随着人类社会工业化进程的加快，温室气体排放量随之增加，导致温室效应加剧。在所有温室气体中，CO2占比最多、贡献最大，被认为是引起全球变暖的主要因素。人为排放的CO2主要来自工业生产过程中化石燃料的燃烧，为实现碳中和目标，除了推广清洁能源、提高能源利用效率和增加植物碳汇等措施外，对工业排放的CO2进行捕集封存必不可少。目前限制CO2捕集和分离工艺应用的主要因素是成本过高，为解决该问题，开发第2代低能耗固体CO2吸附材料对推动工业源CO2减排具有重要意义。Li4SiO4凭借较高的吸附容量、较低的再生能耗和成本在高温CO2捕集领域具有良好的应用前景。为推进Li4SiO4材料在碳捕集、利用和封存（CCUS）工艺中的应用，综述了Li4SiO4基吸附材料的研究进展，介绍了不同合成方法及合成条件对Li4SiO4材料的影响，论述了材料的性能改性方法及其影响机制，归纳了近年来Li4SiO4材料的成型及应用技术，最后总结了目前Li4SiO4基吸附材料发展过程中面临的挑战并提出该领域的发展趋势。Li4SiO4吸附CO2的过程可分为化学吸附和孔内扩散，其中扩散过程是Li4SiO4吸附CO2的决速步骤，通过调控合成工艺可获得具有更小粒径及多孔结构的吸附剂材料，从而促进CO2扩散过程。此外，利用碱金属盐负载也可改善吸附剂表面活性点位，从而提高其吸附动力学。对于材料成型应用，传统挤压造粒易造成Li4SiO4颗粒孔道结构破坏和比表面积降低，一般可通过模板支撑和造孔剂添加进行改善，对于成型材料还需合适的反应器及吸脱附工艺匹配，目前这些研究有待进一步优化。Li4SiO4基材料处于从基础研究向工程应用过渡的阶段，除了对吸附材料有更高活性及稳定性需求外，其规模化生产及成型、合成成本、吸脱附能耗、应用场景及捕集后CO2的处理处置等也是亟待研究的重点方向。

With the acceleration of human society industrialization, greenhouse gas emissions have been increasing, leading to the intensification of the greenhouse effect. Among all greenhouse gases, CO2 accounts for the largest proportion and contributes the most,which is considered to be the main factor causing global warming. Anthropogenic CO2 emissions mainly come from the combustion of fossil fuels during industrial production. In order to achieve the goal of carbon neutrality, CO2 capture and storage of industrial waste gases is an essential technological measure in addition to measures such as promoting clean energy, improving energy use efficiency and increasing plant carbon sinks. Currently, the main factor limiting the application of CO2 capture and separation processes is the high cost. To solve this problem, the development of the second generation of low energy consumption solid CO2 adsorbent materials is of great significance to promote CO2 emission reduction from industrial sources. Li4SiO4 shows good application prospects in the field of high temperature CO2 capture due to its high adsorption capacity, low regeneration energy consumption and cost. To promote the application of Li4SiO4 materials in carbon capture, utilization and sequestration (CCUS) technology, this paper reviewed the current research progress of Li4SiO4-based adsorbent materials, introduced the effects of different synthesis methods and synthesis conditions on Li4SiO4 materials, discussed the methods of performance modification of the materials and their influence mechanisms, and summarized the pelleting of Li4SiO4 materials and their application technologies in recent years. The adsorption process of CO2 by Li4SiO4 in the double-shell model can be divided into chemical adsorption and pore diffusion, in which the diffusion process is the decisive step of CO2 adsorption by Li4SiO4. Through the regulation of the synthesis process, adsorbent materials with smaller particle size and porous structure can be obtained, thereby promoting the diffusion process of CO2. In addition, the active sites of the adsorbent can be improved by alkali metal salt loading, so as to improve its adsorption kinetics. For the material molding applications, the traditional extrusion granulation is likely to cause the destruction of Li4SiO4 particle channel structure and the reduction of specific surface area, which can be generally improved by template support and pore-forming agent. For the moulding materials, appropriate reactor and adsorption and desorption process matching are needed, and these aspects need to be further optimized. Finally, this paper summarized the current challenges in the development of Li4SiO4-adsorption materials and put forward the development trend of this field. Li4SiO4-based materials are undergoing a transition from basic research to engineering application. In addition to the demand for higher activity and stability of adsorption materials, their large-scale production and granulation, synthesis cost, energy consumption of adsorption and desorption, application scenarios and treatment and disposal of CO2 after capture are also key directions to be urgently studied.

0 引言

1 Li4SiO4吸附CO2机理研究

2 Li4SiO4基吸附剂制备方法

   2.1 固相法制备Li4SiO4基吸附剂

   2.2 溶胶凝胶法制备Li4SiO4基吸附剂

   2.3 沉淀法制备Li4SiO4吸附剂

   2.4 其他方法制备Li4SiO4吸附剂

3 Li4SiO4基吸附剂的改性研究

   3.1 微观结构优化

   3.2 Si源和Li源的选择

   3.3 金属离子掺杂

   3.4 熔融盐负载

4 Li4SiO4基吸附剂的成型及应用

   4.1 成型研究

   4.2 Li4SiO4吸附剂的应用

5 结语与展望