Interfacial Processes in Ionic Liquid‐Modified Catalysts: Olefin Replacement and Desorption on Pt(111)

Abstract Hydrogenation of 1,3‐butadiene to 1‐butene with high selectivity is crucial in hydrocarbon processing. One powerful route to tailor the selectivity of the involved surface reactions is the SCILL (solid catalyst with ionic liquid layer) concept. In this context, we recently demonstrated that ionic liquids (ILs) selectively modify the adsorption of 1,3‐butadiene over 1‐butene, that is, the initial step of the hydrogenation of 1,3‐butadiene on Pt(111). Herein, we now address the next reaction step, namely, how ultrathin layers of the IL [C 8 C 1 Im][PF 6 ] influence olefin displacement from Pt(111). Using temperature‐programmed X‐ray photoelectron spectroscopy, we track structural and compositional film changes and olefin desorption with increasing temperature. We find that i) IL deposition onto a saturated 1‐butene layer enhances the displacement and desorption of 1‐butene by a factor of 2.8; ii) 1,3‐butadiene remains unaffected by the IL; and iii) IL decomposition on Pt(111) is shifted to higher temperatures by 80 ± 10 K.