钙镁复盐吸收剂脱除煤气中二氧化碳的机理研究

The development of MgO–CaCO3 absorbent at middle temperature contributes significantly to the reduction of the energy consumption for CO2 capture during the water gas shift reaction. Identifying the CO2 capture characteristics of the MgO–CaCO3 absorbent under coal gas conditions is the key to the usage of the absorbent. The affecting mechanism of the absorbent component and the coal gas composition on the activity of the absorbent, and the kinetic characteristics of the reactions will be investigated in this project. The preparation of the MgO–CaCO3 absorbent was conducted by the co-precipitation methods and by the modification of natural calcium and magnesium minerals. The experimental investigation includes the absorption activity tests, the characterization of the sample component and its crystal structure, and the detection of the reaction intermediates by in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy. Based on the experimental studies, the key factors affecting the CO2 absorption activity of the double salts and the affecting mechanism will be explored, and the preparation of the absorbent will be optimized. The effect of the reaction temperature, pressure, and the H2O and H2S in the coal gas on the absorption and regeneration performance of the absorbent will also be investigated. In addition, based on the kinetic reaction tests with H2O or not, the reaction kinetic model will be established, with the considering of the H2O affecting mechanism. The project results will provide the theoretical basis for the preparation of the MgO–CaCO3 absorbent with high activity and for the industrial use of the CO2 absorbent during the water–gas shift process.

中温条件下钙镁复盐二氧化碳吸收剂的开发对降低水汽变换过程的碳捕集能耗具有重要意义。明确煤气条件下钙镁复盐吸收剂的碳捕集特性是实现该吸收剂运用的关键。本申请项目将开展吸收剂组分和煤气条件对吸收剂吸收性能的影响研究和吸收剂反应动力学特性研究。通过共沉淀法、NaNO3改性钙镁矿物法进行钙镁复盐的制备。结合吸收剂的活性测试、样品成分与结构的表征、原位红外技术对反应中间体的监测，探寻影响钙镁复盐吸收剂活性的关键因素及影响机理，优化吸收剂制备工艺。研究反应温度、压力及煤气中H2O、H2S对吸收剂吸收和再生性能的影响规律。基于吸收剂在有无H2O条件下的反应动力学研究和H2O的影响机理研究，建立反应动力学模型。研究结果为吸收性能较好的钙镁复盐吸收剂制备及其在水汽变换过程进行碳捕集的工业运用提供理论依据。

中温条件下钙镁复盐二氧化碳吸收剂的开发对降低水汽变换过程的碳捕集能耗具有重要意义。本项目采用实验研究、理论分析和模型计算相结合的技术路线，围绕镁基吸收剂吸收能力的优化和吸收再生反应动力学特性的改善开展研究。揭示了NaNO3和CaCO3对镁基吸收剂吸收性能的影响机理，提出了改善吸收剂吸收性能的方案，为镁基吸收剂的制备和运用提供了理论依据。.主要研究成果：.1）通过对NaNO3改性白云石和共沉淀法制备的镁基吸收剂的吸收性能研究，明确了熔融NaNO3通过提供离子液体通道促进Mg2+扩散而改善镁基吸收剂的吸收性能，是影响吸收剂吸收性能的关键；碱土金属CaCO3通过降低镁基吸收剂的CO2平衡分压来改善吸收剂的高温吸收性能。.2）优化了NaNO3改性白云石制备的CaCO3促进的镁基复盐吸收剂的活化工艺，并对理论CO2吸收能力较高的NaNO3直接改性的MgO基吸收剂的制备工艺进行了优化。提出程序升温方法、控制吸收剂再生程度法或增大CO2分压以及引入H2O等方法改善NaNO3直接改性的MgO基吸收剂碳酸化反应速率。.3）H2O影响研究表明H2O可通过改善吸收剂的表面特性和影响离子扩散速率来改善吸收剂吸收再生反应速率，同时H2O还会降低相同条件下吸收剂碳酸化反应所需CO2平衡分压。.4）利用收缩核模型对NaNO3直接改性的MgO基吸收剂的吸收、再生反应的动力学参数进行了计算。针对350-400oC高温条件下CO2平衡分压对反应速率的显著影响，在动力学计算中引入了PCO2-PCO2,eq因子。.经过三年研究，项目达到了预期的成果数量，目前已发表SCI论文3篇，被Springer外文期刊邀稿并发表英文综述1篇，EI论文1篇，国内核心期刊1篇，会议论文1篇，申请发明专利3项，其中1项已授权。以上成果本项目均为第一标注。结合项目研究，培养博士生1名（在读）。