Synthesis Chemistry and Properties of Ni Catalysts Fabricated on SiC@Al2O3 Core-Shell Microstructure for Methane Steam Reforming

Hyunju Lee,Doohwan Lee

doi:10.3390/catal10040391

Abstract

Heat and mass transport properties of heterogeneous catalysts have significant effects on their overall performance in many industrial chemical reaction processes. In this work, a new catalyst micro-architecture consisting of a highly thermally conductive SiC core with a high-surface-area metal-oxide shell is prepared through a charge-interaction-induced heterogeneous hydrothermal construction of SiC@NiAl-LDH core-shell microstructures. Calcination and reduction of the SiC@NiAl-LDH core-shell results in the formation of Ni nanoparticles (NPs) dispersed on SiC@Al2O3, referred to as Ni/SiC@Al2O3 core-shell catalyst. The Ni/SiC@Al2O3 exhibit petal-like shell morphology consisting of a number of Al2O3 platelets with their planes oriented perpendicular to the surface, which is beneficial for improved mass transfer. For an extended period of methane-stream-reforming reaction, the Ni/SiC@Al2O3 core-shell structure remained stable without any significant degradation at the core/shell interface. However, the catalyst suffered from coking and sintering likely associated with the relatively large Ni particle sizes and the low Al2O3 content. The synthesis procedure and chemistry for construction of supported Ni catalyst on the core-shell microstructure of the highly thermal conductive SiC core, and the morphology-controlled metal-oxide shell, could provide new opportunities for various catalytic reaction processes that require high heat flux and enhanced mass transport.

Highlights

Heterogeneous catalytic reactions often occur, coupled with the intrinsic reaction kinetics on catalyst surfaces and the mass and heat transport via the inter- and intra- structures of the solid catalysts [1]
The synthesis chemistry of the catalysts depends on the heterogeneous hydrothermal construction of a bimetal Ni and Al layered double hydroxide (NiAl-layered double hydroxides (LDHs)) shell selectively on the surface of silicon carbide (SiC) particles
Supported Ni catalysts with significantly enhanced heat and mass transport properties can be prepared through hydrothermal reaction of metal salt precursors with highly thermal-conductive

Summary

Introduction

Heterogeneous catalytic reactions often occur, coupled with the intrinsic reaction kinetics on catalyst surfaces and the mass and heat transport via the inter- and intra- structures of the solid catalysts [1]. For industrial reaction processes that require intensive heat and mass flux with rapid load-follow-up performance, metal foams are utilized for catalyst preparation in order to improve thermal conductivity [6] In such a scheme, non-active high-surface-area metal oxides, such as alumina, are initially deposited on the metal foam surface, followed by immobilization of the desired active metals or metal oxides on the surface. Non-active high-surface-area metal oxides, such as alumina, are initially deposited on the metal foam surface, followed by immobilization of the desired active metals or metal oxides on the surface This approach is difficult to apply for the preparation of small catalyst particles or pellets that are commonly utilized in industrial heterogeneous catalytic processes

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