There is an increasing commercial interest in finding alternative ways to produce phenol that overcome the disadvantages of the current cumene process used to synthesize phenol. The drivers for the change are both economic and environmental. A direct oxidation route for producing phenol
from benzene is based on using N2O as an oxidizing agent in the gas phase
in the presence of modified Fe-ZSM5 zeolite. One of the main objectives was
to examine the effect of different Si/Al ratios, temperatures and iron content on
the selective conversion of benzene to phenol with a desire to achieve high
selectivity and minimise catalyst deactivation. Also one of the research
objectives was to identify the active sites in the catalyst and design the
catalyst which is able to delay coke formation. The methodology was to
incorporate iron directly at extra-framework positions via liquid ion-exchange.
In this project, a series of selective Fe-ZSM5 catalysts with different Si/Al
ratios have been prepared and evaluated for selective formation of phenol.
The catalyst samples were characterized (by Atomic Absorption Spectroscopy
(AAS), Malvern mastersizer and Nitrogen adsorption using N2 at 77 K via
Micromeritics to determine the elemental composition, average particle size,
BET surface area and pore size distribution) and their catalytic activities
compared. A quantitative comparison between the number of active sites
using isopropylamine decomposition method shows that active sites increase
as the Si/Al ratio increased and also as the iron content increased. (Continues...).
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.