Molecular Simulation Study On Gas Asorption And Diffusion In Boron Nitride Nanotubes

In twenty-first century, with the development on carbon nanotubes, researchers started to focus on a new type of nanotube materials, which have a similar structure with carbon nanotubes, namely boron nitride material. By means of experimental and theoretical studies, researchers found that boron nitride nanotubes show better properties than carbon nanotubes.For example, better temperature resistance, excellent semiconductor materials, etc. At the same time, by means of quantum mechanicalcalculations and experiments, researchers also proved that boron nitride nanotubes have advantages in hydrogen storage. Although a lot of researches have been performed on boron nitride nanotubes, gas adsorption and diffusion properties have not been systematically studied so far. Therefore, in this work, molecular simulations were performed to carry out a systematic study on the gas adsorption and diffusion peroperties in boron nitride nanotubes. The contents of this work are as follows:1.Using GCMC molecular simulation method, gas adorption and selectivity were simulated for CH4/CO2 mixture with the ratio of 9:1, diameter of boron nitride nanotubes varying from 7 to 30 A at 298K, with pressure varying from 0.01 bar-100bar. Compared with carbon nanotubes, boron nitride nanotubes show higher adsorption capacity and selectivity.2.Molecular dynamics simulations were performed to calculate the diffusion pathways of CO2 and CH4 in the boron nitride nanotubes with high gas asorption performance revealed by the above GCMC simulation, and their self-diffusion coefficients were further obtained. Compared with carbon nanotubes, the results of this work proved that boron nitride nanotubes have advantages on gas transportation.3.New boron nitride nanotubes weredesigned. GCMC and MD simulations were peroformed on the adsorptionand diffusion of CH4/CO2mixture in them. The results show that the modified boron nitride nanotubes have improved performance, providing useful information for guiding the future design of new boron nitride nanotubes.