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Alcohol Dehydrations over ZSM‐5 Type Zeolites, Montmorillonite Clays and Pillared Montmorillonites
Author(s) -
Lin HungEn,
Ko AnNan
Publication year - 2000
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200000068
Subject(s) - chemistry , montmorillonite , catalysis , calcination , alcohol , acid strength , dehydration , dehydration reaction , inorganic chemistry , zeolite , zsm 5 , ethanol , propanol , adsorption , carbenium ion , nuclear chemistry , organic chemistry , biochemistry
The reactions of aliphatic alcohols (ethanol, 1‐propanol and 2‐propanol) were studied at 1 atm and 150–300°C by using ZSM‐5 type zeolites, montmorillonites, and pillared montmorillonites. With H‐ZSM‐5 (X) Y zeolites, the total number of acid sites increases with a decrease of Si0 2 /Al 2 O 3 molar ratio (X) and calcining temperature (Y). In addition, apparent increase in the ratio of strong to weak acid sites occurs with increasing X or decreasing Y. The acidities of M‐ZSM‐5 (51) 600 zeolites follow the sequence: Li = Na < K < Cs. Pillared clays exhibit both larger surface areas and more acid sites than the clays. The alcohol conversions decrease in the order of 2‐propanol < 1‐propanol < ethanol, in accordance with the relative stabilities of the corresponding carbenium ions. The catalytic activities are parallel to the total number of catalyst acid sites and the reaction temperature. Favorable formations of ethers are observed at low reaction temperature and small contact time on a catalyst with weak acid strength. Simple consecutive reactions and combined pathway of parallel and consecutive reactions are proposed, respectively, for the dehydration of ethanol and for those of 1‐propanol and 2‐propanol.