Novel Solid Amine Sorbents and Their Uses in Fluidized-Bed Process for Carbon Dioxide Separation

Project: Research project

Description

SUMMARY OF PROPOSED WORK Supplemental travel funds are requested for co-PI of the project to travel to the NSF 2012 CBET Grantee Conference. The NSF 2012 CBET Grantee Conference will be held from Wednesday, June 6, 2012 to Friday, June 8, 2012 at the Hyatt Regency Baltimore and the Baltimore Convention Center. The NSF CBET Grantee Conference provides the opportunity for building more effective and collaborative relationships amongst the community of CBET grantees and Program Directors. The conference is designed to enable awardees to share their technical achievements with the NSF Program Directors and also to learn about current (and/or new) NSF/CBET programs, practices, and supplemental funding mechanisms. CBET Program and Cluster-specific sessions will also facilitate discussions amongst these smaller communities to address topics of specific interest. The conference agenda will provide multiple outlets for networking and interaction with program officers and other grantees in efforts to promote discussions and potential collaborations.

Description

Synthesis of effective sorbents with high CO2 sorption capacity and fast kinetics is critical to the development of an efficient technology for carbon dioxide capture. The present NSF project is focused on synthesis and characterization of high performance solid amine sorbents on silica aerogel and development of a new fluidized bed adsorption process to capture carbon dioxide. The primary objective of our research project is to prepare high performance solid sorbents using nanostructured silica aerogels as supports, impregnated or functionalized (grafted) with amines to capture (adsorb) CO2. These solid support particles have many desirable properties not found in more commonly used solid sorbents such as amine coated activated carbon, molecular sieve zeolites, carbon containing fly ash, anthracite coal particles, high surface area silicas, and micron size ceramic particles coated with sodium carbonate. Our goal is to obtain high performance sorbents with CO2 sorption capacity of more than 4 mmol CO2/g sorbent. The secondary objective of this project is to configure our synthesized sorbents in a micro-jet assisted gas fluidized bed to study the sorption/desorption characteristics of CO2 when the bed of amine impregnated or functionalized aerogels is fluidized with a mixture of CO2 and nitrogen (simulated flue gas). Desorption will be studied using temperature swing, i.e., nitrogen gas at temperatures greater than 100oC. We will use micro-jet assistance to smoothly fluidize our sorbents since we expect these impregnated or functionalized powders will be very difficult to fluidize conventionally (by aeration alone). We have studied coating amine on the supports of MCM-41, SBA-16 and Cabot hydrophilic and hydrophobic silica aerogels with nanometer pores. These supports were impregnated or coated with the following amines: 1,8-Diazabicycloundec-7-ene (DBU), tetraethylenepentaamine (TEPA), and diethanolamine (DEA), polyethyleneimine (PEI) , 3- aminopropyl triethoxysilane (APTES), N-(2-aminoethyl)-3- aminopropyltrimethoxysilane (AEAPS), (3- trimethyloxysilylpropyl)- diethylenetriamine (TA), and some ionic liquids. We studied various methods to prepare the supported amine sorbents, including wet impregnation, grafting , reaction with NH3 and reaction using ALD. The results have been summarized in the first year annual report. The best result was recently obtained on a sorbent with TEPA on a hydrophilic silica aerogel support prepared by a new synthesis method. In this new method, TEPA is dissolved in a solvent at a high temperature. The solution with high

Description

The increasing use of fossil fuels to meet energy needs during the past three decades has led to much higher carbon dioxide emissions into the atmosphere. Rising CO2 concentrations have been reported to account for half of the greenhouse effect that causes global warming. It is therefore essential to develop efficient and cost-effective CO2 management schemes to curb its emission into the atmosphere. The very high costs associated with current CO2 separation technologies require research and development of new technologies that will allow for economically acceptable methods for the capture and sequestration of CO2. Because of their unique properties due to their large porosity, open pore structure, very large surface area and very small primary particle size per unit mass, we believe that nanostructured, high surface area, high porosity, aerogels and/or silica nanopowders modified with amine groups will act as efficient super sorbents to separate CO2 from a flue gas stream. The adsorbed CO2 can then be desorbed at higher temperature, so as to regenerate the sorbents so that they can be reused over many cycles. However, no work has been reported on using these types of supports to immobilize amine to act as sorbents for CO2 capture. We also plan to configure the nanostructured sorbents in a micro-jet assisted fluidized bed rather than a packed bed. Using a fluidized bed has many advantages over a packed bed, such as low pressure drop, good mixing, temperature uniformity, continuous powder handling, and higher catalyst or sorbent effectiveness factors, which heretofore have not been utilized because of the difficulty in obtaining smooth, bubble-less fluidization of ultra-fine powders or nanostructured aerogels. Intellectual Merit: The research project will include synthesizing the amine surface-modified aerogels and silica nanopowders using a variety of chemicals with active amine functionalities, either chemically bonded to the support or immobilized within the porous support, and using different coating methods to produce an optimum amine modified sorbent. We will study the amount of amine loading and its interaction with the support by TGA/DSC and FTIR. CO2 adsorption/desorption equilibrium and kinetics on these super sorbents will be studied using a Cahn microbalance. We will then configure the most promising amine modified sorbents, first in a packed bed (for comparison purposes) and then in a fluidized bed, to measure their ability to separate carbon dioxide from simulated flue gas. We will regenerate the sorbents by raising the temperature and determining the effect of cycling the sorbent over many cycles on their adsorption/desorption and stability properties. Modeling will focus on understanding the sorption equilibrium and sorption kinetics of amine modified sorbents and predicting the performance of the fluidized bed under different operating conditions.
StatusFinished
Effective start/end date7/15/106/30/13

Funding

  • National Science Foundation (NSF): $241,803.00

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Fluidized bed process
Sorbents
Amines
Carbon dioxide
Aerogels
Fluidized beds
Silica
Sorption
Desorption
Packed beds
Flue gases
Adsorption
Powders
Temperature
Kinetics