Simulation of Steady-State Methanol Flux through a Model Carbon Nanotube Catalyst Support

Nonequilibrium molecular dynamic (MD) simulations were performed to show transport of a water-methanol solution through a novel catalysis membrane, constructed from single-walled carbon nanotubes (CNTs) with a Pt monolayer catalyst at the membrane's exit. These calculations are directed toward understanding methanol transport dynamics in the CNT core, past the Pt coating, and to find the conditions for optimal efficiency as a function of both CNT diameter and pressure. Probability density function calculations for various methanol observables show that methanol primarily travels along the pore wall, which is ideal for methanol to interact efficiently with a catalyst at the exit. From the percent of methanol that passed through the pores within the minimum of the Lennard-Jones potential (2(sigma pt-O)(1/6)), we estimate the residence time of methanol flux past the Pt monolayer in the range of 2-6 Ps. The mass transport percent efficiency of the methanol flowing past the catalyst site is as high as 86% for (10,10) CNTs at flow velocities near 100 cm/s. Optimal diameters are ca. 1 nm, and flow rates should be < 100 cm/s.