CO2 poisoning effect on HY zeolite dehydration catalyst
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The poisoning effect of CO2 on a HY catalyst for the dehydration of 2-(2-hydroxyethyl)-pyridine (HEP) to 2-vinylpyridine (VP) has been investigated by FT-IR analysis in the presence and absence of pyridine. CO2 was found to adsorb on sites not occupied by pyridine,i.e. on weak basic sites accompanying the strongly acidic sites, characteristic of Y zeolites in the protonated form. When the basic sites are occupied by preadsorbed CO2, HEP dehydration cannot take place any more through the minor mechanism, involving a couple of acid-base sites, and the reaction proceeds only through the major mechanism, involving a carbocation intermediate, on Brönsted acid sites only.
KeywordsHY zeolite alcohol dehydration CO2 poisoning effect
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