Preparation of Alumina Supported Palladium Catalysts by Sol-Gel Method
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- 作者：Shemseddine Fessi and Abdelhamid Ghorbel
- 关键词：precursor chemistry ; Pd/Al2O3 catalyst ; thermal stability
- 刊名：Journal of Sol-Gel Science and Technology
- 出版年：2000
- 出版时间：2000
- 年：2000
- 卷：19
- 期：1/3
- 页码：417-420
- 全文大小：KB
文摘
The chemical reactivity of the aluminium-sec-butoxide (ASB) and the palladium acetylacetonate Pd(acac)2, used as precursors for the preparation of the alumina supported palladium catalysts by sol-gel method was investigated by the spectroscopic study of the precursor mixture during ageing, using FTIR, UV-VIS and 27Al NMR. The obtaind results showed that acetylacetonate ligands were linked to aluminum when the mixture was aged at 40°C. This was proved by the bands observed at 1530 and 1600 cm–1 in the FTIR spectra, the band obtained at 289 nm in the UV-VIS spectra and the 27Al NMR sharp peak at 3 ppm. Furthermore, in order to avoid the Pd(acac)2 reduction to metallic palladium by the SB occurring when the mixture is aged for 3 h, an optimum ageing time should be selected. The precursors modification and the preservation of the palladium oxidation state during ageing could be the required conditions to create a bond between palladium and aluminium during the gelation step. This should be the reason of the thermal stability improvement of the alumina supported palladium catalyst prepared by the sol-gel method.