Hollow zeolite encapsulated Ni–Pt bimetals for sintering and coking resistant dry reforming of methane

Abstract

Highly dispersed Ni–Pt bimetallic nanoparticles encapsulated in hollow silicalite-1 single crystals (1.5Ni–0.5Pt@Hol S-1) were a superior catalyst for sintering and coking resistant dry (CO₂) reforming of CH₄. Large Ni particles loaded on the surface of solid silicalite-1 crystals triggered coke formation, which simultaneously degraded the catalytic activity of small Ni particles. With Ni encapsulated in hollow crystals, the small Ni particles inhibited coke formation. The encapsulating shell prevented coke formed outside from degrading the activity of nickel on the inside, leading to stable high activity even in the presence of carbon. Compared with single metals (Ni or Pt), 1.5Ni–0.5Pt@Hol S-1 enhanced the dispersion of nickel and platinum. In the dry reforming of methane, the 1.5Ni–0.5Pt@Hol S-1 catalyst operated stably under high gaseous hourly space velocity (GHSV = 72 000 ml g⁻¹ h⁻¹) without any inert gas. Only 1.0 wt% carbon deposition was observed by thermogravimetric analysis (TGA) after 6 h of the reaction. Hollow zeolite crystals can reliably support coke resistant catalysts for dry reforming of CH₄ and multi-metallic catalysts with well-dispersed nanoparticles.