Developing metal-organic framework(MOF)materials with the moisture-resistant feature is highly desirable for CO_(2)capture from highly humid flue gas.In this work,a new core-shell MOF@MOF composite using Mg-MOF-74 wit...Developing metal-organic framework(MOF)materials with the moisture-resistant feature is highly desirable for CO_(2)capture from highly humid flue gas.In this work,a new core-shell MOF@MOF composite using Mg-MOF-74 with high CO_(2)capture capacity as a functional core and hydrophobic zeolitic imidazolate framework-8(ZIF-8)as a protective shell is fabricated by the epitaxial growth method.Experimental results show that the CO_(2)adsorption performance of the core-shell structured Mg-MOF-74@ZIF-8 composites from water-containing flue gas is enhanced along with their improved hydrophobicity.The dynamic breakthrough results show that the Mg-MOF-74@ZIF-8 with three assembled layers(Mg-MOF-74@ZIF-8-3)can capture 3.56 mmol-g^(-1)CO_(2)from wet CO_(2)/N_(2)(VCO_(2):V_(N_(2))=15:85)mixtures,which outperforms Mg-MOF-74(0.37 mmol·g^(-1))and most of the reported physisorbents.展开更多
铬氧化物材料(Cr8O21)用作锂一次电池正极材料时放电倍率性能较差。利用高温固相法以Al_(2)O_(3)、TiO_(2)对Cr8O_(21)进行包覆改性,通过金属氧化物间的协同作用提升了Cr_(8)O_(21)的倍率性能。X射线衍射(XRD)结果显示包覆Al_(2)O_(3)、...铬氧化物材料(Cr8O21)用作锂一次电池正极材料时放电倍率性能较差。利用高温固相法以Al_(2)O_(3)、TiO_(2)对Cr8O_(21)进行包覆改性,通过金属氧化物间的协同作用提升了Cr_(8)O_(21)的倍率性能。X射线衍射(XRD)结果显示包覆Al_(2)O_(3)、TiO_(2)不会改变Cr_(8)O_(21)的晶体结构;扫描电子显微镜(SEM)、能量散射光谱(EDS)结果表明Al2O3和Ti O2都均匀包覆在Cr_(8)O_(21)表面。Cr_(8)O_(21)/Al_(2)O_(3)复合材料以质量比50∶1复合时放电性能最佳,比容量为342 m Ah/g (0.05 m A/cm^(2))、291 m Ah/g(1.0 m A/cm^(2)),容量保持率85%;Cr_(8)O_(21)/TiO_(2)复合材料以质量比100∶1复合时放电性能最佳,比容量为362 m Ah/g(0.05 m A/cm^(2))、303 m Ah/g (1.0 m A/cm^(2)),容量保持率83.75%。在大电流密度下无电压低头现象,容量保持率皆高于Cr8O21的容量保持率(75%)。展开更多
Nanosized solid superacids SO_(4)^(2−)/TiO_(2)and S_(2)O_(8)^(2)−/TiO_(2),as well as MCM-41-supported SO_(4)^(2−)/ZrO_(2),were prepared.Their structures,acidities,and catalytic activities were investigated and compare...Nanosized solid superacids SO_(4)^(2−)/TiO_(2)and S_(2)O_(8)^(2)−/TiO_(2),as well as MCM-41-supported SO_(4)^(2−)/ZrO_(2),were prepared.Their structures,acidities,and catalytic activities were investigated and compared using XRD,N2 adsorption-desorption,and in situ FTIR-pyridine adsorption,as well as an evaluation reaction with pseudoionone cyclization.The results showed that SO_(4)^(2−)/TiO_(2)and S_(2)O_(8)^(2)−/TiO_(2)possess not only nanosized particles with diameters<7.0 nm,a BET sur-face greater than 140 cm2/g and relatively regular mesostruc-tures with pores around 4.0 nm,but also a pure anatase phase and strong acidity.Different from the Lewis acid nature of SO_(4)^(2−)/ZrO_(2)/MCM-41,SO_(4)^(2−)/TiO_(2)and S_(2)O_(8)^(2)−/TiO_(2)exhibit mainly Brønsted acidities.The strongest Brønsted acid sites were produced on SO_(4)^(2−)/TiO_(2)promoted with H2SO4,while Lewis acid sites on S_(2)O_(8)^(2)−/TiO_(2)even stronger than those on SO_(4)^(2−)/ZrO_(2)/MCM-41 were generated when persulfate solu-tion was used as sulfating agent.Because of their distinct acid natures,SO_(4)^(2−)/TiO_(2)and S_(2)O_(8)^(2)−/TiO_(2)exhibited catalytic activities for the cyclization of pseudoionone that were much higher than that of SO_(4)^(2−)/ZrO_(2)/MCM-41.It can be concluded that the existence of more Brønsted acid sites was favorable for proton participation in the cyclization reaction.展开更多
基金supported by the National Natural Science Foundation of China(51772329,51972340,and 51825201)。
文摘Developing metal-organic framework(MOF)materials with the moisture-resistant feature is highly desirable for CO_(2)capture from highly humid flue gas.In this work,a new core-shell MOF@MOF composite using Mg-MOF-74 with high CO_(2)capture capacity as a functional core and hydrophobic zeolitic imidazolate framework-8(ZIF-8)as a protective shell is fabricated by the epitaxial growth method.Experimental results show that the CO_(2)adsorption performance of the core-shell structured Mg-MOF-74@ZIF-8 composites from water-containing flue gas is enhanced along with their improved hydrophobicity.The dynamic breakthrough results show that the Mg-MOF-74@ZIF-8 with three assembled layers(Mg-MOF-74@ZIF-8-3)can capture 3.56 mmol-g^(-1)CO_(2)from wet CO_(2)/N_(2)(VCO_(2):V_(N_(2))=15:85)mixtures,which outperforms Mg-MOF-74(0.37 mmol·g^(-1))and most of the reported physisorbents.
基金National Key Research and Development Program(2018YFB2001800)National Natural Science Foundation of China(51961021,52001152)Undergraduate Innovation and Entrepreneurship Training Program(DC2021011,DC2021018,DC2021036)。
文摘铬氧化物材料(Cr8O21)用作锂一次电池正极材料时放电倍率性能较差。利用高温固相法以Al_(2)O_(3)、TiO_(2)对Cr8O_(21)进行包覆改性,通过金属氧化物间的协同作用提升了Cr_(8)O_(21)的倍率性能。X射线衍射(XRD)结果显示包覆Al_(2)O_(3)、TiO_(2)不会改变Cr_(8)O_(21)的晶体结构;扫描电子显微镜(SEM)、能量散射光谱(EDS)结果表明Al2O3和Ti O2都均匀包覆在Cr_(8)O_(21)表面。Cr_(8)O_(21)/Al_(2)O_(3)复合材料以质量比50∶1复合时放电性能最佳,比容量为342 m Ah/g (0.05 m A/cm^(2))、291 m Ah/g(1.0 m A/cm^(2)),容量保持率85%;Cr_(8)O_(21)/TiO_(2)复合材料以质量比100∶1复合时放电性能最佳,比容量为362 m Ah/g(0.05 m A/cm^(2))、303 m Ah/g (1.0 m A/cm^(2)),容量保持率83.75%。在大电流密度下无电压低头现象,容量保持率皆高于Cr8O21的容量保持率(75%)。
文摘Nanosized solid superacids SO_(4)^(2−)/TiO_(2)and S_(2)O_(8)^(2)−/TiO_(2),as well as MCM-41-supported SO_(4)^(2−)/ZrO_(2),were prepared.Their structures,acidities,and catalytic activities were investigated and compared using XRD,N2 adsorption-desorption,and in situ FTIR-pyridine adsorption,as well as an evaluation reaction with pseudoionone cyclization.The results showed that SO_(4)^(2−)/TiO_(2)and S_(2)O_(8)^(2)−/TiO_(2)possess not only nanosized particles with diameters<7.0 nm,a BET sur-face greater than 140 cm2/g and relatively regular mesostruc-tures with pores around 4.0 nm,but also a pure anatase phase and strong acidity.Different from the Lewis acid nature of SO_(4)^(2−)/ZrO_(2)/MCM-41,SO_(4)^(2−)/TiO_(2)and S_(2)O_(8)^(2)−/TiO_(2)exhibit mainly Brønsted acidities.The strongest Brønsted acid sites were produced on SO_(4)^(2−)/TiO_(2)promoted with H2SO4,while Lewis acid sites on S_(2)O_(8)^(2)−/TiO_(2)even stronger than those on SO_(4)^(2−)/ZrO_(2)/MCM-41 were generated when persulfate solu-tion was used as sulfating agent.Because of their distinct acid natures,SO_(4)^(2−)/TiO_(2)and S_(2)O_(8)^(2)−/TiO_(2)exhibited catalytic activities for the cyclization of pseudoionone that were much higher than that of SO_(4)^(2−)/ZrO_(2)/MCM-41.It can be concluded that the existence of more Brønsted acid sites was favorable for proton participation in the cyclization reaction.
