Departmental Papers (CBE)

Document Type

Journal Article

Date of this Version

April 2004

Comments

Postprint version. Published in Journal of Molecular Catalysis A: Chemical, Volume 212, Issues 1-2, 2 April 2004, pages 309-314.
Publisher URL: http://dx.doi.org/10.1016/j.molcata.2003.11.015

Abstract

We have studied the vapor-phase reaction of acetic acid with propene over H-[Al]ZSM-5 and H-[Fe]ZSM-5 molecular sieves between 425 and 600 K, for acetic acid partial pressures of 25 to 50 Torr, with propene:acetic acid ratios between 1 and 4. Reasonable conversions were obtained above 450 K. Both H-[Fe]ZSM-5 and H-[Al]ZSM-5 showed high activities at 450 K, with selectivities to propyl acetates of ~90% using a propene:acetic acid ratio of 2 and ketones formed by dehydration of the acetates making up most of the remaining products. The reaction rate was completely stable at 450 K for at least 20 h, and the product distribution was insensitive to the reactant feed ratio for a propene:acetic acid ratio above 2. On H-[Fe]ZSM-5, dehydration of the acetates became increasingly important at higher temperatures, with the selectivity to ketones approaching 80% at 525 K. At still higher temperatures, reaction pathways that did not involve propyl acetates became important. The high selectivity for forming propyl acetates and the absence of olefin oligomerization is believed to result from having the acid sites occupied (saturated) by acetic acid. Finally, the acid-site density measured on H-[Fe]ZSM-5 after weeks of catalyst testing remained the same as the initial site density, showing that this material has sufficient stability for fine-chemicals synthesis.

Keywords

Acetic acid, Propene, Propyl acetate, H-ZSM-5, H-[Fe]ZSM-5, Brønsted acidity

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Date Posted: 06 February 2006

This document has been peer reviewed.