Single Atom Sites in Ga-Ni Supported Catalytically Active Liquid Metal Solutions (SCALMS) for Selective Ethylene Oligomerization.

Abstract

Supported catalytically active liquid metal solutions (SCALMS) are materials composed of a liquid metal alloy deposited on a porous support. Due to the dynamic properties of the liquid metal alloy, these systems are suggested to form single atom sites, resulting in unique catalytic properties. Ga-Ni SCALMS were successfully applied to ethylene oligomerization, yielding catalysts that were stable up to 120 h time on stream. A workflow based on synchrotron-based X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) as well as density function theory (DFT) and ab initio molecular dynamics (AIMD) simulations was applied to investigate the nature of the active species in these materials. The combination of XPS with DFT calculations indeed indicates the presence of isolated single Ni atoms on the liquid metal surface, while TEM measurements show high dynamics in the liquid metal with intermetallic phase dissolution and transformation. Furthermore, DFT/AIMD methods allowed for rationalizing the role of hydrogen pretreatment in enriching the Ni atom at the surface of the liquid metal alloy.