Selective production of para-xylene and light olefins from methanol over the mesostructured Zn–Mg–P/ZSM-5 catalyst

Abstract

The mesostructured Zn–Mg–P/ZSM-5 catalyst is efficient in converting methanol to p-xylene and light olefins, with the additional mesoporosity compensating for the activity loss during modification.

Controlling the product selectivity in the conversion of methanol to the feedstock for phenol production

“…In the literatures, the HZSM-5 used for methanol to aromatics contained high amount of Brønsted acid sites (BAS) compared to that of Lewis acid sites (LAS). 3,9,10,13 Zn impregnation on such HZSM-5 decreased BAS and increased LAS significantly. 3,9,10,13 This resulted in an increase in the aromatics selectivity and a decrease in alkanes selectivity.…”

“…Similar observations had been reported in other works. 2,3,9,13 3.3.2 HZSM-5 vs. Si/HZSM-5. Si passivation of the HZSM-5 led to a signicant (48.5%) decrease in BAS, and a smaller (20%) decrease in LAS ( Table 5).…”

“…3,9,10,13 This resulted in an increase in the aromatics selectivity and a decrease in alkanes selectivity. 3,9,10,13 The increase in the aromatic selectivity was attributed to Zn-LAS (ZnOH + ) that could accelerate aromatization and dehydrogenation reactions. The selectivity of alkenes varied in different studies, however.…”

Zn-P Co-Modified Hierarchical ZSM-5 Zeolites Directly Synthesized via Dry Gel Conversion for Enhanced Methanol to Aromatics Reaction

“…The diffusion properties and anti-coking abilities were increased. Thirdly, the presence of P species can stabilize the framework aluminate of zeolites and improve the hydrothermal stability of the catalysts [21]. Therefore, the Zn-P co-modified ZSM-5 zeolites exhibited a much longer lifetime.…”

“…Therefore, the introduction of Zn into ZSM-5 zeolite decreases the Brønsted (B) acid sites and increases the proportion of medium-strong acid sites due to the formation of ZnOH + species. Recently, the multipleoxides-modified ZSM-5 zeolites were demonstrated to be a class of efficient catalysts for selective methanol conversion to p-xylene [20,21]. The primary metal modification, typically the low cost and non-toxic Zn species, is aimed to enhance the dehydro-cyclization and MTA reactivity [22,23].…”