Membrane-Mediated Delivery of Carbon Dioxide for Consumption by Photoautotrophs: Eliminating Thermal Regeneration in Carbon Capture

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• 作者：James D. Noel ; William J. Koros ; Benjamin A. McCool ; Ronald R. Chance
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2012
• 出版时间：March 28, 2012
• 年：2012
• 卷：51
• 期：12
• 页码：4673-4681
• 全文大小：323K
• 年卷期：v.51,no.12(March 28, 2012)
• ISSN：1520-5045

文摘

Photoautotrophs, such as microalgae and cyanobacteria, use sunlight to convert inorganic carbon, especially dissolved CO₂ and bicarbonates, to organic materials, commonly biofuels or biofuel precursors. For large-scale biofuel production, the CO₂ abundance in ambient air is not sufficient and CO₂ must be delivered in a concentrated form, ideally captured from anthropogenic sources such as flue gas streams from power plants. Carbon dioxide capture and delivery to the photoautotrophic culture can add significantly to the cost of biofuels. Much of that cost can be attributed to the regeneration of the CO₂ sorbent, a generally energy intensive process. Herein, a liquid-based CO₂ delivery methodology is described and demonstrated. The system involves a conventional CO₂ sorption system (exemplified by an amine-functionalized sorbent), and a carbonate stripping solution that produces a bicarbonate-rich solution after contacting the absorber. The latter solution serves as the feed stream for a CO₂ selective membrane with the permeate side of the membrane being swept by a seawater solution, designed as a model for a photoautotrophic culture medium. Changes in pH and carbon content of the solutions, as well as the lack of any ionic transport across the membrane, are consistent with molecular transport of CO₂. The CO₂ flux is shown to be consistent with the chemical potential differential provided by the carbon-rich stripping solution and the carbon-depleted seawater solution. In application to biofuel production, the driving force would be sustained by carbon consumption in the photosynthetic process. Thus, photosynthesis provides much of the energy for the CO₂ sorbent regeneration in the form of the regenerated carbonate stripping solution. The overall liquid-based CO₂ delivery process described here provides the potential for a more cost-effective biofuel production process.