高微孔容积BN气凝胶/HKUST-1复合材料的构筑及其吸附储存甲烷性能研究

The development of economical and efficient materials for methane storage is the key to promoting the widespread use of natural gas as an alternative clean fuel. In this project, the problem of macropores due to accumulation in the crystal of HKUST-1, a star material for adsorbing methane, is proposed. Three-dimensional network BN aerogels constructed by cross-linking of porous BN micro/nanofibers are used as the substrate. Porous BN fibers with a strong adsorption of copper ions will provide anchoring sites for the metal precursors and direct HKUST-1 for directional assembly in the macro and mesopores of the BN aerogels. The resulting BN aerogels/HKUST-1 composite materials are equivalent to filling BN fibers with high micropore volume into the pores created by HKUST-1 packing, which increased the methane storage density of the composite materials. The research contents include the control synthesis of BN aerogels/HKUST-1 composites, the influence of the synthetic conditions on the structure, density and pore structures of the products, the adsorption amount and adsorption curve of methane on the composite materials, as well as the theoretical model and the mechanism of the adsorption for methane storage. The project will lay the foundation for obtaining methane adsorption and storage materials with high adsorption capacity and good stability under room-temperature, medium/low-pressure conditions, and is of great significance for promoting the wide application of natural gas.

开发经济高效的甲烷储存材料是推广天然气作为清洁替代燃料的关键。本项目针对吸附甲烷的明星材料——HKUST-1 [Cu3(BTC)2(H2O)3]（BTC=均苯三酸）晶体粉末堆积空隙大的问题，拟采用由多孔BN纤维交联构筑的三维网络状BN气凝胶作为基底，对铜离子具有强吸附作用的BN纤维将为金属前驱体提供锚定位点并引导HKUST-1在气凝胶的大孔内中定向组装，最终合成的BN气凝胶/HKUST-1复合材料相当于由高微孔容积的BN纤维填充HKUST-1的堆积空隙，提高了材料的甲烷存储密度。研究内容包括开发BN气凝胶/HKUST-1复合材料的控制合成方法、揭示合成条件与产物结构、密度、孔结构的关系、获得甲烷的吸附量和吸附曲线、建立甲烷吸附理论模型、阐明吸附储存甲烷的机理。本项目将为最终获得在室温、中低压条件下具有高吸附容量和良好稳定性的甲烷储存材料奠定基础，对推动天然气能源的广泛应用具有重要意义。

开发经济高效的甲烷储存材料是推广天然气作为清洁替代燃料的关键，本项目以提高金属有机框架材料（MOF）对气体分子的吸附储存性能为出发点，旨在通过与多孔基底复合和将颗粒致密化的策略，实现大幅度提高吸附剂吸附气体分子性能的目的。目前，项目围绕致密化HKUST-1块体、氮化硼气凝胶和以多孔氮化硼为基底的MOF复合型吸附剂的开发方面进行了如下工作：发展了一种高效可控地制备BN气凝胶的方法，通过超声波辅助结合冷冻干燥的方法实现由p-BN微米纤维构筑的BN气凝胶的制备；通过控制干燥温度的方法制备的HKUST-1块体，既增加了致密度，又保留了利于气体传输的微孔和介孔结构；采用p-BN作为基底材料，构筑了具有多级孔结构的p-BN@HKUST-1和p-BN@ZIFs复合材料，并通过控制复合材料中的MOF的比例，有效调控复合材料中的密度和微孔/介孔的体积比，验证了MOF与BN气凝胶的复合优势；解释了形成致密化块体材料和与p-BN形成复合材料两种处理方式对HKUST-1吸附储存气体分子性能的影响规律：致密化HKUST-1块体的密度接近HKUST-1完美单晶的理论值，从而显著增加其体积吸附量，p-BN@HKUST-1复合材料则通过复合效应增强了气体分子在吸附剂内部的传输速度和有效锚定；研究了p-BN@Zn/Co-ZIF复合材料高效捕获CO2分子对催化还原性能的重要作用。以上方法的建立和机理的阐述为最终获得在室温、中低压条件下具有高吸附容量和良好稳定性的甲烷高压储存材料奠定基础，对推动天然气能源的广泛应用具有重要意义。