(104b) Carbon-Supported Platinum and Palladium Nano-Particle Catalysts for Vapor-Phase Hydrogenation of Furan, Crotonaldehyde and Selective Hydrogenation of Acetylene

The vapor-phase hydrogenation of furan, crotonaldehyde and selective hydrogenation of acetylene were carried out over carbon-supported Pd and Pt nano-particle catalysts. Carbon-supported Pt and Pd nano-particles exhibited unique catalytic properties due to size-dependent electronic and geometric properties of the noble metal nano-particles for hydrogenation reactions. Platinum and palladium nano-particles smaller than 10 nm were synthesized by different methods, such as reduction by alcohols and microemulsion methods, followed by the nano-particle deposition on Vulcan XC-72 carbon support by adsorption and wet impregnation, respectively. The catalysts were characterized by the N₂ porosimetry (surface area), X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM studies demonstrated well-defined distributions of the platinum and palladium particles and the particle size calculation showed that the metal particles were in the range of 2 to 7 nm. The characterization results revealed that the shape and size of the nano-particles synthesized depended on the synthesis method used. The effect of space time, temperature and the hydrogen to feed mole ratios were studied in a tubular fixed-bed microreactor at atmospheric pressure over a temperature range of 100 to 350⁰C. For hydrogenation of furan over Pt catalysts, tetrahydrofuran (THF) was the main product at low temperature (<200⁰

C), but at higher temperatures (>200⁰C) the main product was butane for a H2/furan mole ratio of 10. At higher H₂/furan mole ratios (≈15), trace amounts of 1-butanol were also detected. Over the Pt catalysts, the selectivity to butane was 100 mol. % at 350⁰C. The Pd catalysts were more active for furan hydrogenation and THF was the only one product observed. For a H₂/furan mole ratio of 5 and a complete conversion of furan, THF was obtained with a 99.4% yield at much lower temperatures (225⁰C). The products distribution indicated that, the hydrogenolysis of furan took place over Pt catalysts more readily than the hydrogenation of furan ring, whereas Pd selectively hydrogenates the furan ring to tetrahydrofuran without hydrogenolysis. Hydrogenation of crotonaldehyde and acetylene over Pt and Pt catalysts was also conducted and the results of this study will be also presented and discussed in this talk.