Nanosized Ni/SiO2 Catalyst Prepared by Homogeneous Precipitation in Wet Silica Gel
Abstract:A Ni/SiO2 catalyst was prepared by homogeneous precipitation of nickel hydroxide in a sol-gel-derived wet silica gel. The preparation process consists of two successive steps: gelation of silica in the presence of nickel nitrate and urea at 50 °C, followed by aging at higher temperature, typically at 80 °C, to decompose the urea. The decomposition of urea increases the pH of the solution in the wet gel, leading to the concurrence of structural rearrangement of silica gel and deposition of nickel species. As a result, the structure of the silica changes from a ramified polymeric network into particle aggregates that entrap the nickel cations in the particles. The resulting Ni/SiO2 contains large mesopores that have high thermal stability up to 1000 °C and highly dispersed Ni metal particles with typical crystallite size of 4 nm even at high Ni content at 20 wt%.
Document Type: Research Article
Affiliations: 1: Department of Materials Technology, Faculty of Engineering, Chiba University, Yayoi, Inage, Chiba 263-8522, Japan 2: Department of Materials Science, School of Engineering, University of Shiga Prefecture, 2500 Hassaka, Hikone, Shiga 522-8533, Japan
Publication date: June 1, 2001
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