(582ae) Hydrogenation of Phenol to Cyclohexanone Via Tubular Nanofiber Supported Catalyst

Hydrogenation
of phenol to cyclohexanone via tubular nanofiber supported catalyst

Lin
Pan and G. G Chase

Abstract

Cyclohexanone is the key
intermediate in the manufacture of nylon-6 and nylon-66. The hydrogenation of
phenol process is commonly used in industry due to the lower temperature
requirement and less byproducts generation compared with the oxidation of
cyclohexane¹. The hydrogenation process could happen through two path
ways: one step or two step reaction. The one step reaction (Figure 1) is applied
here. The hydrogenation can be conducted either in liquid phase (low
temperature) or gas phase (high temperature). The temperature needed for the
one-step reaction is lower than that needed for the two step reaction².

The liquid phase reaction is preferred
in our work because the operation conditions are easier to establish and
control in a laboratory environment. Researchers have evaluated many catalysts
for use in liquid phase phenol hydrogenation. The catalysts have been applied
as dispersed particles in the liquid as a pseudo homogeneous reaction and the
catalyst particles have been immobilized on monolithic support structures for
heterogeneous reaction. Each approach has its advantages and disadvantages. In
general, hydrogen bubbles must transport through the liquid phase to the
catalyst particles for the reaction to occur. The transport of individual
bubbles to a catalyst particle is somewhat random and challenging to predict. To
our knowledge no previous research has evaluated the performance of catalyst
supported on a gas-liquid barrier membrane. The membrane is in the form of a
hollow tube. Hydrogen gas flows through the inside of the tube and aqueous
phenol flows on the outside of the tube. The objective of this work is to the
feasibility and to evaluate the reaction kinetics of a prototype tubular
membrane reactor shown in Figure 2. The membrane is fabricated using electrospinning
techniques.

Figure 1. The one step reaction
pathway of phenol hydrogenation

Figure 2. Designed reactor of
tubular hydrogenation reactor

Reference

1.    
Liu, Huizhen,
et al. "Selective phenol hydrogenation to cyclohexanone over a dual
supported Pd–Lewis acid catalyst." Science 326.5957 (2009):
1250-1252.

2.    
Shore, Sheldon
G., et al. "Vapor phase hydrogenation of phenol over silica supported Pd
and Pd-Yb catalysts." Catalysis Communications 3.2 (2002):
77-84.