Engineering a layered-differentiation core–shell architecture: NiCoAlOx@Pt/ZSM-5 for synergistically enhanced activity and dual H2O/SO2 resistance in propane oxidation

Abstract

Pt-based catalysts, though efficient for alkane C–H activation, suffer from water and SO₂ poisoning due to competitive adsorption on Pt sites. Herein, a core–shell Ni₁Co_0.5AlO_x@Pt/ZSM-5 catalyst was constructed via supramolecular assembly to improve the anti-poisoning performance, featuring a layered differentiation function. The ZSM-5 shell selectively sequesters H₂O and SO₂, preventing their access to Pt sites, while promoting the formation of active species such as Pt⁰, Co³⁺, and adsorbed oxygen. The optimized catalyst exhibits enhanced activity, water resistance, and sulfur tolerance in propane combustion. In situ DRIFTS confirmed the oxidation pathway as follows: propane is first activated at Pt⁰ sites to form isopropyl species, subsequently oxidized via Co³⁺-mediated sites to intermediates such as propene and acetate salts, and finally fully converted into CO₂ and H₂O with the participation of adsorbed oxygen. DFT calculations elucidated that this catalyst achieves superior propane oxidation activity and dual H₂O/SO₂ resistance via strengthened propane adsorption, reduced reaction energy barriers, and selective trapping of H₂O/SO₂ by the ZSM-5 shell. This atomic-level insight verifies that H₂O and SO₂ are preferentially sequestered by the ZSM-5 shell (rather than occupying Pt active sites), thus ensuring efficient propane/O₂ diffusion to Pt surfaces. This work provides a rational design strategy for robust, poisoning-resistant VOC oxidation catalysts.