Aminosilane-Grafted Polymer/Silica Hollow Fiber Adsorbents for CO₂ Capture from Flue Gas

Abstract

Amine/silica/polymer composite hollow fiber adsorbents are produced using a novel reactive post-spinning infusion technique, and the obtained fibers are shown to capture CO₂ from simulated flue gas. The post-spinning infusion technique allows for functionalization of polymer/silica hollow fibers with different types of amines during the solvent exchange step after fiber spinning. The post-spinning infusion of 3-aminopropyltrimethoxysilane (APS) into mesoporous silica/cellulose acetate hollow fibers is demonstrated here, and the materials are compared with hollow fibers infused with poly(ethyleneimine) (PEI). This approach results in silica/polymer composite fibers with good amine distribution and accessibility, as well as adequate porosity retained within the fibers to facilitate rapid mass transfer and adsorption kinetics. The CO₂ adsorption capacities for the APS-infused hollow fibers are shown to be comparable to those of amine powders with similar amine loadings. In contrast, fibers that are spun with presynthesized, amine-loaded mesoporous silica powders show negligible CO₂ uptake and low amine loadings because of loss of amines from the silica materials during the fiber spinning process. Aminosilica powders are shown to be more hydrophilic than the corresponding amine containing composite hollow fibers, the bare polymer as well as silica support. Both the PEI-infused and APS-infused fibers demonstrate reduced CO₂ adsorption upon elevating the temperature from 35 to 80°C, in accordance with thermodynamics, whereas PEI-infused powders show increased CO₂ uptake over that temperature range because of competing diffusional and thermodynamic effects. The CO₂ adsorption kinetics as probed via TGA show that the APS-infused hollow fiber adsorbents have more rapid uptake kinetics than their aminosilica powder analogues. The adsorption performance of the functionalized hollow fibers is also assessed in CO₂ breakthrough experiments. The breakthrough results show a sharp CO₂ front for APS-grafted fibers, indicating fast kinetics with comparable pseudo-equilibrium capacities to the CO₂ equilibrium capacities measured via thermogravimetric analysis (TGA). The results indicate the post-spinning infusion method provides a new platform for synthesizing composite polymer/silica/amine fibers that may facilitate the ultimate scale-up of practical fiber adsorbents for flue gas CO₂ capture applications.

Department(s)

Chemical and Biochemical Engineering

Keywords and Phrases

3-Aminopropyl Trimethoxysilane; Adsorption Performance; APS; Breakthrough Experiment; Composite Hollow Fibers; Functionalization of Polymers; Hollow Fiber; RTSA; Adsorption; Amines; Carbon Dioxide; Fibers; Flue Gases; Grafting (Chemical); Kinetics; Mesoporous Materials; Polymers; Powders; Silica; Thermodynamics; Thermogravimetric Analysis; Spinning (Fibers); 3 Aminopropyltrimethoxysilane; Silane Derivative; Silicon Dioxide; Chemistry; Isolation and Purification; Pressure; Scanning Electron Microscopy; Thermogravimetry; Microscopy, Electron, Scanning; Pressure; Propylamines; Silanes; CO2 Capture; Hollow Fiber Adsorbents; Solid-Supported Amines

International Standard Serial Number (ISSN)

1944-8244; 1944-8252

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2013 American Chemical Society (ACS), All rights reserved.

Publication Date

01 May 2013

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