Clay materials modified with amino acids for purification processes of biogas and natural gas ...

67 Pages·2016·2.71 MB·English

Clay materials modified with amino acids for purification
processes of biogas and natural gas

Joanna Juźków

Thesis to obtain the Master of Science Degree in

Chemical Engineering

Supervisor: Prof. Dr. Moisés Luzia Gonçalves Pinto

Examination Committee

Chairperson: Prof. Carlos Manuel Faria de Barros Henriques
Supervisor: Prof. Moisés Luzia Gonçalves Pinto
Memeber of the Committee: Prof. João Manuel Pires da Silva

July 2016
ACKNOWLEDGEMENTS

In the first place I would like to thank my supervisor, prof. Moisés Luzia Gonçalves Pinto for the
opportunity to conduct my work in Lisbon, valuable guidance during the research, sharing the
knowledge, patience and motivation that allowed me to successfully complete my thesis.

I would like to offer my special thanks to prof. João Pires da Silva for helpful suggestions,
encouragement and enjoyable cooperation.

I am also very grateful to Ana Cristina Fernandes for her assistance in the research and helping hand.

I am very thankful to all the workers and students of Grupo de Adsorção e Materiais Adsorventes of
Center of Chemistry and Biochemistry of the Faculty of Sciences of the University of Lisbon for
wonderful collaboration and friendly atmosphere.

I also want to thank my dearest parents and sister for their constant support, faith in me and love.
ABSTRACT

Biogas and natural gas purification is an issue of a great industrial importance. Due to decrease of
calorific value of the fuel, corrosion and dry ince formation as a result of carbon dioxide presence in
methane, the concentration of CO needs to be reduced to ppm level. Adsorption on a natural sorbent
2
has drawn the attention of researchers recently, as a low-cost, environmentaly friendly and effective
way of gas treatment. In the present research samples of montmorillonite were intercalated with amino
acids: glycine, arginine and L-histidine at pH 7 and pH 5 in order to enhance adsorption properties of
the clay materials. The obtained adsorbents were analyzed with FTIR, XRD, thermogravimetry with
DSC and nitrogen adsorption-desorption. Conducted tests confirmed retention of amino acid
molecules in the clay structure and increase of porosity of materials in the result of intercalation.
Investigations of methane and carbon dioxide adsorption on the prepared samples were conducted
and adsorption isotherms were plotted. Clays intercalated with arginine and L-histidine adsorbed more
CO than in case of glycine. Materials prepared at pH 5 showed better results than samples obtained
2
at pH 7. The adsorbent with the highest adsorption capacity was ARG-5 with 0.80 mmol/g of CO
2
adsorbed. The most selective material for CH /CO separation was L-HIST-5, which up to 0.7 molar
4 2
fraction of CH adsorbed only CO from the mixture at relatively low pressure 100 kPa. The obtained
4 2
results showed a promising possibility for further application of intercalated clay materials in industrial
gas treatment processes.

Keywords: adsorption, montmorillonite, amino acids, methane purification, carbon dioxide separation
OBJECTIVES

The main aim of present research was to characterize the adsorption properties of amino acid
intercalated monmorillonite materials for the methane and carbon dioxide separation. The samples
were investigated with analytical methods: FTIR, XRD, thermogravimetry and nitrogen adosrption-
desprtion to prove the amino acids renention in the caly structure and their influence on the surface
area and porosity of clay material. Adsorption measurements of CO and CH were conducted and
2 4
adsorption isotherms were plotted in order to evaluate the adsorption capacity of the intercalated clays
in the function of pressure. Selectivity of the samples was calculated with MathCAD software and
phase diagrams of adsorption of carbon dioxide and methane from binary mixture were prepared to
determine the separation abilities of prepared materials.
TABLE OF CONTENTS

I. INTRODUCTION...................................................................................................................1
II. THEORETICAL PART ..........................................................................................................2
1. Natural gas and biogas...................................................................................................2
1.1. Fossil fuels and CO issue .......................................................................................2
2
1.2. Biomass ..................................................................................................................2
1.3. Biogas energy .........................................................................................................3
1.4. Natural gas ..............................................................................................................6
1.5. Biogas production – anaerobic digestion ................................................................7
1.6. Biogas and natural gas upgrading ..........................................................................8
1.7. Gas purification methods ..................................................................................... 11
1.7.1. Physical adsorption .................................................................................. 11
1.7.2. Chemical adsorption ................................................................................ 11
1.7.3. Adsorption on a solid surface .................................................................. 11
1.7.4. Membrane separation .............................................................................. 12
1.7.5. Cryogenic separation ............................................................................... 12
1.7.6. Pressure swing adsorption....................................................................... 12
2. Clay materials as adsorbents ...................................................................................... 13
2.1. Low-cost adsorbents ............................................................................................ 13
2.2. Clays .................................................................................................................... 14
2.3. Clay structure ....................................................................................................... 14
2.4. Smectites ............................................................................................................. 16
2.5. Properties of clays ............................................................................................... 17
2.5.1. Ion exchange ........................................................................................... 17
2.5.2. Swelling .................................................................................................... 18
2.5.3. Acidity ....................................................................................................... 18
2.5.4. Intercalation ............................................................................................. 18
2.6. Montmorillonite ..................................................................................................... 19
2.7. Amino acid intercalation ....................................................................................... 20
2.8. Adsorption of carbon dioxide on amino acid intercalated montmorillonite .......... 22
III. EXPERIMENTAL PART ..................................................................................................... 24
1. Materials preparation ................................................................................................... 24
2. Characterization methods ........................................................................................... 25
2.1. Fourier-transform infrared spectroscopy .............................................................. 25
2.2. XRD ...................................................................................................................... 26
2.3. Thermogravimetry ................................................................................................ 27
2.4. Nitrogen adsorption-desorption ........................................................................... 28
3. High pressure adsorption line ...................................................................................... 28
4. Methodology of methane and carbon dioxide adsorption measurements .................. 29
5. Data evaluation ............................................................................................................ 30
IV. RESULTS AND DISCUSSION .......................................................................................... 31
1. Fourier-transform infrared spectroscopy ..................................................................... 31
2. XRD ............................................................................................................................. 35
3. Thermogravimetry ....................................................................................................... 37
4. Nitrogen adsorption-desorption ................................................................................... 39
5. Adsorption isotherms ................................................................................................... 41
5.1. Carbon dioxide and methane adsorption at pH 7 at 25 oC .................................. 41
5.2. Carbon dioxide and methane adsorption at pH 5 at 25 oC .................................. 42
5.3. Carbon dioxide adsorption at pH 5 at 25 oC and 45 oC ........................................ 43
6. Selectivity .................................................................................................................... 44
7. Phase diagrams ........................................................................................................... 45
V. CONCLUSIONS ................................................................................................................. 49
VI. REFERENCES................................................................................................................... 50
VII. ANNEX 1 ............................................................................................................................ 54
VIII. ANNEX 2 ............................................................................................................................ 56
LIST OF FIGURES

Figure 1. Comparison of different CO emissions connected with different options of electricity
2
production .................................................................................................................................................4
Figure 2. Number of plants and total installed capacity in Europe in years 2010-2014 ...........................5
Figure 3. Energy produced from biogas power plants in Poland in years 2003-2013 .............................6
Figure 4. Anaerobic digestion steps .........................................................................................................7
Figure 5. Dependence of Wobbe index of CO content and relative density of the biogas .................. 10
2
Figure 6. Origin of low-cost adsorbents ..................................................................................................13
Figure 7. Schema of 1:1 and 2:1 clay minerals structures .....................................................................15
Figure 8. Classification of clays ............................................................................................................. 16
Figure 9. The structure of monmorillonite .............................................................................................. 19
Figure 10. Structural formulas of glycine, arginine and L-histidine ........................................................20
Figure 11. Forms of glycine ions in aqueous solution depending on pH ...............................................21
Figure 12. Intercalation of amino acids on montmorillonite depending on pH value ..............................22
Figure 13. Mechanism of CO adsorption on amino acid intercalated montmorillonite ........................ 23
2
Figure 14. Scheme of amino-acid intercalated MMT materials preparation ......................................... 25
Figure 15. Simplified schema of the adsorption line ............................................................................. 29
Figure 16. FTIR spectra for pure glycine, arginine and l-histidine ......................................................... 31
Figure 17. The FTIR spectra for MMT, L-histidine intercalated MMT samples L-HIST-7 and L-HIST-5
and pure L-histidine ............................................................................................................................... 32
Figure 18. The FTIR spectra for MMT, arginine intercalated MMT samples GLY-7 and GLY-5 and pure
arginine .................................................................................................................................................. 33
Figure 19. The FTIR spectra for MMT, glycine intercalated MMT samples GLY-7 and GLY-5 and pure
glycine .................................................................................................................................................... 34
Figure 20. XRD plots for amino acid modified MMT materials obtained at pH 7 .................................. 35
Figure 21. XRD plots for amino acid modified MMT materials obtained at pH 5 .................................. 36
Figure 22. TG DSC analysis of mass loss and heat flow against temperature for adsorbent materials
prepared at pH 7 .................................................................................................................................... 37
Figure 23. TG DSC analysis of mass loss and heat flow against temperature for adsorbent materials
prepared at pH 5 .................................................................................................................................... 38
Figure 24. Isotherms of nitrogen adosprtion-desorption for pure MMT and amino acid intercalated
MMT samples at pH 7 ........................................................................................................................... 39
Figure 25. Isotherms of nitrogen adosprtion-desorption for pure MMT and amino acid intercalated
MMT samples at pH 5 ........................................................................................................................... 40
Figure 26. Adsorption isotherms of carbon dioxide and methane adsorption at 25oC on amino acid
intercalated MMT samples prepared at pH 7 ........................................................................................ 42
Figure 27. Adsorption isotherms of carbon dioxide and methane adsorption at 25oC on amino acid
intercalated MMT samples prepared at pH 5 ........................................................................................ 43
Figure 28. Adsorption isotherms of carbon dioxide adsorption at 25oC and 45oC on amino acid
intercalated MMT samples prepared at pH 5 ........................................................................................ 44
Figure 29. Selectivity of aminoacid intercalated MMT adsorbents against pressure ............................ 45
Figure 30. Phase diagrams at 100 kPa describing separation of CH between gaseous and adsorbed
4
phase as a function of mole fraction of CH in adsorbed phase ........................................................... 46
4
Figure 31. Phase diagrams for L-HIST-7, ARG-7, L-HIST-5, ARG-5 and GLY-5 ................................. 47
LIST OF TABLES

Table 1. Top natural gas exporters in 2010 ..............................................................................................7
Table 2. Typical composition of natural gas and biogas ..........................................................................9
Table 3. Typical specifications of composition on feed to LNG plant and on pipeline gas ................... 10
Table 4. θ values for basal peak obtained in XRD plots for MMT and amino acid modified MMT
materials, corresponding interlayer spacing and expansion of MMT in the effect of amino acid
intercalation ........................................................................................................................................... 36
Table 5. Porosity and surface properties characteristics of pure MMT and amino acids modified MMT
materials ................................................................................................................................................ 41
LIST OF ABBREVIATIONS

ARG-5 montmorillonite intercalated with arginine prepared at pH 5
ARG-7 montmorillonite intercalated with arginine prepared at pH 7
ARG pure pure arginine
CEC concentration of exchangeable cations
CHP combined heat and power
C constant
1
C constant
2
C constants
3
d the interplanar distance [Ǻ]
FTIR Fourier-transfer infrared spectroscopy
G Gibbs free energy [J]
GHG greenhouse gas
GLY-5 montmorillonite intercalated with glycine prepared at pH 5
GLY-7 montomrillonite intercalated with glycine prepared at pH 7
GLY pure pure glycine
K equilibrium constant
L-HIST-5 montomrillonite intercalated with L-histidine prepared at pH 5
L-HIST-7 montomrillonite intercalated with L-histidine prepared at pH 7
L-HIST pure pure L-histidine
LNG liquiefied natural gas
MMT raw montmorillonite
n the positive integer
n amount of moles of gas adsorbed on the unit of mass of adsorbent [mmol/g]
ads
n0 standard-state loading for pure CO
CO2 2
n0 standard-state loading for pure CO
CO2 2
p pressure [kPa]
PSA pressure-swing adsorption
R gas constant
S selectivity of the clay material for CO /CH mixture
CO2/CH4 2 4
T temperature [oC]
TG DSC thermogravimetry with differential scanning calorimetry
XRD X-ray diffraction
xa CO molar fraction in the adsorbed phase
CO2 2
xa CH molar fraction in the adsorbed phase
CH4 4
xg CO molar fraction in the gas phase
CO2 2
xg CH molar fraction in the gas phase
CH4 4
λ the wavelength of incident wave (λ=1.5406 Ǻ)
θ the scattering angle [o]