High Stability of Methanol to Aromatic Conversion over Bimetallic Ca,Ga-Modified ZSM-5

Abstract

The production of valuable aromatics and the rapid catalyst deactivation due to coking are intimately related in the zeolite-catalyzed aromatization reactions. Here, we demonstrate that these two processes can be decoupled by promoting the Ga/HZSM-5 aromatization catalyst with Ca. The resulting bimetallic catalysts combine high selectivity to light aromatics with extended catalyst lifetime in the methanol-to-aromatics process. Evaluation of the catalytic performance combined with detailed catalyst characterization suggests that the added Ca interacts with the Ga-LAS, with a strong effect on the aromatization processes. A genetic algorithm approach complemented by ab initio thermodynamic analysis is used to elucidate the possible structures of bimetallic extraframework species formed under reaction conditions. The promotion effect of minute amounts of Ca is attributed to the stabilization of the intra-zeolite extraframework gallium oxide clusters with moderated dehydrogenation activity.

Global optimization of extraframework ensembles in zeolites: structural analysis of extraframework aluminum species in MOR and MFI zeolites

“…This methodology has been successfully employed earlier on a wide range of solid systems including zeolite catalysts. 12,41,45…”

“…5,6 GO algorithms have been successfully used to address the structural problem of the active sites in heterogeneous catalysis including oxides, 7,8 supported metal nanoparticles, 9 electrocatalytic interfaces, 10 and, since quite recently, also zeolite-based catalysts. 11,12…”

“…5,6 GO algorithms have been successfully used to address the structural problem of the active sites in heterogeneous catalysis including oxides, 7,8 supported metal nanoparticles, 9 electrocatalytic interfaces, 10 and, since quite recently, also zeolite-based catalysts. 11,12 Zeolites are porous, crystalline aluminosilicates, whose reactivity and catalytic behaviour can be widely adjusted by modifying them with extraframework (EF) metal-containing species. 13,14 The structural and catalytic properties of such EF species depend on the chemical composition (lattice Si/Al ratio), the presence of heteroatoms, and the topological properties of the confining zeolite matrix.…”

Copper dual-atom catalyst mediated C3–H amination of indoles at room temperature

“…9 More importantly, zeolites can be readily modified by metals, 10 such as Ga-ZSM-5 zeolite for the catalytic conversion of methanol to aromatics, where the incorporation of Ga into ZSM-5 substantially enhances the catalytic properties. 11 Their utilization in organic transformation reactions is, however, greatly under-explored. But undoubtedly, given the above apparent merits, zeolite supported metal nanocatalysts are an increasingly potent candidate for organic synthesis reactions, in general.…”

Coke Formation over Zeolite Catalysts in Light Alkanes Aromatization and Anti-Carbon-Deposition Strategies and Perspectives: A Review

“…The inert gas treatment can remove impurity molecules in the catalyst before reaction and increase the exposure active sites; pretreatment with reducing gases such as H 2 and CH 4 can change the structures of metal sites via pre-reducing or pre-carburizing. , For metals with carbonized structures (such as Fe and Mo), pre-reduction causes the original oxidation state metal to be easily converted into the most effective activated carbonized structure . In addition, the operating conditions of the catalytic reaction, , such as space velocity, feed material composition, pressure, , and temperature of the reaction, also directly affect coke formation.…”