氢气是重要的化工原料和能量载体，氢气分离净化是制氢过程中必不可少的环节。本文旨在开发基于稀土合金吸附剂的H2直接净化分离(HDPS)工艺。具体针对吸附剂毒化机理、毒化问题解决方法、吸附剂造粒成型方法、HDPS工艺设计与改进逻辑、HDPS装备开发与小试验证等几个方面进行了深入的研究。CO、H2S等杂质气体易造成H2吸附剂中毒失效。本文采用密度泛函分析及分子动力学模拟的方法，构建了稀土合金H2吸附剂的表面结构模型以及CO、H2S、H2等气体分子模型，研究气体粒子在合金表面的竞争吸附行为及相互影响规律，分析杂质气体的毒化机理与吸附剂中毒过程。探究表面氟化对合金表面晶体结构的影响，阐释表面氟化处理提升吸附剂抗毒性的原因。揭示了工作温度对吸附剂毒化过程的影响规律，结果表明提升工作温度有利于杂质气体解吸，可抑制毒化进程。将表面氟化处理与工作温度调控两种方法相结合，提出了中温HDPS工艺方法，解决了吸附剂中毒问题。通过高温高压吸附性能表征，以及混合气体固定床穿透实验，验证吸附剂的CO、H2S耐受性。二者的分别达到5%及0.5%以上，可满足工业应用的需求。采用完全粉化-粘结成型的制备思路，成功制得形状大小均匀、抗粉化性能良好的吸附剂颗粒。基于已有的传统变压吸附(PSA)工艺研究成果，提炼中温HDPS工艺步骤的设计改进逻辑。首先，建立PSA模型，利用数值模拟的方法，剖析吸附量、吸附解吸速率、吸附选择性、工艺步骤、工艺参数对净化效率的影响规律和影响机制。从吸附剂性能与工艺过程的角度，剖析影响净化效率的短板因素，分析各种效率改进方法的作用机制与局限性。然后，分析产品气吸附与杂质吸附两类PSA工艺的相似性。模拟吸附塔内气体流动分布规律，确定中温HDPS工艺中的关键参数，归纳工艺参数的优化方法。最后，建立重整制氢-净化-燃料电池的系统模型，以系统的净发电效率作为参考指标，评估中温HDPS与传统PSA净化能耗，验证了中温HDPS的高效性。设计搭建了HDPS小试装置，采用中温HDPS工艺流程，实现了甲醇重整气的净化。当产品气纯度为94.6%时，回收率达到96.8%。200个吸放氢循环前后，吸附剂性能没有明显衰减，吸附剂使用寿命得到初步验证。最后，针对床层压阻问题和工艺连续性问题，从吸附塔结构改进的角度提出解决思路。
Hydrogen is an important chemical engineering raw material and energy carrier. Hydrogen separation and purification is an essential segment in the process of hydrogen production. The purpose of this research is to develop hydrogen direct purification and separation (HDPS) technology to achieve simple and efficient separation, purification, enrichment of hydrogen. In this article, the poisoning mechanism of rare earth alloy adsorbents was proposed; the poisoning tolerance of adsorbent was improved; the granulation method of adsorbent was developed; HDPS cyclic procedure design and improvement logic were discussed, and a bench-scale HDPS apparatus were developed, on which HDPS was realized.Impurity gases such as CO and H2S are poisonous and will lead to the failure of hydrogen adsorbents. In chapter 2, using density functional analysis method, we constructed the models of rare earth alloy crystal and CO, H2S, H2 moleculars. The competitive adsorption behaviors of different gas molecules/atoms on adsorbent surface were analyzed; the interactions between impruties and hydrogen were revealed; and the poisoning mechanism of adsorbent was proposed. The effect of surface fluorination on alloy surface structure was studied and the reason why surface fluorination could enhance the poisoning resistance of adsorbents was explained. The effect of operating temperature on the poisoning process is clarified by using Ab-initio molecular dynamics simulation.In chapter 3, combining the two methods of surface fluorination treatment and working temperature control, we proposed elevated temperature HDPS process method and solved the problem of adsorbent poisoning. Based on the results of adsorption capacity measurment and breakthrough experiments, the CO, H2S tolerance of adsorbent was verified and the working performance were evaluated. The tolerance concentration of them was 5% and 0.5%, respectively. Adopting the preparation idea of complete pulverization-bonding molding, adsorbent particles with uniform shape and size, and good pulverization resistance were successfully prepared.Based on the results of conventional pressure swing adsorption (PSA) technical process studies, the elevated temperature HDPS procedure design and improvement logical was distilled. Firstly, a PSA model was established. The effects of adsorption capacity, adsorption and desorption rate, adsorption selectivity, PSA procedure steps, and technological parameters on purification efficiency were analyzed by using simulation method. From the perspective of adsorbent performance and cycle procedure, the shortcoming factors that restrict purification efficiency were given; the effect and limitations of various efficiency improvement methods were analyzed. Secondly, the similarities between PSA-impurity adsorption and PSA-product gas adsorption were analyzed. The gas distribution and mass transfer in the adsorption tower were analyzed; the key parameters of elevated temperature HDPS process were determined; and the optimization methods of HDPS process parameters were summarized. At last, a system model including reforming hydrogen production, purification and proton exchange membrane fuel cell was established. The net power generation efficiency of the system was used as the criterion to evaluate the purification energy consumption of elevated temperature HDPS and traditional PSA. The efficiency of elevated temperature HDPS was verified.Bench-scale HDPS apparatuses were designed and built. Elevated temperature HDPS process was adopted to realize the purification of methanol reforming gas. When the purity of product gas was 94.6%, the recovery rate was 96.8%. After 200 hydrogen absorption and desorption cycles, the performance of adsorbent had little difference, and the service life of adsorbent has been preliminarily verified. Finally, in response to the problems that bed pressure drop was large and HDPS procedure was discontinuous, the solutions were put forward from the perspective of improving the structure of the adsorption tower.
