Catalysts in Coronas: A Surface Spatial Confinement Strategy for High-Performance Catalysts in Methane Dry Reforming

Abstract

One of the grand challenges in industrial catalytic processes is the inevitable sintering and aggregation of conventional supported catalysts to large particles, leading to the decrease of activity and even deactivation with time. Herein, a surface spatial confinement strategy was employed to design high-performing catalysts for the dry reforming of methane (DRM). Specifically, active nickel (Ni) nanoparticles (NPs) were confined on the surface of a dendritic mesoporous silica (DMS) in the form of the “catalysts in coronas”. The Ni/DMS catalyst exhibited a high catalytic performance close to its equilibrium conversion (76% conversion for CH4 at 700 °C). More importantly, the prepared catalyst remained stable after 145 h time-on-stream at 700 °C without noticeable carbon deposition. This sintering and coking resistance was found to arise from the surface spatial confinement effect in which the three-dimensional dendritic layers in the corona posted a steric barrier against migration and aggregation of Ni NPs and size of Ni NPs was controlled below 5 nm, hence against sintering and coking. Meanwhile, the mesoporous feature of the layered wall facilitated mass transport of reactants to Ni species and further boosted catalysis. This strategy should be broadly applicable to a range of metal- and metal oxide-supported catalysts in high-temperature heterogeneous reactions, such as DRM, water gas shift reaction, and vehicle emission control related reactions.

Mechanistic and multiscale aspects of thermo-catalytic CO2conversion to C1products

“…Precious metals (e.g., Ru, Rh) exhibit superior activity but are limited and expensive, and thus R&D efforts have been shifted towards abundant and active metals like Ni. 92,94,96,222,343,344 To increase the catalyst performance while retaining its stability and resistance to coke formation, several approaches such as carbon gasification 221,[345][346][347] through introducing redox or basic materials, alloying active metals (e.g., Ni) with other metals, 228,[348][349][350][351] and enhancing the thermal stability of active metal particles by strong interaction with the support or confinement inside stable structures [352][353][354][355] have been attempted. In order to reduce coke formation and improve catalyst stability/activity, numerous strategies involving modification in the catalyst surface composition and metalsupport interaction have been attempted.…”

CH<sub>4</sub>-CO<sub>2</sub> reforming: challenges and outlook

“…有序介孔材 料, 如分子筛MCM-41 [149] 、SBA-15 [150] 、KIT-6 [151] 等 都可以被用于Ni基DRM催化剂的载体. 例如, Zhang ; (g) TGA研究催化剂积碳 [148] (网络版彩图) 及花状载 体 [178] 也被用于稳定Ni颗粒, 并在DRM反应中表现出 良好的性能.…”

Electrocatalysis in confined spaces: interplay between well-defined materials and the microenvironment

“…14,15 Recently, confined catalysis in emerging porous materials, such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and polymer layers, has been considered as an effective strategy in modulating the diffusion and transport of reactants to promote catalysis. 10,16,17 The comprehensive discussion of confinement effects in conventional thermal catalysis can be found elsewhere, 15,16,18 and is beyond the scope of this article.…”