Abstract
Unsupported, bulk phase palladium sulfide has been studied for the selective hydrogenation of acetylene. The sample underwent significant change during thermal pretreatments, the extent of which depends on temperature. Exposure to hydrogen at temperatures of 150°C or above results in the loss of sulfur from the sample, primarily as hydrogen sulfide. As sulfur is lost, the sample is progressively transformed from a sulfur rich phase (PdS) to a sulfur lean phase (Pd4S) via an intermediate phase (Pd16S7). Reduction at 250°C produces a material, which contains Pd4S as the surface phase, whereas reduction at 350°C results in a largely pure Pd4S phase. Thermal treatments which produce a Pd4S surface display excellent catalytic properties. At complete acetylene conversion at 250°C, ethylene selectivites of 82.8% and 90.0% were obtained under non-competitive and competitive conditions, respectively. Beneficial catalytic properties arise from the uniformity of Pd sites due to the crystal structure of Pd4S along with electronic influences on the adsorption/desorption processes arising from sulfur neighbours. No indications of deactivation or significant deposition of carbon were observed over Pd4S sample after 50 h on stream.
Original language | English |
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Pages (from-to) | 204-215 |
Number of pages | 12 |
Journal | Journal of Catalysis |
Volume | 364 |
Early online date | 14 Jun 2018 |
DOIs | |
Publication status | Published - Aug 2018 |
Bibliographical note
We thank Diamond Light Source for beamline access B18 (SP15151-5) and are grateful to the expertise and help provided by Dr Emma Gibson (UK Catalysis Hub, Harwell) and Diego Gianolio (Beamline Scientist on B18) whilst data collecting. XPS data collection was performed at the EPSRC National Facility for XPS (‘HarwellXPS’), operated by Cardiff University and UCL, under contract No. PR16195. We would also like to thank Prof. Philip R. Davies for helpful discussions on XPS data analysis. This work was partly supported by the National Key Research and Development Program of China (2016YFB0301601), National Natural Science Foundation of China.Keywords
- Acetylene
- ethylene
- selective hydrogenation
- palladium sulphide