Molybdenum Induced Framework Reorganization in ZSM‑5 Nanopillars for Stable Oxidative Methane Coupling

ZSM‑5 nanopillars (Si/Al = 36) were synthesized under hydrothermal conditions and post‑synthetically treated with Na₂MoO₄ to introduce atomically dispersed molybdenum (Mo) species in the framework structure. Structural characterization (XRD, TEM, MAS NMR) reveals a framework reorganization upon Mo incorporation, including a space‑group transition (Pnma → P2₁/n), unit‑cell expansion, and a pronounced decrease in silanol defects. The results show about 75% reduction in silanol site density, consistent with silanol healing and partial dealumination while preserving the nanopillared morphology of the Mo-containing ZSM-5. Pyridine and low‑temperature CO‑probe FTIR indicate a redistribution and slight strengthening of Brønsted and Lewis acid sites. The Mo‑containing ZSM‑5 nanopillars compare to parent ZSM-5 nanopillars showed enhanced performance in the oxidative coupling of methane (OCM), achieving higher CH₄ conversion (15% vs. 11%), markedly improved C₂₊ selectivity (70% vs. 21%), and increased ethylene fraction at 775°C, while maintaining stable activity and selectivity over 45 h on stream. The results demonstrate that combining morphology control with targeted Mo‑induced framework reorganization is an effective strategy to tune acidity and obtain structurally stable zeolite nanopillars for OCM application.