A Principle for Highly Active Metal Oxide Catalysts via NaCl-Based Solid Solution

Summary

Toward the preparation of industrial metal oxide catalysts, sacrificial organic templates, excessive solvents, complex impregnation, and drying steps are generally required. Here, we report a versatile rule for the simple synthesis of highly porous metal oxides with well-dispersed noble metal species. Porous metal oxides (Co₃O₄, Fe_xO_y, and Cr₂O₃) are obtained with some surface areas (e.g., Cr₂O₃: 224 m²·g⁻¹) beyond the record value. Surprisingly, small noble metal nanoparticles (e.g., Pd: 3.1 and Pt: 3.2 nm) could be incorporated by this solid-state process simultaneously. Corresponding Rh-Co₃O₄, Pd-Fe_xO_y, and Pt-Cr₂O₃ exhibit excellent performance: CH₄ combustion (T₉₀ = ∼360°C and thermal stability: >100 h at 680°C), hydrogenation of nitrobenzene and derivatives (turnover number [TON] = 2.49 × 10⁴, 300 mmol per run), and reversed water gas shift (RWGS) reaction (44% CO₂ conversion with ∼98% CO selectivity and thermal stability: >100 h at 500°C), respectively. Therefore, current principle via a NaCl-based solid solution could provide a solid-state, fast, and efficient route for processing metal oxide catalysts.