Recently, iChEM researcher, Prof. Junling Lu from University of Science and Technology of China (USTC) collaborated with Prof. Shi-Qiang Wei from National Synchrotron Radiation Laboratory which made significant achievement in selective hydrogenation of 1,3-butadiene through single-atom Pd. The result was published in JACS (J. Am. Chem. Soc., 2015, 137, 10484-10487)

Atomically dispersed noble metal catalyst has attracted rapidly increasing attention due to its unique catalytic properties and maximized atom efficiency for low-cost. However, synthesis of such single-atom catalyst (SAC) is not trivial because single metal atoms are often very mobile on surface and tend to aggregate to form clusters or nanoparticles due to high surface free energy, especially under reaction conditions. Synthesis of SACs from gas phase could be an even greater challenge since it is usually carried out at elevated temperatures, which would significantly accelerate metal atom aggregations during synthesis.

Prof. Junling Lu group have successfully demonstrated that atomically dispersed Pd on graphene can be achieved using ALD by a careful control over the oxygen functional groups on the graphene surface. HAADF-STEM and XAFS both confirmed the dominant presence of isolated Pd atoms. When the single-atom Pd1/graphene catalyst was evaluated in selective hydrogenation of 1,3-butadiene, it revealed superior catalytic performance (1) showing about 100% butenes selectivity, especially the highest ever 1-butene selectivity of ∼70% at a conversion of 95% at a mild reaction condition of about 50 °C. (2) Pd1/graphene showed excellent durability against deactivation via either metal atom aggregation or coking during a total 100 h of reaction time on stream. (3) Pd1/graphene illustrated remarkably high catalytic performance by suppressing the propene conversion to a low ratio, and preserving high selectivity to butenes and especially to 1-butene at high conversion. Finally, the work suggests that SACs might open up new opportunities in selective hydrogenation reactions for improved selectivity and durability.

The co-authors of this work are Ph.d student Huan Yan (synthesize/characterization), Ph.d student Hao Cheng (XAFS) and a master student Hong Yi (test). The work was financially supported by NSFC (21473169, 11135008, and 51402283), and the Fundamental Research Funds for the Central Universities (WK2060030014), and the startup funds from University of Science and Technology of China.

Link:http://pubs.acs.org/doi/abs/10.1021/jacs.5b06485