Hydrate-Based CO2 Capture from Integrated Gasification Combined

Hydrate-based CO2 capture and/or H2 purification from integrated gasification combined cycle (IGCC) syngas has been a more and more attractive technol...
0 downloads 0 Views 1MB Size
Subscriber access provided by READING UNIV

Article

Hydrate-based CO2 capture from IGCC syngas with TBAB and nano Al2O3 Ze-Yu Li, Zhi-Ming Xia, Xiao-Sen Li, Zhao-Yang Chen, Jing Cai, Gang Li, and Tao Lv Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b03605 • Publication Date (Web): 09 Jan 2018 Downloaded from http://pubs.acs.org on January 13, 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 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.

Energy & Fuels 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 33 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

Hydrate-based CO2 capture from IGCC syngas with TBAB and nano

2

Al2O3

3 4 5 6 7 8 9 10 11 12 13 14 15 16

Ze-Yu Lia,b,c,d,e, Zhi-Ming Xiaa,b,c,d, Xiao-Sen Lia,b,c,d*, Zhao-Yang Chena,b,c,d, Jing Caia,b,c,d, Gang Lia,b,c,d, Tao Lva,b,c,d a

Guangzhou institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou, 510640,

People’s Republic of China b

CAS Key laboratory of gas hydrate, Guangzhou, 510640, People’s Republic of China

c

Guangdong Provincial Key laboratory of New and Renewable Energy Research and Development,

Guangzhou, 510640, People’s Republic of China d

Guangzhou Center for Gas Hydrate Research, Chinese Academy of Sciences, Guangzhou, 510640,

People’s Republic of China e

University of Science and Technology of China, Nano Science and Technology Institute, Suzhou

215123, People’s Republic of China

17

ABSTRACT: Hydrate-based CO2 capture and/or H2 purification from IGCC syngas has been

18

more and more attractive technology in both environmental and clean energy fields. This

19

work focused on both microcosmic and macroscopic studies for the CO2/H2 hydrate formation

20

process with synergic additives comprised Tetra-n-butyl Ammonium Bromide (TBAB) and

21

nano Al2O3. The experiments were carried out with 0.5 wt % nano Al2O3 and 1, 5, 10 and 11

22

wt % TBAB, respectively. The microcosmic study shows that, with the synergic additives, the

23

CO2/H2 mixture hydrate formed mainly on the nano Al2O3 surface and formed semiclathrate

24

structure. Additionally, the macroscopic study shows that the synergic additives could

25

remarkably promote the gas uptake and separation efficiency. Noteworthy, compared with

26

unitary TBAB, THF and CP, the synergic additives could increase the gas uptake for the

27

CO2/H2 hydrate formation process by approximate 43.62%, 230.56% and 173.27%,

28

*

29

E-mail: [email protected].

To whom correspondence should be addressed: Telephone: +86 20 87057037. Fax: +86 20 87057037.

1

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 2 of 33

30

respectively. The experimental results indicate that the synergic effect of TBAB and nano

31

Al2O3 is helpful for hydrate-based CO2 capture from IGCC syngas.

32

1. INTRODUCTION

33

Global warming resulted by the increasing emission of greenhouse gas is widely

34

considered to be the urgent problem in the 21st century.

1

35

cycle (IGCC), as one of new clean energy technologies, has prominent contribution on

36

retarding the climate change. The essential of this approach, in fact, is that the CO2 capture

37

from CO2/H2 mixture gas. Removal of CO2 from mixture gas can be achieved by a serious of

38

technologies such as physical absorption, chemical adsorption, membranes, cryogenic

39

distillation, and so on. 2-5 However, these methods have the individual issues of large energy

40

consumption, apparatus corrosion, easily caused second pollution or low capacity, and so

41

forth. Hence, it is necessary to develop a cost-effective and environment-friendly

42

capture/separation technology for CO2 capture and separation.

Integrated gasification combined

43

Hydrate-based CO2 capture from IGCC is one of the new technologies which based on gas

44

hydrate formation process to capture CO2 and purify H2. Gas hydrates are nonstoichiometric

45

compounds existing in lattice structures which are made up by host molecules and guest

46

molecules.

47

component between hydrate phase and gaseous phase. For instance, the hydrate formation

48

pressure of H2 is 300 MPa while that of CO2 is 2.91 MPa at 280 K. 7 Spencer et al. 8 made an

49

economic assessment, and reported that the cost for capturing CO2 from CO2/H2 syngas by the

50

hydrate methods is about 10 dollars per ton CO2, which is pretty cost-effective.

51

6

The basis for the hydrate-based CO2 capture is the selective partition of CO2

However, for industrial utilization, hydrate-based CO2 capture still need further study to 2

ACS Paragon Plus Environment

Page 3 of 33 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

52

enhance the gas storage and to accelerate the gas hydrate formation rate. 9, 10 In order to lower

53

the hydrate formation pressure and improve the hydrate formation rate, some additives such

54

as TBAB, 11-13 THF (Tetrahydrofuran), 14-16 and CP (Cyclopentane) etc. 17-19 were proposed to

55

enhance the gas hydrate formation process. Kamata et al.

56

semiclathrate hydrate with water molecules, and it was suitable for small guest gas molecules

57

separation. Li et al.

58

pure system of TBAB, the experimental results indicated that it has better gas storage and

59

separation efficiency for TBAB system than pure water system. Duc et al.

60

0.29 mol % TBAB was the optimum concentration for reducing CO2 composition from

61

CO2/N2 mixture. What else, THF hydrates have pretty well cavity structure which are suitable

62

for guest gas molecules storage. Lee et al.

22

63

concentration

from

64

non-environmental-protection chemical and easily cause environment pollution. As for the

65

study on CP by Zhang et al. 23, they found that the hydrate formation and dissociation could

66

significantly enrich CO2 from 40 to 98 mol % at 282 K for pure CP system. Furthermore, Li

67

et al.

68

capture from IGCC syngas with 5 vol% CP is 3 mmol gas/mol.

69

24

11

for

20

reported the TBAB could form

studied on hydrate-based CO2 separation from CO2/H2 syngas in the

the

CO2

capture

21

presented that

reported that 1 mol %THF was the optimum CO2/H2

syngas.

Whereas,

THF

is

reported that, at 4.5 MPa and 273.15 K, the gas uptake for the hydrate-based CO2

However, besides the above additives, heat and mass transfer is demonstrated to be the 25-27

70

most difficult and significant for the gas hydrate formation process.

71

researchers proposed the idea that using nano fluid to enhance the heat and mass transfer

72

processes. Park et al.

73

the gas uptake of methane hydrate by 300 %. And then the effect of the MWCNTs was

28

Recently, some

reported that the muti-carbon nanotubes (MWCNTs) could increase

3

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

74

compared with the oxide muti-walled carbon nanotubes (OWMCNTs) on the methane hydrate

75

formation process in terms of gas uptake, they found that the OMCNTs had a better

76

performance in gas uptake. 29 Kakati et al. 30 used the nano Al2O3 and Sodium dodecyl sulfate

77

(SDS) to enhance the CH4 gas hydrate formation process, and demonstrated that the gas

78

uptake of 0.8 wt % nano Al2O3 and 0.03 wt % SDS was 2.5 times more than that of pure water.

79

Choi et al. 31 found that the gas uptake of the 0.2 wt % nano Al2O3 and 0.6 wt % SDS system

80

was 3.74 times higher than that of 10 wt % THF system, they explained that the nano Al2O3

81

promoted the solution system thermal conductivity, while SDS reduced the surface tension of

82

CO2 and water molecules. Indeed, the research for hydrate-based CO2 capture from IGCC

83

syngas with nano fluid is still faultiness, and need further study. As a porous medium, nano

84

Al2O3 has pretty performance on heat and mass transfer feature. Also, as a well-known

85

thermodynamic promoter, TBAB could relieve the gas hydrate formation condition. Therefore,

86

this work focused on the kinetic, separation efficiency and microcosmic study for CO2

87

removal from CO2/H2 syngas with TBAB and nano Al2O3.

88

2. EXPERIMENTAL SECTION

89

2.1. Material. Table 1 summarizes all the materials for this work. In pre-combustion IGCC

90

power station, the treated syngas mainly consists 60 mol % H2. Hence, the 40 mol % CO2 and

91

60 mol % H2 mixture gas was simulated as the syngas in this work. The de-ionized water was

92

prepared in the laboratory by DZG-303A, EPED. What else, all the chemicals including

93

TBAB and nano Al2O3 were provided directly by purchasing without further treatment.

94

The particle size distributions of the nano Al2O3 were measured by the Mastersizer 2000

95

particle size analyzer (Malvern Instruments. Ltd., Britain). As shown in Figure 1, the average 4

ACS Paragon Plus Environment

Page 4 of 33

Page 5 of 33 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

96

particle size of the nano Al2O3 sample is about 550 nm, which could mix with water and form

97

homogeneous colloidal dispersion in relatively lower concentration (99.99

BEST-REAGENT,CHENGDU

Nano Al2O3

200-600 nm

XFNANO,NANJING

624

32

ACS Paragon Plus Environment

Page 33 of 33 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

625 626 627 628 629 630 631 632 633

Table 2. Summary of the experimental conditions and results Texpa

Pexpb

RTc

Pfinald

CCRe

CCHf

S.Fr.g

(K)

(MPa)

(min)

(MPa)

(%)

(%)

(%)

0.1 wt % Nano Al2O3

279.65

3.00

49

2.62

-

-

-

2

0.5 wt % Nano Al2O3

279.65

3.00

105

2.46

-

-

-

3

0.8 wt % Nano Al2O3

279.65

3.00

220

2.44

-

-

-

281.25

3.08

122

2.61

28.65

78.71

39.86

281.25

3.09

120

2.56

26.62

88.97

45.49

281.25

3.07

123

2.23

27.38

80.22

50.31

281.25

3.00

125

2.37

25.01

81.97

55.71

Exp. No.

System

1

4 5 6 7

634 635 636

a.

0.5 wt % Nano Al2O3+1wt%TBAB 0.5 wt % Nano Al2O3+ 5 wt %TBAB 0.5 wt % Nano Al2O3+10 wt %TBAB 0.5 wt % Nano Al2O3+11 wt %TBAB

Experimental temperature;

reaction completed;

e.

b.

Original pressure;

c.

Reaction time; (tconstant-t0); f.

d.

Final pressure when

CO2 composition in the Residual gas; CO2 composition in the hydrate phase; g.

Split fraction.

33

ACS Paragon Plus Environment