Skeletal Ni Prepared By Quenching Technique And Nano-Sized Pt/C For The Hydrogenation Of Aromatic Ring And Nitro Group

Skeletal Ni(S-Ni) with the sponge-like structure is a kind of well-known catalyst widely used in many hydrogenation processes. S-Ni offers several advantages such as easy separation, purification and recycling procedure. How to improve the activity, selectivity and life time of the S-Ni has been attracting worldwide attention for decades. The skeletal Ni prepared by rapidly quenching technique(QS-Ni), was a sort of effective and environmentally benign catalyst. In petrochemical industry, QS-Ni has been applied for the hydrorefining of hexanolactam using magnetically stabilized bed reactor. However, very limited knowledge has been accumulated on the application of QS-Ni in fine chemicals. In this thesis, the S-Ni and QS-Ni were separately obtained by the conventional method and rapidly quenching technique. We studied typical applications of S-Ni and QS-Ni in the hydrogenation of aromatic rings and nitro groups. Results showed that the QS-Ni was much more active than S-Ni.1. The application of QS-Ni in the hydrogenation of aromatic ring was studied by the selective hydrogenation of biphenyl(BP) to cyclohexylbenzene(CHB).The QS-Ni showed excellent activity and selectivity to CHB. Excellent 100% BP conversion and 99.4% CHB selectivity were obtained in one-pot reaction under 70℃and 1.0MPa H2 pressure. Effects of different reaction parameters were also investigated and the rate constant at different temperature was calculated. The activation energy for BP and CHB hydrogenation separately were 36.1 kJ·mol-1 and 44.7kJ·mol-1. The molecule structures of BP and CHB were optimized to one of their minimum-energy isomers using the Gaussian03 quantum chemistry code and frequency calculation was performed. Results showed that the dihedral of BP (40～51°) is smaller than that of CHB(90°). The geometric effect may play important roles in controlling the selectivity to CHB.2. S-Ni catalyst was used for the efficient deep hydrogenation of C9 Petroleum resin (C9PR). The reaction was conducted at 180℃and 7.0MPa H2 pressure. The products are colorless (less than 1# by Fe-Co colorimeter) with excellent thermal stability, light resistance and compatibility with other resins. The C9PR hydrogenation in pilot scale was successfully finished in 50L autoclave. After making use of C9-solvent and QS-Ni, the production cost was remarkably decreased. The consumed amounts of QS-Ni decreased 23.5% comparing with that of S-Ni. Based on the experimental results, the C9PR hydrogenation process in commercial scale had been successfully running in Daqing Huake Co. Ltd..3. The activity and life time of S-Ni and QS-Ni were compared in the hydrogenation of 3-(β-nitro-benzenesulfonyl)-ethanol to 3-(β-amino-benzenesulfonyl)-ethanol. Under 70℃and 1.0MPa H2 pressure, the conversion was 100% and the selectivity was higher than 97% over QS-Ni. The QS-Ni showed better performance than S-Ni and was repeatedly recycled for 30 times, when the activity still remained. Based on the above results, the S-Ni and QS-Ni were used for the hydrogenation of 3-(β-nitro-benzenesulfonyl)-ethanol industrially. The unit consumption of QS-Ni(1.23%) was lower than the consumption of S-Ni(2.10%). The component concentration during the reaction process was monitored by HPLC and the reaction mechanism was studied.4. The QS-Ni was used for the preparation of N-arylhydroxylamine(HA) by catalytic hydrogenation method, however, the selectivity was low and far behind satisfaction. The Pt colloid supported on carbon was tested to be an active and selective catalyst for the partial hydrogenation of nitroaromatics to the corresponding HAs, indicating this was an additive-free green catalytic approach for synthesis of HA. In order to explore the hydrogenation reaction mechanism of the formation of HA, m-dinitrobenzene was chosen as a model substrate. Under 10℃and 0.1 MPa H2 pressure, the maximum yield of N-(3-nitro-phenyl)-hydroxylamine was 92.3% at 100% conversion.