Study on Catalytic Hydrogenation of Cardanol
|Keywords||cardanol catalytic hydrogenation Kinetics density viscosity solubility UNIFAC model separation|
Cardanol, the major components of cashew nut shell liquid, is abundant and has high values of development and application.But cardanol will darken and polymerize because there are 1～3 C=C in the unsaturated side chain of the chief constituents of cardanol.Consequently, it is very important to systematically investigate cardanol, and improve its stability and applicability.It was proved by preliminary experiment that hydrogenation could improve the antioxidizability and anti-polymerizality of cardanol.In this work, the catalytic hydrogenation reaction of cardanol was carried out by using Raney nickel as catalyst. Then the effects of the reaction temperature, pressure of hydrogen, reaction time, the amount of catalyst and stirred speed on the conversion were systematically studied by the method of homogeneous design and One-factor experimental design. As the results showed us,when the temperature is 118℃,reaction time is 4.5 h, the amount of catalyst is 1.38% of the material quantity, the pressure of hydrogen is 3.6 MPa, ard the stirred speed is 400 r·min-1,the conversion can reach 100%. The result affords theoretical support for industrialization.The experiment of catalytic hydrogenation of cardanol was carried out on Raney nickel catalyst at the condition of eliminating internal and external diffusion. The kinetics data have been collected experimentally from 2.5 to 4 MPa and 373.15 to 393.15 K, respectively. Then the intrinsic kinetics of catalytic hydrogenation reaction of cardanol was studied, and the appropriate intrinsic kinetics model was selected to be regressed and tested reliable by experimental data. It was proved that the catalytic hydrogenation of cardanol is second order irreversible series-parallel reaction. The kinetic parameters (Ea, K0) and kinetic equation were obtained through fitting, the equations are as follows: These results improve the hydrogenation reaction consecutive parallel reaction kinetics theory, and provide a theoretical basis for industrial design.The data of saturation vapor pressure was determinated and used to fit Antoine equation, and the average molar heat of vaporization was calculated by Benoit Pierre Emile Clapeyron-Rudolph Clausius equation.Densities and viscosities of the binary mixtures of 3-pentadecylphenol with ethanol and n-heptane were determined by using Ostwald-Sprengel-type picnometers and Ubbelohde capillary viscometer under atmospheric pressure. The temperature was range from 283.15 K-308.15 K. The experimental values of densities and viscosities were correlated by the VTF equation, and then parameters were fitted and used to obtain calculated values.The total average standard deviations between the measured and fitted values were less than 1.5%.The results provide thermodynamic data for the separation and purification of 3-pentadecylphenol in industrialized operation.Solid-liquid equilibrium data is important foundation of the separation and purification. In this wok, dynamic method was used to determine the solubilities of 3-pentadecylphenol in ethanol, acetone, toluene, ethyl acetate chloroform, ethoxyethane, tetrachloromethane, n-heptane, and n-hexane, which didn’t appear in related literatures.The results are correlated withλh equation, Apelblat equation, Wilson equation, and UNIFAC model, then enthalpy of solution and enthalpy of excess were calculated. Because the average deviation of the values predicted by separate original UNIFAC model from the experimental valves is 55.87%, one new group was defined as PhOHCH2 in this article. With the method of procedural seeking optimum, the volume parameters and surface-area parameters of new groups were obtained, and the new interaction parameters were also obtained. Conseqently, the modified UNIFAC can perfectly predict the solubilities of the systems in this work, and the total average relative error is 7.95%.Through analysing the experimental data of solubilities, the solubility of 3-pentadecylphenol in n-heptane changes significantly by temperature, this is good for the crystallization of 3-pentadecylphenol.In order to determine better crystallization conditions, the metastable zone width of the 3-pentadecylphenol was determined by mensurating super-solubility in n-heptane. The results show that the metastable state in n-heptane decreases when the temperature increasing. The range of metastable width is 1.6K～4.33 K. Under experimental conditions, the effects of the amount of solvent, chilling temperature, stirred speed and crystal frequency on the conversion were systematically studied by the method of homogeneous design.3-pentadecylphenol can be obtained through vacuum distillation and two-step crystallization, and its purity can reach more than 99.5%.The product was characterized by MS,IR and H-NMR, and identified as 3-pentadecylphenol.This work established solid theoretical foundation of the industrial production of 3-pentadecylphenol.