Study On Catalyic Performance Of Nano- Porous Chitosan-Acylated By Metal Tetrakis(4-Carboxylphenyl)Porphyrins

In order to imitate the catalytic cavity site of Cytochrome P-450 enzyme, metal tetrakis(4-carboxylphenyl)porphyrins[M TCPPs] were synthesized and nano-porpus chitpsan [np-CTS] was prepared, and then the M TCPPs were acylated on np-CTS into biomimetic catalytic materials, M TCPPs/np-CTS. The M TCPPs/np-CTS were characterized by various spectroscopic techniques. The catalytic activities for an oxidation of ethylbenzene over the materials were researched. The experimental results indicate that the M TCPPs/np-CTS provided a catalytic cavity site to mimick Cytochrome P-450 enzyme and gave fully play the best catalytic activity of the supported metalloporphyrins. Only amount of 1.0 mg of the core catalyst, M TCPP in the employed catalytic material can be used for 5 times in the ethylbenzene oxidation. This greatly improved the catalytic efficiency of the immobilized M TCPP. Major contents of this thesis are listed as follows:1. According to some literiture methods, the M TCPPs were synthesized and nano-porous or nonporous chitosan(np-and nonp-CTS) were prepared, and then the former were covalently binded to the latter forming the biomimetic catalytic materials, M TCPPs/np-CTS and M TCPPs/nonp-CTS, respectively.2. Ultraviolet-visible spectra (UV-vis), scanning electron microscope (SEM), Specific surface area (BET), Fourier transform infrared spectra (FT-IR), X-ray Diffraction (XRD) and Thermo-gravimetric analysis (TG) patterns and other testing methods were applied to characterize the catalytic materials in order to make sure the structure of the M TCPPs/np-CTS and M TCPPs/nonp-CTS for explaining their catalytic properties.3. A catalysis for the aerobic oxidation of ethylbenzene over the catalytic materials was explored, the effect of the catalytic reaction conditions such as reaction temperature, air pressure, catalyst amount and reaction time on their catalytic properties were studied in detail. Optimal reaction conditions of the oxidation over the catalytic materials and the catalytic properties of the reused M TCPPs/np-CTS under the best reaction conditions were also researched. The catalytic power for the kind catalytic materials are synthetically evaluated by comparing the catalytic efficency of M TCPPs/np-CTS with that of M TCPPs/nonp-CTS.4. Experimental results show that compared with the unsupported catalysts, the catalytic performances of the nano-porous chitosan-grafted metalloporphyrins can be fully played. Every catalyst can be reused 5 times for the oxidation. Therefore their catalytic efficency were better raised. The order of catalytic activity and efficiency for them is as follows:Co TCPP/np-CTS> Fe TCPP/np-CTS> Mn TCPP/np-CTS. On average, for each gram of cobalt tetrakis(4-carboxylphenyl)porphyrin grafted in the nano-porous chitosan, the catalyst can be used 5 times for the oxidation, with 19.57% yields of ketone and alcohl,70.12% selectivity to ketone and alcohl and catalyst turnover numbers (TON) of 7.11×105.5. According to experimental results and relative literatures, a possible mechanism for the aerobic oxidation of ethylbenzene over M TCPP/np- or nonp-CTS is deduced.