NANO-NICKEL PARTICLES: SYNTHESIS, CHARACTERIZATION AND CATALYTIC HYDROGENATION

• Main Authors: Kuang-Yu Jao, 饒光宇
• Other Authors: An-Nan Ko
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/76200721127317623980

碩士 === 東海大學 === 化學系 === 93 === The hydrogenation of cinnamaldehyde(CALD)、citronellal(CTN) and t,t,c-1,5,9-cyclododecatriene(CDT) has been studied using a fixed- bed, integral-flow reactor and a batch reactor. Pd/Si-MCM-48, Ni/Si-MCM-41, Ni( nano ), Ni( 325 mesh ) and Ni( 100 mesh ) were utilized as catalysts. These materials were characterized with XRD, particle size analysis, TEM, N2 adsorption, FT-IR, TPD of NH3 and TPR of H2. Ni/MCM-41 exhibits hexagonal structure with Ni aggregates of nanometer size and low Lewis acidity. The mean size of nano-Ni particles and that of Ni ( 325 mesh ) are 20 nm and 30 μm, respectively. However, Ni containing Si-MCM-41 has higher reduction temperature than nano-nickel particle. In the reaction of CALD over (X%)Pd/Si-MCM-48 catalysts, the catalytic activity enhances with the Pd content and the main product is hydrocinnamaldehyde. The Ni ( nano ) catalyst shows better catalytic activities in the hydrogenation of both CALD and CTN. Different reaction paths are observed for the CTN reaction using Ni/Si-MCM-41 and Ni particles that are attributed to the apparent difference of catalyst acidity. With Ni/Si-MCM-41, the major product is isopulegol (IPG) that is formed via isomerization of CTN on the catalyst Lewis acid sites. With Ni particles, successive hydrogenation yields citronellol (CTNOL). These catalysts were applied to the hydrogenation of CDT at 10 bar of H2 in a batch reactor using methylcyclohexane as the solvent. The system is free of diffusional limitation at 800 rpm, and good catalytic activity is attained at the reaction temperature of 50℃. The Ni( nano ) catalyst exhibits much better results than other catalysts.