The Preparation Of Novel NiFe-LDHs And The Study Of Their Catalytic Permance

As we all know, precious metal catalysts is expensive, so it is of great value to prepare non-precious metal catalysts with low cost and excellent performance ,which is well conform to green chemistry. The highly dispersed metal-based catalyst could be obtained by calcining LDH precursors.Nitrogen-doped carbon material owns higher electron transport properties due to the doping of electron-rich nitrogen, which can be derived from calcining melamine. Carbon-coated structure supported NiFe@CN catalyst was prepared by pyrolyzation NiFe-LDH/melamine hybrid , it showed novel structure of core-shell and performed well in the reaction of o-chlorobenzene selectively catalytic hydrogenation to o-CAN. Pd/LDH catalyst is prepared using flower-like NiFe-LDH as support and the performance for the hydrogenation of o-nitrotoluene is studied.In this work, we firstly prepared NiFe-LDH precursors with different Ni/Fe ratios and Ni(OH)2 with the method of nucleation crystallization separation method, and mixed them with melamine respectively and uniformly, then calcined them in N2. After the self-reduction process, we obtained the NiFe@CN catalyst successfully. We study the catalytic performance of different catalysts next. At the same time ,we synthesised flower-like NiFe-LDH with high surface area using complex-agent, and prepared Pd/LDH catalyst with the protection of PVP ,the flower-like NiFe-LDH is used as support. We compared it with the NiFe-LDH support synthesized by nucleation crystallization separation method to study the effect of catalyst support on the catalytic performance.(?)Based on the lattice orientation effect and the lowest energy effect of LDHs, calcinated NiFe-LDH/melamine precursor in N2 atmosphere and obtained NiFe@CN catalyst with core-shell structure. Through the characterization of XRD?STEM?XPS?H2-TPD?CO2-TPD and so on we studied the relationship of structure and catalytic relationship of catalysts. In the process of O-CAN selective hydrogenation ,the yield can reach nearly 99.5% with convertion of 100% under mild condition (0.5MPa,80?).It was used for a series of aromatic nitro compounds selectively catalytic hydrogenation and the performance was wonderful,which proved the strong universality of catalysts.(?) Taking full advantage of the flower-like NiFe-LDH with high surface area prepared Pd/LDH catalyst with the protection of PVP , compared it with the NiFe-LDH support synthesized by nucleation crystallization separation method to study the effect of catalyst support on the catalytic performance through the characterization of XRD?BET?XPS?TEM and so on .The catalysts with flower-like NiFe-LDH suipport performed more outstandingly .Test results showed that the palladium nanoparticles on the flower hydrotalcite was smaller, and the distribution was more even, the interaction between palladium particles and flower hydrotalcite was stronger.