding method for cyclic CO2 capture

In this study, a novel one-step graphite moulding pelletization method was used to produce porous Li4SiO4 adsorbent pellets conveniently. The produced pellets were primarily composed of Li4SiO4 phase from X-ray diffraction analysis. The as-prepared adsorbent pellets exhibited good sphericity and a uniform diameter distribution of 2–2.5 mm. The detected porous structure resulting from the fast release of gases during the synthesis process could increase the porosity of pellets significantly and lead to a greater specific surface area of 1.02 m2/g. This pelletization method produced a high CO2 capture capacity of 0.22 g/g at the 50th cycle when the adsorption process was performed at 550 °C under 15 vol% CO2 for 30 min. Moreover, the extra contraction force due to the shrinkage during the chemical reaction of the calcination process could enhance the mechanical strength of the pellets, resulting in the high compression strength (2.84 MPa) and the superior attrition resistance (a weight loss of 6.72% after 2000 cycles). The good overall performance (i.e., CO2 capture capacity and mechanical strength) of the produced pellets in this work indicates that the graphite moulding method may be applied in the synthesis of Li4SiO4 adsorbent pellets for CO2 capture.