CONTROL OF ACTIVE SITE FOR SUPPORTED METAL CATALYST BY SUPERCRITICAL DRYING METHOD

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In order to obtain a supported metal catalyst with a well-dispersed metal component, supercritical drying was adopted instead of using a conventional thermal drying in preparation by impregnation method.First, Ni/SiO_2 catalysts were prepared by the solution-sol-gel method and the subsequent removal of the solvent via low-temperature supercritical drying (LTSCD) using CO_2 as a supercritical fluid. The results indicated that Ni over SiO_2 support prepared by LTSCD has well-dispersed Ni particles and the particle size distribution of Ni is uniformly.Furthermore, Ni/SiO_2 catalysts prepared by LTSCD showed the superior catalytic performance for benzene hydrogenation to cyclohexane as compared with the Ni/SiO_2 catalyst prepared by a conventional thermal drying.Second, it was found that the Pt dispersion of Pt/Al_2O_3 catalysts prepared by LTSCD using CO_2 improves 60% in comparison with the conventional impregnation method. This result is a large result of showing the possibility of drastically reducing the Pt amount.Finally, the high-temperature supercritical drying (HTSCD) equipment was manufactured. Ni/SiO_2 catalysts prepared by HTSCD had well-dispersed Ni particles and the superior catalytic performance, in comparison with Ni/SiO_2 catalysts prepared by LTSCD.