NSF/EPA Partnership for Environmental Research: New Methods for Carbon Dioxide Separation and Recovery [TSE01-F]

CTS-0124445二氧化碳分离回收新方法M. Rakowski DuBois和R. D. NobleUniversity of科罗拉多，Boulder，CO摘要本项目的主要目标是开发一种有效的电化学泵送方法，用于将酸性气体从排放源中分离出来，并将其浓缩用于回收和/或处理。 电化学泵送方法正被应用于从稀气流中去除和回收CO2的具体问题。 研究活动包括鉴定和合成适当的CO2分子载体。 目前正在评估三种不同类型的CO2分子载体，它们的优缺点各不相同。 在一种方法中，还原氧化还原活性醌以产生具有足够强度的碱，以在从废物流源吸收时直接结合CO2。 在以这种方式捕获CO2之后，醌-CO2络合物被电化学氧化以释放浓缩的CO2并再生氧化形式的载体。 第二种方法开发了氧化还原活性金属络合物，其与碳酸氢根离子在类似的循环中起作用。 这些具有空气稳定和水溶性的优点。 第三种方法研究产生电化学控制的pH摆动的醌载体。 CO2在高pH下与醌还原产生的氢氧根离子络合，在低pH下由醌氧化产生释放。每个载体系统的工作包括反应吸收速率和CO2的结合常数作为载体氧化态的函数的电化学研究和电化学泵系统的研究，以确定适当的操作参数，再现性和稳定性的特点，以及能源效率。 此外，正在对吸收/解吸和相关的传质现象进行过程模拟研究和调查。 目前大气中的二氧化碳浓度比工业化前的水平显著增加，随着化石燃料的继续使用，二氧化碳水平将继续上升。 在这种情况下，气候模型预测会出现严重的全球变暖，对环境造成严重影响。 必须开发有效的方法，以捕获和储存二氧化碳供将来使用或以稳定的形式隔离。 捕获二氧化碳最简单的方法是从大型生产商（如发电厂，化工厂等）的废水中捕获，然后二氧化碳通过与大气混合而稀释。 然而，据估计，利用当今最好的技术，从发电厂废气中回收二氧化碳将导致其整体效率降低20-30%。 基于先前研究和建模研究的估计表明，具有适当分子载体的电化学泵送过程可以比当前用于CO2回收的常规方法有效得多。 随着合适的载体的开发，该方法应该可以应用于从工业工厂的废物流中有效去除CO2以及其他酸性气体。

CTS-0124445New Methods for Carbon Dioxide Separation and Recovery M. Rakowski DuBois and R. D. NobleUniversity of Colorado, Boulder, CO AbstractThe broad objective of this project is to develop an efficient electrochemical pumping process for separating an acid gas from emission sources and concentrating it for recovery and/or disposal. The electrochemical pumping approach is being applied to the specific problem of removing and recovering CO2 from dilute gas streams. The research activities include the identification and synthesis of appropriate molecular carriers for CO2. Three different types of molecular-based carriers for CO2, which differ in their advantages and disadvantages, are being evaluated. In one approach, a redox-active quinone is reduced to produce a base of sufficient strength to bind CO2 directly in absorption from the waste-stream source. After CO2 is captured in this manner, the quinone-CO2 complex is oxidized electrochemically to release concentrated CO2 and to regenerate the oxidized form of the carrier. A second approach develops redox-active metal complexes that function in a similar cycle with bicarbonate ion. These have the advantage of being air-stable and water-soluble. A third approach investigates quinone carriers that produce an electrochemically controlled pH swing. CO2 is complexed at high pH by hydroxide ions generated by quinone reduction and released at low pH produced by quinone oxidation. Work on each carrier system includes electrochemical studies of the reaction-absorption rates and binding constants of CO2 as functions of carrier oxidation state and studies of the electrochemical-pumping systems to determine appropriate operating parameters, characteristics of reproducibility and stability, and energy efficiencies. In addition, process-modeling studies and investigations of absorption/desorption and related mass transport phenomena are being carried out. Current CO2 concentrations in the atmosphere have increased significantly from pre-industrial levels, and as the use of fossil fuels continues, CO2 levels will continue to rise. In this scenario, climate models predict a significant global warming with serious environmental impacts. Efficient methods must be developed in which CO2 is captured and stored for future use or sequestered in a stable form. The easiest point to capture CO2 is from the waste streams of large producers such as power plants, chemical plants, etc. before the CO2 is diluted by mixing with the atmosphere. It is estimated, however, that with today's best technology the recovery of CO2 from the exhaust of power plants will result in a 20-30% reduction in their overall efficiency. Estimates based on prior research and modeling studies suggest that an electrochemical pumping process with appropriate molecular carriers can be much more efficient than current conventional approaches for CO2 recovery. As appropriate carriers are developed, this process should find application in the efficient removal of CO2 as well as other acid gases from waste streams of industrial plants.