2.2.2 Kinetic study
The kinetic studies were conducted on a plug-flow fixed-bed reactor. The
experimental set-up is depicted in Figure S1. The tubular reactor with
the inner diameter of 4 mm and length of 10 cm was made of 316L
stainless steel. Amberlyst 15 was dried at 378 K for 24 h until the
content of water in the catalyst was below 1% as determined by the Karl
Fischer method. Then, 1.0 g of the catalyst (d p< 0.5 mm) diluted with quartz sand (0.1 mm <d p < 0.8 mm) to avoid temperature
runaway was loaded in the reaction zone. The remaining space was filled
with quartz sand. Prior to the reaction, the catalyst bed was further
purged with N2 at 373 K to remove water. After being
cooled down to below the reaction temperature, cyclohexene and acetic
acid with a prescribed molar ratio was continuously pumped into the
reactor at a flow rate 60 g h–1. Each study was last
for 2–3 h, during which the effluent was sampled several times to
ensure that the reaction has reached the steady state. The reaction rate
is calculated as follows:
in which C6 represents cyclohexene, while C6E represents the resulting
ester. x represents the molar fraction, which is dimensionless.F is the total molar flow rate in mol h–1. AndW represents the catalyst mass with unit in kg. Both the
thermodynamic and kinetic studies were repeated at least twice.