Modulating Synthesis Of Functionalized Metal-Organic Frameworks For Gas Storage And Separation

Gas storage and separation on environmental protection,energy utilization and industrial production has always been hot topics to be concerned and researched by the society.Especially now,for abating greenhouse effect caused by consumption of fossil fuel and satisfying the demand for the widespread use of clean energy,an effective and energy saving technology needs to be urgently developed to separate carbon dioxide and nitrogen and store clean energy such as hydrogen and methane.Porous materials as adsorbents were applied on gas storage and separation and metal-organic frameworks（MOFs）are highly attractive porous materials with favorable properties including robust structure,considerable surface area,tunable pore channel.Modification of the metal-organic frameworks（MOFs）by functionalizing ligands has been investigated for improved properties.In this work,by introducing substituents to the backbone of organic linkers,isostructural dihydroxy-/dialkoxy-functionalized UiO-66 were delicately constructed.By varying the synthetic conditions such as the kinds and does of modulators and the temperature,the samples were synthesized with high crystallinity and good surface morphology.A combination of the computer software and characterization techniques such as TGA and ¹H NMR was sophisticatedly used for calculating structural defects and investigating the influence on crystal structures after introducing substituents.Pure-component CO₂,CH₄,N₂,and H₂adsorption isotherms on the microporous synthesized materials were investigated under the pressure up to 10 MPa at 303 K.By applying the ideal adsorbed solution theory（IAST）model,the enhanced adsorption selectivity for CO₂/N₂,CO₂/CH₄,CH₄/N₂and CO₂/H₂binary mixtures was observed compared to the parent material and dihydroxy functionalization endows the material with high selectivity for CO₂/H₂.Moreover,the diethoxy-functionalized material with narrowed cavities exhibits improved high pressure H₂adsorption due to structural defects and strong overlapping potentials.