Low-Temperature NO Reduction over Fe-Ni Alloy Nanoparticles Using Synergistic Effects of Fe and Ni in a Catalytic NO-CO-C3H6-O2 Reaction

Abstract

A platinum-group-metal-free catalyst comprising Fe-Ni alloy nanoparticles on a γ-Al2O3 support was investigated for use in three-way catalytic converters, with particular attention being paid to its NO reduction activity. The catalyst showed activity for the simultaneous removal of NO, CO, and C3H6 in the stoichiometric NO-CO-C3H6-O2 reaction. Low-oxidation-state Fe sites were found to be effective for NO reduction, while their oxidation by this reaction induced catalyst deactivation. Ni atoms adjacent to the low-oxidation-state Fe atoms were found to stabilize them by catalyzing the consumption of the O atoms in the nanoparticles for CO oxidation, which indirectly promoted further NO reduction.

Activity–Composition Relationships of Fe–Ni–Cu Ternary Nanoparticles Supported on Al2O3 as Three-Way Catalysts for NO Reduction

“…This is a recognized trend for a wide range of non-PGM catalysts. 7,10,20,26,37,38 A typical data for Fe 0.33 Ni 0.33 Cu 0.33 is shown in Figure 1, where the NO conversion reaches almost 100% at 600 °C and changes little during 1 h. When the reaction at 600 °C was extended to 8 h, the NO conversion was stabilized at approximately 95% and showed no sign of catalyst deactivation. The catalyst exhibited the activity for CO/C 3 H 6 oxidation superior to those of reference PGM catalysts (Pt/Al 2 O 3 and Rh/Al 2 O 3 ) but was less active for NO reduction (Supporting Information, Figure S2).…”

“…The oxidation resistance of metallic surfaces is also a problem in the use of non-PGM transition metals in TWCs. The surfaces of metal nanoparticles may be oxidized in the presence of unreacted O 2 (<0.5%) and abundant water vapor (5–10%). − Although this oxidation occurs even when using PGMs, − it is accelerated for 3d transition metal elements. , Thermodynamically, oxidation by H 2 O is possible for Fe at T ≤ 1000 °C but impossible for Ni, Co, and Cu . However, for all of these metals, oxidation by O 2 is thermodynamically favorable.…”

Selective Hydrogenation Properties of Ni-Based Bimetallic Catalysts

“…The only difference between the two impregnation methods is whether two metal precursors are loaded on a support simultaneously or successively [26]. Sn-or Fe-containing Ni-based alloy nanoparticles were prepared by the coprecipitation method [28,29]. However, in most cases, the reduction of two metal precursors does not occur at the same time because of the difference in their reduction potentials [30].…”

“…Co-impregnation Sn H 2 [28] Co-impregnation Fe H 2 [29] Successive impregnation Cu H 2 [31] SOMC/M Sn H 2 [32] SOMC/M Zn H 2 [33] CVD Sn H 2 [34] Eng 2022, 3 63 Table 1. Cont.…”

Zero-to-Two Nanoarchitectonics: Fabrication of Two-Dimensional Materials from Zero-Dimensional Fullerene

“…As generally known dimensionality of materials is a crucial factor to determine functions and properties of the materials. In addition to zero-dimensional [ 77 , 78 , 79 ], one-dimensional [ 80 , 81 , 82 ], three-dimensional [ 83 , 84 , 85 ], and further integrated functional materials [ 86 , 87 ], various two-dimensional materials have been paid special attention [ 88 , 89 , 90 ]. Two-dimensional materials have their unique electronic properties [ 91 , 92 ] and play important roles in interfacial sciences [ 93 , 94 ].…”