Acetylene Hydrogenation - Multidimensional Temporal Evolution on LCC

Dr. Zehua Li

Acetylene Hydrogenation: Hüls process 
The Hüls process developed at World World II times and later continued in Germany gives an impression about the complexity of the current technology to separate acetylene from ethylene if the selective hydrogenation is not possible. So, there is a real and very direct necessity for a performance version catalyst towards selective acetylene hydrogenation.

Laterally Condensed Catalyst (LCC)
Existing Pd alloy catalysts for gas purification underperform in concentrated feeds, necessitating novel concepts. Atomistic simulations unveil superior selectivity of Pd:C solid solutions that optimize chemisorption energies and preclude sub-surface hydrogen, verified here with model thin films. Multiple design criteria deduced from conventional catalysts facilitate synthesizing a self-repairing Pd:C system of a laterally condensed catalyst (LCC). A Pd layer prepared on a designated SiO₂ buffer layer enables control of reactive interface, sub-surface volume and extended functional interface towards the buffer. Function and metric are supervised by microscopy and operando spectroscopy. This catalyst design shows, ethylene productivity >1 kmol C₂H₄/g_Pd/hour is reproducibly achieved and benchmarked against known catalysts.

Multidimensional Temporal Evolution on LCC
The ethylene selectivity of acetylene hydrogenation is governed by multidimensional processes in space and time, necessitating a deep understanding of working catalyst formation and development with a specifically designed catalyst as LCC structure, we could comprehensively investigate its multidimensional processes (Pd LCC and Pd-Au LCC) from local electronic, mesoscopic, and macroscopic scales to evaluate dynamic interfaces by microscopy and operando spectroscopy. To suppress the deactivation of Pd-based LCC caused by sintering, site blocking, and carbon-induced instability, a series of  buffer layers (SiO₂, ZnO, C, AlO_x, SiN_x) were added below Pd layer to form functional interface as it could tune the electronic properties, geometric properties and structure-activity relationship.