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，越来越多地使用化石燃料来满足能源需求，导致向大气中排放的二氧化碳要高得多。据报道，二氧化碳浓度上升是导致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，以遏制其向大气的排放。目前与二氧化碳分离技术相关的成本非常高，需要研究和开发新技术，以实现经济上可接受的二氧化碳捕获和封存方法。由于其巨大的孔隙率、开放的孔结构、非常大的比表面积和非常小的单位质量的初级颗粒尺寸而具有独特的性质，我们相信纳米结构、高比表面积、高孔隙率、气凝胶和/或经胺基团修饰的二氧化硅纳米粉末将作为高效的超级吸着剂来从烟气中分离二氧化碳。然后，吸附的二氧化碳可以在更高的温度下解吸，以便再生吸着剂，以便它们可以在多次循环中重复使用。然而，还没有关于使用这些类型的载体来固定胺作为二氧化碳捕获剂的工作的报道。我们还计划将纳米结构的吸附剂配置在微射流辅助的流态化床中，而不是填充床中。与填充床相比，使用流态床具有许多优点，如低压降、良好的混合、温度均匀、连续的粉末处理和较高的催化剂或吸附剂效率因数，这些优点到目前为止还没有被利用，因为难以获得光滑、无泡的超细粉末或纳米结构气凝胶的流态化。智力优势：该研究项目将包括使用各种具有活泼胺功能的化学品合成胺表面修饰的气凝胶和二氧化硅纳米粉末，这些化学品要么化学结合到载体上，要么固定在多孔载体中，并使用不同的涂层方法来制备最佳的胺修饰吸附剂。我们将用TGA/DSC和FTIR研究胺的负载量及其与载体的相互作用。用卡恩微天平研究二氧化碳在这些超强剂上的吸附/解吸平衡和动力学。然后，我们将配置最有希望的胺改性吸附剂，首先在填充床中(用于比较目的)，然后在流态化床中，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和确定多次循环对吸附剂的吸附/解吸和稳定性的影响来再生吸附剂。建模将侧重于了解胺改性脱硫剂的吸附平衡和吸附动力学，并预测不同操作条件下沸腾床的性能。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、流态化、分离工艺和环境科学方面的广泛教育和培训。他们还有一个额外的优势，那就是通过与Cabot和AVEKA的工程师互动，获得行业视角，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。合作伙伴将担任亚利桑那州立大学本科或研究生课程的客座讲师，他们将在课堂上向亚利桑那州立大学的学生介绍研究的不同方面。合作伙伴还将努力瞄准亚利桑那州立大学庞大的本科生、少数族裔和女性人才库，让他们作为研究型学生加入该项目。使用胺修饰的、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级的固体载体与流态化过程的独特组合，是开发有效地从烟道气中捕获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消耗了至少20%的燃煤或天然气产生的能源，而且还涉及大量的设备和运行成本。这项研究的成功实施将为二氧化碳捕集提供大量的节能，因为它提高了二氧化碳的吸收能力，吸附剂的可回收性，降低了床层的压降和连续操作的能力。这也将有助于提高行业S对在独特应用中使用纳米结构和纳米尺寸颗粒存在的无数机会的认识，并将有助于确保美国在二氧化碳捕获、温室气体减排和环境保护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.