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Significant Influence of Zn on Activation of the C‐H Bonds of Small Alkanes by Brønsted Acid Sites of Zeolite
Author(s) -
Stepanov Alexander G.,
Arzumanov Sergei S.,
Gabrienko Anton A.,
Parmon Valentin N.,
Ivanova Irina I.,
Freude Dieter
Publication year - 2008
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200800569
Subject(s) - chemistry , alkane , zeolite , catalysis , butane , activation energy , propane , brønsted–lowry acid–base theory , inorganic chemistry , adsorption , hydrogen bond , organic chemistry , molecule
Herein, we analyze earlier obtained and new data about peculiarities of the H/D hydrogen exchange of small C 1 – n ‐C 4 alkanes on Zn‐modified high‐silica zeolites ZSM‐5 and BEA in comparison with the exchange for corresponding purely acidic forms of these zeolites. This allows us to identify an evident promoting effect of Zn on the activation of CH bonds of alkanes by zeolite Brønsted sites. The effect of Zn is demonstrated by observing the regioselectivity of the H/D exchange for propane and n‐ butane as well as by the increase in the rate and a decrease in the apparent activation energy of the exchange for all C 1 – n ‐C 4 alkanes upon modification of zeolites with Zn. The influence of Zn on alkane activation has been rationalized by dissociative adsorption of alkanes on Zn oxide species inside zeolite pores, which precedes the interaction of alkane with Brønsted acid sites.