Adsorption and Separation Mechanism of Thiophene/Benzene in MFI Zeolite: A GCMC Study

Selective removal of thiophene from aromatic components is one of the key challenges facing the petrochemical industry. The adsorption and separation mechanism from the molecular viewpoint can guide and upgrade the relative adsorption based technology. Therefore, we performed the grand canonical ensemble Monte Carlo (GCMC) simulation to investigate the adsorption performance and mechanism of competitive adsorption. Density distribution and radial distribution functions (RDF) analysis give a more detailed description of the adsorption sites. For pure component adsorption, donut-shaped adsorption sites were obtained for both benzene and thiophene from the straight channel point. From the viewpoint of the zigzag channel, the sorbates follow the straight line shape distribution at low loading and the S shape distribution at high loading. As for the binary component adsorption, more benzene adsorbs in the zeolite than thiophene at low pressure; however, thiophene competes successfully at high pressure. This can be explained by the key factor: at low pressure, the size effect plays an important role. While the pressure increases, the interaction energy dominates the process. Analyzing RDFs of the binary adsorption, we observed that when benzene competes with thiophene, the preferential adsorption sites do not change; however, the emergence possibility of benzene gets smaller.