Study Of The Catalytic Hydrogenation Of Turpentine Monoterpene Over The Modified Regeneration Of Spent Fluid Catalytic Cracking Catalyst

Spent fluid catalytic cracking catalysts (SFCC) are degraded as the surface of which contaminated by the heavy metals (Ni、V and Fe) and coke. In addition to discharge to the air directly, a large number of spent catalyst are dumped into landfills, resulting in the pollution of ground water and soil, as well as posing a high level of resource waste. Turpentine oil, a natural essential oil obtained via the renewable biomass resource pine oleoresin. Pinane, the production of the hydrogenation of turpentine can be used as a versatile feedstock for terpenoid spice and a wide variety of chemicals. In this paper, a novel metal-free catalyst was prepared by utilizing nickel deposited in SFCC directly and supplementing some new nickel onto the SFCC (a catalyst supporter) and used to the hydrogenation of turpentine monoterpene and the thermodynamic and kinetic analysis. The process will provide a theoretical basis for the development of high value-added production obtained via turpentine and the application of SFCC. The main contents of the study are as follows:The coke deposited on the surface and the pores of SFCC was removed via the method of high temperature roasting oxidation, then the non-noble metal Ni/SFCC was prepared by solution impregnation, using the SFCC after activation and regeneration as the supporter. The surface area, phase, morphology, nickel loading, the group structure and the valence state of nickel of the prepared catalyst was characterized by BET, XRD, SEM-EDS, FT-IR, XPS and FT-IR. The result of BET indicated that the specific surface area increased after calcination; It can be seen from the SEM that Ni crystal presented rhombus structure with the elemental form; XRD analysis showed that the SFCC supported nickel catalyst is composed by ZSM-5, Al2O3 and Y molecular sieve, which is excellent catalyst supporter material, Ni and NiO of Ni/SFCC and its precursor existed on the catalyst as the form of crystalline grain; The FT-IR analysis stated that there is no covalent bond of Si-O(H)-Ni, and the interaction is weak; XPS analysis illustrated that Ni existed in SFCC in the form of oxidation state of +2 valent state, however, in the SFCC supported Ni catalyst Ni is appeared in the form of both Ni2+ and Ni3+. The result of repeated use of the catalyst displayed the structure of SFCC is stable as the catalyst activity and selectivity have not changed obviously after 13 times of use with the conversion of the content of the turpentine monoterpene pinene 93.68% and the selectivity of cis-pinane 93.10%, which indicated that the structure of the self-synthetic Ni/SFCC is stable.The conversion of pinene and selectivity of pinane were chosen as the evaluation index to design the single factor experiment, and the effects of the catalyst dosage, reaction temperature and reaction pressure etc. on the hydrogenation of turpentine monoterpene over Ni/SFCC were investigated at a 2-L FYX-2G stainless steel autoclave. The process of turpentine monoterpene was optimized via the method of response surface experimental design. The Box-design result stated that the optimal conditions of reaction time, temperature, hydrogen pressure, and stirring speed were found to be 2.3 h, 110℃,3.2 MPa and 540 rpm, respectively, with the conversion of the content of the turpentine monoterpene pinene 98.90% and the selectivity of cis-pinane 94.00%. Effects of temperature and reaction time on conversion and selectivity of pinane pinene was significant.Taking pinene, the content of turpentine monoterpene as the model compound, the hydrogenation of pinene as the probe reaction, the thermodynamical analysis of the hydrogenation of pinene was conducted using the group contribution method, and the parameters of the thermomechanic were calculated at the temperature of 363～413 K. Besides, the effects of temperature and pressure on the hydrogenation of pinene were also investigated. The result indicated that the enthalpies of the catalytic hydrogenation of pinene were-112.96～-112.16 kJ·mol-1, and the reaction is exothermic reaction; the Gibbs free energy of the catalytic hydrogenation of pinene were-34.59～-21.01 kJ·mol-1, and the reaction is a spontaneous process; The reaction equilibrium constant was 453～94515 under constant pressure.The internal and external diffusion effects in the hydrogenation of turpentine monoterpene process over Ni/SFCC were conducted via the experiment of the size and speed at the chemical kinetic control region on 373～ 393 K and 2～6 MPa. The changes of concentration of the component with the time were studied using gas chromatography online tracking system. The kinetic models of Langmuir-Hinshewood hyperbolic type (abbreviations as L-H) and Power-Law power type (abbreviations as P-L) of the hydrogenation of turpentine monoterpene were established by the diagnosis and the Levenberg-Marquart method of MATLAB. The most suitable model was: and the surface reaction of adsorbed hydrogen atoms and pinene molecules over nickel catalyst was the rate-controlling step. The power law rate equation showed that the hydrogenation of turpentine was parallel reaction, and the activation energies for the hydrogenation of pinenes to cis- and trans-pinane were 59.42 kJ·mol-1 and 98.38 kJ·mol-1, respectively. The kinetic models described the hydrogenation of turpentine monoterpene well with satisfactory accuracy compared to experimental observations.