Preparation And Structure-Property Correlation Of Supported Ni-based Bimetallic Catalysts Derived From Layered Double Hydroxides Precursor

Supported noble metal catalysts are widely used in petrochemical industry and fine chemical engineering because of their high catalytic performance in various redox reactions. However, noble metal is not earth-abundant and expensive, therefore, study of novel non-noble metal catalysts for the substitution of noble metal is an urgent and important task in recent years. The diversification of catalytic active components has made it possible for the efficient application and substitution of noble metal. In this paper, highly and stably dispersed bimetallic PdNi and NiMn catalysts are synthesized by using layered double hydroxides (LDH) as precursor. This novel preparation method can decrease the loading of noble metals and increase the performance of non-noble metal catalysts.Initially, Ni was introduced into the matrix of LDH to construct NiMgAl-LDH nano material in order to enhance the efficiency of noble metals. Subsequently, PdCl42- precursor was uniformly adsorbed onto the surface of LDH layers. After co-reduction, a novel supported bimetallic, PdNi/MgAl-MMO catalyst was obtained. Pd and Ni are well dispersed because of the lattice orientation effect of LDH, together with the barrier property of MgO and Al2O3 during the reduction process. Choosing the selective hydrogenation of acetylene as the probe reaction, the catalytic performance over the PdNi catalysts prepared by three different methods: LDH precursor, impregnation-reduction, and sol-gel are compared. The influence of preparation method on the structure, morphology, dispersion and the interaction between metal component as well as the structure-property correlation of PdNi bimetallic nanocatalysts are investigated.To achieve the substitution of noble metals, Ni and Mn are simultaneously introduced into the matrix of LDH to give a novel NiMn-LDH catalytic material. The unique two-dimensional structure of LDH can separate the active sites of Ni and Mn to avoid the unwanted aggregation of active sites. Meanwhile, the synergy effect of Ni and Mn facilitates the reaction. Using the oxidation of benzyl alcohol as the probe reaction, the catalytic performance of non-noble NiMn-LDH was determined in the absence of solvent. The influence of Ni/Mn ratio and thermal treatment on the catalytic performance was also investigated. A possible reaction mechanism was then proposed, which may provide a theoretical insight into the design of high-efficient non-noble catalyst for the oxidation of benzyl alcohol.