The Preparation And Catalytic Performances Of The Confined Ruthenium Metal And Alloy Nanoparticles Catalyst

Noble metal Ru catalysts have good catalytic hydrogenation performance, especially in hydrogenation of aromatic compounds, the application of Ru catalyst is very extensive. In recent years, researchers found that the micro confined structure have important influence to the interaction between metal nanoparticles and its surrounding environment, resulting a great influence of catalytic properties. This instruct people to design a new type of metal nanometer materials and alloy catalyst, give full play to the precious metal catalytic efficiency, meet the needs of efficient utilization of noble metal catalysts.In this thesis, based on layer confined effect of hydrotalcite (LDHs),RuMgAl-LDHs were prepared by precipitation through urea hydrolysis, then the catalyst materials that metal Ru restricted domain in LDHs layers were obtained by reduction treatment under hydrogen atmosphere. In addition, we prepared Al2O3-supported NiRu bimetallic catalysts by reduction of precursors of Ni2+Ru3+Al3+-containing layered double hydroxides (NiRuAl-LDHs) in hydrogen atmosphere. The migration of Ru in the cationic layers and the morphology of NiRu alloy particles were characterized by several characterization techniques. The impact of trace Ru for the Ni-based catalysts on reducibility and catalytic performance were explored. Two catalysts were exerted to catalytic evaluation in the hydrogenation of benzene and pyrolysis gasoline (PyGas). The research contents are as follows:(1) RuMgAl-LDHs were prepared by precipitation through urea hydrolysis, Characterization results show that ruthenium cations via isomorphic substitution of Mg or A1 cations and uniformly distributed in the the cationic layers of NiRuAl-LDHs. The metal Ru restricted domain in LDHs layers were obtained by constroling reduction temperature under hydrogen atmosphere.The HRTEM results show the gather of metal Ru in the cationic layers to the edge of the hydrotalcite, and this phenomenon is more obvious in the sample made at fixed pH. The catalysts exhibits excellent catalytic properties for the hydrogenation of benzene at the reduce temperature of 100?. Higher or lower reduction temperature will lead to the decline of catalytic performance.(2) novel Al2O3-supported NiRu bimetallic catalysts (NiRu/Al2O3) were synthesized by reduction of precursors of Ni2+Ru3+Al3+-containing layered double hydroxides (NiRuAl-LDHs) in hydrogen atmosphere, which were in situ grown on the surface and in the pore canals of microsphericaly-Al2O3 support. Addition of trace Ru enhanced the reducibility of Ni2+ and formed the homogeneous NiRu alloy phase. The appropriate amounts of substitution of Ni for Ru enhance the catalytic performance in the hydrogenation of pyrolysis gasoline (PyGas) by suppressing the coke formation, producing more H spillover from NiRu metal to supports and decreasing the size of Ni metal particles in terms of the hydrogenation reactivity.