Precipitation of Ni and NiO nanoparticle catalysts on zeolite and mesoporous silica by rotary chemical vapor deposition

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Ni and NiO catalytic nanoparticles were precipitated onto mesoporous silica and zeolite by rotary chemical vapor deposition (RCVD) using NiCp₂ as a precursor. The diameter of the nanoparticles precipitated onto zeolite increased from 5 to 50 nm when the oxygen flow rate (R_O2) increased from 0 to 0.33 × 10⁻⁶ m³ s⁻¹, whereas that of the nanoparticles precipitated onto mesoporous silica was 5 nm, independent of R_O2. The nanoparticles could be precipitated inside of the mesoporous silica pores but outside the zeolite pores. The highest H₂ production rate in the methanol–steam reforming reaction was 1150 × 10⁻³ mol kg⁻¹ s⁻¹ at 633 K, which was achieved with a Ni/NiO catalyst on mesoporous silica, and this H₂ production rate is almost six times greater than that of the best Ni catalysts reported in literature.