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

摘要在过去的三十年里，为了满足能源需求，越来越多地使用化石燃料，这导致了更多的二氧化碳排放到大气中。据报道，二氧化碳浓度的上升是造成全球变暖的温室效应的一半原因。因此，必须制定有效和具有成本效益的二氧化碳管理计划，以限制其排放到大气中。目前二氧化碳分离技术的成本非常高，因此需要研究和开发新技术，以便采用经济上可接受的方法来捕获和隔离二氧化碳。由于其独特的性质，由于它们的大孔隙率，开放的孔隙结构，非常大的表面积和非常小的单位质量的初级颗粒尺寸，我们相信纳米结构，高表面积，高孔隙率，气凝胶和/或纳米二氧化硅修饰胺基将作为高效的超级吸附剂，从烟道气流中分离二氧化碳。然后，吸附的二氧化碳可以在更高的温度下解吸，从而使吸附剂再生，从而可以在许多循环中重复使用。然而，使用这些类型的支撑固定胺作为二氧化碳捕获的吸附剂的工作尚未报道。我们还计划在微射流辅助流化床中配置纳米结构的吸附剂，而不是在填充床中配置。与填充床相比，使用流化床具有许多优点，如低压降、混合良好、温度均匀、连续处理粉末以及更高的催化剂或吸附剂效能因子，这些优点由于难以获得超细粉末或纳米结构气凝胶的光滑、无气泡流化而尚未得到利用。智力优势：该研究项目将包括使用多种具有活性胺功能的化学物质合成胺表面改性气凝胶和二氧化硅纳米粉，这些化学物质可以与载体化学结合或固定在多孔载体中，并使用不同的涂层方法来生产最佳的胺改性吸附剂。我们将通过热重分析/差热分析和红外光谱研究胺的负载量及其与载体的相互作用。这些超吸附剂的二氧化碳吸附/解吸平衡和动力学将使用卡恩微天平进行研究。然后，我们将配置最有前途的胺改性吸附剂，首先在填充床（用于比较目的）中，然后在流化床中，以测量它们从模拟烟气中分离二氧化碳的能力。我们将通过提高温度来再生吸附剂，并确定多次循环对吸附剂的吸附/解吸和稳定性的影响。建模将侧重于了解胺改性吸附剂的吸附平衡和吸附动力学，并预测流化床在不同操作条件下的性能。更广泛的影响：从事这项研究的本科生和研究生将接受粒子技术、纳米技术、流化、分离过程和环境科学方面的广泛教育和培训。他们还将获得额外的优势，即通过与Cabot和AVEKA工程师的互动，获得工业视角，这些工程师同意提供他们的专业知识，并为项目提供指导和建议。他们将在适当的亚利桑那州立大学本科或研究生课程中担任客座讲师，在那里他们将在课堂上向亚利桑那州立大学的学生展示研究的不同方面。合作项目负责人还将努力吸引亚利桑那州立大学为数众多的少数族裔本科生和女性人才库作为研究学生加入该项目。利用胺改性、非常高的表面积、纳米结构气凝胶或二氧化硅纳米粉末而不是微米大小的固体载体与流化床工艺的独特结合，是开发一种有效捕获烟气中二氧化碳的新技术的变革性方法。现有的从烟道气中分离二氧化碳的技术至少消耗燃烧煤或天然气产生的能源的20%，而且还涉及大量的设备和运行成本。由于提高了CO2的吸附能力、吸附剂的可回收性、降低了流化床的压降和连续运行的能力，所提出的研究的成功实施将为CO2捕集提供大量的节能。它还将有助于促进工业发展。美国意识到在独特的应用中使用纳米结构和纳米尺寸的颗粒存在着无数的机会，这将有助于确保美国在二氧化碳捕获、减少温室气体和保护环境方面的竞争力和技术领先地位。

AbstractThe 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. Broader Impacts: Undergraduate and graduate students working on the research will receive broad education and training in particle technology, nanotechnology, fluidization, separation processes, and environmental science. They will also have an additional advantage of gaining an industrial perspective by interacting with Cabot and AVEKA engineers who have agreed to lend their expertise, and provide guidance and advice to the project. The Co-PIs will serve as guest lecturers in appropriate ASU undergraduate or graduate courses, where they will present different aspects of the research to ASU students in the classroom. The Co-PIs will also strive to target the large ASU undergraduate minority and woman talent pool to join the project as research students. The unique combination of using amine modified, very high surface area, nanostructured aerogels or silica nanopowders rather than micron-sized solid supports with a fluidized bed process is a transformational approach in developing a new technology for the efficient capture of CO2 from flue gas. The existing technologies for CO2 separation from flue gas consume at least 20% of the energy generated by burning coal or natural gas and also involve substantial equipment and operation costs. The successful implementation of the proposed research should offer substantial energy saving for CO2 capture because of improved CO2 sorption capacity, recyclability of the sorbent, reduced pressure drop of the fluidized bed and the ability for continuous operation. It will also serve to increase industry?s awareness of the myriad opportunities that exist for using nanostructured and nano-size particles in unique applications and will contribute to ensuring US competitiveness and technological lead in the area of CO2 capture, the reduction of greenhouse gases, and the preservation of the environment.