373106 Modeling the Thermodynamics and Dynamics of Fluids Confined in Three-Dimensionally Ordered Mesoporous (3DOm) Carbon Materials

Monday, November 17, 2014: 1:10 PM
310 (Hilton Atlanta)
Anish Desouza, Chemical Engineering, Univserity of Massachusetts, Amherst, MA and Peter A. Monson, Chemical Engineering, University of Massachusetts, Amherst, MA

Three-dimensionally ordered mesoporous (3DOm) carbons recently emerged as a step in the synthesis of mesoporous zeolite-based materials [1]. 3DOm carbons are templated by colloidal crystals formed from silica nanoparticles. A range of pore sizes of the 3DOm carbon can be obtained by using colloidal crystals with various primary particle sizes (e.g., 10, 20, 30, 40 nm). The resulting materials consist of spherical pores interconnected by windows created by sintering in the silica sphere assembly. They can be used to template the assembly of zeolites within the pores created by the pores. These materials represent an important approach in the search for carbon materials with a high degree of order.

In this work we use a lattice gas model to study adsorption equilibrium and dynamics in 3DOm carbons. The 3DOm structure is superimposed onto a lattice model and this is done by the coarse graining of configurations from Monte Carlo simulations of hard sphere solids.  This approach allows us to study several important effects upon the adsorption properties, including spatial disorder in the initial sphere assembly, as well the degree of sintering and size polydispersity in the silica spheres. Using mean field density functional theory we consider the effects of window size upon the adsorption hysteresis including the transition from cavitation to pore blocking. DMFT calculations provide visualizations of the evolution of the three-dimensional density distribution and reveal mechanisms in the dynamics of pore filling in these systems.

[1] Fan, W., M.A. Snyder, S. Kumar, P.-S. Lee, W.C. Yoo, A.V. McCormick, R.L. Penn, A. Stein, and M. Tsapatsis, Hierarchical nanofabrication of microporous crystals with ordered mesoporosity. Nat Mater, 2008. 7(12): p. 984-991.

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