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

在过去的三十年里，越来越多地使用化石燃料来满足能源需求，导致了更高的二氧化碳排放到大气中。据报道，二氧化碳浓度上升占导致全球变暖的温室效应的一半。因此，至关重要的是制定有效和具有成本效益的二氧化碳管理计划，以遏制其向大气中的排放。与目前的CO2分离技术相关的非常高的成本要求研究和开发新的技术，以允许经济上可接受的CO2捕获和封存方法。由于它们的独特性质（由于它们的大孔隙率、开孔结构、非常大的表面积和非常小的每单位质量的初级粒度），我们相信用胺基改性的纳米结构的、高表面积、高孔隙率的气凝胶和/或二氧化硅纳米粉末将充当有效的超级吸附剂以从烟道气流中分离CO2。然后，吸附的CO2可以在更高的温度下解吸，以便再生吸附剂，使得它们可以在许多循环中重复使用。然而，还没有关于使用这些类型的载体来将甲胺用作CO2捕集的吸附剂的工作报道。我们还计划在微射流辅助流化床而不是填充床中配置纳米结构的吸附剂。使用流化床相对于填充床具有许多优点，例如低压降、良好的混合、温度均匀性、连续的粉末处理和较高的催化剂或吸附剂有效因子，迄今为止由于难以获得超细粉末或纳米结构气凝胶的平滑、无气泡流化而没有利用这些优点。智力优势：该研究项目将包括使用各种具有活性胺官能团的化学品合成胺表面改性的气凝胶和二氧化硅纳米粉末，这些化学品可以化学键合到载体上或固定在多孔载体内，并使用不同的涂覆方法来生产最佳的胺改性吸附剂。我们将通过TGA/DSC和FTIR研究胺负载量及其与载体的相互作用。将使用Cahn微量天平研究这些超级吸附剂上的CO2吸附/脱附平衡和动力学。然后，我们将配置最有前途的胺改性吸附剂，首先在填充床中（用于比较目的），然后在流化床中，以测量它们从模拟烟道气中分离二氧化碳的能力。我们将通过升高温度再生吸附剂，并确定吸附剂循环多次对其吸附/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。他们还将有一个额外的优势，即通过与卡博特和AVEKA工程师互动来获得工业视角，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。合作PI将担任客座讲师在适当的ASU本科或研究生课程，在那里他们将提出研究的不同方面，以ASU学生在课堂上。Co-PI还将努力争取亚利桑那州立大学的大型本科少数民族和女性人才库作为研究生加入该项目。使用胺改性的、非常高表面积的、纳米结构的气凝胶或二氧化硅纳米粉末而不是微米尺寸的固体载体与流化床工艺的独特组合是开发用于从烟道气中有效捕集CO2的新技术的变革性方法。现有的从烟道气中分离CO2的技术消耗至少20%的由燃烧煤或天然气产生的能量，并且还涉及大量的设备和操作成本。所提出的研究的成功实施应提供大量的节能CO2捕获，因为改进的CO2吸附能力，吸附剂的可回收性，降低流化床的压降和连续操作的能力。它也将有助于增加工业？美国认识到在独特的应用中使用纳米结构和纳米尺寸颗粒的无数机会，并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领域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.