Study On Catalytic Disproportionation Of Turpentine

The reaction kinetics of catalytic disproportionation of turpentine as raw material was investigated, and on-line tracking analysis for the changes of major chemical components during catalytic disproportionation of turpentine was studied. Meanwhile, the optimal process conditions for preparation of p-cymene from turpentine were searched. After main chemical components of disproportionated products were determined, we discussed the reaction kinetic model of catalytic disproportionation of turpentine. The main contents as follows.CP-3380 gas chromatography of Varian in America was chosen to analyze the components of disproportionated turpentine. The settled conditions of chromatogram used were: BP×5 capeillary column of chromatogram, the flow rate of nitrogen as carrier gas 45mL·min^-1, the flow rate of hydrogen 30mL·min^-1, the flow rate of air 300mL·min^-1, pressure before columniation 0.07MPa, temperature of check machine 523.15K, temperature of boil room 523.15K, split stream ratio 50:1, sample volume 0.01μL, range 10, and raising temperature by five steps programThe results showed that the materials ratio, the amounts of catalyst, stirring rate, reaction temperature and reaction time were the main influencing factors. By uniform design method, the influence of those five factors above on the disproportionation of turpentine were studied further. So the optimal reaction conditions have been determined by uniform design software as follows: materials ratio of turpentine to sulfate 1.0, the amounts of catalyst 0.2%, stirring rate 500r·min^-1, reaction temperature 393.15K, reaction time 10h. Under the best processing condition, optimized result was demonstrated by three parallel experiments. Quantity of the disproportionated products were analyzed by capillary column GC Analyse Method, in which the average yield of pinene was 98.03% (mass percent), and the average yield of p-cymene was 61.02% (mass percent).The reaction kinetics of catalytic disproportionation of turpentine over Pd/C catalyst and 20% H₂SO₄ were investigated at temperature 353.15K-393.15K. The kinetic model parameters in Arrhenims equation were also determined, and pre-exponential factors were k₀₁=6.49×10⁹h^-1, k₀₃=3.41×10⁸h^-1, k₀₄=6.35×10¹⁰h^-1, and the activation energies were E_a1=77.86kJ·mol^-1, E_a3=71.33kJ·mol^-1, E_a4=80.18kJ·mor^-1 separately, while the reaction rate constants were confirmed as k₁=6.49×l0⁹exp(-1126.4/T),k₃=3.41×10⁸exp(-1031.9/T),k₄=6.35×10¹⁰exp(-1159.9/T) for opening-ring reaction of bicyclic monoterpene, hydrogenation reaction of bicyclic monoterpene, and dehydrogenation reaction of momocyclic monoterpene respectively. The final results demonstrated that kincrease with temperature increasing. In the scope of the above temperatures monoterpene hydrogenation and dehydrogenation can be regarded as the first order reactions(α₁≈α₃≈α₄≈1). Through proof-tested using the kinetic models and parameters, it was showed that the calculated results were agreed well with the experimental data.