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Title: CO 2 capture properties of lithium silicates with different ratios of Li 2O/SiO 2: an ab initio thermodynamic and experimental approach

Abstract

The lithium silicates have attracted scientific interest due to their potential use as high-temperature sorbents for CO 2 capture. The electronic properties and thermodynamic stabilities of lithium silicates with different Li 2O/SiO 2 ratios (Li 2O, i 8SiO 6, Li 4SiO 4, Li 6Si 2O 7, Li 2SiO 3, Li 2Si 2O 5, Li 2Si 3O 7, and a-SiO 2) have been investigated by combining first-principles density functional theory with lattice phonon dynamics. All these lithium silicates examined are insulators with band-gaps larger than 4.5 eV. By decreasing the Li 2O/SiO 2 ratio, the first valence bandwidth of the corresponding lithium silicate increases. Additionally, by decreasing the Li 2O/SiO 2 ratio, the vibrational frequencies of the corresponding lithium silicates shift to higher frequencies. Based on the calculated energetic information, their CO 2 absorption capabilities were extensively analyzed through thermodynamic investigations on these absorption reactions. We found that by increasing the Li 2O/SiO 2 ratio when going from Li 2Si 3O 7 to Li 8SiO 6, the corresponding lithium silicates have higher CO 2 capture capacity, higher turnover temperatures and heats of reaction, and require higher energy inputs for regeneration. Based on our experimentally measured isotherms of the CO 2 chemisorptionmore » by lithium silicates, we found that the CO 2 capture reactions are two-stage processes: (1) a superficial reaction to form the external shell composed of Li 2CO 3 and a metal oxide or lithium silicate secondary phase and (2) lithium diffusion from bulk to the surface with a simultaneous diffusion of CO 2 into the shell to continue the CO 2 chemisorption process. The second stage is the rate determining step for the capture process. By changing the mixing ratio of Li 2O and SiO 2, we can obtain different lithium silicate solids which exhibit different thermodynamic behaviors. Based on our results, three mixing scenarios are discussed to provide general guidelines for designing new CO2 sorbents to fit practical needs.« less

Authors:
 [1];  [2];  [3];  [2];  [1];  [1];  [4]
  1. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
  2. Univ. Nacional Autonoma de Mexico, Del. Coyoacan (Mexico). Inst. de Investigaciones en Materiales
  3. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); West Virginia Univ., Morgantown, WV (United States). School of Medicine
  4. Univ. of Minnesota, Minneapolis, MN (United States). School of Physics and Astronomy
Publication Date:
Research Org.:
National Energy Technology Lab. (NETL), Pittsburgh, PA, and Morgantown, WV (United States). In-house Research
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1094997
Report Number(s):
NETL-PUB-673
Journal ID: ISSN 1463-9076
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 15; Journal Issue: 2013
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Duan, Yuhua, Pfeiffer, Heriberto, Li, Bingyun, Romero-Ibarra, Issis C., Sorescu, Dan C., Luebke, David R., and Halley, J. Woods. CO2 capture properties of lithium silicates with different ratios of Li2O/SiO2: an ab initio thermodynamic and experimental approach. United States: N. p., 2013. Web. doi:10.1039/c3cp51659h.
Duan, Yuhua, Pfeiffer, Heriberto, Li, Bingyun, Romero-Ibarra, Issis C., Sorescu, Dan C., Luebke, David R., & Halley, J. Woods. CO2 capture properties of lithium silicates with different ratios of Li2O/SiO2: an ab initio thermodynamic and experimental approach. United States. doi:10.1039/c3cp51659h.
Duan, Yuhua, Pfeiffer, Heriberto, Li, Bingyun, Romero-Ibarra, Issis C., Sorescu, Dan C., Luebke, David R., and Halley, J. Woods. Fri . "CO2 capture properties of lithium silicates with different ratios of Li2O/SiO2: an ab initio thermodynamic and experimental approach". United States. doi:10.1039/c3cp51659h.
@article{osti_1094997,
title = {CO2 capture properties of lithium silicates with different ratios of Li2O/SiO2: an ab initio thermodynamic and experimental approach},
author = {Duan, Yuhua and Pfeiffer, Heriberto and Li, Bingyun and Romero-Ibarra, Issis C. and Sorescu, Dan C. and Luebke, David R. and Halley, J. Woods},
abstractNote = {The lithium silicates have attracted scientific interest due to their potential use as high-temperature sorbents for CO2 capture. The electronic properties and thermodynamic stabilities of lithium silicates with different Li2O/SiO2 ratios (Li2O, i8SiO6, Li4SiO4, Li6Si2O7, Li2SiO3, Li2Si2O5, Li2Si3O7, and a-SiO2) have been investigated by combining first-principles density functional theory with lattice phonon dynamics. All these lithium silicates examined are insulators with band-gaps larger than 4.5 eV. By decreasing the Li2O/SiO2 ratio, the first valence bandwidth of the corresponding lithium silicate increases. Additionally, by decreasing the Li2O/SiO2 ratio, the vibrational frequencies of the corresponding lithium silicates shift to higher frequencies. Based on the calculated energetic information, their CO2 absorption capabilities were extensively analyzed through thermodynamic investigations on these absorption reactions. We found that by increasing the Li2O/SiO2 ratio when going from Li2Si3O7 to Li8SiO6, the corresponding lithium silicates have higher CO2 capture capacity, higher turnover temperatures and heats of reaction, and require higher energy inputs for regeneration. Based on our experimentally measured isotherms of the CO2 chemisorption by lithium silicates, we found that the CO2 capture reactions are two-stage processes: (1) a superficial reaction to form the external shell composed of Li2CO3 and a metal oxide or lithium silicate secondary phase and (2) lithium diffusion from bulk to the surface with a simultaneous diffusion of CO2 into the shell to continue the CO2 chemisorption process. The second stage is the rate determining step for the capture process. By changing the mixing ratio of Li2O and SiO2, we can obtain different lithium silicate solids which exhibit different thermodynamic behaviors. Based on our results, three mixing scenarios are discussed to provide general guidelines for designing new CO2 sorbents to fit practical needs.},
doi = {10.1039/c3cp51659h},
journal = {Physical Chemistry Chemical Physics. PCCP (Print)},
number = 2013,
volume = 15,
place = {United States},
year = {Fri Jul 26 00:00:00 EDT 2013},
month = {Fri Jul 26 00:00:00 EDT 2013}
}