Ethene oligomerization on H-ZSM-5 in relation to ethoxy species

Abstract

The oligomerization of ethene over H-ZSM-5 was studied by infrared (IR) spectroscopy.

Spectroscopic investigation into the design of solid–acid catalysts for the low temperature dehydration of ethanol

“…The disappearance of this band is also accompanied by the broadening of the band at 2880 cm -1 . This signal has previously been observed when adsorbing ethylene onto ZSM-5, [29] suggesting that, at temperatures as low as 200 o C, ethylene is being formed at the acid sites.…”

“…Further evidence of the presence of the ethoxy species can be seen at 1485, 1450 and 1395 cm -1 . [28,29] These three signals are characteristic of the surface bound ethoxy species confirming its formation at low temperatures (< 150 o C). [29] This last observation suggests that is commonly attributed to methyl rocking of C-C-O-C-C species, which suggests the early (low temperature) formation of diethyl ether species.…”

“…[28,29] These three signals are characteristic of the surface bound ethoxy species confirming its formation at low temperatures (< 150 o C). [29] This last observation suggests that is commonly attributed to methyl rocking of C-C-O-C-C species, which suggests the early (low temperature) formation of diethyl ether species. [24,25,30] It is noted that other bands may also be attributed to diethyl ether, though these bands (2982, 2875, 1485, 1450 and 1395 cm -1 ) typically overlap with ethanol and the ethoxy species.…”

“…This is accompanied by a change in the 3000 to 2880 cm -1 region where the intensity of the peaks at 2903 and 2875 cm -1 decrease as the signal at 2938 cm -1 increases. [24,29] As these signals are still present above 200 o C, they are attributed to the chemisorbed ethoxy species. This is likely due to a decrease in all four of the ethanol peaks (2982, 2938, 2903 and 2875 cm -1 ), and an increase in the ethoxy signal (2938 and 2982 cm 1 ).…”

A density functional theory study on ethylene formation and conversion over P modified ZSM-5

“…21 Currently, many researchers base their studies of ethylene dimerization on the stepwise and concerted mechanisms. [21][22][23][24][25] Zhang Jia et al conducted a theoretical study on the stepwise pathway of dimerization reaction and concerted dimerization reaction pathway of ethylene on HZSM-5. 26 The calculation results showed that the concerted reaction needs more activation energy, and thus the dimerization reaction of ethylene on HZSM-5 occurs as the stepwise reaction, in which in the first step, the ethylene molecule is protonated as the rate-limiting step.…”