Comparison of dinitrodiamminepalladium with palladium nitrate as a precursor for Pd/SiO 2 with respect to catalytic beha
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Catalysis Letters Vol. 99, Nos. 3–4, February 2005 (Ó 2005) DOI: 10.1007/s10562-005-2133-5
Comparison of dinitrodiamminepalladium with palladium nitrate as a precursor for Pd/SiO2 with respect to catalytic behavior for ethane hydroformylation and carbon monoxide hydrogenation Junitsu Sakauchi, Hirotoshi Sakagami, Nobuo Takahashi*, Takeshi Matsuda and Yuzo Imizu Department of Materials Science, Kitami Institute of Technology, 165 Koen-cho, Kitami, Hokkaido 090-8507, Japan
Received j; accepted j
The catalytic behavior of the two kinds of Pd/SiO2 catalysts prepared from dinitrodiamminepalladium and palladium nitrate are compared for ethene hydroformylation and carbon monoxide hydrogenation. The catalyst prepared from dinitrodiamminepalladium, on which very fine particles of Pd were observed, showed high activity for ethene hydroformylation. On the other hand, the catalyst prepared from palladium nitrate, on which relatively large particles of Pd were observed, showed high activity for CO hydrogenation. KEY WORDS: Pd/SiO2 catalysts; ethene hydroformylation; carbon monoxide hydrogenation.
1. Introduction Effects of metal particle size on catalytic behavior of supported metal catalysts have been recognized to be one of the important subjects in the field of supported metal catalysts for a long time [1–6]. In general, the number of active sites is determined with the hydrogen chemisorption data. It has been commonly pointed out, however, that the distribution pattern of metal particle size should be clarified in addition to the adsorption profiles. We have previously reported that Pd/SiO2 catalysts prepared from dinitrodiamminepalladium showed higher Pd dispersion than those from palladium nitrate [7]. The catalytic activity of the former for ethene (C2 H4 ) hydroformylation was high compared with that of the latter. However, we did not clarify the details of the particle size distribution on them. In the present work, X-ray diffraction measurements and transmission electron microscope measurements were performed in order to clarify the particle size distribution. In addition, catalytic behavior of the two-types of Pd/SiO2 for carbon monoxide (CO) hydrogenation has been compared with that for C2 H4 hydroformylation.
2. Experimental Catalysts, which contained 2.0 wt% of Pd as metal, were prepared by a conventional impregnation method from palladium nitrate (Pd(NO3 )2 , dissolved in H2 O) or dinitrodiamminepalladium (Pd(NO2 )2 (NH3 )2 , dissolved in aqueous ammonia). Four kinds of silica gel supports used were obtained from Fuji Silysia Chemical Ltd. Values for specific surface area and average pore
diameter on them were as follows; No.1 (300 m2 /g, 10 nm), No. 2 (190 m2 /g, 15 nm), No. 3 (100 m2 /g, 30 nm) and No. 4 (90 m2 /g, 50 nm). All catalysts were reduced with hydrogen (100 cc(STP)/min) at 773 K for 3 h. In the following part, the catalysts prepared from Pd(NO3 )2 on SiO2 of Nos. 1, 2, 3 and 4 are represented by A-1, A-2, A-3 and A-4, respectively. In the same way, the catalyst B-1 was prepared from Pd(NO2 )2 (NH3 )
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