Catalytic performance of novel Ni catalysts supported on SiC monolithic foam in carbon dioxide reforming of methane to synthesis gas

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Abstract

Carbon dioxide reforming of methane to synthesis gas has been investigated with Ni catalysts supported on SiC monolithic foam. The structure and properties of the catalysts were characterized by BET, SEM and XRD techniques. The novel catalysts exhibited not only the highest activity but also remarkable stability. Of which, 7 wt%Ni/SiC showed the highest activity at 750 °C, During the 100 h performance testing experiment on stream, the conversion of CH4 and CO2 remained almost constant, at about 94.0% and 95.0%, respectively.

Introduction

The process of carbon dioxide reforming of methane to synthesis gas has received considerable attention in recent years, because this reaction has several advantages over steam reforming or partial oxidation of methane. First, the ratio of H2 and CO from CO2 reforming of methane is one [1]. Secondly, it has important environmental implications as greenhouse gases, methane and CO2, were converted into a valuable feedstock. Ni-based catalysts are widely used for CO2 reforming of methane because of the high activity and low cost [2], [3], [4], [5], [6], [7]. However, a rapid deactivation due to carbon deposition and/or sintering of the metal particles has been reported on Ni/oxidic support catalysts [2]. Some researchers have greatly enhanced the catalytic activity and stability of Ni catalysts by using different supports [3], [4]. The effects of supports [5], [6], [7] on the coke formation and stability of Ni-based catalysts were also extensively investigated.

Recent advances have been made in research on monolithic catalyst supports [8], such as SiC. SiC crystallized exhibits a high thermal conductivity and mechanical strength, a low specific weight and chemical inertness, their properties required to be a good heterogeneous catalyst support [9], especially for high endothermic and/or exothermic reactions where the precise control of the temperature inside the catalyst bed is extremely important. So far the SiC with medium surface area can be also synthesized in a foam monolith structure [10], which offers several advantages when used in catalytic reactions. The open structure of the monolith also provides a low-pressure drop and high diffusivity of both the reactants and products. Recently SiC-based monolithic catalysts have been widely employed in several catalytic reactions [11], [12], [13], [14].

Considering the upstanding performance of Ni and SiC, the novel Ni catalysts supported on SiC monolithic foam was studied in CO2 reforming of methane to synthesis gas in this paper.

Section snippets

Catalyst preparation

Silicon carbide in a monolithic foam form (diameter 9 mm, length 20 mm), which is provided by Institute of Metal Research Chinese Academy of Sciences, was used as a support for the catalyst. The catalysts were prepared by the incipient wetness impregnation method from an aqueous solution of Ni(NO3)2 · 6H2O. Then the catalyst was dried at 120 °C for 12 h, and calcined in air at 700 °C for 3 h.

Activity measurements

The catalyst was reduced with H2 (20 ml/min) at increasing temperature from ambient to 700 °C at a rate of 10 

Results and discussion

A series of Ni/SiC catalysts with various amounts of Ni loading (1, 3, 5, 7, 9 and 11 wt%) were tested for their activity at 750 °C (Fig. 1). It was found that optimum Ni loading was approximately 7 wt%, since it showed much higher catalyst activity than the other catalysts. The CO2 conversion has been found to be higher than CH4 conversion for all catalysts since the reverse water gas shift reaction occurs simultaneously with the CO2 reforming of CH4 [1].

The catalytic activities of the 7 wt%Ni/SiC

Conclusions

In this work, a novel Ni/SiC foam monolithic catalyst was investigated for carbon dioxide reforming of methane to synthesis gas. The effect of Ni loading, the temperature and stability over Ni/SiC monolithic foam catalysts have been employed. The results indicate that 7 wt% is the most appropriate amount of Ni loading on the catalysts. This monolithic foam catalyst shows high catalytic activity and stability during the 100 h performance testing experiment. Much more studies about this catalyst

Acknowledgement

The authors are grateful to Prof. Jinsong Zhang (Institute of Metal Research Chinese Academy of Sciences) for providing SiC monolithic foam support.

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