Preparation Of P-BN/ZIF-8 Composites And Their Gas Adsorption Properties Study

The widespread use of fossil fuels has caused an increasing concentration of CO₂ in the atmosphere,which has brought serious problems to the global environment and human activities.Therefore,capturing and storing CO₂ is an urgent issue.At present,it is a research hot spot in the scientific community to find new adsorption materials with high CO₂adsorption capacity,high selectivity and strong regeneration ability.Porous boron nitride(p-BN)has high specific surface area,rich pore structure and high stability,and has certain CO₂adsorption capacity.It has been widely used in the field of CO₂ gas adsorption,but p-BN has low selectivity for CO₂.In order to solve the above problems,a new type of porous material——ZIF-8 is introduced in this subject.ZIF-8 has large pore volume,high specific surface area,good stability and high CO₂ adsorption capacity,and has attracted much attention in the field of CO₂ adsorption and separation.Therefore,we used p-BN as the substrate and composited ZIF-8 nanocrystals with p-BN to prepare p-BN@ZIF-8 composite materials.The morphology,structure,and CO₂ gas adsorption and separation properties of the materials were studied.Compared with boron nitride substrates with different morphologies,a new porous adsorbent with high adsorption capacity,high selectivity and good stability is expected.The main research contents are as follows:(1)ZIF-8 nanocrystals were supported on the surface of porous boron nitride microrods(p-BNMR)by impregnation method and solvent method.Then,p-BNMR@ZIF-8 composite material capable of efficiently capturing and separating CO₂ gas was obtained.The effects of reaction time and growth times of ZIF-8 on the morphology,structure and CO₂ adsorption performance of composite were studied to explore the best preparation process.The adsorption thermal calculation,cyclic stability test and CO₂ dynamic adsorption test were carried out on the p-BNMR@ZIF-8-3 composite with the best CO₂ adsorption effect.Finally,the selective adsorption behavior of p-BNMR@ZIF-8-3 composite to CO₂ in CO₂/N₂ mixed gas was predicted by using ideal adsorption solution theory.(2)Four kinds of boron nitride(boron nitride nanofibers(p-BNNF),boron nitride foam(p-BNFM),boron nitride nanosheets(BNNP),boron nitride nanospheres(BNNS))with different morphologies are selected as substrates,and the optimal preparation process conditions are adopted.Four kinds of composites,p-BNNF@ZIF-8-3,p-BNFM@ZIF-8-3,BNNP@ZIF-8-3 and BNNS@ZIF-8-3,were obtained by compounding with ZIF-8nanocrystals,respectively.The effect of the microstructure of boron nitride substrate on the CO₂ adsorption performance of the composites was investigated,and the adsorption and selectivity of p-BNFM@ZIF-8 on CO₂ gas were emphatically analyzed.