title: Probing the Role of Zr Addition versus Textural Properties in Enhancement of CO₂ Adsorption Performance in Silica/PEI Composite Sorbents.
abstract: Polymeric amines such as poly(ethylenimine) (PEI) supported on mesoporous oxides are promising candidate adsorbents for CO2 capture processes. An important aspect to the design and optimization of these materials is a fundamental understanding of how the properties of the oxide support such as pore structure, particle morphology, and surface properties affect the efficiency of the guest polymer in its interactions with CO2. Previously, the efficiency of impregnated PEI to adsorb CO2 was shown to increase upon the addition of Zr as a surface modifier in SBA-15. However, the efficacy of this method to tune the adsorption performance has not been explored in materials of differing textural and morphological nature. Here, these issues are directly addressed via the preparation of an array of SBA-15 support materials with varying textural and morphological properties, as well as varying content of zirconium doped into the material. Zirconium is incorporated into the SBA-15 either during the synthesis of the SBA-15, or postsynthetically via deposition of Zr species onto pure-silica SBA-15. The method of Zr incorporation alters the textural and morphological properties of the parent SBA-15 in different ways. Importantly, the CO2 capacity of SBA-15 impregnated with PEI increases by a maximum of ∼60% with the quantity of doped Zr for a "standard" SBA-15 containing significant microporosity, while no increase in the CO2 capacity is observed upon Zr incorporation for an SBA-15 with reduced microporosity and a larger pore size, pore volume, and particle size. Finally, adsorbents supported on SBA-15 with controlled particle morphology show only modest increases in CO2 capacity upon inclusion of Zr to the silica framework. The data demonstrate that the textural and morphological properties of the support have a more significant impact on the ability of PEI to capture CO2 than the support surface composition.
authors.affiliation: School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive, NW, Atlanta, Georgia 30332, United States.
authors.forename: Miles A
authors.initials: MA
authors.lastname: Sakwa-Novak
authors.affiliation: School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive, NW, Atlanta, Georgia 30332, United States.
authors.forename: Adam
authors.initials: A
authors.lastname: Holewinski
authors.affiliation: School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive, NW, Atlanta, Georgia 30332, United States.
authors.forename: Caroline B
authors.initials: CB
authors.lastname: Hoyt
authors.affiliation: School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive, NW, Atlanta, Georgia 30332, United States.
authors.forename: Chun-Jae
authors.initials: CJ
authors.lastname: Yoo
authors.affiliation: Department of Chemistry, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors.forename: Song-Hai
authors.initials: SH
authors.lastname: Chai
authors.affiliation: Department of Chemistry, University of Tennessee , Knoxville, Tennessee 37996, United States.|Chemical Sciences Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37830, United States.
authors.forename: Sheng
authors.initials: S
authors.lastname: Dai
authors.affiliation: School of Chemical & Biomolecular Engineering, Georgia Institute of Technology , 311 Ferst Drive, NW, Atlanta, Georgia 30332, United States.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Jones
mesh_terms: D000327:Adsorption; D002245:Carbon Dioxide / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry*; D012822:Silicon Dioxide / Q000138:chemical synthesis / Q000737:chemistry*; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry*
chemical_list: D002245:Carbon Dioxide; D012822:Silicon Dioxide; D011094:Polyethyleneimine; D015040:Zirconium