The Preparation Of NiTi-LDHs And The Study Of Their Catalytic Performance

The heterogeneous nickel based catalysts always suffer from the agglomerate of the active component and the inactivation in the circulation experiment. The introduction of nickel element to the layer double hydroxides (LDHs) plate makes it highly disperse on the plate by atomic scale and the LDHs with nickel were calcined and reduced to obtain the highly dispersed nickel based catalysts. And, the highly dispersed nickel based catalysts were used to study the hydrogenation of environmental pullants halogenated nitrobenzenes. At the same time, utilization the abundant hydroxyl groups on the LDHs, the nanosize gold supported on the LDHs to study the catalytic performance for the oxidation of benzyl alcohol.LDHs are two-dimensional layer materials which are composed of layer cation and interlayer anion. For its low cost, simple synthesis methods and excellent performance, the LDHs have been widely respected. Recently, the LDHs has been well investigated in absorption, flame retardant, photoelectricity, catalysis, medicine by scholars.In this paper, the NiTi-LDHs were prepared by the supersaturated co-precipitation. And the highly dispersed nickel based catalysts were obtained by calcination and reduction of NiTi-LDHs. Moreover, the as prepared catalysts were used to investigate the catalytic performance for the hydrogenation of halogenated nitrobenzenes. The relationship between catalytic performance and the structure of catalysts has been found. At the same time, utilization the abundant hydroxyl groups on the LDHs, the nanosize gold supported on the LDHs to study the catalytic performance for the oxidation of benzyl alcohol.(一) Utilization of the lattice orientation effect and the lowest energy effect of LDHs, the highly dispersed nickel based catalysts were prepared by calcination and reduction of NiTi-LDHs precursors. Through the XRD, TPR, XPS, HRTEM, PL characterizations, the relationship between catalytic performance and structure of catalysts has been investigated. Moreover, the halogenated nitrobenzenes can be effectively catalytic hydrogenation on the as prepared catalysts at the mild reaction condition (0.2 MPa,90℃), which can be attributed by the synergistic effect between highly dispersed nickel species and surface oxygen vacancies. And the excellent catalytic performance of the catalysts can keep unchanged after five times recycle.(二) Utilization of the abundant hydroxyl groups on the LDHs, the nanosize Au nanoparticles were loaded on the surface of NiTi-LDHs through chemical reduction method by sodium borohydride. Through XRD, TEM, HRTEM, XPS characterizations, the Au nanoparticles were highly dispersed on the support and strong interaction between Au nanoparticles and support has also been found. And the surface Ti3+ defects, acting as Lewis basic sites, would activate the molecule of benzyl alcohol. More importantly, the benzyl alcohol can be effectively oxidation to benzaldehyde on the as prepared catalysts at the reaction condition that oxygen act as oxygen source. Moreover, the excellent catalytic performance of the catalysts can keep unchanged after five times recycle.