氮化硼纳米片改性Mg-MOF-74的制备及其水稳定性研究

Preparation and Water Stability Performance of Modified Mg-MOF-74 via Boron Nitride Nanosheet

MOF-74的甲烷吸附能力优异,但是受到其水稳定性差的影响,使其应用受到限制。采用水热一锅法制备Mg-MOF-74晶体材料,并利用氮化硼薄纳米片(h-BN)对其进行改性制备出1wt%h-BN@Mg-MOF-74材料。同时,对Mg-MOF-74和1wt%h-BN@Mg-MOF-74表面结构进行表征,对水稳定性和甲烷吸附性能进行测试分析。结果表明,Mg-MOF-74结构完整,比表面积大;经过720 h浸泡后,通过X射线衍射(XRD)测试发现其衍射峰出现偏移且相对强度发生变化。通过比表面积测试,发现氮化硼修饰的Mg-MOF-74比表面积仅略微减小,但是其水稳定性得到显著增强,经过720 h浸泡后,晶体结构未发生太大变化。甲烷吸附测试结果表明,Mg-MOF-74对甲烷吸附值达到711 cm^3·g^-1,经过水浸泡后,其甲烷吸附值降为144 cm^3·g^-1,而1wt%h-BN@Mg-MOF-74浸泡前后在甲烷吸附值上无明显变化,表明它的水稳定性得到了提高。

Mg-MOF-74 was synthesized through a solvothermal method.On basic of the poor water stability of Mg-MOF-74,1wt%h-BN@Mg-MOF-74 was synthesized via h-BN nanosheet modification.The crystal structure of original Mg-MOF-74 and 1wt%h-BN@Mg-MOF-74 were characterized,as well as water stability and CH4 adsorption performance were analyzed.The results show that original Mg-MOF-74 with complete structure and excellent surface area.Exposed to water for 720 hours,its diffraction peak shifted significantly and the surface area decreased.The results of BET surface area test reveal that Mg-MOF-74 modified by h-BN have lower surface area,but its water stability increased.After exposed to water for 720 hours,1wt%h-BN@Mg-MOF-74 still remains the integrity of crystal structure.CH4 adsorption test show that the CH4 adsorption capacity of Mg-MOF-74 reached 711 cm^3·g^-1,after exposed to water,the CH4 adsorption capacity of Mg-MOF-74 reduced to 144 cm^3·g^-1.On the contrary,this favorable CH4 adsorption of MOFs modified by 1wt%h-BN did not change significantly before and after exposure to water,indicating that its water stability was improved significantly.