| Silica supported Pd catalysts loaded with five different ionic liquids are tested for the selective acetylene hydrogenation. For each catalyst, the highest acetylene conversion is always achieved when H2/C 2H2 is 10/1 and the highest ethylene selectivity is usually achieved with 2/1 H2/C2H2 ratio. The maximum ethylene yield varies with ionic liquids and H2/C 2H2 ratios used. All the catalysts except Pd/EmimBF 4/SiO2 exhibit good catalytic stability under constant temperature and H2/C2H2 ratio conditions.;The thermal stability of Pd on ionic liquid supported catalysts was tested with TGA. The decomposition and reduction of Pd precursor in 5%H2/N 2 starts at 30°C and is completed at 120°C to pure palladium. However, there is no significant Pd peak in the TGA study over the catalysts when the ionic liquid with [Bmim] as the cation is used. However, there are several small decomposition peaks indicating up to 5% of impurities in purchased ionic liquid. |
