Author: Bryce DutcherPublisher:
ISBN: 9781339054704
Category : Amines
Languages : en
Pages : 171
Book Description
Strong evidence exists suggesting that anthropogenic emissions of CO2 have been contributing to global climate change. Because of this, it becomes imperative to mitigate anthropogenic CO2. Unfortunately, the best available current technology for CO2 capture, amine scrubbing, is a costly operation due to the energy required for regeneration of the amine. Solid Na2CO3 is considered a potential alternative to amine scrubbing due to its low heat of reaction, but it is not commercially viable due to its low reaction rates for both CO2 sorption and desorption. In order to increase the reaction rate, this project studied nanoporous FeOOH and TiO(OH)2 as supporting materials for Na2CO3. Because regeneration of the sorbent is the most energy-intensive step when using Na2CO3 for CO2 sorption, this project focused on the decomposition of NaHCO3, which is equivalent to CO2 desorption. FeOOH and TiO(OH)2 are shown to be thermally stable with and without the presence of NaHCO3 at temperatures necessary for sorption and regeneration, up to about 200°C. More significantly, it is observed that these supports not only increase the surface area of NaHCO3, but they also have a catalytic effect on the decomposition of NaHCO3. For example, the rate constant for the decomposition of NaHCO3 at 120 °C is increased from 0.02 min-1 without a support to 0.46 min-1 with 50 wt.% FeOOH and 0.39 min-1 with 50 wt.% TiO(OH)2. The activation energy is reduced from 80 kJ/mol without a support to 44 kJ/mol with 50 wt.% FeOOH and to 35 kJ/mol with 50 wt.% TiO(OH)2. This increase in reaction rate could translate into a substantial decrease in the cost of using Na2CO3 for CO2 capture. Amine-functionalized sorbents, like solid Na2CO3, have potentially lower energy requirements than aqueous amines due to the absence of bulk water, and they retain many of the advantages of aqueous amines such as high reaction rates and high CO2 capacity. Here, the structure and stability of a recently developed amine functionalized silica sorbent is investigated.
