Molecular dynamics as a tool to study effect of Na+ cations on diffusion of SO2 in Y zeolite

Since most carbonaceous or hydrocarbon fuels and the ores of many metals contain sulfidic sulfur, as a result, vast volumes are produced in the processing and utilization of hydrocarbon fuels such as power plants, refineries and metallurgical units of metal extraction. High levels of sulfur dioxide production releasing it into the atmosphere is one of the chemical threats to the environment. On the other hand, sulfur dioxide has widespread uses in the wood pulp industry and the manufacture of paper, textile and food processing. However, the outstanding use (more than 98%) is the production of sulfuric acid [1]. The existence of these mutual characteristics has led to the development of adsorption and removal processes. The present study evaluates the diffusion of SO2 gas in silica Y zeolite cages (Si/Al=) and Y zeolite with 48 or 64 Na+ cations per unit cell (Si/Al=3,2) by MD simulation. All simulations have been done using DL_POLY_2.17 [2] program. The MD simulations were performed within the NVE ensemble at 300, 400, 500 and 600 K. The behavior of SO2 was investigated for loading of 24 molecules per unit cell (mol/u.c.). Self-diffusion coefficients of guest molecules in Y zeolite are presented in Table 1.As the temperature increases, the self-diffusion coefficient increases in all three types Y zeolite, because molecular movements at higher temperatures lead to more successful jump between sites. The presence of Na+ cations in two zeolites Si/Al=2,3 will lead to a decrease in the diffusion of SO2. The SO2 molecules preferentially reside near the cations due to the stronger attraction [3].