Propane Aromatization Tuned by Tailoring Cr Modified Ga/ZSM‐5 Catalysts

Abstract

Accelerating propane dehydrogenation in propane aromatization is vital because it is the first and rate control step. In this study, we introduced Cr to Ga/ZSM‐5 by tuning its impregnation sequence and amount, which was expected to accelerate the dehydrogenation step and improve aromatization performance. The impregnation sequence of Cr on catalyst not only affected the interaction between Ga and ZSM‐5, but also tuned the amount of dehydrogenation active species Cr3+. Due to the plenty of Cr3+ species and strong interaction between Ga species and ZSM‐5, 2Cr/GaZ5 catalyst accelerated the dehydrogenation step and improved the aromatization process. More light hydrocarbons were preferred to be produced and were further converted into BTX on 2Cr/GaZ5 catalyst. Excessive Cr on catalyst caused the formation of Cr2O3 particles with worse dispersion. The aggregated Cr2O3 decreased the strong acidity of catalyst, which could not further promote propane conversion and decreased the aromatization ability of catalyst.

Recent Progress of Ga-Based Catalysts for Catalytic Conversion of Light Alkanes

“…However, there are some problems such as low aromatic selectivity and high coke deposition to make it possess low stability. By the introduction of aromatized metal components, such as Ga [30][31][32][33][34][35], Ni [36], Cr [37], Zn [38,39], Mo [40], etc., to construct bifunctional catalysts, these problems can be effectively solved.…”

Unraveling the Structure–Activity–Stability Relationship over Gallium-Promoted HZSM-5 Nanocrystalline Aggregates for Propane Aromatization

“…In the aspect of the regulation of Ga-modified HZSM-5 properties, researchers mainly focus on the existing state of gallium species, − HZSM-5 properties, , the interaction between gallium species and HZSM-5, , and the influence of additives. − It is reported that the gallium introduction method (mechanical mixing, impregnation, hydrothermal, and ion exchange methods), atmosphere pretreatment (hydrogen or oxygen), and calcination temperature have a large influence on the state of gallium species, which not only affects the dehydrogenation rate of alkanes and the yield of aromatics but also affects the catalyst stability. − In terms of the regulation of HZSM-5 properties, researchers have modified the acid properties of HZSM-5 by changing the Si/Al ratio to improve the performance in the light alkane aromatization reaction. Regulation of pore structure, such as the introduction of mesoporous structures, is beneficial for enhancing diffusion rate and retarding rapid deactivation of catalysts. , The introduction of promoters such as Pd, Ag, Ni, Pt, and Cr can increase the dehydrogenation activity and improve catalytic activity. − Changing the operating conditions such as reaction temperature, space velocity, and feed composition will also affect the aromatization performance of catalysts. , Although many studies have been executed on the propane aromatization process over Ga-modified HZSM-5 zeolites, systematic studies of the structure–reactivity relationship and coke formation in propane aromatization over Ga-modified HZSM-5 catalysts have rarely been reported. The coke formed in the alkane aromatization reaction will cover the acid sites and block the pore structure of the catalyst, resulting in rapid catalyst deactivation.…”

Mechanistic Insight into the Promotional Effect of CO2 on Propane Aromatization over Zn/ZSM-5

“…Toward the building blocks of value-added chemicals, the production of aromatics such as benzene, toluene, and xylene (BTX) from propane is more lucrative and also can expand the application of propane. In recent years, the aromatization of light hydrocarbons, as an alternative route to traditional naphtha-based production of aromatics, has been developed and eased the tension of the traditional route, which has attracted increasing attention in both academia and industry. − …”