透氧膜反应器用于高纯氢分离的相关基础研究

Technologies for hydrogen purification are an important link for the development of hydrogen economics. To solve the high cost of Pd membranes, low permeability of protonic conducting ceramic membranes and low stability of the two types of membranes in H2S containing atmosphere, we propose using oxygen permeable ceramic membranes to separate hydrogen with high separation rate, high selectivity, low cost and good stability. To separate hydrogen, low-purity hydrogen and steam are fed to the two sides of the membrane, respectively. Water molecules split into hydrogen and oxygen ions at elevated temperature, and then oxygen ions diffuse across the membrane and react with the low-purity hydrogen to produce water. High-purity hydrogen is acquired after condensation and drying of the outlet gas of the steam side. In this project we plan to propose a new design principle for membrane materials, and prepare membrane materials with high permeability and stability under reducing atmosphere. Then, based on the membrane materials, we create high efficient catalysts to speed up the water splitting reaction in the hydrogen separation process, construct catalytic membrane reactors for hydrogen separation, investigate the reaction mechanism of water splitting, understand the reaction-separation coupling effects, deduce a proper mathematical model to describe the hydrogen separation process, and optimize the operation conditions of the membrane reactor. We wish this investigation can help the development of hydrogen separation technologies and supply routes for new technologies.

氢气纯化技术是决定氢经济发展中的重要一环。针对传统钯膜成本高、质子导电陶瓷膜渗透性低以及二者在含H2S气氛中稳定性差等问题，本项目提出了用混合导体透氧膜分离氢气的新方法，该方法不仅氢分离速率高、选择性高，而且成本低、稳定性好。氢分离原理是：在膜的两侧分别通入低纯度氢气和水蒸汽，高温下水得到电子分解成氢气和氧离子，氧离子透过膜与低纯度氢气反应生成水并释放出电子。水蒸汽侧气体经冷凝干燥后即可得高纯氢气。本项研究将首先通过对膜材料的设计理念的创新，制备出在还原气氛中具有高渗透性和高稳定性的膜材料；然后基于膜材料，设计适用于氢分离过程的高效水分解催化剂，构建氢分离催化膜反应器。研究水分解反应在膜反应器中的反应机理，深入认识氢分离催化膜反应器中反应-分离耦合作用规律，建立描述氢分离过程的数学模型，优化操作条件等，为发展高效节能氢分离技术提供了新思路。

氢气作为一种清洁、高效、可持续的新能源载体，被视为21世纪最具发展潜力的清洁能源，是人类的能源战略发展方向。针对传统钯膜成本高、质子导电陶瓷膜渗透性低以及二者在含H2S气氛中稳定性差等问题，本项目提出了用混合导体透氧膜分离氢气的新方法，该方法不仅氢分离速率高、选择性高，而且成本低、稳定性好。项目围绕膜材料、催化剂及膜反应器新过程开展了研究工作。设计合成了70 wt% Ce0.85Sm0.15O1.925 - 30 wt% Sr2Fe1.5Mo0.5O6-δ (SDC-SFM) 和75 wt% Ce0.85Sm0.15O1.925 - 25 wt% Sm0.6Sr0.4Cr0.3Fe0.7O3-δ (SDC-SSCF)双相膜材料，两相之间有好的化学兼容性。SDC-SFM在还原气氛中具有良好的稳定性和高电导率，在540h氢分离实验中表现出高稳定性。详细研究了贵金属催化剂和非贵金属催化剂对该膜反应器中的核心反应，即水分解反应的催化作用，并对催化剂的结构做了详细表征。开展了膜制备工艺研究，获得了致密层厚度仅为40μm的非对称膜。考察了非对称膜载体对膜渗透性能的影响，发现由于氢气和水分子在高温扩散快，载体的浓差极化效应不显著，而催化剂的活性对膜渗透性能影响较大。制备了非对称结构的SDC-SSCF双相膜材料，并将其用于水分解制氢，在整个的550 h测试过程中，制氢速率一直保持很稳定，即使将H2S的浓度提高到500-1000ppm，该膜反应器依然可以稳定运行（>400 h）。说明该膜反应器有希望与IGCC过程结合实现CO2捕获的同时提升发电效率。本项目的研究过程中，在Angew. Chem. Int. Ed.，AIChE J.，J. Membr. Sci.等期刊上发表研究论文15篇，申请发明专利4件，完成了既定目标。