Co₁/Ru Single-Atom Alloy Catalyst for Sustainable Polypropylene Hydrogenolysis to Long-Chain Liquid Products.

Abstract

Achieving selective polyolefin waste hydrogenolysis into fuels and chemicals requires architectures that disrupt Ru─Ru ensembles without compromising the intrinsic activity of the state-of-the-art Ru catalyst. While metal modifiers can beneficially tune selectivity, they have been shown for high promoter-metal contents, with associated penalties in structural definition and potential practicality. Here, we engineer cobalt speciation on Ru through impregnation to disclose how promotion spans the entire compositional space realizing a titania-supported Co₁/Ru single-atom alloy catalyst (Co₁₀Ru₉₀, 3 mol% total metal content) that resolves these trade-offs. Ex situ and operando analyses reveal that these bimetallic ensembles containing Ru─Co─Ru sites display a distinctively high barrier for over-hydrogenolysis at late reaction stages while preserving the intrinsic activity of Ru. As a result, virgin polypropylene and post-consumer waste were almost fully converted with a consistently high C₁₁₊ yield of up to 60% (78% total liquids), compared to <5% over the monometallic Ru counterpart. Process-level simulations predict economically viable and environmentally sustainable operation enabled by the high single-pass yields of long-chain liquid products. These results reveal a wide compositional landscape for Ru promotion and recommend its second-metal-content single-atom alloy limit as the most promising strategy for further catalyst design efforts.