A highly efficient Ga/ZSM-5 catalyst prepared by formic acid impregnation and in situ treatment for propane aromatization

Abstract

A simple method for the preparation of a Ga/ZSM-5 catalyst for propane aromatization was established by formic acid impregnation and in-situ treatment. The catalyst prepared by this novel method showed remarkably superior activity of propane aromatization. Under the conditions: T = 540 °C, P = 100 kPa, WHSV = 6000 ml/(g·h) and with a N 2 /C 3 H 8 molar ratio of 2, the highest propane conversion and 10 selectivity of BTX (benzene, toluene and xylene) on H-Ga/SNSA catalyst achieved was 53.6% and 58.0% respectively, much higher than that of the catalyst prepared using traditional impregnation method (38.8% and 48.2%). The catalysts were characterized by nitrogen physical adsorption, ICP-AES, DRIFT, Py-FTIR, NH 3 -TPD, H 2 -TPR, XPS and 27 Al MAS NMR techniques. The characterization data indicated that this facile methodology enhanced the dispersion of Ga species and promoted the formation of highly 15 dispersed (GaO) + species, which could exchange acidic protons (Brønsted acid sites) of the zeolite framework contributing to the strong Lewis acidity. The super catalytic behavior was attributed to the synergistic effect between strong Lewis acid sites generated by the (GaO) + species and the Brønsted acid sites. 75

A strategy to convert propane to aromatics (BTX) using TiNp4 grafted at the periphery of ZSM-5 by surface organometallic chemistry

“…This process is also used industrially to upgrade light alkanes such as ethane, propane and butane in the petroleum refinery. [6][7][8][9] ZSM-5 is known to be one of the best catalysts for the aromatization reaction mostly due to its controllable acidity, its high-temperature stability and its shape selectivity due to its pore structure. Most of the reported studies indicate that the yield of aromatics can be increased mainly by using a doping metal.…”

Aromatization over nanosized Ga-containing ZSM-5 zeolites prepared by different methods: Effect of acidity of active Ga species on the catalytic performance

“…Ausavaukhi et al [13] prepared a series of Ga-containing ZSM-5 zeolites via impregnation and physical mixing and determined that the GaO + species act as stronger Lewis acid sites. Xiao et al [14,15] also reported that the extraframework GaO + species in impregnated ZSM-5 samples can react with the acidic protons of the zeolite framework and contribute to a strong Lewis acidity, which is favorable for dehydrogenation during propane aromatization under a N 2 atmosphere. Rodrigues et al [16,17] studied the nature and activity of gallium species for the aromatization of propane under H 2 and concluded that the reduced gallium species, which were obtained via hydrogen reduction of GaO + species (GaH 2 + ), in the impregnated ZSM-5 zeolites serve as the actual active sites for propane activation.…”

Selective Production of Benzene, Toluene and p‐Xylene (BTpX) from Various C1‐3 Feedstocks over ZSM‐5/Silicalite‐1 Core‐Shell Zeolite Catalyst

“…Alkylation and disproportionation of toluene are another route to produce xylenes. So far, zeolite catalysts for BTX synthesis from C 1‐3 feedstocks like methanol (MeOH), dimethyl ether (DME), ethanol (EtOH), acetone and so on have been widely studied . However, separation of p ‐xylene from other isomers is a serious issue because the difference in boiling points between them is too small to separate them by distillation.…”