粉煤灰基沸石CHA制备及其分离工业废气中CO2的基础研究

Ion-exchanged zeolites CHA show high selectivity of different gases, thus they have important application in capturing CO2 from industrial emissions.However, zeolites CHA are usually synthesized by traditional hydrothermal methods with high-cost and complex processes. In the present study, zeolites CHA will be prepared from coal-fly ash. Then,the zeolites CHA will be ion-exchanged for acquiring better seperation performance.The as-synthesized materials will be characterized by x-ray diffraction, scanning and transmission electron microscopy, thermo-gravimetric, gas chromatography-mass spectrometry, and pressure swing adsorption devices, etc. The mechanisms of synthesizing zeolites CHA will be investigated. Furthermore, the CO2 adsorption thermodynamics and kinetics on the modified zeolites CHA will be studied, followed by the optimation of the pressure swing adsorption processes. Finally,the whole process including preparation, ion-exchange, and capturing CO2 from industrial emissions will be evaluated by economic analysis and environmental assessment.This study will provide a new way for high-value added applications of fly ash, and offer more effective and less expensive adsorbents for capturing CO2 from industrial emissions.Furthermore, this study will greatly reduce the cost of CO2 capture by pressure swing adsorption, promote the application of CO2 capture and storage, and have significance in the decrease of greenhouse gas emissions.

离子交换改性的沸石CHA具有优良的气体吸附选择性，在变压吸附法捕集工业废气中CO2的领域有广泛的应用前景，但传统方法制备沸石CHA的工艺复杂，原料成本高。本课题拟以粉煤灰为原料制备不同硅铝比的沸石CHA，再采用不同阳离子对制备沸石CHA进行离子交换改性。将借助XRD、SEM、气相色谱质谱联用仪、变压吸附装置等先进分析手段，深入研究粉煤灰基沸石CHA的形成及离子交换机理，探讨离子交换后的材料吸附分离工业废气中CO2过程的动力学和热力学，对变压吸附分离CO2过程进行优化，最后对粉煤灰基沸石CHA制备、改性及其吸附分离工业废气中CO2过程开展经济分析和环境评价。本课题的研究将为粉煤灰的高附加值综合利用提供一种新的途径，同时为变压吸附法捕集CO2温室气体提供成本低廉、高效的吸附材料，将有效降低变压吸附法分离工业废气中CO2的成本，有助于碳捕集与封存技术的推广应用,对于温室气体的减排具有重要意义。

沸石CHA因其独特的物理化学特性，在变压吸附捕集工业废气中CO2领域有广泛的应用前景。传统方法制备沸石CHA合成工艺复杂，原料成本高，若以粉煤灰为原料制备沸石CHA，不仅解决了粉煤灰的环境污染问题，提高了粉煤灰产品的附加值，而且为沸石CHA找到一种廉价的原料，具有广泛的经济效益和应用价值。本课题在此研究背景下，以粉煤灰为原料制备不同硅铝比的沸石CHA，探明了反应过程中有价元素相互作用机制，系统研究了产物结构对气体吸附分离性能的影响机制，确定产物吸附气体的理论模型，阐明了粉煤灰基沸石CHA分离混合气体中CO2的吸附热力学和动力学机制。本课题开展了粉煤灰基沸石CHA捕集工业废气中CO2的应用研究发现，粉煤灰基沸石CHA对CO2/CH4和CO2/N2的选择吸附因子近似∞，在温度60℃的吸附分离效果最好；而混合气体的穿透实验分析显示，CO2/N2混合气体与CO2/CH4混合气体可以采用粉煤灰基沸石CHA进行高效分离，且吸附选择系数都可达到∞，分离性能远优于目前所有的物理吸附剂。因此，本项目以粉煤灰为原料，在不添加任何有机模板剂、氟离子或晶种的情况下，采用碱融水热法制备了高纯菱沸石。产物具有超高CO2/N2和CO2/CH4分离性能，可高效分离烟道气、天然气、煤层气等混合气体中的CO2，在温室气体捕集、天然气清洁生产领域有广泛的应用前景。