Theoretical insight into the polymerization of ethylene on the surface of 3A zeolite: A DFT + kMC study

Separation is the core process of ethylene production, in which the reaction gas is usually dried using 3A zeolite. In this work, ethylene polymerization on the surface of 3A zeolite were investigated by the combination of Density Functional Theory (DFT) and kinetic Monte Carlo (kMC). DFT calculations showed that stepwise mechanism is the dominant path of ethylene dimerization on the surface of 3A zeolite. Then the effect of temperature on the polymerization of ethylene was studied by kMC simulation. When the temperature is higher than 473 K, ethylene begins to polymerize to form corresponding species, which cover the surface and reduce the dehydration performance of 3A zeolite. Based on these, the desorption process with low temperature using pure ethylene as desorption gas for 3A zeolite regeneration is proposed, which can avoid the use of N2, and reduce the equipment investment and energy consumption.