3dd Silica
Undergraduate/Graduate Category: Engineering and Technology Degree Level: Bachelor of Science Abstract ID# 1202
Aminopolymer Impregnated MCM-‐36 and 3dd Silica Katherine Conner, Christopher Cogswell, Madeline Finkenaur, David Urick, Rachel Vozikis and Sunho Choi
Method
Abstract Porous solid adsorbents are currently being studied for their potential use as an effective way to capture carbon dioxide. These absorbents are known to have high surface areas and low heats of adsorption, making them ideal for capturing carbon dioxide. The perfect adsorbent would possess high amine loading abilities and high adsorption capacity. A 2-‐dimensional pillared porous silicate material, MCM-‐36, was impregnated with polymers containing amines. The large pore interlayer space was the main factor in determining MCM-‐36 as the ideal material to study. The large pores prevent the amines from becoming stuck within the channels and allowing space for CO2 to be captured. The capability for this material to absorb CO2 was then investigated. The material was then loaded with polyethylenimine (PEI) first to fill these large pores. Experimentation showed that the capture capacity will increase slightly for low PEI loadings, but will decrease a significant amount with high loadings. There are many indicators showing this is due to the blockage of large pore space when high polymer loading occurs. To sidestep this issue, the impregnation of a smaller polymer into the small pore space was then performed. Preliminary results show that this material possesses significantly increased capacity, showing that the pore space can be preferentially loaded with amine. Furthermore, this work suggests a method for pore-‐amine optimization on hybrid sorbents where the various pore morphologies and sizes are used for specific amine impregnation schemes.
The synthesis of both MCM-‐36 and 3dd silica can be found in previous literature. • The MCM-‐36 samples were impregnated with PEI to form a supported-‐amine adsorbent. Each sample was impregnated with varying amounts of PEI to see if there was a difference in capture capacity. • The 3dd silica is loaded with polyethylenimine (PEI) to fill in the large mesopore space • The small micropore space is loaded with tetraethylene Pentamine(TEPA) • Both materials were examined using x-‐ray diffraction and thermogravimetric analysis to measure CO2 capture • Nitrogen adsorption/desorption was analyzed to determine BET surface area and BJH pore volume of the materials.
Figure 3-‐MCM-‐36 vs 3dd Silica
Introduction
Goal
Adsorption Capacity
good
good
Fast sorption kinetics
good
Stability in humid conditions
good
Low-‐energy regeneration
bad
Long-‐term stability
bad
good bad
good
MCM-‐36: • The addition of amines to the MCM-‐36 shows a significant decrease in the surface area and pore volume of the metal. For samples loaded with a low percent weight of PEI, the surface area will initially increase but will eventually hit a maximum and drop back down to the minimum value. • This is also observed when comparing carbon dioxide capture capacity with the PEI weight percent loaded on the MCM-‐36. The addition of PEI leads to a decrease in the ability for carbon dioxide to diffuse into the pore space. • This makes 2-‐D solids an unlikely material to use for optimum carbon dioxide capture. 3dd Silica: • The x-‐ray diffraction results show that loading the silica with amines does not change the pore structure of 3dd as shown in the graph below. Pore volume does not decrease significantly as well. • The addition of PEI to the silica leads shows a plateau of the capture capacity as the amine weight percent increases as opposed to MCM-‐36 which significantly decreases 3dd-m Silica
500
3dd-m TEPA loaded
450
3dd-m PEI loaded
400
Volume of Adsorbate (cc/g)
4 3.5 3 2.5 2
good bad
good bad
TEPA 3dd
350 300 250 200 150
0 0
Sample Name 3dd Silica 3dd + PEI 3dd + TEPA
0.5
good
PEI 3dd
50
1
Metal Organic Frameworks
Bare 3dd
100
5
10
15 20 Degrees 2 Theta
25
30
100
200
300
BET Surface Area (m^2/g) 746 69.2 77.186
400 500 Pressure (Torr)
600
700
800
900
BJH Pore Radius (Angstroms) 79.7 79.1 78.913
BJH Pore Volume (cc/g) 0.364 0.259 0.227
• The amine efficiency does slow down, but the graph below shows it slows at a much higher value compared to MCM-‐36. The max efficiency is 50% or 2 moles of amine for every 1 mole of CO2 to react 1.2
3dd + PEI MCM + PEI
1.2
Amine Efficiency
Capture Capcity (mmol/g)
1.4 1 0.8 0.6 0.4 0.2 0 0
5
10 15 Amine weight%
MCM + PEI 3dd + PEI
1 0.8 0.6 0.4 0.2 0
20
0
5
10 Amine Weight%
15
20
• The amount of CO2 captured in around the first 10 minutes or less of the capture appears to be relatively constant for 3dd+PEI compared to MCM-‐36 which varies. 120
Conclusion
MCM + PEI 3dd + PEI
100 80 60 40 20 0 0
good
Figure 3-‐3dd silica after amine loading
Results
% of equillibrium capacity achieved
Zeolites
Figure 2-‐3dd silica before amine loading
1.5
• The overall goal of this research is to determine the most efficient way to find a material which contains both high amine loading and adsorption capacity so it can be used as a carbon dioxide capture system. • There is little to no research on the relationship between amine loading and adsorption capacity as well as amine loading and adsorption kinetics. • The diffusion and kinetic characteristics of MCM-‐36 was studied in in order to help achieve this goal, which showed the addition of aminopolymers into the pore space of MCM-‐36 will not regain or overtake the capture capacity that bare MCM-‐36 achieves because CO2 cannot flow freely in all dimensions. Liquid Amines, e.g. MEA
Figure 1-‐3dd silica before amine loading
Intensity (a.u.)
• Carbon dioxide capture is becoming increasingly popular with climate change on the rise due to an increase in carbon dioxide in the environment • This research is focused around zeolites, specifically a 2D porous metal MCM-‐36 and a 3dd silica. • Porous solid adsorbents which posses high surface area and low heat of adsorption. • The high surface area and porosity should theoretically create the best conditions for carbon dioxide gas to be captured within the metal. These solids must be able to reach a high selectivity for carbon dioxide over other gases in order for it to be an effective means of capturing the gas. • Currently, aqueous amine absorbents are the main process used as a capture system, but this is not the most ideal due to poor energy regeneration and stability. • This is why using porous solids containing amine groups by impregnation is being investigated as a potential capture system.
5
10 Amine Weight%
References
15
20
1. Cogswell, Christopher F., et al. "Effect of Pore Structure on CO2 Adsorption Characteristics of Aminopolymer Impregnated MCM-‐36." Langmuir 31.15 (2015): 4534-‐4541.
• The results show the addition of aminopolymers into the pore space of MCM-‐36 will not regain or overtake the capture capacity • High weight percentages of amines will lead to a degradation in the capture and kinetic characteristics likely due to the inability of carbon dioxide to diffuse through the pore channels. • 3dd silica showed more results because the ability to absorb carbon dioxide does not decrease after amine loadings. The amine efficiency does decrease as it is loaded with more amine, but at a higher efficiency than MCM-‐36. • This shows that for the 3dd silica the pores stay open and amines can be accessed even after achieving maximum amine loadings. • The 3dd silica suggests that 3D pore systems it can still retain its ability to capture carbon dioxide while filling the pores with PEI while 2D cannot.
Aminopolymer Impregnated MCM-‐36 and 3dd Silica Katherine Conner, Christopher Cogswell, Madeline Finkenaur, David Urick, Rachel Vozikis and Sunho Choi
Method
Abstract Porous solid adsorbents are currently being studied for their potential use as an effective way to capture carbon dioxide. These absorbents are known to have high surface areas and low heats of adsorption, making them ideal for capturing carbon dioxide. The perfect adsorbent would possess high amine loading abilities and high adsorption capacity. A 2-‐dimensional pillared porous silicate material, MCM-‐36, was impregnated with polymers containing amines. The large pore interlayer space was the main factor in determining MCM-‐36 as the ideal material to study. The large pores prevent the amines from becoming stuck within the channels and allowing space for CO2 to be captured. The capability for this material to absorb CO2 was then investigated. The material was then loaded with polyethylenimine (PEI) first to fill these large pores. Experimentation showed that the capture capacity will increase slightly for low PEI loadings, but will decrease a significant amount with high loadings. There are many indicators showing this is due to the blockage of large pore space when high polymer loading occurs. To sidestep this issue, the impregnation of a smaller polymer into the small pore space was then performed. Preliminary results show that this material possesses significantly increased capacity, showing that the pore space can be preferentially loaded with amine. Furthermore, this work suggests a method for pore-‐amine optimization on hybrid sorbents where the various pore morphologies and sizes are used for specific amine impregnation schemes.
The synthesis of both MCM-‐36 and 3dd silica can be found in previous literature. • The MCM-‐36 samples were impregnated with PEI to form a supported-‐amine adsorbent. Each sample was impregnated with varying amounts of PEI to see if there was a difference in capture capacity. • The 3dd silica is loaded with polyethylenimine (PEI) to fill in the large mesopore space • The small micropore space is loaded with tetraethylene Pentamine(TEPA) • Both materials were examined using x-‐ray diffraction and thermogravimetric analysis to measure CO2 capture • Nitrogen adsorption/desorption was analyzed to determine BET surface area and BJH pore volume of the materials.
Figure 3-‐MCM-‐36 vs 3dd Silica
Introduction
Goal
Adsorption Capacity
good
good
Fast sorption kinetics
good
Stability in humid conditions
good
Low-‐energy regeneration
bad
Long-‐term stability
bad
good bad
good
MCM-‐36: • The addition of amines to the MCM-‐36 shows a significant decrease in the surface area and pore volume of the metal. For samples loaded with a low percent weight of PEI, the surface area will initially increase but will eventually hit a maximum and drop back down to the minimum value. • This is also observed when comparing carbon dioxide capture capacity with the PEI weight percent loaded on the MCM-‐36. The addition of PEI leads to a decrease in the ability for carbon dioxide to diffuse into the pore space. • This makes 2-‐D solids an unlikely material to use for optimum carbon dioxide capture. 3dd Silica: • The x-‐ray diffraction results show that loading the silica with amines does not change the pore structure of 3dd as shown in the graph below. Pore volume does not decrease significantly as well. • The addition of PEI to the silica leads shows a plateau of the capture capacity as the amine weight percent increases as opposed to MCM-‐36 which significantly decreases 3dd-m Silica
500
3dd-m TEPA loaded
450
3dd-m PEI loaded
400
Volume of Adsorbate (cc/g)
4 3.5 3 2.5 2
good bad
good bad
TEPA 3dd
350 300 250 200 150
0 0
Sample Name 3dd Silica 3dd + PEI 3dd + TEPA
0.5
good
PEI 3dd
50
1
Metal Organic Frameworks
Bare 3dd
100
5
10
15 20 Degrees 2 Theta
25
30
100
200
300
BET Surface Area (m^2/g) 746 69.2 77.186
400 500 Pressure (Torr)
600
700
800
900
BJH Pore Radius (Angstroms) 79.7 79.1 78.913
BJH Pore Volume (cc/g) 0.364 0.259 0.227
• The amine efficiency does slow down, but the graph below shows it slows at a much higher value compared to MCM-‐36. The max efficiency is 50% or 2 moles of amine for every 1 mole of CO2 to react 1.2
3dd + PEI MCM + PEI
1.2
Amine Efficiency
Capture Capcity (mmol/g)
1.4 1 0.8 0.6 0.4 0.2 0 0
5
10 15 Amine weight%
MCM + PEI 3dd + PEI
1 0.8 0.6 0.4 0.2 0
20
0
5
10 Amine Weight%
15
20
• The amount of CO2 captured in around the first 10 minutes or less of the capture appears to be relatively constant for 3dd+PEI compared to MCM-‐36 which varies. 120
Conclusion
MCM + PEI 3dd + PEI
100 80 60 40 20 0 0
good
Figure 3-‐3dd silica after amine loading
Results
% of equillibrium capacity achieved
Zeolites
Figure 2-‐3dd silica before amine loading
1.5
• The overall goal of this research is to determine the most efficient way to find a material which contains both high amine loading and adsorption capacity so it can be used as a carbon dioxide capture system. • There is little to no research on the relationship between amine loading and adsorption capacity as well as amine loading and adsorption kinetics. • The diffusion and kinetic characteristics of MCM-‐36 was studied in in order to help achieve this goal, which showed the addition of aminopolymers into the pore space of MCM-‐36 will not regain or overtake the capture capacity that bare MCM-‐36 achieves because CO2 cannot flow freely in all dimensions. Liquid Amines, e.g. MEA
Figure 1-‐3dd silica before amine loading
Intensity (a.u.)
• Carbon dioxide capture is becoming increasingly popular with climate change on the rise due to an increase in carbon dioxide in the environment • This research is focused around zeolites, specifically a 2D porous metal MCM-‐36 and a 3dd silica. • Porous solid adsorbents which posses high surface area and low heat of adsorption. • The high surface area and porosity should theoretically create the best conditions for carbon dioxide gas to be captured within the metal. These solids must be able to reach a high selectivity for carbon dioxide over other gases in order for it to be an effective means of capturing the gas. • Currently, aqueous amine absorbents are the main process used as a capture system, but this is not the most ideal due to poor energy regeneration and stability. • This is why using porous solids containing amine groups by impregnation is being investigated as a potential capture system.
5
10 Amine Weight%
References
15
20
1. Cogswell, Christopher F., et al. "Effect of Pore Structure on CO2 Adsorption Characteristics of Aminopolymer Impregnated MCM-‐36." Langmuir 31.15 (2015): 4534-‐4541.
• The results show the addition of aminopolymers into the pore space of MCM-‐36 will not regain or overtake the capture capacity • High weight percentages of amines will lead to a degradation in the capture and kinetic characteristics likely due to the inability of carbon dioxide to diffuse through the pore channels. • 3dd silica showed more results because the ability to absorb carbon dioxide does not decrease after amine loadings. The amine efficiency does decrease as it is loaded with more amine, but at a higher efficiency than MCM-‐36. • This shows that for the 3dd silica the pores stay open and amines can be accessed even after achieving maximum amine loadings. • The 3dd silica suggests that 3D pore systems it can still retain its ability to capture carbon dioxide while filling the pores with PEI while 2D cannot.
