煤矸石基多孔硅材料的调控制备、表面改性及吸附CO2的研究

Adsorption process is seen as an important development direction because it can be used to reclaim high purity CO2. However, a core issue is considered about how to develop high selective, high effective, low cost, and low desorption energy consumption adsorbing materials and low energy consumption in CO2 separation processes. For this issue, new ideas are put forward as follows: One is to perpare struction-controllable porous silicate material using coal gangue from Wujialiang coal preparation plant in Inner Mongolia, which were perared from the amorphous silicon oxide. Based on the special physicochemical properties and surface characteristics,the porous material can be used to high effectively capture CO2. Another is to modify the surface of porous material using amine-base odifier with grafting and impregnation methods, so the CO2 adsorption selectivity of porous material can be improved.The basic adsorption and desorption data before and after modification of porous silicate material will be determined and the dynamic relations will be also founded. From the macroscopical adsorption and desorption dynamic data, the effects from adsorption reversibility on adsorption and desorption isotherms are discussed, breakthrough curves for the CO2 adsorption are protracted, and the circular adsorption parameters are ascertained. Based on the modern spectral instruments and surface analysis techniques, the adsorption and desorption mechanism are discussed, the mechanism and law of CO2 fixation are definituded, and quantitative relation between the adsorption performance and molecular structure are tried to obtain. Furthermore, the basic data and theoretical basis are provided for the development of effective adsorbents for the CO2 capture using the porous silicate material. Compared with other sorbents, the coal gangue based porous silicate material shows strong adsorption performance, low preparation cost, and low desorption energy consumption for CO2 capture. In addition, the task the implementation will be very significant to develop the high-efficiency technology for CO2 capture from flue gases and the new functions of porous silicate material.

吸附法捕集CO2具有节能、可回收高纯度CO2等优点，技术核心是吸附剂。如何提高吸附剂对CO2的吸附效率和选择性，降低吸附剂的价格及再生成本是实际应用的瓶颈。本项目对此提出了新的解决对策：(1)利用多年研究的内蒙古武家梁选煤厂煤矸石，通过非晶态SiO2提取转化，制备结构可控的多孔硅材料，基于材料特殊的理化性质和表面特性，实现CO2的高效捕集；(2)利用材料表面特有的硅羟基，以有机胺类化合物为改性剂，以嫁接法和浸渍法对材料表面进行修饰，提升CO2的吸附性能和选择性。测定多孔硅材料改性前后吸附-脱附CO2的基础数据，建立动力学关系；结合宏观吸附-脱附动力学数据，考察吸附可逆性对吸附-脱附等温线的影响，确定循环吸附参数；采用现代波谱及表面分析技术，研究吸附-脱附机制，明确固碳机理及规律，力求建立吸附性能与分子结构间的内在联系，为发展煤矸石基多孔硅材料为捕集CO2的高效吸附剂提供基础数据和理论依据。

吸附法捕集CO2具有节能、可回收高纯度CO2等优点，技术核心是吸附剂。如何提高吸附剂对CO2的吸附效率和选择性，降低吸附剂的价格及再生成本是实际应用的瓶颈。本项目对此提出了新的解决对策：.(1)对煤矸石制备提硅液的条件进行研究。确定最佳提硅条件为：煅烧温度为1000°C；碱液浓度为25%；反应温度为106°C，反应时间为2 h；石碱比为0.5: 1，在该条件下提硅率达到40.24%。.(2)对提硅液制备多孔硅材料的条件进行研究。确定最优合成条件为：合成温度为98°C，合成时间为2 h；Ca/Si摩尔比为0.5: 1；pH值为12.70，在该条件下，多孔硅材料对CO2的吸附能力为36.69 mg/g。采用浸渍法对材料进行改性后，不同的改性剂均能提高材料的吸附性能。其中EDA改性效果最佳，在25°C时，改性多孔硅材料对8% CO2的吸附量为83.5 mg/g，胺二氧化碳捕集效率高达58 %.(3)对多孔硅材料的组成和结构进行研究。结果表明：多孔硅材料是由C、O、Ca、Na、Si和Mg六种主要元素组成的无固定晶型的非晶态混合物，主要以Ca2+、Na+、SiO32-和CO32-、Mg2+等离子形式存在，材料中还包含一定量的吸附水和结晶水，可为CO2气体的吸附提供吸附位点。.(4)对多孔硅材料吸附CO2进行吸附相平衡和动力学研究。DL模型可以准确地描述CO2在多孔硅材料上的吸附行为。吸附动力学拟合结果符合LDF模型。根据吸附热力学分析可知，多孔硅材料CO2的吸附主要以物理吸附为主，整个吸附过程是熵减少过程，且属于自发地放热过程，是焓驱动过程。此外，10次脱附-吸附循坏实验后，多孔硅材料表现出较好的再生性能。.以此工作为支撑，张建斌入选内蒙古杰出青年基金，发表论文10篇，申请发明专利1项，培养研究生9人。研究不限于最初计划，经过深入的研究，确定了类似物煤矸石、炉渣基多孔材料的制备方法，并实现了对挥发性有机物、苯酚等及吸附及降解。该方法为类似多孔材料的制备提供了重要的参考，这也为2019年国家基金项目“煤矸石基介孔硅酸盐基复合吸附材料的创建及化学吸附CO2的研究”的申报提供了重要的基础数据和理论依据。