(36h) Methods of Coating Ceramic Supports with Carbon in the Case of Supported Ni-Based Catalysts Formulations

Nickel (Ni) based catalysts have been widely investigated and industrially used in methane reforming for hydrogen production. In accordance with to recent publications and patents nickel spinel-based catalyst are proven highly efficient for steam and dry reforming.

In the present study, ceramic-supported metallic Ni and Ni-spinel catalyst are modified by adding a carbon layer on the ceramic support prior to Ni impregnation. The use of silica and alumina supports surface modification followed by nickel impregnation has never been investigated so far. The rationale for this modification relies on the capacity of carbon layer to be eventually heated by microwaves; the latter would allow for lower overall temperature environments in the case of endothermic reactions such as methane reforming.

The study focuses on understanding the effect of the carbon-coating type on the Ni deposition/distribution, and on the achieved heating rates. The carbon coating was done by surface modification of silica and alumina with hexane and oleic acid at high temperature, followed by calcination under hydrogen. The carbon layer thickness and the type of carbon on the surface was proven to depend on (1) oleic acid/hexane mass ratio and (2) calcination temperature.

The following synthesis methods have been tested to deposit metallic Ni or Al-Ni-spinel (NiAl₂O₄) on the surface of the carbon-coated alumina and silica: (a) polyol-sonication process; (b) hydrothermal synthesis; (c) plasma deposition and (d) surface modification. The latter has proven to be the method that provided the best deposition results.

The so-derived catalytic formulations were investigated using different characterization methods (SEM, EDX, BET, XPS, DRX). It has been shown that the type of carbon coating on the surface depends on the preparation method and that the latter influenced the catalyst deposition. A comparison between the catalyst deposition on carbon coated silica and carbon coated alumina shows that coated alumina provides a higher Ni deposition on the catalyst surface.