The hydrogenation of phenol can take place either in vapor or in liquid phase.
Both processes today employ palladium - based catalyst, but with different supports
and activators.
In vapor - phase phenol hydrogenation the operating conditions are usually tem-
peratures of 140 – 170 ° C and a pressure slightly above atmospheric [1, 11] . Older
processes based on nickel - type catalyst have two distinct reaction steps, namely
full hydrogenation to cyclohexanol followed by dehydrogenation. Modern pro-
cesses based on palladium - type catalysts can achieve over 90% yield in cyclohexa-
none in a single reactor. The product is mainly the KA - oil, but more cyclohexanol
may be supplied on demand. The suppression of the dehydrogenation reactor
including expensive equipment for achieving high temperatures represents a sig-
nifi cant economic advantage.