| 초록 |
The performance of Ti-modified Pd catalysts, either supported on TiO2 or promoted with TiO2, in the selective hydrogenation of acetylene was investigated by a steady-state reaction test and the catalyst surface was characterized by CO chemisorption, IR, XPS, and ethylene TPD.The TiO2-promoted Pd catalysts, particularly when reduced at 500oC, showed a higher selectivity for ethylene production than either Pd/TiO2 or Pd/SiO2 catalysts.CO-IR studies showed suppressed adsorption of CO, particularly the multiply coordinated species, on the TiO2-promoted catalysts suggesting that the Pd surface was diluted with the Ti species.Analyses of the catalysts by XPS and ethylene-TPD showed that the Pd surface was also modified electronically by the Ti species.Accordingly, the improved performance of the TiO2-promoted catalysts in acetylene hydrogenation results from both geometric and electronic modifications of the Pd surface by the Ti species. |
