2.2.1 Thermodynamic study
Thermodynamic studies were carried out on METLER TOLEDO RC1 reaction calorimeter fitted with an MP06 medium-pressure 500 mL-capacity glass autoclave. Prior to the reaction, 100 g of Amberlyst 15 were 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. The autoclave containing the catalyst was sealed and pressurized to 0.6 MPa with N2for air tightness test. Then, the autoclave was pressurized to 0.3 MPa, and cyclohexene and acetic acid with a total weight of 200 g were pumped into the autoclave with a prescribed acetic acid/cyclohexene ratio. After being heated to the desired temperature for a certain period, the liquid was sampled and analyzed gas chromatographically. The attainment of the equilibrium of esterification was judged based on the detection that the compositions of the liquid in two successive analyses were identical.