(113c) Studies of the Combined Effect of Si/Al and Temperature On the Templated Synthesis of Platinum Nanostructures in Mordenite
Zeolites are aluminosilicate crystalline structures with pores ranging between 0.4 to 1.4 nm. Depending on the zeolite framework, these pores can form one, two, or three-dimensional channels. These channels can be theoretically used in the templated synthesis of metal sub-nanostructures. In the case of zeolite frameworks with one-dimensional channels, such as mordenite, the pores can be used in the synthesis of metal nanowires. A synthesis process of metal nanostrucures using zeolites as templates will depend on many factors such as precursor compounds, zeolite framework, zeolite composition, and temperature. In the present work we are focused on the combined effect of zeolite composition and temperature on the template synthesis process. Metropolis Monte Carlo simulations and geometric minimizations using the pcff forcefield have been done to study the effect of the zeolite's silicon to aluminum ratio (Si/Al) and the temperature on the positioning of Pt metal atoms inside the mordenite (MOR) framework. It has been found that at low Si/Al, low and high temperatures promote the positioning of Pt atoms inside the main pore channels of the MOR framework, which is where metal nanowires could be formed. On the other hand, high Si/Al and low temperatures promotes the positioning of Pt atoms in the side pockets of the MOR structure. This suggests that there are in fact optimal conditions for the formation of subnanometer wires in zeolites.