Displacement and Diffusion of Methane and Carbon Dioxide in SBA

Subscriber access provided by UNIV OF CALIFORNIA SAN DIEGO LIBRARIES

Article

Displacement and Diffusion of Methane and Carbon Dioxide in SBA-15 Studied by NMR Yuanli Hu, Xiulian Pan, Xiuwen Han, and Xinhe Bao J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/acs.jpcc.6b12250 • Publication Date (Web): 09 Jan 2017 Downloaded from http://pubs.acs.org on January 15, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

The Journal of Physical Chemistry C is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The Journal of Physical Chemistry

Displacement and Diffusion of Methane and Carbon Dioxide in SBA-15 Studied by NMR ‡

†

†

†

† Yuanli Hu, , Xiulian Pan,*, Xiuwen Han and Xinhe Bao*,

†

State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese

Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China ‡

Graduate University of Chinese Academy of Sciences, Beijing 100049, China

ACS Paragon Plus Environment

1


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 20

ABSTRACT: With increasing concern about the environmental impact of shale gas exploitation, non-aqueous fracturing with carbon dioxide has emerged as a promising alternative to increase gas production, at the same time, to store large amounts of CO2. The key process of CH4 displacement by CO2 is worth a systematic investigation from both aspect of experiment and simulation. In this work, the CH4 and CO2 displacement was studied with in situ 13C NMR in the pores of silica (SBA-15), which were functionalized with organic groups such as phenyl and cyclohexyl, in order to model the organic matter in shale with different aromaticity. Due to the stronger adsorption strength and higher capacity of CO2 in SBA-15, CH4 can be easily stripped out of the pores by CO2, while the reverse process to displace CO2 with CH4 is not effective. Even though the displacement effect in the pores of SBA-15 with a higher aromaticity is relative better at room temperature, the superiority is eliminated by high temperature. Furthermore, the results of pulse field gradient (PFG) NMR demonstrate that the self-diffusion coefficient of CO2 is an order of magnitude smaller than that of CH4 and the existence of CO2 slows down the diffusion of CH4 slightly. The gas diffusion in both scenario follows the trend: SBA-15 > SBA-phenyl > SBA-cyclohexyl.


2

Page 3 of 20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Introduction Over the last decade, shale gas has received extensive attention as an important energy resource.1, 2 Utilization of this rich resource still relies on efficient exploitation, which in turn relies on knowledge of its fundamental properties. It is known that shale gas, which is mainly composed of methane, is trapped in the organic and inorganic nanopores of the shale.3 In order to increase the permeability of the shale and to enhance the recovery of the shale gas, fracking has been widely used.4, 5 Water is a well-accepted fracturing fluid used in commercial shale gas production due to its low price. However, its availability accompanied by other issues such as drought, flow-back water disposal and potential freshwater contamination, have triggered wide controversies in the development of shale gas.6 Enforcing more stringent regulations are necessary to minimize these environmental risks.7,

8

A typical non-aqueous

fracturing fluid is supercritical carbon dioxide, which is a promising alternative. Because of its low surface tension, CO2-base fluids can possibly create more extensive fracture networks than water-based fluids and avoid the problem of water block in hydraulic fracturing.6, 9 In addition to the benefits of enhanced gas recovery, large amounts of CO2 can be sequestrated underground at the same time.10 However, only limited field-scale projects with CO2 as a fracturing fluid have been implemented due to the operational difficulties and uncertainties.11 Further fundamental research on CO2 adsorption and CH4 displacement is required to bring forward more efficient exploitation of shale gas, as well as carbon dioxide sequestration. The adsorption and displacement of CH4 and CO2 was studied by molecular dynamic (MD) simulations using carbon materials, e.g., graphene and carbon nanotube, to model typical organic structure of kerogen in the shale.12-14 For the inorganic component, montmorillonite was widely studied, as it is one of the most common types of clay minerals.15-17 However, the majority of these previous studies focused on the adsorption behaviour of gas molecules, while the displacement and diffusion properties were rarely investigated and the mechanism was poorly


3


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 20

understood. Taking into account of the nanopores in clay minerals and the typical structures of kerogen, our previous research chose the well-ordered mesoporous materials SBA-15 modified with typical organic groups of kerogen to model the shale, i.e. the aromatic phenyl and non-aromatic cyclohexyl groups.18 1H pulsed field gradient (PFG) NMR and MD simulation results demonstrated that diffusion of methane was faster in SBA-15 modified with higher aromaticity, which was likely associated with the maturity of the pores.19 Here we took a step further to investigate the role of CO2 in the displacement of CH4 in such model with in situ

13

C NMR. The influence of

temperature was also taken into consideration. The displacement effect in SBA-15 modified with phenyl is better than that with cyclohexyl, while no obvious difference can be detected at a higher temperature. In addition, 13C and 1H pulsed field gradient (PFG) NMR was adopted to measure the self-diffusion coefficients of CO2 and CH4, respectively. The slower diffusion of CO2 than CH4 also favours the sequestration of CO2. The existence of CO2 will slow down the diffusion of CH4 slightly due to the increasing pressure of the system. Our attempt to monitor the gas displacement process in NMR opens up the possibility to connect the traditional chemical kinetic analysis with new application scenario such as energy exploitation. The study reveals the key parameters which could influence gas production.

Experimental Section Simulation Experiment about Gas Displacement on NMR SBA-15 is a typical mesoporous silica material with two-dimensional hexagonal p6mm symmetry.20 Pure silica SBA-15 with an average pore diameter of 6.5 nm was purchased form Nanjing JCNANO Technology Co. Ltd. The pore walls were modified with phenyl and cyclohexyl groups via hydrolysis and condensation reaction of Si-OH on the surface of SBA-15 using trimethoxysilane, as in our previous report.18 Then the specific SBA-15 sample with 40~60 mesh was filled in a 5 mm


4

Page 5 of 20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


vacuum NMR tube (Wilmad-LabGlass). The special design of the NMR tube allowed the introduction of gas without exposure to air. After degassing overnight at 393 K to remove the adsorbed gas and water, the sample tube was transferred to the NMR spectrometer. Before the displacement experiment, the NMR probe was heated to the target temperature and was kept for 30 min to allow equilibrium. During the methane displacement experiment, the sample was exposed to 56 kPa

13

CH4 (Aldrich, 99%

atom 13C) and kept for 15 min to allow equilibrium before carbon dioxide injection. Once 103 kPa

13

CO2 (Aldrich, 99% atom

13

C) was introduced, in situ

13

C NMR

spectra began to record uninterruptedly until no obvious change of the signals could be detected. On the contrary, for the carbon dioxide displacement experiment, 56 kPa 13

CO2 and 103 kPa 13CH4 was introduced in turn to the sample tube. Compared to the

limited trajectory length of several nanoseconds in the displacement process studied by MD simulations,13, 14 our experiments performed on the NMR facility lasted for nearly 1 hour, which were closer to the real situation. NMR Experiment NMR experiments were performed on a Bruker Avance III-400 MHz spectrometer equipped with a Quattro Nucleus Probe (QNP). The probe could generate a maximum gradient amplitude of 56 G/cm in the z direction. The 13C spectra were acquired with a π/2 pulse length of 10 µs and recycle delay time of 1 s by accumulating 16 scans. The inversion recovery sequence was used to measure the spin-lattice relaxation times (T1) of 13CH4 and 13CO2. At the equilibrium pressure about 120 kPa, the T1 was 28 ms and 160 ms for 13CH4 and 13CO2, respectively. Thus we could ensure the recycle delay long enough for quantitative analysis. Taking into account of the system response time, the sampling time-interval was 24 s. The whole process usually lasted for 50~80 min. When detecting the self-diffusion diffusivity of CO2, the degassed sample was filled in a 5 mm vacuum NMR tube, then CO2 was introduced into the tubes by opening of the piston above the sample tube. The influence of CO2 on the diffusion of CH4 could also be determined by measuring the self-diffusion diffusivity of CH4 after


5


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 20

the introduction of CO2 into the sample tube. The PFG measurements were carried out using the stimulated echo sequence with bipolar gradients, i.e., 13 interval sequence, in order to eliminate the influence of magnetic susceptibility effect that exists in beds of porous particles.21 The spin echo attenuation Ψ could be obtained by linearly increasing the gradient strength while keeping the diffusion time ∆ and the gradient pulse length δ constant. The δ and ∆ values were set to 380 µs and 1.2 ms for 1H PFG NMR, respectively. While for 13C PFG NMR, the δ and ∆ values were set to 2.54 ms and 10 ms, respectively. The spin echo attenuation can be fitted by: Ψ=

= × exp − Δ + 1 − × exp − Δ

(1)

where D1 and D2 denote the self-diffusion coefficients of the components related to diffusivities of the gas molecules in the gas phase and those adsorbed on the wall of SBA-15, respectively, and p is the fraction of the molecules with the diffusivity D1 among the total number of molecules. The wave number q is the product γδg, γ is the nuclear gyromagnetic ratio and g is the amplitude of the gradient pulse.

Results and Discussion In situ 13C NMR spectra in the process of 13CH4 displacement and 13CO2 displacement for SBA-phenyl and SBA-cyclohexyl at 297 K are presented in Figure 1 and Figure S1, respectively. The signals at -8 and 127 ppm are attributed to respectively. During the process of

13

decreases while the concentration of

13

CH4 and

13

CO2,

CH4 displacement, the concentration of 13CH4 13

CO2 increases dramatically till the system

reaches the equilibrium. In contrast, in the samples pre-adsorbed with 13CO2, there are always some 13CO2 left even after sufficient time is allowed to reach equilibrium upon introduction of 13CH4. This suggests that either CO2 has a higher adsorption capacity or stronger adsorption strength, which cannot be displaced by methane completely. The reason could be the appreciable quadrupole moment existing in the CO2


6

Page 7 of 20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


molecules, which results in stronger interaction with the adsorbate. In contrast, there only exists a much weaker octupole moment in CH4 molecules.22 In order to quantitatively track the variations of gas contents during the displacement processes, the relative concentrations of

13

CO2 and

13

CH4 were

investigated by integrating the areas of NMR spectra, which were normalized referring to that at the initial time (t = 0). Figure 2 shows the time-dependent methane displacement and carbon dioxide displacement processes on SBA-phenyl at different temperatures (see Figure S2 for the results on SBA-cyclohexyl). It should be noted that the experimental data are slightly more dispersed at a higher temperature, which is due to lowered sensitivity of NMR spectra. One sees that in the methane displacement process, at t = 0, the concentration of CH4 starts at a maximum value; and with time on stream, the concentration levels off. It can be expected that at t =∞, the concentration of CH4 and CO2 reaches minimum and maximum value, respectively. Careful fitting of the displacement data indicates that the concentration variation follows well exponential functions, as described by eq 2 and 3: Y = a − a × exp −t/

(2)

Y = b + c × exp −t/

(3)

!

where Y represents the concentration of the gas molecules at the time t, and

!

denote the characteristic time constants for the displacement process to reach an

equilibrium. Take the methane displacement process as an example, the value of a and b represent the equilibrium adsorption capacity of CO2 and CH4, respectively. Similar definitions could be found for the process of carbon dioxide displacement. The best-fitted parameters of the equilibrium adsorption capacities and the characteristic equilibrium time constants at different experimental conditions were plotted in Figure 3 and summarized in Table S1-S4 to be clearer (see ESI†). As shown in Figure 3a, the concentration of the residual CH4 at the equilibrium status remains mostly at the same level of 0.4, which means that about 60% of the


7


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 20

methane molecules are dismissed from the pores of SBA-15. Very interestingly, the temperature affects the displacement process. The equilibrium adsorption capacity of CO2 decreases drastically from nearly 2.5 at 297 K to 1.1 at 353 K whereas that of CH4 remains temperature independent. This demonstrates that the response of CO2 for temperature is more sensitive than CH4. Figure 3b shows the variations of the characteristic equilibrium time constants in the process of methane displacement. It can be clearly seen that the time constants decrease rapidly with the increasing temperatures, which suggests that the high temperature accelerates the methane displacement process. This phenomenon can be attributed to the faster molecular motion at a high temperature. As seen from Figure 1, the signals of 13CO2 are stronger than 13CH4. Therefore, a smaller standard deviation is expected for extracting the time constants for 13CO2. It would be much more reliable to use the time constant for 13CO2 to characterize the efficiency of methane displacement. Furthermore, Figure 3b demonstrates that the time constants for SBA-phenyl are slightly longer than that of SBA-cyclohexyl and the difference reduces at a higher temperature. The best-fitted parameters in the carbon dioxide displacement process were plotted in Figure 3c and 3d. Obviously, the amount of 13CH4 entering the pores of SBA-15 in the presence of carbon dioxide is much less than that of the displacement process. The concentration of the residual decreases while the amount of

13

13

CO2 during methane

13

CO2 at the equilibrium

CH4 entering the SBA-15 pores increases with the

increasing temperature, which is surprising and differs obviously from the methane displacement (Figure 3a). The above results clarify that the adsorption of carbon dioxide in SBA-15 is more sensitive to temperature than that of methane. It appears that a higher temperature could impede the adsorption of gas molecules in SBA-15, and its influence is stronger on carbon dioxide. Therefore, more adsorption sites are likely released, which may allow methane adsorption. In addition, it can be seen that the characteristic equilibrium time constants in the carbon dioxide displacement process are much smaller than that in methane displacement (Figure 3d), especially


8

Page 9 of 20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


for that of methane. It demonstrates that displacement of carbon dioxide with methane reaches equilibrium much faster than the reversed process, i.e., methane displacement. Considering the amount of CO2 stripped by CH4, a shorter time constant is related to the stronger adsorption strength of CO2, leading to an insufficient displacement by CH4. Consequently, the striping action aborts quickly. The time constants for CO2 are longer than CH4 in both processes, and the differences are greater in the CO2 displacement process, suggesting asynchronous dynamics of methane and carbon dioxide in the displacement processes. The introduction of another molecule disturbs the original equilibrium state. Thus, additional time is needed to reach a new equilibrium and the heavier molecule CO2 usually needs more time. The detailed features of dynamics in the non-equilibrium process would need further exploration to grasp a more elaborate picture. In addition, Figure 3 shows that the different functional groups on the SBA-15 surface also affect the time constants of the displacement processes only at 297 K and there is almost no difference at a higher temperature. In both CH4 and CO2 displacement processes, the time constants for CO2 in SBA-phenyl are longer than that in SBA-cyclohexyl. It revealed that the SBA-phenyl has a stronger adsorption strength than SBA-cyclohexyl, and could absorb more CO2 molecules, which requires a longer time to reach equilibrium both for the adsorption and desorption processes. However, the faster molecular motion at a higher temperature obviously overcomes the influence of the functional groups. A faster displacement process can be expected at a higher pressure, since molecular motion is facilitated, as reported by Reznik et al. on coal cores.23 Therefore, we expect that increasing the pressure of carbon dioxide could facilitate the displacement efficiency. However, there are very limited number of studies so far. No apparent relationship was reported between the methane release characteristics by CO2 injection and the petrographic properties of the coals.24 In our experiments, the small and simple functional groups such as phenyl and cyclohexyl do not exert as strong effects on the efficiency of gas displacement as the temperature.


9


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 20

Furthermore, we investigated the diffusion behaviour of CO2 in the pure and organic modified SBA-15 pores by

13

C PFG NMR, as shown in Figure 4a and 4b.

Similar to our previous study on the diffusion of CH4,18 there are two states for CO2 in SBA-15: the free gas (with a diffusivity of D1) and the adsorbed gas in the pores of SBA-15 (with a diffusivity of D2). In general, the diffusivity of CO2 decreases with pressure, and D2 is one order of magnitude lower than D1. It is also noted that diffusivity of CO2 is one order of magnitude lower than that of CH4. These findings agree well with the self-diffusion coefficients of CH4 and CO2 obtained from MD simulation in MOF-5 and silicalite.25, 26 As shown in Figure 4 a, b, the diffusivity of CO2 in the three samples follows a trend: SBA-15 > SBA-phenyl > SBA-cyclohexyl, the same as we observed for CH4 in our previous study. Comprehensive understanding on the effect of CO2 on the diffusion behaviour of CH4 would be significant for the industrial exploitation of shale gas and carbon dioxide sequestration. Therefore, we allowed adsorption of SBA-15 and the organic-modified samples with 5 kPa CO2, followed by adsorption of CH4. 1H PFG NMR was applied to measure the diffusivities, D1 and D2, of CH4 as a function of pressure. As shown in Figure 4 c, d, both D1 and D2 decrease in the presence of CO2. They follow the same trend as that in the absence of CO2 in the pores of SBA-15 and the modified pores: SBA-15 > SBA-phenyl > SBA-cyclohexyl. The role of CO2 is likely to increase the pressure of system, thus aggravating the steric hindrance between diffusion molecules. Surprisingly, D1 of CH4, which likely corresponds to the free CH4 molecules, is much more affected by CO2 than D2. This indicates that the pre-adsorbed CO2 creates obstacles for diffusion of the free CH4 molecules whereas it does not affect too much the adsorbed CH4 molecules in the modified pores. This was because the organic modification mainly occurred in the pores of the SBA-15, the organic groups dominated the diffusion of methane in their territory. Thus CO2 can only played the major role outside of pores of the SBA-15. Even though the amount of CO2 was relatively low here, we could still find that the presence of CO2 slightly


10

Page 11 of 20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


inhibits the diffusion of methane in the pores of SBA-15.

Conclusion In summary, we simulated the displacement processes of methane and carbon dioxide in the nanopores of shale, which was investigated by in situ

13

C NMR. The results

show that SBA-15 and that modified with the organic functional groups exhibit stronger adsorption strength and higher adsorption capacity for CO2 than CH4. Thus, the pre-adsorbed CH4 within the pores can be effectively displaced by CO2 and the time needed to reach equilibrium depends on the temperature and the properties of the pores. In the presence of organic matters, particularly with a higher aromaticity, such as SBA-phenyl, the displacement is more efficient than that in SBA-cyclohexyl at relatively low temperature. However, to gain understanding of the generality of the organic matter effects will require more sophisticated experiments with larger functional groups. In addition, the diffusivities of CO2 in SBA-15 and the modified pores are slower than CH4. The presence of CO2 in the pores suppresses the diffusion of CH4 following a general tendency of SBA-15 > SBA-phenyl > SBA-cyclohexyl. This study shows clearly that higher adsorption capacity and slower diffusivity of CO2 make it rather suitable as a fracturing fluid.

ASSOCIATED CONTENT

Supporting Information. In situ 13C NMR spectra for the SBA-cyclohexyl in the process of 13CH4 displacement and

13

CO2 displacement. The time-dependence of

13

CH4 and

13

CO2 displacement for

SBA-cyclohexyl at different temperatures. Additional analytical data of the equilibrium adsorption capacities and characteristic equilibrium time constants. This material is available free of charge via the Internet at http://pubs.acs.org.


11


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 20

AUTHOR INFORMATION Corresponding Author *Email: [email protected], Tel: +86-411-84379969 *Email: [email protected], Tel: +86-411-84686637

Notes The authors declare no competing financial interest. ACKNOWLEDGMENT This work was supported by the “Strategic Priority Research Program” of the Chinese Academy of Sciences (grant XDB10020202). We gratefully thank Dr. Guangjin Hou for the fruitful discussion.

REFERENCES (1) Arora, V.; Cai, Y. Y. US Natural Gas Exports and Their Global Impacts. Appl. Energy 2014, 120, 95-103. (2) Stephenson, E.; Shaw, K. A Dilemma of Abundance: Governance Challenges of Reconciling Shale Gas Development and Climate Change Mitigation. Sustainability 2013, 5, 2210-2232. (3) Loucks, R. G.; Reed, R. M.; Ruppel, S. C.; Jarvie, D. M. Morphology, Genesis, and Distribution of Nanometer-Scale Pores in Siliceous Mudstones of the Mississippian Barnett Shale. J. Sediment. Res. 2009, 79, 848-861. (4) Heller, R.; Vermylen, J.; Zoback, M. Experimental Investigation of Matrix Permeability of Gas Shales. AAPG Bull. 2014, 98, 975-995. (5) Norris, J. Q.; Turcotte, D. L.; Rundle, J. B. Anisotropy in Fracking: A Percolation Model for Observed Microseismicity. Pure Appl. Geophys. 2014, 172, 7-21. (6) Middleton, R. S.; Carey, J. W.; Currier, R. P.; Hyman, J. D.; Kang, Q.; Karra, S.;


12

Page 13 of 20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Jiménez-Martínez, J.; Porter, M. L.; Viswanathan, H. S. Shale Gas and Non-Aqueous Fracturing Fluids: Opportunities and Challenges for Supercritical CO2. Appl. Energy 2015, 147, 500-509. (7) Wang, Q.; Chen, X.; Jha, A. N.; Rogers, H. Natural Gas from Shale Formation The Evolution, Evidences and Challenges of Shale Gas Revolution in United States. Renewable Sustainable Energy Rev. 2014, 30, 1-28. (8) Stephenson, M. H. Shale Gas in North America and Europe. Energy Sci. Eng. 2016, 4, 4-13. (9) Ishida, T.; Aoyagi, K.; Niwa, T.; Chen, Y. Q.; Murata, S.; Chen, Q.; Nakayama, Y. Acoustic Emission Monitoring of Hydraulic Fracturing Laboratory Experiment with Supercritical and Liquid CO2. Geophys. Res. Lett. 2012, 39, L16309. (10) Edwards, R. W. J.; Celia, M. A.; Bandilla, K. W.; Doster, F.; Kann, C. M. A Model to Estimate Carbon Dioxide Injectivity and Storage Capacity for Geological Sequestration in Shale Gas Wells. Environ. Sci. Technol. 2015, 49, 9222-9229. (11) Honari, A.; Bijeljic, B.; Johns, M. L.; May, E. F. Enhanced Gas Recovery with CO2 Sequestration: The Effect of Medium Heterogeneity on the Dispersion of Supercritical CO2–CH4. Int. J. Greenhouse Gas Control 2015, 39, 39-50. (12) Yuan, Q.; Zhu, X.; Lin, K.; Zhao, Y. P. Molecular Dynamics Simulations of the Enhanced Recovery of Confined Methane with Carbon Dioxide. Phys. Chem. Chem. Phys. 2015, 17, 31887-31893. (13) Wu, H.; Chen, J.; Liu, H. Molecular Dynamics Simulations About Adsorption and Displacement of Methane in Carbon Nanochannels. J. Phys. Chem. C 2015, 119, 13652-13657. (14) Lin, K.; Yuan, Q.; Zhao, Y.; Cheng, C. Which Is the Most Efficient Candidate for the Recovery of Confined Methane: Water, Carbon Dioxide or Nitrogen? Extreme Mech. Lett. 2016, 9, 127-138. (15) Kadoura, A.; Narayanan Nair, A. K.; Sun, S. Molecular Dynamics Simulations of Carbon Dioxide, Methane, and Their Mixture in Montmorillonite Clay Hydrates. J.


13


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 20

Phys. Chem. C 2016, 120, 12517-12529. (16) Kadoura, A.; Narayanan Nair, A. K.; Sun, S. Adsorption of Carbon Dioxide, Methane, and Their Mixture by Montmorillonite in the Presence of Water. Microporous Mesoporous Mater. 2016, 225, 331-341. (17) Yang, N.; Liu, S.; Yang, X. Molecular Simulation of Preferential Adsorption of CO2 over CH4 in Na-Montmorillonite Clay Material. Appl. Surf. Sci. 2015, 356, 1262-1271. (18) Hu, Y.; Zhang, Q.; Li, M.; Pan, X.; Fang, B.; Zhuang, W.; Han, X.; Bao, X. Facilitated Diffusion of Methane in Pores with a Higher Aromaticity. J. Phys. Chem. C 2016, 120, 19885-19889. (19) Werner-Zwanziger, U.; Lis, G.; Mastalerz, M.; Schimmelmann, A. Thermal Maturity of Type Ii Kerogen from the New Albany Shale Assessed by 13C CP/MAS Nmr. Solid State Nucl. Magn. Reson. 2005, 27, 140-148. (20) Zhao, D.; Huo, Q.; Feng, J.; Chmelka, B. F.; Stucky, G. D. Nonionic Triblock and Star Diblock Copolymer and Oligomeric Surfactant Syntheses of Highly Ordered, Hydrothermally Stable, Mesoporous Silica Structures. J. Am. Chem. Soc. 1998, 120, 6024-6036. (21) Cotts, R. M.; Hoch, M. J. R.; Sun, T.; Markert, J. T. Pulsed Field Gradient Stimulated Echo Methods for Improved Nmr Diffusion Measurements in Heterogeneous Systems. Journal of Magnetic Resonance (1969-1992) 1989, 83, 252-266. (22) Wilcox, J. Carbon Capture; Springer: New York, 2012. (23) Reznik, A. A.; Singh, P. K.; Foley, W. L. An Analysis of the Effect of CO2 Injection on the Recovery of in-Situ Methane from Bituminous Coal: An Experimental Simulation. SPE J. 1984, 24, 521-528. (24) Bhowmik, S.; Dutta, P. Investigation into the Methane Displacement Behavior by Cyclic, Pure Carbon Dioxide Injection in Dry, Powdered, Bituminous Indian Coals. Energy Fuels 2011, 25, 2730-2740.


14

Page 15 of 20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(25) Skoulidas, A. I.; Sholl, D. S. Self-Diffusion and Transport Diffusion of Light Gases in Metal-Organic Framework Materials Assessed Using Molecular Dynamics Simulations. J. Phys. Chem. B 2005, 109, 15760-15768. (26) Makrodimitris, K.; Papadopoulos, G. K.; Theodorou, D. N. Prediction of Permeation Properties of CO2 and N2 through Silicalite Via Molecular Simulations. J. Phys. Chem. B 2001, 105, 777-788.


15


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 1. In situ

13

C NMR spectra for the SBA-phenyl in the process of

Page 16 of 20

13

CH4

displacement (a) and 13CO2 displacement (b) at 297 K.


16

Page 17 of 20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 2. Time-dependence of 13CH4 and 13CO2 displacement: methane displacement (a-c) and carbon dioxide displacement (d-f) for SBA-phenyl at different temperatures (297, 323 and 353 K, respectively from top to bottom figure).


17


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 20

Figure 3. Equilibrium adsorption capacities (a, c) and the characteristic time constants to reach equilibrium (b, d) as a function of the temperature in the methane displacement (a, b) and carbon dioxide displacement (c, d).


18

Page 19 of 20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 4. Variations of D1 (a) and D2 (b) of CO2 as a function of pressure in the pores of SBA-15 and those modified with phenyl and cyclohexyl groups; the variations of D1 (c) and D2 (d) of CH4 as a function of pressure in the pores pre-adsorbed with 5 kPa CO2.


19


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 20

TOC Graphic


20

Displacement and Diffusion of Methane and Carbon Dioxide in SBA

Recommend Documents