In this work, the evaporation of the liquid cyclohexane is used to remove the heat of reaction in a novel phase transition reactor for hydrogenation of benzene to form cyclohexane under elevated pressure up to 3.0 MPa. The reactor is of fixed-bed with Pd catalyst, 20 mm in diameter and 100 cm in height. The operation conditions are 150 ℃ in inlet temperature, 1.1〜6.9 h^-1 in LHSV and 330〜1910 in volume ratio of hydrogen to liquid. The experimental results show that the conversion of benzene is over than 99.99% and the yield of cyclohexane also over than 99.9% .

A mixture of benzene (accounting for 15%〜25%) and cyclohexane is used as feed to prevent the abrupt temperature rise in the bed. The bed axial temperature distribution indicates the phase transition behavior of the liquid feed which varies from the liquid state, via the mixed phase, and eventually to the gaseous state. So there exists a three phase´s regime in the catalyst bed.