Organic Solvent-assisted Synthesis Of Porous BN Fibers With High Aspect Ratios And Their Properties Study

With the rapid development of the global economy,environmental problems have become increasingly prominent.Porous boron nitride(BN),as an inorganic non-carbon porous material,possesses high specific surface area,rich pore structure,excellent chemical stability and oxidation resistance that make it greatly advanced in enviormental governance.The practical application effect of porous BN depends not only on its microscopic morphology and structure,but also on its macroscopic morphology.It is greatly significant to regulate the microscopic morphology of porous BN and realize the granulation and molding of porous BN.In this paper,an organic solvent-assisted method for synthesizing porous BN fibers with high aspect ratio was developed.Based on the product,the porous BN granulation and adsorption desulfurization and CO₂ dynamic adsorption peoformance of porous BN particles were researched.The main contents are as follows:1.Methane was mixed with a hot melamine diboronic acid(M·2B)solution and heat exchange method was performed to realize a large number of nucleation precipitation of M·2B fibers in a short time.M·2B fibers was pyrolyzed to obtain porous BN fiber with uniform morphology,with an average diameter of 150 nm,and length of few?m.The effects of different pyrolysis temperatures on the pore structure and specific surface area of the prepared porous BN fibers were studied.Results have shown that porous BN fibers prepared by pyrolysis at 1100°C possesses a specific surface area up to 1758 m²/g,showing good adsorption capacity for thiophene and dibenzothiophene in simulated oil,and sulfur adsorption reached at 36.28 mg S g^-1 and 28.36 mg S g^-1,respectively.2.Organic solvent-assisted synthesis of M·2B fibers are granulated to prepare M·2B particles with a size of centimeters,which are composed by a large number of M·2B fibers interwoven and carried;Pyrolysis was performed to prepare porous BN particles assembled from porous BN fibers.The effects of different pyrolysis temperatures on the pore structure and specific surface area of the prepared porous BN particles were studied.The result have shown that the specific surface area of porous BN particles prepared by pyrolysis at 1100°C is?873 m²/g,which has a good adsorption capacity for thiophene and dibenzothiophene in simulated oil,and the adsorption desulfurization amounts reached at 28.82 mg S g^-1 and 24.34mg S g^-1.Although the specific surface area and adsorption desulfurization of porous BN particles are reduced compared to BN powder,with granular morphology,it is easy to recycle and therefore possesses high practical value.3.The dynamic adsorption performance of porous BN particles in different pyrolysis temperatures for CO₂ were studied and the dynamic adsorption breakthrough curve of porous BN particles for CO₂ was tested under different pressures and temperatures were obtained,The analysis showed that the penetration time and adsorption amount of porous BN particles for CO₂ increased rapidly with the increase of the measurement pressure,and showed a relatively stable adsorption performance on CO₂ in the measurement temperature at an range of 5-35°C.The porous BN particles prepared at 1100°C possesses the longest penetration time at 5°C and 10 bar,reaching 6.01 min,with an adsorption capacity of 8.29 mmol/g,showing a high dynamic adsorption capacity for CO₂.The measurement of breakthrough curve is of great significance for the purification and separation of CO₂.