High-Temperature Sorption Process for Oxygen Removal and Air Separation

该项目旨在研究与开发基于钙钛矿型陶瓷吸附剂的新型高效高温氧气吸附工艺相关的基本问题，用于氧气去除和空气分离。 新的吸附工艺利用了某些钙钛矿型陶瓷的独特性能，这些陶瓷可以在高温（300- 800 ℃）下吸附大量氧气，但不能吸附其他气体。 本研究选用三种不同组成的钙钛矿型陶瓷材料作为吸附剂。 通过柠檬酸盐法和加压烧结法制备了各种尺寸的吸附剂颗粒和颗粒。 用重量法和点缺陷和团缺陷模型对这些陶瓷中氧位的热力学缺陷平衡进行了实验研究。 该缺陷平衡研究提供了这些吸附剂的氧吸附等温线数据。 用TGA/DSC研究了这些陶瓷吸附剂的吸附热和有序-无序相变。 这些陶瓷吸附剂上的氧吸附动力学进行了实验研究的瞬态重量法和建模使用一个简单的线性驱动力模型和一个更复杂的模型的基础上的双极扩散理论。 通过膨胀测量法和磨损试验系统地研究了陶瓷吸附剂颗粒的化学和机械稳定性。 最后，进行了固定床除氧或空气分离实验，以获得基于这一新概念的实际分离过程设计的数据。该项目代表了基于这一新的非传统吸附剂组开发吸附过程的第一次努力。 从根本上说，该项目可能导致开发大量具有传统吸附工艺所不具备的独特分离特性的新吸附工艺。 如果使用烃来再生吸附剂，则该方法可以扩展以提供用于烃的部分氧化的具有改进的选择性的新的化学反应器。 在实践方面，提出的吸附过程是基于钙钛矿型陶瓷优先平衡吸附氧。 这种吸附过程的成功开发将对空气分离和除氧的工业过程产生重大影响。

This project is aimed at studying fundamental issues related to the development of a new, efficient high-temperature oxygen sorption process based on perovskite-type ceramic sorbents for oxygen removal and air separation. The new sorption process takes advantage of the unique properties of certain perovskite-type ceramics which can adsorb a large quantity of oxygen, but not other gases, at high temperatures (300-800oC). Three perovskite-type ceramic materials with different compositions are selected as the sorbents for this study. The sorbent pellets and particles of various sizes are prepared by citrate and press-sintering methods. The thermodynamic defect equilibrium for oxygen sites in these ceramics is being studied experimentally by the gravimetric method and theoretically using point-defect and cluster-defect models. This defect equilibrium study provides oxygen-sorption isotherm data for these sorbents. Heat of sorption and order-disorder phase transformation of these ceramic sorbents is studied also by TGA/DSC. Oxygen sorption kinetics on these ceramic sorbents are investigated experimentally by the transient gravimetric method and modeled using a simple linear-driving-force model and a more complex model based on the ambipolar diffusion theory. The chemical and mechanical stability of the ceramic sorbent particles is being studied systematically by dilatometry and attrition tests. Finally, fixed-bed experiments for oxygen removal or air separation are conducted to obtain data for design of a practical separation process based on this new concept. This project represents the first effort in developing sorption processes based on this new group of non-traditional sorbents. On the fundamental side, this project may lead to development of a large number of new sorption processes with unique separation characteristics that are not offered by the traditional sorption processes. If a hydrocarbon is used to regenerate the sorbent, this process can be extended to provide new chemical reactors for partial oxidation of hydrocarbons with improved selectivity. On the practical side, the proposed sorption process is based on perovskite-type ceramics with preferential equilibrium sorption for oxygen. Successful development of this sorption process will have a significant impact on industrial processes for air separation and oxygen removal.