A Novel Mesoporous SiO2 Material with MCM-41 Structure from Coal

Subscriber access provided by UNIV OF SCIENCES PHILADELPHIA

Environmental and Carbon Dioxide Issues

A novel mesoporous SiO2 material with MCM-41 structure from coal gangue: preparation, ethylenediaminemodification, and adsorption properties for CO2 capture Hong Du, Liang Ma, Xiaoyao Liu, Fei Zhang, Xinyu Yang, Yu Wu, and Jianbin Zhang Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b00318 • Publication Date (Web): 19 Mar 2018 Downloaded from http://pubs.acs.org on March 20, 2018

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 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 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.

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 48 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

Energy & Fuels

A novel mesoporous SiO2 material with MCM-41 structure from coal gangue: preparation, ethylenediamine-modification, and adsorption properties for CO2 capture Hong Du1,2, Liang Ma1,2, Xiaoyao Liu1,2, Fei Zhang1,2, Xinyu Yang1,2, Yu Wu1,2, and Jianbin Zhang1,2* 1 College of Chemical Engineering, Inner Mongolia University of Technology, Hohhot 010051, China 2 Inner Mongolia Engineering Research Center for CO2 Capture and Utilization, Hohhot 010051, China *To whom correspondence should be addressed. Tel.: +86-471-6575722; Fax: +86-471-6575722. E-mail: [email protected] (J. B. Zhang) Abstract: A novel mesoporous SiO2 material (M-SiO2) with MCM-41 structure was readily fabricated from the inexpensive coal gangue via hydrothermal reaction in the presence of cetyltrimethyl ammonium bromide (CTAB) for CO2 capture. Based on orthogonal experimental results, the optimum conditions for the preparation of M-SiO2 were identified as follows: the SiO32leaching of 21 g/L from coal gangue, the CTAB concentration of 0.25 mol/L, the HCl concentration of 2.5 mol/L, the hydrothermal temperature of 393.15 K, and the hydrothermal time of 20 h. Under the optimum condition, the M-SiO2 exhibited an adsorption capability of 9.61 mg/g to 8 % CO2 at 298.15 K. To further improve the CO2 adsorption performance, the M-SiO2 was chemically modified using ethylenediamine (EDA), and the optimum conditions for the modification of M-SiO2 were identified as follows: the impregnation time of 10 h, the drying temperature of 343.15 K, and the ratio of EDA: M-SiO2 = 2: 1. Under the optimum conditions, the adsorption capability of EDA-modified M-SiO2 (EDA-M-SiO2) was increased by 83.5 mg/g. The obtained M-SiO2 and

ACS Paragon Plus Environment

Energy & Fuels 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

EDA-M-SiO2

were

systemically

characterized

by

Page 2 of 48

N2

adsorption-desorption

isotherms,

thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction measurements techniques. The analytical results indicated that the M-SiO2 was mainly composed of O and Si in the form of SiO2 with a specific surface area of 156 m2/g, and part of M-SiO2 exhibited a similar structure to MCM-41. Moreover, the mechanisms of EDA-modification and CO2 adsorption were investigated and discussed in detail. KEYWORDS: Mesoporous SiO2 material; Coal gangue; CO2; Adsorption; Ethylenediamine.

1. INTRODUCTION Over the past several decades, there have been growing concerns about the greenhouse effect and global warming. Since more studies indicated the increased CO2 emission is the primary cause of global warming,1 the studies on CO2 capture has become a hot research topic in both academic and industrial fields.2 As one of the important methods, the adsorption for CO2 capture is often used to carry out a correlational study by using activated carbon,3 alumina,4 and molecular sieve.5 Among these adsorption materials, the mesoporous silicon materials, including MCM-48,6 SBA-15,7 and MCM-41,8, 9 have been widely used for the adsorption of a variety of gases, such as CO2 and NO,10,11 because of their high porosity, large specific surface areas and pore volumes, especially their easiness of chemical modification for maximizing the loading capability of CO2.12 The body of porous materials is mainly composed of SiO2 with the CO2 adsorption capabilities in the range of 0.001 to 1.0 mol/kg.13 To enhance their CO2 adsorption capabilities, the surfaces of these materials are often modified by various chemical methods. For example, mercaptopropyl trimethoxysilane,14 aluminum,15 and diazonium salts16 were used to modify SBA-15, mesoporous silica (MCF-17) and silica, respectively, to enhance their CO2 adsorption capabilities. Similarly, Leal et al.17 reported that


Page 3 of 48 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

Energy & Fuels

the adsorption capability of silica gel grafted with aminopropyl groups was approximately 27 mg/g in pure one atmosphere CO2 and 296.15 K after investigated their CO2 adsorption isotherms. Zheng et al.14 also reported the ethylenediamine (EDA)-SBA-15 sorbent could adsorb around 20 mg/g of CO2 from one atmosphere 15 % CO2 in N2 at 298.15 K, with an adsorption capability of 86 mg/g at 295.15 K in pure one atmosphere CO2. However, in previous studies, tetraethyl orthosilicate (TEOS)7,18-21 was often used as the silicon source to prepare porous materials which typically results in a significant increase in production cost, thus severely limiting their practical applications as adsorption materials. Coal gangue is a hazardous solid waste of coal production in the excavation and washing processes. According to the statistics, there are lots of coal gangue hills, and the amount of coal gangue increases by 659 million tons annually, in China.22 Such a large quantity of coal gangue pile causes a severe social, environmental, and economic problems.23 Although coal gangue is used as the traditional construction materials to a certain degree,24 the scale and level of utilization as a whole are very low because of their low value-added products, secondary pollution, and difficult large-scale industrial production. In fact, coal gangue is a natural mineral with a content of 66.3 % silicon,25 which is of great significance if it can be fully utilized. Hence, the utilization of coal gangue as a raw material to prepare porous SiO2 for CO2 capture has not received considerable attention. In our previous report,26 EDA possesses a strong CO2 absorption. For example, Zheng et al. reported that EDA could modify SBA-1514 to enhance the CO2 adsorption capability, which provides helpful information for this work. To the best of our knowledge, using the coal gangue as raw material modified by EDA to prepare mesoporous SiO2 material (M-SiO2) with MCM-41 structure is rarely reported in the literature; consequently, efficient utilization of coal gangue for CO2 adsorption remains a significant challenge.


Energy & Fuels 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

In this work, an efficient and economical method for CO2 cyclic capture with high CO2 recovery rate by using a novel M-SiO2 with MCM-41 structure modified by EDA (EDA-M-SiO2) was reported. The optimum conditions for the preparation of M-SiO2 and the optimum modified conditions for the modification of M-SiO2 were confirmed by the results of orthogonal array experiments. The prepared M-SiO2 and EDA-M-SiO2 were characterized by thermogravimetric analysis (DG-DTG), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction measurement (XRD), and N2 adsorption-desorption isotherm techniques. The developed process provides an alternative approach to the utilization of coal gangue which is of great significance for the environmental protection and waste utilization.

2. EXPERIMENTAL SECTION 2.1 Materials The component of coal gangue sample used in this work is mainly SiO2 (53.1 %),27 as shown in Table 1, which was friendly supplied by Wujialiang coal preparation plant from Inner Mongolia province, China. To improve the properties, the sample was activated by calcination.28 Cetyltrimethyl ammonium bromide (CTAB) were purchased from Tianjin Wind Ship chemical technology Co., Ltd. NaOH, HCl, and other chemicals were analytical grade without further purification. Table 1 2.2 The preparation of M-SiO2 In this work, the M-SiO2 was synthesized using SiO32- leachate from coal gangue. The process for the production of SiO32- leachate with 40.24 % yield was reported in our previous work.28 CTAB aqueous solution was added to SiO32- leachate with stirring at T = 313.15 K. The resulting reaction


Page 4 of 48

Page 5 of 48 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

Energy & Fuels

mixture was stirred until the completeness of reaction. After that, the as-prepared SiO32- leachate reacted with HCl at pH of 10.0 in the presence of CTAB via a hydrothermal method. Finally, the product was washed with hot water, filtrated, dried, and calcined to remove the remaining template in the M-SiO2. In this process, the effects of preparation conditions, including HCl concentration (c), pH values of the reaction medium, hydrothermal temperature (T), and reaction time (t) on the adsorption properties of final products were systematically studied. The schematic procedure was presented in Fig. 1. Fig. 1 2.3 The chemical modification of M-SiO2 The impregnation method29 was applied to the synthesis of the EDA-M-SiO2. In a typical experiment, 2 g EDA was dissolved in 20 g anhydrous ethanol and stirred at room temperature for 40 min until the EDA completely dissolved. Subsequently, 2 g M-SiO2 was added to the prepared EDA solution. After the resulting dispersion was stirred for additional 10 h, the reaction mixture was filtered, and the collected filter cake was dried in a vacuum oven at 343.15 K for 24 h. Finally the obtained sample was named as the EDA-M-SiO2. 2.4 Adsorption test The CO2 adsorption experiment was carried out in a flow system at T = 298.15 K and ambient pressure (Atmosphere of Hohhot is 88.93 kPa) according to the following procedure. A fixed column loaded with the M-SiO2 or EDA-M-SiO2 was placed in a thermostatic water bath to maintain a constant temperature. An 8.0 vol% CO2 was passed through the samples with a flow rate of 30 mL·min-1 for CO2 adsorption, which was detected by Intelligent CO2 for data collection every 1 s, to record the correlation between CO2 concentration and time. The adsorbed amounts of CO2 (q,


Energy & Fuels 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 48

mg/g) were calculated from the Eq. (1).

=

( )

(1)

where v is gas velocity, mL/min; M is CO2 molar mass, 44 g/mol; Vm is Molar volume of gas, 22.4 L/mol; m is the quality of sample, g; t is adsorption time, s; Co and Ct are CO2 content of import and extortion, %, and is 8 vol%. 2.5 Characterization The XRD patterns of M-SiO2 before and after modificaton of the samples were checked by XRD analysis (Shimadzu, D/max-2200/PC) with Cu Kα radiation operated at 40 kV and 40 mA. The phase transition characteristics and functional groups of the samples were determined through FTIR technology, using the KBr pellet technique (Nicolet, Nexus 670), in the frequency region of 4000 to 400 cm-1. The microstructure and morphology of samples was analyzed by SEM analysis (Quanta FEG 650). TEM analysis was carried out by using a JEOL JEM-2100F field emission electron microscope with an acceleration voltage of 200 kV. The BET specific surface areas of the samples were calculated by N2 adsorption isotherms obtained from a 3H-2000PS2 BET instrument with the Barrett-Joyner-Halenda (BJH) theory analyzer at 77 K. All the samples were degassed under vacuum at 353.15 K for 4 h before testing. The pore size distributions in the adsorption branches of the isotherms were obtained by using the Barret-Joyner-Halenda (BJH) method. The pore size and total volume were calculated based on pore size distribution curves. The thermal stability of the sample was determined by thermogravimetry and differential thermogravimetry (TG-DSC) analysis by using an America Thermal Analysis Q50TGA at a heating rate of 10 K/min. X-ray photoelectron spectroscopy (XPS) data were obtained with a KRATOS Axis ultra X-ray photoelectron spectrometer with a monochromatized AlKα X-ray (hν = 100MeV) operated at 225W. All measurements of mass were performed on an electronic balance with an accuracy of 0.1 mg


Page 7 of 48 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

Energy & Fuels

(Sartorius BS224S), and the uncertainty of mole fraction was estimated about ± 0.0001.

3. RESULTS AND DISCUSSION 3.1 Effect of preparation conditions on the CO2 adsorption capability on the M-SiO2 3.1.1 Effect of HCl concentration The HCl concentration was set at 1.5, 2, 2.5, 3 and 3.5 mol/L, and the other parameters were set as [CTAB] = 0.25 g/10 mL H2O, T = 393.15 K, and t = 24 h. After adding HCl, the silica gel was obtained from the SiO32- leaching. The effect of HCl concentration on the CO2 adsorption capability on the M-SiO2 was shown in Fig. 2(a). (the data for adsorption of CO2 (q, mg/g) was computed by the Eq. (1) at the equilibrium value of 7.96 vol% and the time used for each adsorption value were respectively 1548s, 1525s, 2400s, 1396s, 1188s.

=

( )

(1)

where v is gas velocity, mL/min; M is CO2 molar mass, 44 g/mol; Vm is Molar volume of gas, 22.4 L/mol; m is the quality of sample, g; t is adsorption time, s; Co and Ct are CO2 content of import and extortion, %, and is 8 vol%.) Fig. 2 As shown in Fig. 2(a), the CO2 adsorption capability increased with the increase of HCl concentration in the HCl concentration range of 1~2.5 mol/L, but decreased with the increase of HCl concentration in the range of 2.5~3.5 mol/L. When the HCl concentration was 2.5 mol/L, the adsorption exhibited a maximum value of 9.61 mg/g. This phenomenon is attributed to the fact that the initial reaction rate of SiO32- with H+ increases with rising HCl concentration. However, a higher reaction rate leads to a faster settlement velocity which in turn results in the formation of the large aggregates and a reduction in the porosity of the prepared synthesis materials. When the HCl concentration was 2.5 mol/L, the porosity of the prepared materials might be optimal. As a result, the adsorption exhibited a maximum value of 9.61 mg/g. Therefore, the suitable HCl concentration ACS Paragon Plus Environment

Energy & Fuels 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 48

for the preparation of M-SiO2 was identified as 2.5 mol/L. 3.1.2 Effect of the CTAB addition amounts The effect of various CTAB addition amounts on the CO2 adsorption capability on the M-SiO2 was analyzed at 0.05, 0.1, 0.25, 0.5, and 0.75 g/10 mL H2O, and the other parameters were set T = 393.15 K, [HCl] = 2.5 mol/L, and t = 24 h, the results are shown in Fig. 2(b). (the data for adsorption of CO2 (q, mg/g) was computed by the Eq. (1) at the equilibrium value of 7.96 vol% and the time used for each adsorption value were respectively 2091s, 2384s, 2400s, 2441s, 2200s.

=

( )

(1)

where v is gas velocity, mL/min; M is CO2 molar mass, 44 g/mol; Vm is Molar volume of gas, 22.4 L/mol; m is the quality of sample, g; t is adsorption time, s; Co and Ct are CO2 content of import and extortion, %, and is 8 vol%.) As can be seen from Fig. 2(b), when the addition amount of CTAB increased from 0.05 g/10 mL H2O to 0.25 g/10 mL H2O, the CO2 adsorption capability increased continuously. In contrast, when the addition amount of CTAB increased from 0.25 g/10 mL H2O to 0.75 g/10 mL H2O, the CO2 adsorption capability decreased. Evidently, the CO2 adsorption capability exhibited a maximum value of 9.61 mg/g when the addition amount of CTAB was 0.25 g/10 mL H2O. This phenomenon can be explained by the low surfactant concentration that is below the critical micelle concentration (CMC)30 when the addition amount of CTAB was low, which results in severe agglomeration of the obtained M-SiO2 after the calcination. Since the formed M-SiO2 possesses small surface area and few pores (Table 2), the CO2 adsorption amount on the M-SiO2 is low. When the CTAB addition amount was 0.25 g/10 mL H2O around the CMC, the agglomeration phenomenon disappeared.31 Moreover, the M-SiO2 exhibited a high specific surface area, regular pore and large porosity (Table 2(the data for adsorption of CO2 (q, mg/g) was computed by the Eq. (1) at the equilibrium value of 7.96 vol%. ACS Paragon Plus Environment

Page 9 of 48 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

Energy & Fuels

=

( )

(1)

where v is gas velocity, mL/min; M is CO2 molar mass, 44 g/mol; Vm is Molar volume of gas, 22.4 L/mol; m is the quality of sample, g; t is adsorption time, s; Co and Ct are CO2 content of import and extortion, %, and is 8 vol%.)). Accordingly, the CO2 adsorption capability increased to the maximum of 9.61 mg/g. With increasing of CTAB addition amount, the asymmetry of CTAB solution increased, which resulted in the formation of irregular shape of the M-SiO2 and the decrease in the order degree of the internal channel.32 As a result, the CO2 adsorption capability decreased. Taken together, the optimal CTAB concentration was selected as 0.25 g/10 mL H2O. Table 2 3.1.3 Effect of hydrothermal temperature A set of initial values were selected at T (hydrothermal temperature) = (303.15, 323.15, 373.15, 393.15 and 423.15) K, [CTAB] = 0.25 g/10 mL H2O, [HCl] = 2.5 mol/L, and t (impregnation time) = 24 h to study the influence of hydrothermal temperature on the CO2 adsorption capability on the M-SiO2, and the results are shown in Fig. 2(c). (the data for adsorption of CO2 (q, mg/g) was computed by the Eq. (1) at the equilibrium value of 7.96 vol% and the time used for each adsorption value were respectively 2003s, 1571s, 2976s, 2400s, 3196s.

=

( )

(1)

where v is gas velocity, mL/min; M is CO2 molar mass, 44 g/mol; Vm is Molar volume of gas, 22.4 L/mol; m is the quality of sample, g; t is adsorption time, s; Co and Ct are CO2 content of import and extortion, %, and is 8 vol%.) As shown in Fig. 2(c), with increasing hydrothermal temperature, the CO2 adsorption capability gradually increased to the maximum value of 9.61 mg/g at 393.15 K, and then the CO2 adsorption capability decreased. Since high temperature promotes the hydrolysis and crosslinking of the silicon components,33 the CO2 adsorption capability increased with the increase of synthesis temperature. However, when the temperature increased to 423.15 K, electrostatic interaction between CTAB and SiO32- was weaken, which led to the reduction in the number of the M-SiO2’s pores34 and the ACS Paragon Plus Environment

Energy & Fuels 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 48

decrease in the CO2 adsorption capability. Therefore, the following experiments were carried out at T = 393.15 K. 3.1.4 Effect of hydrothermal time The effect of hydrothermal time on the CO2 adsorption capability on the M-SiO2 was studied at t = 12, 16, 20, 24 and 28 h, [CTAB] = 0.25 g/10 mL H2O, T = 393.15 K, and [HCl] = 2.5 mol/L, and the results are shown in Fig. 2(d). (the data for adsorption of CO2 (q, mg/g) was computed by the Eq. (1) at the equilibrium value of 7.96 vol% and the time used for each adsorption value were respectively 1319s, 2828s, 2400s, 2400s, 2774s..

=

( )

(1)

where v is gas velocity, mL/min; M is CO2 molar mass, 44 g/mol; Vm is Molar volume of gas, 22.4 L/mol; m is the quality of sample, g; t is adsorption time, s; Co and Ct are CO2 content of import and extortion, %, and is 8 vol%.) As can be seen from Fig. 2(d), the CO2 adsorption capability increased with increasing reaction time and reached the maximum CO2 adsorption capability of 9.61 mg/g at 20 h. After that, the CO2 adsorption capability decreased gradually with extended reaction time. When the hydrothermal time was short, the reaction mixture was heterogeneous, which decreased the porosity of M-SiO2. In contrast, extended hydrothermal time could enlarge the entrance sizes35 of M-SiO2, so that the CO2 adsorption capability increased. However, longer hydrothermal time changed the mesoscopic structure of M-SiO2,35 which is unfavorable for the CO2 adsorption. Thus, the optimum reaction time was set to t = 20 h. 3.2 Orthogonal test To identify the optimal combination of reaction conditions, we performed 3-level 4-factor orthogonal array experiment, which is a well-established approach for the determination of the best combination of variables.36 The orthogonal design table and results are shown in Table 3. (the data ACS Paragon Plus Environment

Page 11 of 48 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

Energy & Fuels

for adsorption of CO2 (q, mg/g) was computed by the Eq. (1) at the equilibrium value of 7.96 vol%.

=

( )

(1)

where v is gas velocity, mL/min; M is CO2 molar mass, 44 g/mol; Vm is Molar volume of gas, 22.4 L/mol; m is the quality of sample, g; t is adsorption time, s; Co and Ct are CO2 content of import and extortion, %, and is 8 vol%.) Table 3 Table 4 From Table 4, it can be seen clearly that the ranges of these four factors were in the order of range (hydrothermal temperature = 1.280) > range (C [HCl] = 1.164) > range (C [CTAB] = 1.013) > range (hydrothermal time = 0.256), which unambiguously confirmed that the maximum and minimum affecting factors of the experiments are the hydrothermal temperature and hydrothermal time, respectively. Therefore, the maximum CO2 adsorption capability of 9.61 mg/g was observed at the conditions of [CTAB] = 0.25 g/10 mL H2O, T = 393.15 K, [HCl] = 2.5 mol/L, and t = 20 h. 3.3 Modified M-SiO2 3.3.1 Effect of impregnation time The effect of various impregnation times on the CO2 adsorption capability on the EDA-M-SiO2 was analyzed at 5, 10, 15, and 20 h, and the other parameters were set T (drying temperature) = 343.15 K, and M-SiO2: EDA = 1: 1, and the results are shown in Fig. 3(a). Fig. 3 Fig. 3(a) showed that the CO2 adsorption capability increased gradually at the impregnation time from 5 to 10 h, and then the CO2 adsorption capability decreased with extended impregnation time. At impregnation time of 10 h, the adsorption capability exhibited a maximum value of 24.37 mg/g. Initially, the impregnation time is insufficient, which results in insufficient effective -NH2 in the reaction of EDA with M-SiO2, and low the CO2 adsorption capability. With increasing impregnation time, part of M-SiO2 is covered with amino groups, which limits the physical adsorption of CO2. ACS Paragon Plus Environment

Energy & Fuels 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

After the -NH2 is saturated, the chemical adsorption of CO2 on the EDA-M-SiO2 remains a stable state. 3.3.2 Effect of drying temperature The effect of various drying temperatures on the CO2 adsorption capability on the EDA-M-SiO2 was analyzed at 323.15, 343.15, and 363.15 K, and the other parameters were set at t( impregnation time) = 10 h, and M-SiO2: EDA = 1:1, and the results are shown in Fig. 3(b). The results in Fig. 3(b) showed that CO2 adsorption capability increased firstly and then decreased with the increase of drying temperature. When the drying temperature was 343.15 K, the CO2 adsorption capability reached a maximum value of 24.37 mg/g. Since the low drying temperature is unfavorable for the bonding interactions between –NH2 and Si-OH, the insufficient – NH2 results in a low CO2 adsorption capability. On the other hand, high temperature drives the modification equilibrium to an opposite direction and decrease the CO2 adsorption capability. Therefore, 343.15 K was confirmed as the optimum drying temperature condition. 3.3.3 Effect of ratio of M-SiO2 to EDA The effect of various input ratios of M-SiO2 to EDA (g/g) on the CO2 adsorption capability on the EDA-M-SiO2 was analyzed at 4:1, 2:1, 1:1, 1:2 and 1:3, and the other parameters were set at t ( impregnation time) = 10 h, and T (drying temperature) = 343.15 K, and the results are shown in Fig. 3(C). As shown in Fig. 3(C) showed that CO2 adsorption capability increased firstly and then decreased with the increase of the ratios of EDA to M-SiO2. When the ratio of M-SiO2: EDA was 2: 1, the CO2 adsorption capability reached the maximum value of 35 mg/g. The initial low CO2 adsorption capability is attributed to the insufficient -NH2 when the EDA amount is low. On the other hand, an excessive amount of EDA blocks the adsorption channels partially, which reduces the physical


Page 12 of 48

Page 13 of 48 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

Energy & Fuels

adsorption of CO2. Thus, the ratio of M-SiO2: EDA = 2: 1 was selected as the optimum condition. Taken together, the optimal modification conditions for achieving the maximum CO2 adsorption capability was identified at EDA: M-SiO2 = 1: 3, t (impregnation time) = 10 h, and T (drying temperature) = 343.15 K. Under the optimal modification conditions, when the final adsorption equilibrium was reached, the CO2 adsorption capability of EDA-M-SiO2 was 83.5 mg/g, which was considerably higher than that of the M-SiO2 (9.61 mg/g). Table 5 illustrates the CO2 adsorption capacities of efficient CO2 adsorbents reported in the literature. Table 5 Compared with the reported adsorbents (Table 5), the 8 vol% CO2 adsorption capability on the EDA-M-SiO2 exhibited 0.36-2.16 mmol/g (15.84-95.04 mg/g) adsorption amounts of pure CO2, which is significantly higher than the most of the reported adsorbents. Consequently, this process provides an alternative approach to the utilization of coal gangue for CO2 capture. 3.3.4 Cyclic performance of EDA-M-SiO2 Cyclic performance was an important parameter for adsorbents, which would do well to the utilization of the adsorbents. Six cyclic experiment were did for the CO2 adsorption and the results are shown in Fig. 3(d). As shown in Fig. 3(d) showed that after five cyclic experiments, CO2 adsorption capability decreased near the adsorption amount of M-SiO2. According to the following IR spectrums , after five cyclic

experiment, -NH stretching vibration of 1639 and 1477 cm-1 (Fig. 3e) still exist, the reason of this results might be that: 1) the combination -NH2 with CO2 might be difficult to separate, which would decrease the CO2 adsorption site; 2) free EDA existing in channel of EDA-M-SiO2 decreased, which might decrease the chemical adsorption for CO2. According to the TGA curves for EDA-M-SiO2 after cyclic performance (as Fig. 3(f)) and compared to the TGA curves for EDA-M-SiO2 before cyclic performance (as Fig.10)，the total


Energy & Fuels 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

weight loss for EDA-M-SiO2 after cyclic performance increased from 20 % to 23 %, and the weight loss between 830 - 1090 °C disappeared, which was caused by the decomposition of -NH2 group. The results were consistent with IR spectrums analysis for EDA-M-SiO2 after cyclic performance.

3.4 Characterization of the M-SiO2 and EDA-M-SiO2 3.4.1 SEM and TEM analyses The SEM images of the M-SiO2 and EDA-M-SiO2 are shown in Fig. 4. Fig. 4 SEM images in Fig. 4 showed that M-SiO2 (a1) and EDA-M-SiO2 (a2) consisted of spherical platelets with diameters of roughly 106.7 and 133 nm, respectively. Uniform structure and a large number of pores of the M-SiO2 and EDA-M-SiO2 enhance their capabilities CO2 adsorption. When the M-SiO2 was modified with a large amount of EDA, surface morphology changed and the diameter expanded, which confirmed they were partially coated with the amine and the modification process was successful. The TEM images of the M-SiO2 and EDA-M-SiO2 are shown in Fig. 5 Fig. 5 As shown in Fig. 5, the TEM images revealed that the skeleton structure on the surface of M-SiO2 and EDA-M-SiO2 possessed channel diameters of 2.78 nm (Fig. 5b1) and 0.18 nm (Fig. 5b2), respectively. Moreover, both of them possessed an ordered pore structure and a two-dimensional hexagonal structure, which were similar to MCM-41.45 The clear dark areas on the M-SiO2 and EDA-M-SiO2 indicated the presence of metal dispersion. Considering the process of preparation and the component of a silicon source, we concluded that the metal dispersion might be Al element, which was confirmed by the results of following XPS spectrum studies. Compared with


Page 14 of 48

Page 15 of 48 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

Energy & Fuels

the M-SiO2, the EDA-M-SiO2 had a smaller channel, which was benefited from –NH2 covered and consistent with the SEM results. 3.4.2 XPS analysis The main objective of XPS analysis was to provide a set of binding energy data associated with their corresponding chemical environments46 and to confirm the existence of some metallic elements. Fig. 6 Fig. 6 showed that the bands with peak positions at 284 eV for C 1s, which belonged to the base peak of the instrument for calibrating all the binding energy (BE) values.47 A band with a peak position at 103 eV corresponded to the Si 2p of SiO2.48 A weak band with a peak position at 74.58 eV corresponded to the Al 2p.47 A band with a peak position at 532 eV for O 1s corresponded to an O2- species. The corresponding to Si/O of the materials before and after the modification were determined to be 1.91 and 1.89 (Table 6), respectively, which further confirmed the material was SiO2.46 The above results and analyses indicated that the M-SiO2 was mainly composed of Si and O in the form of SiO2. Analysis of XPS data showed in . Compared with M-SiO2, the contents of Si and O in the modified materials decreased, whereas the content of N increased, which further confirmed that the modification of EDA was successful. Table 6 3.4.3 Elemental analysis The amount of target EDA anchored on surface of the SiO2 particles was firstly quantified by using elemental analysis technique. The elemental contents of C and N were 1.765 % and 0.925 % in the EDA-M-SiO2, respectively, and the percentage of N in blank activated SiO2 was measured to be 0.07% in the M-SiO2. According to the percentage amounts of nitrogen (N %), the amount of


Energy & Fuels 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

EDA was calculated to be 0.6 mmol/g (0.855 % of total weight) on the surface of EDA modified SiO2. 3.4.4 XRD analysis The XRD patterns of M-SiO2 and EDA-M-SiO2 are shown in Fig. 7, in which a1 and a2 represented M-SiO2 and EDA-M-SiO2, respectively. WAXD exhibited a broad peak between 20 ° and 30 ° because of amorphous silica.49 The peaks at 32 ° and 45 ° corresponded to Al2O3,25 indicating the existence of Al element in the structures of M-SiO2 and EDA-M-SiO2. The small-angle XRD patterns of the supports exhibited explicit reflections at low degree and were indexed as the (d100), which was characteristic of a highly ordered hexagonal mesoporous structure of P6mm symmetry.50,51 The results of XRD analysis indicated that the structure of samples were similar to that of MCM-41 and there was no significant change in the microstructure of the M-SiO2 before and after the EDA modification. Fig. 7 3.4.5 FTIR spectra FTIR spectra of M-SiO2 and EDA-M-SiO2 were presented in Fig. 8. Fig. 8 For the M-SiO2, the band at 3439 cm-1 could be attributed to the stretching vibration of hydroxyl in water52 and Si-OH,53 and the band at 1639 cm-1 could be attributed to the bending vibration in water.53 The bands at 2980 cm-1 and 2878 cm-1 corresponded to C-H stretching vibrations of the -CH2 group.14 The bands at 799 cm-1 and 1099 cm-1 were assigned to the symmetric and asymmetric stretching vibration of Si-O-Si,53 respectively. The absorption peak at 473 cm-1 could be attributed to Si-O-Si bending vibration.54 These peaks unambiguously indicated the existence of silicon and water molecules in the M-SiO2.


Page 16 of 48

Page 17 of 48 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

Energy & Fuels

For the EDA-M-SiO2, the band at 806 cm-1 corresponded to Si-O-Si,55 and the bands at 1580 cm-1 and 1487 cm-1 could be attributed to the symmetric stretching vibration and asymmetric stretching vibration of -NH,56 respectively. The bands at 2978 cm-1 and 2887 cm-1 were attributed to C-H stretching vibrations of the -CH2 groups.14 After the EDA modification, the intensity of the band at 1639 cm-1 considerably diminished or disappeared, which indicated that no obvious bending vibration of water was found on the EDA-M-SiO2. Because of the multi molecular association, the band at 3439 cm-1 corresponding to hydroxyl in Si-OH moved to 3414 cm-1. This results confirmed that the EDA modification on the M-SiO2 was successful. 3.4.6 N2 adsorption-desorption isotherms The BET isotherms for M-SiO2 and EDA-M-SiO2 are shown in Fig. 9, and the pore size distribution determined by BJH analysis from the adsorption branch of the BET are depicted in the inset images. Fig. 9 As presented in Fig. 9a1, the isotherm of M-SiO2 was a combination of type III and type IV, which belonged to a typical mesoporous material.5 At the relatively low pressure of less than 0.4, the adsorption uptake was relatively small, whereas an abrupt increase in adsorption uptake was observed in the relatively high pressure region (P/P0 = 0.4-1.0), which could be considered as an indication of pronounced capillary condensation that takes place in mesopores. A large hysteresis loop belonging to H3 type in the isotherm indicated the presence of abundant mesopores and narrow pore size on the M-SiO2 and illustrated that the majority of pore-filling occurred in the relatively high pressure region. The absence of apparently saturated adsorption platform further confirms that the hysteresis loop belongs to the H3 type and the pore structure is irregular, which is similar to the structure of MCM-41. The pore size distribution of M-SiO2 (inset in Fig. 9a1) showed that the


Energy & Fuels 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

average pore diameter, as calculated by the BJH method, was 7.35 nm, which was similar to the pore diameter of MCM-41 in the range of 2 - 10 nm and the BET specific surface area and pore volume of M-SiO2 calculated from the isotherms were 156.639 and 0.2878 cm3·g-1, respectively. For the EDA-M-SiO2, as presented in Fig. 9a2, according to the IUPAC classification, the isotherm was identified as type IV with an H3-type hysteresis loop, suggesting that it possessed a similar mesoporous structure as the M-SiO2 and the modification hardly changed the mesoporous structure of M-SiO2. At the relatively high pressure, the adsorption capability was high, which confirmed hysteresis loop belonged to H3-type. The smaller hysteresis loop suggested that the modification was successful and the –NH2 gmodified covered the channels of M-SiO2 partially. The BET specific surface area, the average pore diameter, and the pore volume of the EDA-M-SiO2 material were determined to be 31.66 m2g-1, 14.95 nm, and 0.1257 cm3 g-1, respectively. 3.4.7 Thermogravimetric analysis TG-DTG curves of the M-SiO2 and EDA-M-SiO2 are shown in Fig. 10. Fig. 10 According to the TG-DTG curves (Fig. 10a1), only one weight loss of about 36.6 % for the M-SiO2 was observed in the temperature range of 50 to 1400 °C. The obvious weight loss occurred between 50 °C and 320 °C, which was attributed to the releasing of adsorbed, crystal water and residual additives. The near flat TG curve in the temperature range of 320 to 1400 °C indicated that the M-SiO2 exhibited an excellent thermal stability. For the EDA-M-SiO2 (Fig. 10a2), the weight loss occurred before 627 °C, which was attributed to the releasing of free EDA, NH3 and intramolecular dehydration. The peak of TG weight loss between 830-1090 °C was caused by the decomposition of -NH2 group, corresponding to the weight loss of about 15.8 %. The TG curve in the temperature range of 320 °C and 1400 °C indicated that


Page 18 of 48

Page 19 of 48 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

Energy & Fuels

the M-SiO2 had an excellent thermal stability. The DSC heat curve displayed the absorption enthalpy of the progress was 49.9 kJ/mol, which confirmed that this process included both physical and chemical adsorption.57 3.4.8 Breakthrough curves analysis Breakthrough curves of the M-SiO2 and EDA-M-SiO2 are shown in Fig. 11. Fig. 11 For M-SiO2, the breakthrough time and breakthrough adsorption were 101 s and 5.26 mg/g respectively. When the adsorption reached equilibrium, the responding time and adsorption amount were 1455 s and 9.36 mg/g, respectively. For EDA-M-SiO2, the breakthrough time and breakthrough adsorption were 351 s and 45.8 mg/g respectively. When the adsorption reached equilibrium, the responding time and adsorption amount were 18967 s and 82.8 mg/g, respectively. According to the breakthrough curves, after modification, the breakthrough time became longer, which proved the longer reaction time between CO2 and sample and the bigger adsorption capacity. 3.4.9 Amine CO2 capture efficiency According to elemental analysis, the increased N% was 9.18%, considering CO2 + 2RNH2→RNHCOO- + RNH3+,14 1 g sample’s CO2 adsorption theoretical value was (1×9.18%)/14×44×1/2＝0.144 g＝144 mg, and 1 g sample’s CO2 adsorption actual value was 83.5 mg, so the amine CO2 capture efficiency was 83.5/144×100%=58%. The reason of high CO2 capture efficiency was that: 1) free EDA existing in channel of EDA-M-SiO2 or existing on the surface of EDA-M-SiO2 would react with CO2; 2) EDA has two amino which ensure the higher capture amount of CO2 molecular; and 3) the block of channel would decrease due to the short chain of EDA. 3.4.10 Complementary analysis for characterization


Energy & Fuels 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

Firstly, the outline of the modified material observed by SEM became blurry and particles’ diameter became larger by measuring a single particle measurement. To explore internal structure of the material, the materials were characterized by TEM whose imagines could clearly made us know that the materials of M-SiO2 and EDA-M-SiO2 possessed the similar pore structure like the MCM-41, which consistent with the XRD imagines results. In TEM, the smaller pore diameter of EDA-M-SiO2, which consistent with the SEM imagines results. In XRD, the intensity of the diffraction peak for EDA-M-SiO2 decreased, which might be due to the introduction of the organic groups in the mesopores, which decreased the order of the mesoporous materials.58 Besides, the peak patterns for M-SiO2 and did not change, which consistent with the TEM imagines results. Then the EDA load was quantified by elemental analysis, the loading of the amino group would provide data supports for the analysis of the interaction between CO2 and EDA, which consistent with the adsorption results of EDA-M-SiO2.

4. CONCLUSIONS A mesoporous silicon material (the M-SiO2) with an ordered pore structure and a two-dimensional hexagonal structure that is similar to MCM-41 could be successfully prepared from inexpensive coal gangue for efficient CO2 adsorption. The preparation method exhibits various advantages, such as readily available and cheap raw materials, and simple process. All of variable, such as [HCl], [CTAB], hydrothermal temperature and hydrothermal time, would make the CO2 adsorption amount increase and then decrease. After modification, the CO2 adsorption amount was improved, the BET specific surface area would decrease and the XRD configuration would not be changed. All of variable, such as M-SiO2: EDA, impregnation time and drying temperature, would make the CO2 adsorption amount increase and then decrease. ACKNOWLEDGMENTS


Page 20 of 48

Page 21 of 48 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

Energy & Fuels

This work was supported by the National Natural Science Foundation of China (21466028), the Program for Grassland Excellent Talents of Inner Mongolia Autonomous Region, Program for New Century Excellent Talents in University (NCET-12-1017), and training plan of academic backbone in youth of Inner Mongolia University of Technology. References (1) Cao, B.; Du, J.; Liu, S.; Zhu, X.; Sun, X.; Sun, H.; Fu, H. Carbon dioxide Capture by Amino-functionalized Ionic Liquids: DFT based Theoretical Analysis Substantiated by FT-IR Investigation. RSC Adv. 2016, 6 (13), 10462-10470. (2) Xue, Z. M.; Zhang, Z. F.; Han, J.; Chen, Y.; Mu, T. C. Carbon dioxide Capture by a Dual Amino Ionic Liquid with Amino-Functionalized Imidazolium Cation and Taurine anion. Int. J. Greenh. Gas. Con. 2011, 5 (4), 628-633. (3) Wang, H. L.; Gao, Q. M.; Hu, J. High Hydrogen Storage Capacity of Porous Carbons Prepared by Using Activated Carbon. J. Am. Chem. Soc. 2009, 131 (20), 7016-7022. (4) Magg, N.; Giorgi, J. B.; Frank, M. M.; Immaraporn, B.; Schroeder, T.; Baumer, M.; Freund, H.-J. Alumina-Supported Vanadium Nanoparticles: Structural Characterization and CO Adsorption Properties. J. Am. Chem. Soc. 2004, 126 (11), 3616-3626. (5) Wei, L. G.; Zhang, H. S.; Dong, Y. L.; Song, W. N.; Liu, X. X.; Zhao, Z. F. Synthesis and Characterization of MCM-49/MCM-41 Composite Molecular Sieve: An Effective Adsorbent for Chromate from Water. RSC Adv. 2016, 6 (75), 71375-71383. (6) Kim, W. J.; Yoo, J. C.; Hayhurst, D. T. Synthesis of MCM-48 via Phase Transformation with Direct Addition of NaF and Enhancement of Hydrothermal Stability by Post-treatment in NaF Solution. Microporous Mesoporous Mater. 2001, 49 (1), 125-137. (7) Kao, K. C.; Lin, C. H.; Chen, T. Y.; Liu, Y. H.; Mou, C.-Y. A General Method for Growing Large


Energy & Fuels 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

Area Mesoporous Silica Thin Films on Flat Substrates with Perpendicular Nanochannels. J. Am. Chem. Soc. 2015, 137 (11), 3779-3782. (8) Tanev, P. T.; Liang, Y.; Pinnavaia, T. J. Assembly of Mesoporous Lamellar Silicas with Hierarchical Particle Architectures. J. Am. Chem. Soc. 1997, 119 (37), 8616-8624. (9) Mori, T.; Kuroda, Y.; Yoshikawa, Y.; Nagao, M.; Kittaka, S. Preparation of a Water-resistant Siliceous MCM-41 Sample, through Improvement of Crystallinity, and Its Prominent Adsorption Features. Langmuir 2002, 18 (5), 1595-1603. (10) Demessence, A.; D’Alessandro, D. M.; Foo, M. L.; Long, J. R. Strong CO2 Binding in a Water-Stable, Triazolate-Bridged Metal−Organic Framework Functionalized with Ethylenediamine. J. Am. Chem. Soc. 2009, 131 (25), 8784-8786. (11) Shin, J. H.; Metzger, S. K.; Schoenfisch, M. H. Synthesis of Nitric Oxide-Releasing Silica Nanoparticles. J. Am. Chem. Soc. 2007, 129 (15), 4612-4619. (12) Steinbacher, J. L.; Landry, C. C. Adsorption and Release of siRNA from Porous Silica. Langmuir 2014, 30 (15), 4396-4405. (13) Wang, Y.; LeVan, M. D. Adsorption Equilibrium of Carbon Dioxide and Water Vapor on Zeolites 5A and 13X and Silica Gel: Pure Components. J. Chem. Eng. Data. 2009, 54 (10), 2839-2844. (14) Zheng, F.; Tran, D. N.; Busche, B. J.; Fryxell, G. E.; Addleman, R. S.; Zemanian, T. S.; Aardahl, C. L. Ethylenediamine-Modified SBA-15 as Regenerable CO2 Sorbent. Ind. Eng. Chem. Res. 2005, 44(9), 3099-3105. (15) Musselwhite, N.; Na, K.; Alayoglu, S.; Somorjai, G. A. The Pathway to Total Isomer Selectivity: n-Hexane Conversion (Reforming) on Platinum Nanoparticles Supported on Aluminum Modified Mesoporous Silica (MCF-17). J. Am. Chem. Soc. 2014, 136 (47), 16661-16665.


Page 22 of 48

Page 23 of 48 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

Energy & Fuels

(16) Sandomierski, M.; Strzemiecka, B.; Chehimi, M. M.; Oelkel, A. V. Reactive Diazonium-Modified Silica Fillers for High-Performance Polymers. Langmuir 2016, 36, 44. (17) Leal, O.; Bolívar, C.; Ovalles, C.; García, J. J.; Espidel, Y. Reversible Adsorption of Carbon dioxide on Amine Surface-Bonded Silica Gel. Inorg. Chim. Acta 1995, 240 (1-2), 183-189. (18) Uemura, T.; Hiramatsu, D.; Yoshida, K.; Isoda, S.; Kitagawa, S. Sol−Gel Synthesis of Low-Dimensional Silica within Coordination Nanochannels. J. Am. Chem. Soc. 2008, 130 (29), 9216-9217. (19) Asaro, F.; Benedetti, A.; Freris, I.; Riello, P.; Savko, N. Evolution of the Nonionic Inverse Microemulsion−Acid−TEOS System during the Synthesis of Nanosized Silica via the Sol−Gel Process. Langmuir 2010, 26 (15), 12917-12925. (20) Wang, W.; Qi, H.; Long, H. B.; Wang, X. Y.; Ru, H. Q. A Simple Ternary Non-Ionic Templating System for Preparation of Complex Hierarchically Meso–Mesoporous Silicas with 3D-Interconnected Large Mesopores. J. Mater. Chem. A 2014, 2 (15), 5363. (21) Hu, J.; Wang, X. G.; Liu, L. Q.; Wu, L. M. A Facile and General Fabrication Method for Organic Silica Hollow Spheres and Their Excellent Adsorption Properties for Heavy Metal Ions. J. Mater. Chem. A 2014, 2 (46), 19771-19777. (22) Zhang, Y. Y.; Ge, X. L.; Nakano, J.; Liu, L. L.; Wang, X. D.; Zhang, Z. T. Pyrite Transformation and Sulfur Dioxide Release during Calcination of Coal Gangue. RSC Adv. 2014, 4 (80), 42506-42513. (23) Ren, J.; Xie, C. J.; Guo, X.; Qin, Z. F.; Lin, J.-Y.; Li, Z. Combustion Characteristics of Coal Gangue under an Atmosphere of Coal Mine Methane. Energy Fuels 2014, 28 (6), 3688-3695. (24) Querol, X.; Izquierdo, M.; Monfort, E.; Alvarez, E.; Font, O.; Moreno, T.; Alastuey, A.; Zhuang, X.; Lu, W.; Wang, Y. Environmental Characterization of Burnt Coal Gangue Banks at Yangquan,


Energy & Fuels 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

Shanxi Province, China. Int. J. Coal. Geol. 2008, 75 (2), 93-104. (25) Zhu, J. M.; Guo, S. H.; Li, X. H. Facile Preparation of a SiO2–Al2O3 Aerogel using Coal Gangue as a Raw Material via an Ambient Pressure Drying Method and Its Application in Organic Solvent Adsorption. RSC Adv. 2015, 5 (125), 103656-103661. (26) Zhao, T. X.; Guo, B.; Han, L. M.; Zhu, N.; Gao, F.; Li, Q.; Li, L. H.; Zhang, J. B. CO2 Fixation into Novel CO2 Storage Materials Composed of 1,2-Ethanediamine and Ethylene Glycol Derivatives. ChemPhysChem 2015, 16 (10), 2106–2109. (27) Li, X. B.; Xu, X. M.; Zhou, Q. S.; Qi, T. G.; Liu, G. H.; Peng, Z. H.; Cui, Y. F.; Li, J. P. Thermodynamic and XRD Analysis of Reaction Behaviors of Gangue Minerals in Roasting Mixture of Scheelite and Calcium Carbonate for Ca3WO6 Preparation. Int. J. Refract. Met. H. 2016, 60, 82-91. (28) Gao, Y.; Huang, H.; Tang, W.; Liu, X.; Yang, X.; Zhang, J. Preparation and Characterization of a Novel Porous Silicate Material from Coal Gangue. Micropor. Mesopor. Mater. 2015, 217, 210-218. (29) Xu, Q.-Q.; Yin, J.-Z.; Zhou, X.-L.; Yin, G.-Z.; Liu, Y.-F.; Cai, P.; Wang, A.-Q. Impregnation of Ionic Liquids in Mesoporous Silica using Supercritical Carbon dioxide and Co-Solvent. RSC Adv. 2016, 6 (103), 101079-101086. (30) Awino, J. K.; Zhao, Y. Molecularly Imprinted Nanoparticles for Selective Binding of Bile Salt Derivatives in Water. J. Am. Chem. Soc. 2013, 135 (34), 12552-12555. (31) Stein, A.; Melde, B. J.; Schroden, R. C. Hybrid Inorganic–Organic Mesoporous Silicates—Nanoscopic Reactors Coming of Age. Adv. Mater. 2000, 12 (19), 1403-1419. (32) Takahashi, H.; Li, B.; Sasaki, T.; Miyazaki, C.; Tsutomu Kajino, A.; Inagaki, S. Catalytic Activity in Organic Solvents and Stability of Immobilized Enzymes Depend on the Pore Size and


Page 24 of 48

Page 25 of 48 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

Energy & Fuels

Surface Characteristics of Mesoporous Silica. Chem. Mater. 2000, 12 (11), 3301-3305. (33) Chen, X. Y.; Huang, L. M.; Li, Q. Z. Hydrothermal Transformation and Characterization of Porous Silica Templated by Surfactants. J. Phys. Chem. B. 1997, 101 (42), 8460-8467. (34) Sui, G.P.; Zhao, Y. S.; Zhang, Q.; Fu, Q. Enhanced Mechanical Properties of Olefin Block Copolymer by Adding A Quaternary Ammonium Salt Functionalized Graphene Oxide. RSC Adv. 2016, (6), 54785-54792. (35) Kim, T.-W.; Ryoo, R.; Kruk, M.; Gierszal, K. P.; Jaroniec, M.; Kamiya, S.; Terasaki, O. Tailoring the Pore Structure of SBA-16 Silica Molecular Sieve through the Use of Copolymer Blends and Control of Synthesis Temperature and Time. J. Phys. Chem. B. 2004, 108 (108), 11480-11489. (36) Li, B.; Luo, X.; Deng, B. B.; Wang, J. F.; McComb, D. W.; Shi, Y. M.; Gaensler, K. M. L.; Tan, X.; Dunn, A. L.; Kerlin, B. A.; Dong, Y. Z. An Orthogonal Array Optimization of Lipid-like Nanoparticles for mRNA Delivery in Vivo. Nano. Lett. 2015, 15 (12), 8099-8107. (37) Zhao, Y. T.; An, C.-B.; Mao, L. M.; Zhao, J. J.; Tang, L. Y.; Zhou, A. F.; Li, H.; Dong, W. M.; Duan, F. T.; Chen, F. H. Vegetation and Climate History in Arid Western China during MIS2: New Insights from Pollen and Grain-size Data of The Balikun Lake, Eastern Tien Shan. Quaternary. Sci. Rev. 2015, 126, 112-125. (38) Chatti, R.; Bansiwal, A. K.; Thote, J. A.; Kumar, V.; Jadhav, P.; Lokhande, S. K.; Biniwale, R. B.; Labhsetwar, N. K.; Rayalu, S. S. Amine Loaded Zeolites for Carbon dioxide Capture: Amine Loading and Adsorption Studies. Micropor. Mesopor. Mater. 2009, 121 (1-3), 84-89. (39) You, H.-S.; Jin, H. L.; Mo, Y.-H.; Park, S.-E. CO2 Adsorption Behavior of Microwave Synthesized Zeolite Beta. Mater. Lett. 2013, 108, 106-109. (40) Minju, N.; Abhilash, P.; Nair, B. N.; Mohamed, A. P.; Ananthakumar, S. Amine Impregnated


Energy & Fuels 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 26 of 48

Porous Silica Gel Sorbents Synthesized from Water–Glass Precursors for CO2 Capturing. Chem. Eng. J. 2015, 269, 335-342. (41) Mason, J. A.; Sumida, K.; Herm, Z. R.; Krishna, R.; Long, J. R. Evaluating Metal–Organic Frameworks for Post-Combustion Carbon dioxide Capture via Temperature Swing Adsorption. Energ. Environ. Sci. 2011, 4(8), 3030. (42)

Wang, K. K.;

Huang, H. L.;

Liu, D. H.; Wang, C.; Li, J. P.; Zhong, C. L.; Covalent

Triazine-Based Frameworks with Ultramicropores and High Nitrogen Contents for Highly Selective CO2 Capture. Environ. Sci. Technol. 2016, 50 (9), 4869–4876. (43) Parvazinia, M.; Garcia, S.; Maroto-Valer, M.; CO2 Capture by Ion Exchange Resins as Amine Functionalised Adsorbents. Chem. Eng. J. 2018, 331,335–342. (44) Acar, B.; Başar, M. S.; Eropak, B. M.; Caglayan, B. S.; Aksoylu, A. E.; CO2 Adsorption over Modified AC

samples:

A

New

Methodology

for

Determining

Selectivity.

Atal.

Today.

doi.org/10.1016/j.cattod.2017.10.011.

(45) Hussain, M.; Song, S.-K.; Lee, J.-H.; Ihm, S.-K. Characteristics of CoMo Catalysts Supported on Modified MCM-41 and MCM-48 Materials for Thiophene Hydrodesulfurization. Ind. Eng. Chem. Res. 2006, 45 (2), 536-543. (46) Soule, S.; Allouche, J.; Dupin, J. C.; Courreges, C.; Plantier, F.; Ojo, W. S.; Coppel, Y.; Nayral, C.;

Delpech,

F.; Martinez,

H.

Thermoresponsive

Gold

Nanoshell@mesoporous

Silica

Nano-Assemblies: an XPS/NMR Survey. Phys. Chem. Chem. Phys. 2015, 17 (43), 28719-28728. (47) L. S. Xiong, R. Chen and F. X. Chen, One-step Solvothermal Synthesis of Al-Promoted Fe3O4 Magnetic Catalysts for the Selective Oxidation of Benzyl Alcohol to Benzaldehyde with H2O2 in water. RSC Adv. 2016, 6 (103), 101048-101060. (48) Han, Y.; Lin, N.; Qian, Y. Y.; Zhou, J. B.; Tian, J.; Zhu, Y. C.; Qian, Y. T. A Scalable Synthesis


Page 27 of 48 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

Energy & Fuels

of N-doped Si Nanoparticles for High-Performance Li-ion Batteries. Chem. Commun. 2016, 52 (19), 3813-3816. (49) Karthikeyan, S.; Pachamuthu, M. P.; Isaacs, M. A.; Kumar, S.; Lee, A. F.; Sekaran, G. Cu and Fe oxides dispersed on SBA-15: A Fenton Type Bimetallic Catalyst for N,N-diethyl-p-phenyl Diamine Degradation. Appl. Catal. B-Environ. 2016, 199, 323-330. (50) Zhong, X.; Jr., J. B.; Duprez, D.; Zhang, H.; Royer, S. Modulating the Copper Oxide Morphology and Accessibility by Using Micro-/Mesoporous SBA-15 Structures as Host Support: Effect on the Activity for the CWPO of Phenol Reaction. Appl. Catal. B-Environ. 2012, 121-122, 123-134. (51) Cho, E.-B.; Yim, S.; Kim, D.; Jaroniec, M. Surfactant-Assisted Synthesis of Mesoporous Silica/Ceria–Silica Composites with High Cerium Content under Basic Conditions. J. Mater. Chem. A 2013, 1 (40),12595. (52) He, J. H.; Fujikawa, S.; Kunitake, T.; Nakao, A. Preparation of Porous and Nonporous Silica Nanofilms from Aqueous Sodium Silicate. Chem. Mater. 2003, 15 (17), 3308-3313. (53) Romero, A. A.; Alba, M. D.; Zhou, W. Z.; Klinowski, J. Synthesis and Characterization of the Mesoporous Silicate Molecular Sieve MCM-48. J. Phys. Chem. B. 1997, 101 (27), 28-29. (54) Takahashi, R.; Sato, S.; Sodesawa, T.; Kawakita, M.; Ogura, K. High Surface-Area Silica with Controlled Pore Size Prepared from Nanocomposite of Silica and Citric Acid. J. Phys. Chem. B. 2000, 104 (51), 12184-12191. (55) Jafari, T.; Jiang, T.; Zhong, W.; Khakpash, N.; Deljoo, B.; Aindow, M.; Singh, P.; Suib, S. L. Modified Mesoporous Silica for Efficient Siloxane Capture. Langmuir 2016, 32 (10), 2369-2377. (56) Quan, F.; Hu, Y.; Liu, X. C.; Wei, C. H. The Cooperative Adsorption Properties of Cetyl/Amino-SBA-15 for 4-Nonylphenol. Phys. Chem. Chem. Phys. 2015, 17, (29) 19401-19409.


Energy & Fuels 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

(57) Huang, K.; Wu, Y.-T.; Dai, S. Sigmoid Correlations for Gas Solubility and Enthalpy Change of Chemical Absorption of CO2. Ind. Eng. Chem. Res. 2015, 54, (41)10126-10133. (58) Li,Y. Z.; Sun ,J. H.; Wu, X.; Lin, L.; Gao, L.; Post-treatment and Characterization of Novel Luminescent hybrid bimodal Mesoporous Silicas. J. Solid State Chem. 2010, 183, 1829–1834.


Page 28 of 48

Page 29 of 48 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

Energy & Fuels

Table 1 Chemical composition of coal gangue (wt%) Table 2 Main BET parameters of M-SiO2 prepared from various CTAB addition amounts Table 3 Orthogonal experiment of the optimal combination Table 4 The results of Orthogonal experiment Table 5 CO2 adsorption capacities on various materials Table 6 XPS analyses of M-SiO2 and EDA-M-SiO2


Energy & Fuels 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 30 of 48

Table 1 Component

SiO2

Al2O3

Na2O

MgO

CaO

K2O

TiO2

Fe2O3

Others

Contents

53.1

20.4

1.32

1.57

0.845

2.73

0.808

4.61

14.61


Page 31 of 48 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

Energy & Fuels

Table 2 Various CTAB addition

Pore diameter

pore volume

CO2 adsorption

(nm)

(mL/g)

(mg/g)

2

BET (m /g) (g/10 mL H2O) 0.05

23.31

12.47

0.0992

7.02

0.10

24.96

9.98

0.0781

6.80

0.25

72.85

7.19

0.1611

9.61

0.50

99.00

7.73

0.2522

7.25

0.75

192.18

5.54

0.2911

6.87


Energy & Fuels 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 32 of 48

Table 3 hydrothermal

hydrothermal

[CTAB]

[HCl]

Result

Experiment time (h)

temperature (K)

(g/10mL H2O)

(mol/L)

(mg/g)

1

20

393.15

0.25

2.5

9.61

2

20

373.15

0.1

3

6.38

3

20

423.15

0.5

2

6.97

4

24

393.15

0.1

2

8.1

5

24

373.15

0.5

2.5

7.56

6

24

423.15

0.25

3

7.10

7

16

393.15

0.5

3

7.26

8

16

373.15

0.25

2

7.87

9

16

423.15

0.1

2.5

7.06

Table 4


Page 33 of 48 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

Energy & Fuels

hydrothermal

hydrothermal

[CTAB]

[HCl]

time (h)

temperature (K)

(g/10mL H2O)

(mol/L)

mean value 1

7.653

8.323

8.193

8.077

mean value 2

7.587

7.270

7.180

6.913

mean value 3

7.397

7.043

7.263

7.647

range

0.256

1.280

1.013

1.164

Table 5 Material

T (K)

P (bar)

Adsorption capability (mmol/g)

Refs.

Microporous carbon ultrafine fibers

298.15

0.04

0.44

37

Unmodified X zeolite

398.15

1.0

0.36

38

Zeolite beta

313.15

1.0

2.16

39

Porous silica gel sorbents

323.15

1.0

1.16

40

EDA-SBA-15 sorbent

298.15

1.0

0.45

14

MOF-177

313.15

1.0

0.65

41

triazine-based frameworks

298.15

1.0

2.61

42

PDVB-VT

273.15

1.0

2.65

43

AC3K-300

298.15

1.0

2.5

44

0.22

This study

1.9

This study

Ambient pressure M-SiO2

298.15

(88.93 kPa in Hohhot) (8 % CO2/N2 mixture) Ambient pressure

EDA-M-SiO2

298.15 (88.93 kPa in Hohhot)


Energy & Fuels 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

(8 % CO2/N2 mixture)


Page 34 of 48

Page 35 of 48 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

Energy & Fuels

Table 6 Elements

M-SiO2

EDA-M-SiO2

N (wt%)

0.54

2.81

Si (wt%)

18.88

16.66

O (wt%)

36.09

31.45

Al (wt%)

1.67

1.88

O/Si

1.91

1.89


Energy & Fuels 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

Fig. 1 The schematic procedure Fig. 2 Effects of different conditions on CO2 adsorption capability on the EDA-M-SiO2. (a) Effect of HCl concentration, (b)Effect of various CTAB addition amounts, (c) Effect of hydrothermal temperature, and (d) Effect of hydrothermal time. Fig. 3 Effects of different conditions on CO2 adsorption capability on the EDA-M-SiO2. (a) Effect of impregnation time, (b) Effect of drying temperature, (c) Effect of ratio of M-SiO2 to EDA, (d) cyclic performance of EDA-M-SiO2, (e) IR spectrum of the EDA-M-SiO2 after five cycles and (f) TGA curves for EDA-M-SiO2 after cyclic performance. Fig. 4 SEM images of the M-SiO2 (a1) and EDA-M-SiO2 (a2) Fig. 5 TEM images of the M-SiO2 (b1) and the EDA-M-SiO2 (b2) Fig. 6 XPS spectra of the M-SiO2 and EDA-M-SiO2 Fig. 7 Low angle and (inset) wide angle XRD patterns of M-SiO2 (a1) and EDA-M-SiO2 (a2) Fig. 8 FTIR spectrum of M-SiO2 and EDA-M-SiO2 Fig. 9 N2 adsorption-desorption isotherm at 77 K and BJH adsorption pore size distribution (inset) of the M-SiO2 (a1) and EDA-M-SiO2 (a2) Fig. 10 TG-DTG curves of M-SiO2 (a1) and EDA-M-SiO2 (a2) Fig. 11 Breakthrough curves of M-SiO2 (a) and EDA-M-SiO2 (b)


Page 36 of 48

Page 37 of 48 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

Energy & Fuels

Fig. 1


Energy & Fuels

10

10

(b)

8

8

Adsorption of CO2 (mg/g)


(a)

6

4

2

6

4

2

0

0

1.5

2.5 3.0 2.0 HCl concentration (mol/L)

0.50 0.25 0.10 0.75 CTAB addition amounts (g/10 mLH2O)

(c)

(d) Adsorption of CO2 (mg/g)

8

6

4

2

0

0.05

3.5

10

10


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 38 of 48

8

6

4

2

0

303.15

323.15

373.15

393.15

423.15

12

Hydration temperature (K)

24 20 16 Hydrothermal time (h)

Fig. 2


28

Page 39 of 48

25

20 15 10 5

20

15

10

5

0

0

5

323.15 K

20

10 15 Impregnation time (h)

(c)

CO2 adsorption (mg/g)

80

30 25 20 15 10 5

2:1

1:1

1:2

(d) EDA-M-SiO2

60 40 20

0

4:1

363.15 K

343.15 K

Dry temperature (K)

35

Adsorption of CO (mg/g) 2

(b)

(a) Adsorption of CO2 ( mg/g)


25

0

1:3

1

2

EDA: M-SiO 2

3 4 cycle times

5

6

105 f

100

6

95

1477

2928 3433

459

90

4

23.3 %

2864

Mass %

1639

85

2

80

1070

75

4000 3500 3000 2500 2000 1500 1000 500

0

-1

Wavenumbers cm

200

0 400 600 800 1000 1200 Temperature

Fig. 3


Heat flow mV

e transmittance,%

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

Energy & Fuels

Energy & Fuels 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

Fig. 4


Page 40 of 48

Page 41 of 48 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

Energy & Fuels

Fig. 5


Energy & Fuels

500000 O1s

800

400000

M-SiO2

Al2p

600

74.58 eV Al-OH

EDA-M-SiO2

CPS

C1s

400

200000

0

Al2p

100000

Si2p

200 Si2s

0

-200

1400

1200

1000

800

600

400

200

0

65

70

75 B.E. (eV)

B.E. (eV)

80

85

5000 25000 M-SiO2

4000

103.4eV

M-SiO2

20000 O1s

Si2p

3000 15000

CPS

CPS

300000

CPS

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 42 of 48

2000

10000

1000 5000

0 0

538

536

534

532

530

528

110

108

B.E. (eV)

106

104 B.E. (eV)

Fig. 6


102

100

98

a1

a2

100

Intensity

intensity

100

Intensity

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

Energy & Fuels

intensity

Page 43 of 48

10

20

30

40

10

50

20

1

2

3

30

40

50

2 θ (°)

2θ (°)

4

5

1

2θ (°)

Fig. 7


2

3 2θ (°)

4

5

Energy & Fuels

M-SiO2

799

1639

2980 2878

473

Transmittance,%

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 44 of 48

3439

1099 EDA-M-SiO2 474 806 1580 1487

2978 2887 3414

4000

3500

3000

2500

1099

2000

1500

1000

500

-1

Wavenumbers cm

Fig. 8


Page 45 of 48

120

4.91 n m

0.0 2

0.0 0 D ia m ete r( n m )

100

20

80 60

60

3

/dD ( nm )

70

Amount adsorbed cm3/g

140

0.0 4

(a1)

3 .42 nm

3

160

dV ( m/g)

180

dV (m /g)/dD (nm)

80

200 Amount adsorbed (cm3/g)

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

Energy & Fuels

50 40

0.006

3.891 nm

(a2)

0.005 0.004 0.003 0.002 0.001 0.000

30

0

10 20 30 40 50 60 70 80

Diameter (nm)

20

40

10 20 0.0

0.2

0.4

0.6

0.8

1.0

0 0.0

0.2

Relative Pressure (P/Po)

Fig. 9


0.4 0.6 0.8 Relative Pressure( P/Po)

1.0

Energy & Fuels

100

a1

a2

100

1.2

45

15

70

90

0.8 0.6

20%

36.6 %

80

95

Mass %

Heat flow mV

30

0.4 85

0

0.2

60 -15 50

0

200

400

600

800

1000

1200

1400

80

0.0 200

Temperature

400

600

800

Temperature

Fig. 10


1000

1200

Heat flow mV

1.0

90 Mass %

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 46 of 48

Page 47 of 48

8

(a)

6

1455 s 9.39 mg/g

4

breakthrough curve M-SiO2

2

101 s 5.26 mg/g

0 0

8

(b) 18967 s

6

CO2 V%

CO2 V%

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

Energy & Fuels

breakthrough curve

4

EDA-M-SiO2

2

351 s 45.8 mg/g

0

500 1000 1500 2000 2500 3000

82.8 mg/g

0

5000 10000 15000 20000 25000

t (s)

t (s)

Fig. 11


Energy & Fuels 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

TOC

Fig. 1 The schematic procedure


Page 48 of 48

A Novel Mesoporous SiO2 Material with MCM-41 Structure from Coal

Recommend Documents