Optimization of Bimetallic Catalysts for the Hydrogenation of Liquid Organic Hydrogen Carriers using Contaminated Hydrogen Gas
Year: 2026
Type: preprint
Abstract: Liquid organic hydrogen carriers enable safe storage of H2 at high densities, but scalable application is impeded by the tolerance towards impurities common in industrial H2 streams, notably CO that poisons noble metals. In this work, we investigated synergistic effects in Pd-, Ru-, and Ni-based catalysts on Al2O3 for benzyltoluene hydrogenation under pure H2 and COcontaminated feeds representative of realistic operation. By enforcing identical metal loadings, dispersion, and mesoporosity across a series of mono- and bimetallic samples, intrinsic metalmetal effects were isolated. XPS reveals a more electron-rich Ni surface phase in the bimetallics, with Ru exerting a stronger influence on the electronic state of Ni than Pd. Catalytic activity of the samples in the presence of CO follows Pd–Ni >> Ni ≳ Ru–Ni >> Pd ≈ Ru. Ni is essential to retain activity under CO, while monometallic Pd and Ru are strongly poisoned. This is due to Nidriven CO methanation which initiates near 525 K on bimetallics. In case of the best-performing Pd–Ni/Al2O3 catalyst, operando DRIFTS identifies isolated Pd sites embedded in Ni that reversibly segregate/redisperse under CO/H2, forming transient Pd2/Pd3 ensembles. Overall, this work shows that selective incorporation of low noble metal contents into Ni is a viable strategy to produce robust, CO-tolerant, and economically attractive catalyst for benzyltoluene hydrogenation under impure hydrogen.
Source: ChemRxiv
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7214152230