Direct alkylation of toluene with ethane on bifunctional zeolite catalysts

Selectivity Enhancement to the Exclusive Formation of Ethyltoluenes and Hydrogen During Dehydroalkylation of Toluene with Ethane

“…Due to the extra-framework Na + ions present within the channels of the 0.4Pt/H-ZSM-5 catalyst, the pore size of the channels is slightly reduced. Therefore, o-ethyltoluene may exclusively be formed on the external surface even at the highest contact times in this study, thus giving rise to smaller relative o-ethyltoluene selectivities than previously observed [14]. After 2 h on stream and at the shortest contact time of 0.12 h, the meta-to para-isomer ratio is about 1.5, increasing to 2 and staying at this value at higher contact times.…”

“…Ethane (99.95 vol.%, Westfalen AG) and nitrogen (99.999 vol.%, Westfalen AG) were fed with an _ n nitrogen = _ n ethane ratio of approximately 5 through a toluene ([99.9%, Merck) saturator containing Chromosorb P-NAW (Macherey-Nagel). Nitrogen was used as an internal standard but also to ensure that a relatively low _ n ethane = _ n toluene feed ratio of 7 ± 1 could be achieved at the high pressure applied (the optimum _ n ethane = _ n toluene feed ratio is about 4 [14]). The reaction was carried out at a total pressure of 30 bar and a reaction temperature of (350 ± 2)°C.…”

“…Although the alkylation of aromatics with alkanes is thermodynamically impaired [13][14][15], high conversions, even surpassing equilibrium, have been reported [13,15]. However, these high conversions come at the expense of severe losses in selectivity.…”

“…Zeolites have especially gained more importance as selective catalysts for alkylation and disproportionation reactions of aromatics [7][8][9]. Recently, propane [10][11][12][13] and ethane [14][15][16] have been investigated as alkylating agents for benzene and toluene on metal-loaded (including Ga and platinum group metals) zeolite catalysts. The bifunctionality is required since an effective dehydroalkylation catalyst typically demands two types of active sites: a metal site for the dehydrogenation of the alkane and an acid site for the alkylation of the alkene intermediate with the aromatic molecule [17].…”

Benzene Alkylation with Propane over Mo Modified HZSM-5

“…Over the past decade, metal-containing zeolites were reported to be potential catalysts for production of alkylbenzenes from benzene and propane. The attention was mainly focused on HZSM-5 zeolite usually modified by metal species such as Ga or Pt [4][5][6][7][8][9][10][11][12][13][14]. Over Pt/HZSM-5, the major products observed include C 1 -C 4 gases, toluene (T), ethylbenzene (EB), isopropylbenzene (iPB), n-propylbenzene (nPB), and other products (in smaller amounts involving alkyl-and polyalkylbenzenes, naphthalene, and its derivatives) [6].…”