Molecular Simulation Studies for the Synthesis of Ni Nanowires in Zeolite Cancrinite
J.A. Huertas-Miranda, L. Quiñones-Fontalvo, M.M. Martínez-Iñesta
University of Puerto Rico, US
Keywords: zeolite, cancrinite, Monte Carlo, nanowires, molecular simulations
Abstract:Evaluation of the spatial distribution of Ni metal atoms inside CAN was done at two Si/ Al ratios and four Ni loadings. Using Sorption from Material Studio 4.0 (Accelrys, Inc.), Metropolis Monte Carlo simulations under the canonical ensemble (298 K) were done to obtain the position of Ni atoms at the most stable energetic conditions. The purpose was to establish what conditions will promote the displacement of metal particles inside the one-dimensional main pores channels, where the nanowires can be formed. The relative position of the zeolite atoms was determined previously from crystallographic data (MS database). To determine the position of the balancing protons in the CAN acidic zeolite, geometry optimizations were done using Forcite from Material Studio 4.0 (Accelrys, Inc.). In both cases, the pcff forcefield was used. Based on the results obtained we can conclude that the presence of Al atoms in the CAN acidic zeolite, at the smallest possible Si/Al ratio, favored the displacement of Ni atoms in the main pore channels. At lower Ni loadings with CAN (Si/Al=1), the formation of Ni clusters was observed. The growth of clusters continues at higher loadings through the main channel until they formed one-dimensional structures that resemble Ni nanowires.