Effects of Ni addition on the performance of Pd-Ag/Al 2O 3 catalysts in the selective hydrogenation of acetylene were investigated. Ni-added Pd-Ag catalysts showed higher conversions than Ni-free Pd-Ag catalyst under hydrogen-deficient reaction conditions, hydrogen/acetylene <2. 0, due to the spillover of hydrogen from reduced Ni to Pd and the suppression of hydrogen penetration into the Pd bulk phase, which enriched the Pd surface with hydrogen. Ethylene selectivity was also increased by Ni addition because the amounts of surface hydrogen originating from the Pd bulk phase, which was responsible for the full hydrogenation of ethylene to ethane, were decreased due to the presence of Ni at the sub-surface of Pd-Ag particles. Added Ni also modified the geometric nature of the Pd surface by blocking large ensembles of Pd into isolated ones, which eventually improved ethylene selectivity.
Bibliographical noteFunding Information:
This work was supported by BASF Aktiengesellschaft, Germany,
the Brain Korea 21 project, the Korea Research Foundation (KRF) through the National Research Laboratory Program, and the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Knowledge Economy.
- Acetylene Hydrogenation