Improving the dehydrogenation function and stability of Zn-modified ZSM-5 catalyst in methanol-to-aromatics reaction by Ca addition
Héctor Vicente (University of the Basque Country)
C. Liu (TU Delft - ChemE/Inorganic Systems Engineering)
Ana G. Gayubo (University of the Basque Country)
Pedro Castaño (University of the Basque Country, King Abdullah University of Science and Technology)
Evgeny A. Pidko (TU Delft - ChemE/Inorganic Systems Engineering)
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Abstract
Adding Zn to the ZSM-5 zeolite effectively increases the aromatic selectivity in the methanol-to-aromatics (MTA) process. The formation of metal-derived Lewis acid sites promotes the dehydrogenation but at the cost of a rapid deactivation of the catalyst by coke, due to the increased aromatic formation. In this work, we impregnated a Zn-modified catalyst (2 wt%) with variable contents of Ca (0.02 and 0.5 wt%) and evaluated their kinetic behavior in the MTA and ethane dehydrogenation reactions. The results proved the superior performance of the Zn(2)Ca(0.02) catalyst due to a synergistic effect between the two metals. The Ca ions limit coke formation from excessive aromatization, increasing catalyst stability and removing Zn clusters, resulting in a recovery of Brønsted acid sites (BAS) active for the formation of light aromatics. Combining these effects results in a more efficient and viable catalyst for aromatic production from methanol.
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