609-26-7Relevant articles and documents
Alkene oligomerization process
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Page 5-6, (2008/06/13)
A process for oligomerising alkenes having from 3 to 6 carbon atoms which comprises contacting a feedstock comprising a) one or several alkenes having x carbon atoms, and, b) optionally, one or several alkenes having y carbon atoms, x and y being different, with a catalyst containing a zeolite of the MFS structure type, under conditions to obtain selectively oligomeric product containing predominant amounts of certain oligomers. The process is carried out at a temperature comprised between 125 and 175° C. when the feedstock contains only alkenes with 3 carbon atoms and between 140 and 240° C., preferably between 140 and 200° C. when the feedstock contains comprises at least one alkene with 4 or more carbon atoms.
Effect of zeolite structure and acidity on the product selectivity and reaction mechanism for n-octane hydroisomerization and hydrocracking
Zhang, Wenmin,Smirniotis, Panagiotis G.
, p. 400 - 416 (2007/10/03)
The activity, product selectivity, and stability of a series of bifunctional zeolite catalysts, primary ZSM-12, USY, and β-zeolite, with different Si/Al ratios were compared for the hydroisomerization and hydrocracking of n-octane. The performance of L-zeolite and mordenite was examined to a lesser extent as well. It was found that the activity per acidic site decreases at the initial stage (1 h on stream) in the following order: ZSM-12 > β-zeolite > mordenite > USY > L-zeolite. For extended periods of operation, the activity of ZSM-12 remains unchanged. The superior stability of ZSM-12 even under accelerating coking conditions results from its unique pore structure, which does not favor coke formation. Its one-dimensional noninterpenetrating puckered channels (5.5 × 6.1 A) act as perfect tubes, which do not trap coke precursors. The branched product selectivity increases with the increase in Bronsted acid site strength of the zeolite catalysts, and thus hydroisomerization is favored at the expense of cracking at a higher Bronsted acid strength. USY-5.8 (CBV-712) showed relatively high initial activity with respect to other USYs. This is probably related to its high surface Al content. The Bronsted acid strength of the USY zeolites decreases in the order USY-2.6 > USY-28 > USY-5.8. The 2,2-DMC6 and 3,3-DMC6 isomers are not favored as final products due to their bulky molecular size even in USY. In addition, the 2,2-DMC6 species is more abundant than 3,3-DMC6 because the rate of isomerization by PCP intermediates decreases in the following order: 2-MC7 > 3-MC7 > 4-MC7. The 2,3-DMC6 concentration is much higher than that predicted by equilibrium, which indicates that the interconversion of 2,3-DMC6 to other dibranched isomers is not preferred. The i-C4/n-C4 ratio detected depends on both the reaction temperature and zeolite pore structure/acidity. Aluminium content determines the type of β-scission. For zeolites with a high concentration of acid sites (Si/Ai about 30), type A β-scission dominates at low temperature, while at lower Al content, type A, B, and C β-scissions are equally important.
