Facile Preparation of Biomass-Derived ... - ACS Publications

Jul 18, 2019 - The SO2 adsorption capacity of BC-3-650 (10.7 mmol g–1) is twice as high as that of CKM-3 (5.1 mmol g–1) and coconut shell-derived ...
2 downloads 0 Views 908KB Size
Subscriber access provided by GUILFORD COLLEGE

Separations

Facile Preparation of Biomass-derived Mesoporous Carbons for Highly Efficient and Selective SO2 Capture Jinghan Zhang, Peixin Zhang, Minyu Li, Ziwei Shan, Jun Wang, Qiang Deng, Zheling Zeng, and Shuguang Deng Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.9b01938 • Publication Date (Web): 18 Jul 2019 Downloaded from pubs.acs.org on July 19, 2019

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 32 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

Industrial & Engineering Chemistry Research

1

Facile Preparation of Biomass-derived Mesoporous

2

Carbons for Highly Efficient and Selective SO2 Capture

3 4 5

Jinghan Zhanga,b, Peixin Zhanga,b, Minyu Lib, Ziwei Shanb, Jun Wanga,b*, Qiang Denga,b,

6

Zheling Zenga,b, Shuguang Deng,c*

7 8

a.

9

Education, Nanchang University, Nanchang 330031, PR China

Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of

10

b.

11

Nanchang 330031, Jiangxi, PR China

12

c.

13

E. Tyler Mall, Tempe, AZ 85287, USA

School of Resource, Environmental and Chemical Engineering, Nanchang University,

School for Engineering of Matter, Transport and Energy, Arizona State University, 551

14 15

*Corresponding author:

16

1. Dr. Shuguang Deng, Tel.: +8613813996873, E-mail: [email protected] (S.

17

Deng)

18

2. Dr. Jun Wang, E-mail:[email protected] (J. Wang)

19 20 1

ACS Paragon Plus Environment

Industrial & Engineering Chemistry Research 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 32

21

Abstract

22

The efficient elimination of SO2 from flue gases and natural gases is critical for energy

23

utilization and environment protection. However, selecting or preparing an efficient

24

adsorbent with a high SO2 capacity, good selectivity, and excellent recyclability is very

25

challenging, and the adsorption mechanism at atomic level is still controversial. We report

26

a facile one-step method for the synthesis of biomass-derived porous carbons with high

27

specific surface areas (1195-1449 m2 g-1), mesoporous pore size (4-6 nm) and good SO2

28

adsorption properties. Our carbon adsorbents exhibited an outstanding SO2 adsorption

29

capacity of 10.7 mmol g-1 at 298 K and 1.0 bar, which is more than twice the SO2 capacity

30

of benchmark carbon material cs1000a (approximately 5.0 mmol g-1) and commercial

31

ordered mesoporous carbon CKM-3 (5.1 mmol g-1). The new carbon adsorbents also

32

showed an unprecedented SO2/CO2, SO2/CH4 and SO2/N2 separation selectivities of 32,

33

127 and 2349, respectively, which are comparable with the best performance MOF

34

adsorbents. Dynamic breakthrough experiments confirmed the feasibility of efficient

35

removal of SO2 from flue gas in an adsorbent column. Even with the presence of water

36

vapor, clear and efficient separation of SO2 could also be achieved with excellent recycling

37

stability. In addition, density function theory simulation further illustrates that -NOx and -

38

OH groups in the carbon frameworks provide strong interactions with SO2 molecules. The

39

carbon adsorbents synthesized in this work are promising for flue gas desulfurization and

40

natural gas purification applications.

41

Keywords: SO2 elimination; high capacity and selectivity; breakthrough experiments;

42

DFT simulation; FGD technology.

43 44 45

1. Introduction The flue gas emissions generated by coal-fired power plants and petroleum refining 2

ACS Paragon Plus Environment

Page 3 of 32 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

Industrial & Engineering Chemistry Research

46

industry contain large amount of SO2 that is recognized as the major sources of acid rain,

47

fog, and haze.1,2 The traditional flue gas desulfurization technologies via limestone-

48

scrubbing or wet-sulfuric-acid methods are effective, but the exhaust gases usually still

49

retain as much as 400 ppm of SO2.3,4 Whereas, such small amount of SO2 would react with

50

organo-amines solutions of the following CO2-scrubbing process, causing the permanent

51

solvent activity loss.5 Thus, developing cutting-edge flue gas desulfurization and

52

purification technologies has attracted great attentions, especially for the removal of trace

53

SO2 contaminant from flue gases and other SO2-containing gases. The physical adsorption

54

of SO2 by porous materials has been regarded as a promising approach for efficient and

55

low-cost deep desulfurization. Traditional porous materials including zeolites,6 porous

56

polymers,7 and mesoporous silica8 have exhibited a low energy penalty in adsorption-based

57

gas mixture separation processes. Unfortunately, these materials generally suffer from

58

relatively low adsorption capacity or selectivity. Recently, metal-organic frameworks

59

(MOFs) have been employed as an emerging SO2 adsorbent with excellent capacity and

60

selectivity.9,10 However, high fabrication cost, low synthesis yields, and irreversible

61

structure degradation after exposure to SO2 have severely limited their large-scale

62

implements.

63

Porous carbons have been considered as potent candidates for practical gas separation

64

and purification, owning to their intrinsic advantages such as low fabrication cost, excellent

65

structure stability, and high surface property amendment ability.11,12 However, considering 3

ACS Paragon Plus Environment

Industrial & Engineering Chemistry Research 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 32

66

the acidic nature of CO2 and SO2 molecules, and much lower concentration of SO2 than

67

that of CO2 in flue gas (CO2: 15%, v/v; SO2: ~3000 ppm), it is very challenging to

68

efficiently remove SO2 from CO2 with a high selectivity. With the increasing requirements

69

for SO2 adsorption and separation, it is urgent to develop efficient porous carbon

70

adsorbents with high adsorption capacity and selectivity.13 For example, Song et al.

71

reported a SO2 adsorption capacity of 0.33 mmol g-1 (based on breakthrough curve, 400

72

ppm SO2) on nitrogen-doped mesoporous carbon at 308 K and 1 bar.14 Sun et al. prepared

73

a N-doped porous carbon showing a SO2 adsorption capacity of 0.75 mmol g-1 (based on

74

breakthrough curve, 500 ppm SO2).15 The abovementioned problems prompt us to develop

75

advanced porous carbons possessing both high SO2 adsorption capacity and excellent gas-

76

mixture selectivity.

77

Oil-tea is a unique edible oil and popular functional food in China, whereas, the oil-

78

tea shells (OTS) accounts for ~60% of the camellia fruit on a wet weight basis.16,17 Huge

79

amount of OTS are produced in the southern China annually, as a lignocellulosic waste,

80

OTS are often discarded directly but without effective utilization. Herein, we prepare OTS-

81

derived porous carbons via a facile one-step activation method. The pore structures could

82

be tuned by altering porogen/OTS ratio and activation temperature. The as-prepared

83

carbons possess a large surface area, suitable pore size, and abundant basic adsorption sites.

84

An excellent SO2 adsorption capacity of 10.7 mmol g-1 is achieved at 298 K and 1 bar with

85

an outstanding SO2/CO2, SO2/CH4, and SO2/N2 selectivity of 32, 127 and 2349, 4

ACS Paragon Plus Environment

Page 5 of 32 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

Industrial & Engineering Chemistry Research

86

respectively. The breakthrough curve is measured to further illustrate the separation

87

performance with a practical flue gas composition in the presence of water vapor and

88

oxygen. Moreover, density functional theory (DFT) calculations are carried out to reveal

89

the selective adsorption mechanism between SO2 molecules and heteroatom adsorption

90

sites.

91

2. Experimental Section

92

2.1. Materials.

93

The oil-tea shell (OTS) used in this study was kindly provided by Hunan Academy of

94

Forestry of China and was crushed to 40 mesh (