Towards Performant Design of Carbon-Based Nanomotors for Hydrogen Separation through Molecular Dynamics Simulations

Clean energy technologies represent a hot topic for research communities worldwide. Hydrogen fuel, a prized alternative to fossil fuels, displays weaknesses such as the poisoning by impurities of the precious metal catalyst which controls the reaction involved in its production. Thus, separating H-2 out of the other gases, meaning CH4, CO, CO2, N-2, and H2O is essential. We present a rotating partially double-walled carbon nanotube membrane design for hydrogen separation and evaluate its performance using molecular dynamics simulations by imposing three discrete angular velocities. We provide a nano-perspective of the gas behaviors inside the membrane and extract key insights from the filtration process, pore placement, flux, and permeance of the membrane. We display a very high selectivity case (omega = 180 degrees ps(-1)) and show that the outcome of Molecular Dynamics (MD) simulations can be both intuitive and counter-intuitive when increasing the omega parameter (omega = 270 degrees ps(-1); omega = 360 degrees ps(-1)). Thus, in the highly selective, omega = 180 degrees ps(-1), only H-2 molecules and 1-2 H2O molecules pass into the filtrate area. In the omega = 270 degrees ps(-1), H-2, CO, CH4, N-2, and H2O molecules were observed to pass, while, perhaps counter-intuitively, in the third case, with the highest imposed angular velocity of 360 degrees ps(-1) only CH4 and H-2 molecules were able to pass through the pores leading to the filtrate area.